SHAKE IT! Does Vibration Eat Horsepower?

Cycle World

Engine vibration...does it eat horsepower? How do we control it? Where does it come from? What's secondary vibration vs. primary? Technical Editor Kevin Cameron and Editor-in-Chief Mark Hoyer discuss the many types of vibration in engines and the various schemes used to control it or let those vibes we love come through.   Looking to buy? Get prequalified https://octane.co/flex/1?a=171  Become a Channel Partner: https://octanemedia.co/home/become-an-advertiser/  Listen on Spotify: https://open.spotify.com/show/6CLI74xvMBFLDOC1tQaCOQ Read more from Cycle World: https://www.cycleworld.com/ Buy Cycle World Merch: https://teespring.com/stores/cycleworld

Transcript

00:00:00Shake it. Let's start vibrating, folks. Welcome to the Second World Podcast.

00:00:05Technical Editor Kevin Cameron is with me, as ever. Mark Hoyer, Editor-in-Chief.

00:00:10We're talking about vibration today. Does vibration consume power in a motorcycle?

00:00:14Where does it come from? What are the biggest sources?

00:00:18What are the negatives? And I guess, you know, does it consume power?

00:00:23Hard to say, I suppose. And, you know, we're going to note the difference between reciprocating pieces of the engine and rotating, and I'll let Kevin get into there.

00:00:35But he's got his agenda going, and I'm guessing we might start at 1847 or the invention of dirt or molecules coming together.

00:00:46Where will we begin, Kevin?

00:00:47Well, I think I'm going to begin by saying I suspect that this title comes from a long-time feeling among older motorcyclists that vibration is just fine with them, and what's the problem with you other wusses?

00:01:08And that's fine.

00:01:09There are people who go like campers who dangle from a cliff face on a nylon cord smaller than your little finger and sleep there in a half-sleeping bag because that's what they like to do.

00:01:24Now, sportsers, mostly people didn't go far on them because they had a homogenizing effect on the contents of the human body.

00:01:37Well, they had a four-speed to go with it.

00:01:39Yeah.

00:01:40Until, gosh, when, God, five-speed, when was that?

00:01:44You know, it was way out of the dark ages.

00:01:48So what I have to say about vibration myself is I can understand that modern people are not accustomed to it, and they don't want it, and they don't have to have it.

00:01:59This is not to say that they ought to be able to put up with it or that they ought to like it.

00:02:04Those are individual choices.

00:02:06The fact is that vibration will loosen fasteners, break frame tubes, and put your hands and feet and seat to sleep.

00:02:20So to my way of thinking, it's worth avoiding all that.

00:02:25And then when aluminum frames came along and they tried to put the old vibrators into them, they cracked.

00:02:32Kenny talked about testing the first square tube aluminum frames for the 0W48-500 two-stroke.

00:02:43They'd get a new frame, they'd go out and run it, and it would come, they'd be cracked by the end of the day.

00:02:48And it went on like that until Yamaha developed alloys and more graceful joints that didn't impose stress concentrations.

00:03:02So today, aluminum frames are a routine fact, and engines have been smoothed out to make them durable.

00:03:12Well, I guess, you know, it occurs to me that back in the early days, we didn't really need counterbalancers,

00:03:20and we didn't really concern ourselves too much with vibration because we were spinning things at 1,800 RPM or 2,000 or 2,500.

00:03:30Yep.

00:03:30So you could run a 45 degree with no balancer because you weren't trying to get, you know, 166 horsepower out of it and rev it to 12,000.

00:03:39So it, well, the basic fact is that motorcycle vibration comes from the engine principally and that it arises because things moving back and forth in a straight line cannot, like rotating things, be balanced by a counterweight.

00:04:04Counterweights go in a circle.

00:04:05So if you have an object that has an eccentric on one end and an equal and opposite eccentric on the other end, it is in static balance.

00:04:17Any place you put it on its fine bearings, it will stay there.

00:04:22But if you rotate it, it will wobble like crazy.

00:04:26And this is what happened with three-cylinder motors.

00:04:30Their center of mass doesn't move.

00:04:32That's beautiful.

00:04:34But they rock and roll when they run and they make your hands go to sleep.

00:04:41Yeah, the 120 does.

00:04:42But then you take a Laverda and it has a 180 triple.

00:04:45So you have one piston up and two pistons down.

00:04:48Yep.

00:04:48And when I had one of those, you know, I did smooth it out quite a bit just by making it run quite evenly.

00:04:53I was very fanatical about the carburetor so that at least each combustion event was the same.

00:05:01But you made a fine joke.

00:05:03It just needs a really large center piston and it'll be as balanced as a four-cylinder.

00:05:08Now, here's an example.

00:05:10We've got an engine that has a two-inch stroke and we're riding around town at 2,500 RPM.

00:05:20What is the peak acceleration of the piston or pistons in such an engine, which incidentally occurs at top dead center?

00:05:30The acceleration at bottom center is a little bit different.

00:05:33And it turns out that using the usual arithmetic, it's 233 times the acceleration of gravity, 233 G.

00:05:47And that's not bad.

00:05:49The engine is much heavier than the piston.

00:05:52This is an important point because as British twins were made bigger, bigger, bigger, they shook more.

00:06:00And that's because the engine didn't get much heavier, but the pistons did.

00:06:06So that's something to consider.

00:06:09But if we tire of the charms of downtown and head for the countryside, taking our engine through the gears to 10,000 RPM,

00:06:20which is four times the 2,500 that I mentioned, the shaking force is going to increase by the square of four, which is 16.

00:06:37And when you multiply 233 by 16, you get roughly 3,700 Gs.

00:06:49Now, that's routine for modern motorcycles.

00:06:55That's not an exceptional number.

00:06:57But now let's say, oh, look here.

00:07:02Current MotoGP engines have a stroke of 48 and a half millimeters.

00:07:06Why, that's almost two inches.

00:07:09It's 1.91 something.

00:07:12What about when they let their, when they soar up to their high node of 18,000 RPM?

00:07:19What will their peak piston acceleration be?

00:07:2511,000 Gs.

00:07:28Approximately that of a shell being fired from a five-inch gun, such as a tank or in the old days, a cruiser.

00:07:41That's a serious amount of force.

00:07:43Now, how is that shaking force of pulling the piston to a stop at top dead center and stopping it again at bottom dead center?

00:07:56At 18,000 RPM, in the middle of its stroke, the piston is going 100 miles an hour or more.

00:08:05In one inch, it will stop completely.

00:08:07Now, imagine the helmet that will fix it so that you could stop in a similar fashion and still go to the party afterwards.

00:08:22These are serious accelerations.

00:08:26How is this shaking force transmitted to the engine?

00:08:30The answer is it is transmitted through bearings.

00:08:32First, the wrist pin in the rod, then the connecting rod bearing on the crank pin, and from there to the main bearings, one on either side of this crank pin.

00:08:49And this is where horsepower is consumed, because the more load you put on a bearing, the greater its friction torque.

00:08:58And therefore, modern engines have pistons that have dwindled away to as close to nothing as we can imagine.

00:09:15Pistons used to look like a bucket or a pail.

00:09:19They were taller.

00:09:20Yes, they were taller than they were in diameter.

00:09:25Now that we're talking about it, sorry, Spotify-ers, but here you go.

00:09:32Ancient style, coffee can.

00:09:34This is a Jaguar piston, but the Velocet, take a drink, looks exactly like this.

00:09:40And then this is out of a Kawasaki 650 twin that we took flat tracking, and we didn't use the stock rods and piston.

00:09:49But there you go.

00:09:50Where's the skirt gone?

00:09:52Yep.

00:09:52Today's piston is an aluminum disc, quite thin, with just enough height to put two or three piston rings into it.

00:10:05With two little modesty tabs hanging down, little skirts, to keep the disc from cocking sideways in the bore.

00:10:13And underneath, turning the piston upside down, you will see two pairs of webs at right angles to each other.

00:10:23And two of those are slightly swollen in one place to form wrist pin bosses.

00:10:31Everything else is gone.

00:10:33This has been done, not only to reduce friction, narrower and narrower rings, and lighter pistons, lower loading on bearings.

00:10:47But it has been done to make it possible to save some of the bearing losses in the three bearings that I just mentioned.

00:11:00Wrist pin, rod big end, and main bearings.

00:11:02The friction in an engine is principally created by the piston rings and the piston.

00:11:12This is because a large area of seal, the ring all the way around the cylinder, is sliding on an extremely thin oil film.

00:11:23So the rate of shear in the lubricant between the ring and the cylinder wall is astronomical.

00:11:30Those little molecules are jumping.

00:11:33And that translates into substantial friction.

00:11:39In the old days, piston crowns had to be thick so they could transmit the heat of combustion occurring above them out to the cooler cylinder wall.

00:11:47Today, with oil cooling jets directed up at the underside of the piston crown, the piston crown has been possible to make it thinner to the point that it is mechanically strong enough to bear the combustion load, plus a factor of safety.

00:12:09Yeah, this is off the topic, but it is friction and it's windage.

00:12:13And if you're spraying oil at the bottom of the piston, you're also losing something to smashing the oil up and you're making heat by doing that.

00:12:22And I've always been fascinated how you balance that out or how you control oil inside of an engine, especially when you're spraying it on the pistons, which are whipping the daylights inside of the engine, as you are pointing out.

00:12:37Well, it's a terrible thing because an engine is a mass of compromises.

00:12:46We'd like to get rid of windage, but we'd like to prevent the center of the piston dome from looking like a hammock with someone substantial sleeping in it.

00:12:57And why does the center of the piston always melt?

00:13:00I was delighted to figure that out one day because it's the farthest away from the heat path out, which is through the cylinder walls and more through the rings than anything else, as I understand.

00:13:12The oil film being the thinnest there.

00:13:14So here we have the nub of where vibration produces power loss.

00:13:26Now, the crankshaft bearings, crankshaft and connecting rod bearings are not a major source of friction.

00:13:32They're normally well-designed, well-lubricated friction, and a plane bearing is like one or two thousandths of the applied load.

00:13:46Not bad.

00:13:49And similar for rolling element bearings.

00:13:54So they're carrying a crushing load, but they're doing it efficiently.

00:13:59Nevertheless, heat is generated, which means horsepower is being lost in the form of oil friction.

00:14:10And this is why engines, one of the reasons why engines need oil coolers.

00:14:17Because, and they need more than casual lubrication of the big end rod bearing,

00:14:24because it has to have oil constantly flowing through it to carry away the heat.

00:14:33And it's good to remember when you're hearing somebody tell you,

00:14:37did you realize that a magneto consumes 75 horsepower?

00:14:42One horsepower equals the heating produced in a kitchen toaster.

00:14:4875 toasters in a little old vertex?

00:14:53I don't think so.

00:14:56So, that's a primary mechanism by which vibration, namely the starting and stopping of the pistons,

00:15:07translates into a large force that must be carried by bearings less than 100% efficient.

00:15:12So, we're talking about trying to shave a few percent off of a loss of a percentage of engine friction

00:15:24that is a few percent of power.

00:15:28Around town, the usual rule of thumb is friction eats up 15% of the power that your engine actually makes.

00:15:39But, as RPM rises, so do inertia loads.

00:15:46So, friction rises.

00:15:49And I remember, and this would be years ago because of 9,200 RPM hasn't been seen as a limit in dirt track for a long time.

00:16:00But, former Harley racing manager Dick O'Brien sounded really annoyed.

00:16:07He said, those privateers, they're trying to run their engines over 9,000, up 9,200 RPM.

00:16:15He said, for Christ's sake, don't they know that their friction loss is like 25% up there?

00:16:24Well, this is another one of the compromises.

00:16:27You work the machine faster in order to perform the power producing cycle more frequently.

00:16:33These little lumps of power being made by the engine, they add up to horsepower.

00:16:42It's important to make the engine capable of revving up and making power at high RPM because that is one of the major paths to high power.

00:16:55But, we have all these forces being generated and needing to take care that nothing gets over-temperatured or overloaded.

00:17:09Now, a single cylinder engine cannot be balanced by anything that you attach to the crankshaft.

00:17:17It can be made to feel better, but the balance weights you attach to the crankshaft are moving in a circle, whereas the piston and its inertia force is moving in a straight line.

00:17:32So, what is done generally is they add to the crankshaft opposite the crankpin, a mass that is functionally equivalent to half of the reciprocating parts, the piston, its rings, the wrist pin and retainers, and the small end of the rod.

00:17:52Those parts are regarded as the reciprocating mass that's going back and forth.

00:17:58So, balancing that by 50% means that when the piston is at top dead center yanking upward with 100 units, the counterweight is down here pulling down with 500 units, 50 units.

00:18:12So, the net force on the main bearings is cut in half.

00:18:16So, what is the price that we pay for this?

00:18:20When the counterweight is at the 90 or 270 position, it's creating a new force that's trying to yank the crankshaft forwards and push it backwards.

00:18:33And this was used in British parallel twins throughout the ages because it's more annoying to have the engine jumping up and down,

00:18:44setting the whole frame into a dreadful buzz than it is for it to be going backwards and forwards.

00:18:53For that reason, and for that reason only, the balance factor, as it's called, the percentage of the reciprocating weight that is added to the crankshaft on those parallel twins was sometimes as much as 85%.

00:19:11So, mostly what they were doing was moving the shaking force from vertical, where it's annoying to the rider, to horizontal, where it's less annoying.

00:19:24Yeah, it would depend on your RPM as well.

00:19:28Absolutely, yes.

00:19:29Because that inertia force goes up as a square.

00:19:32And where you would like it to be the smoothest.

00:19:37So, if you're on the highway a lot on a Vela set, they will run 70% balance factor if you're going to be running it 70 miles an hour with stock-like gearing.

00:19:47And then just pointing out for folks who aren't overly familiar with the British twin, it's essentially a single.

00:19:55Yeah, two pistons moving together.

00:19:57Yeah, the two pistons are 360 degrees apart, meaning they move up and down together.

00:20:03So, it's essentially a single.

00:20:04And it typically lacked a center main bearing as well.

00:20:09So, when Kevin was talking about earlier where you have a piston and a big end spinning around and you have a main on either side,

00:20:17well, that's true today for the most part, although I think some of the parallel twins that, like Polaris and other companies are making,

00:20:26they still have some jump rope crankshafts out there, as they were called.

00:20:31They're the elephant ears flapping because the...

00:20:33The flywheel is bouncing back and forth on the crankshafts.

00:20:37Yeah, wonderful stuff.

00:20:40So, those aspects of the engine consuming power from the main vibration source, which is the reciprocating parts,

00:20:55that has been done away with to the extent possible by making those parts disappear.

00:21:00They're as light as they can practically be at the moment.

00:21:03There are superior materials, which would allow an even lighter piston to be made, but they're quite expensive.

00:21:14This is a so-called...

00:21:18Well, they mix an extremely hard and rigid powder into aluminum by means of extrusion.

00:21:30And it acts as a reinforcement, greatly increasing the strength of the aluminum.

00:21:37In the case of a piston material, I think Formula One did this until they were forbidden by rule,

00:21:44about twice as strong as the present 2618 material that so many makers use.

00:21:54So, it's valuable to cut that load on the main bearings down by 50% by adding a 50% counterweight.

00:22:05But if you add more counterweight, it just makes...

00:22:09Moves the vibration from vertical to horizontal.

00:22:13And in the case of the Velocet, I think that there's probably also a resonance that can happen,

00:22:18that the engine is mounted on a spring, namely the two cradle tubes.

00:22:26And if the engine shaking force comes into resonance with those...

00:22:32the flexibility,

00:22:34then you'll get a vibration period, as it's called.

00:22:39It's RPM dependent.

00:22:40Instead of just increasing as the square of RPM,

00:22:43there's a particular point where you don't want to ride there

00:22:47because it's going to make your bottom go to sleep.

00:22:51Well, Stinson 108 aircraft with the Franklin Flat 6 in it,

00:22:57150 horsepower, 165 horsepower,

00:22:59is fitted with a wood prop originally.

00:23:02And you just flew that around at whatever RPM you wanted to run.

00:23:06With the metal prop,

00:23:08there's a band of RPM where you do not fly.

00:23:11You can pass through it,

00:23:13but you do not fly because the metal prop sets up a resonance

00:23:15and bad things will happen.

00:23:17So you can't put the metal prop on,

00:23:19but you have to follow the rules.

00:23:21And there's a band of RPM, whatever it is,

00:23:22I don't remember, but 2200 to 2300 or something.

00:23:27And you just mark that out on your tack

00:23:29and you're either above or below that at cruise.

00:23:33So we don't wish it to sing.

00:23:34And now you were talking about the frame being a spring

00:23:37and on the Velocet Rally, riding along,

00:23:41we were up in Mad River in the middle of nowhere in California

00:23:45because the Velocet Club would do thousand mile rides over a week.

00:23:48They still do it.

00:23:49I haven't been because it overlaps a family,

00:23:52a large family gathering that we have every year.

00:23:54So I'm gone for a while.

00:23:55But on this one, we're riding through the hills

00:23:57and we stopped at this burger shack.

00:23:59All these Velocets bladding in and we all park.

00:24:04And I was talking to my friend, Bill Getty,

00:24:06who was riding his Venom.

00:24:07And he said, oh, yeah, you know,

00:24:09it seemed like it was vibrating a lot.

00:24:11And then it got really smooth.

00:24:12It was really nice, you know.

00:24:13It's like, yeah, really smooth.

00:24:16I'm like, oh, yeah, cool.

00:24:16And so we ate and we're having our hamburger and a milkshake.

00:24:21And he looks over at his motorcycle

00:24:22and the down tube had cracked completely through.

00:24:25So the backbone was holding the motorcycle together.

00:24:31There was a gap between the down tube, the lug,

00:24:34because it cracked near the lug where the heat had been applied

00:24:36and some passed, you know, and being manufactured.

00:24:39And it did.

00:24:40And so it was a great big leaf spring.

00:24:42And then the vibration of the engine has to go a long way.

00:24:45To get to the steering and the handlebars, yes.

00:24:47Yeah.

00:24:48And, you know, it's like, huh, how can we?

00:24:51We fixed it.

00:24:52We fixed it.

00:24:52We found a drag race team.

00:24:55The guy's running a tow truck.

00:24:57Yeah.

00:24:58We might die.

00:24:58But, you know, we sleeved it and did a rosette weld on it.

00:25:02So we turned a piece of tubing in a lathe

00:25:05and pounded it into the frame

00:25:06and then squeezed it together with ratchet straps

00:25:10and finished the rally.

00:25:13Harry Klinsman, before he became a big man,

00:25:17was a modest-sized lad.

00:25:21And at one point, he rode one of Kawasaki's tandem twins,

00:25:25built only for racing.

00:25:27Had the cylinders one ahead of the other.

00:25:29There were two counter-rotating crankshafts,

00:25:32one ahead of the other, geared together.

00:25:34And Mr. Sato, the designer,

00:25:38had decided that he would have the pistons alternate,

00:25:41180-degree firing order.

00:25:44Well, what that did is it made the whole engine rock like a boat.

00:25:50And Harry Klinsman's going around at Loudoun,

00:25:54trying to get his lap times down.

00:25:56And he comes in and he says,

00:25:58I don't know, this thing is, it feels really weird.

00:26:03I think you ought to have a look at it.

00:26:05So, you have a look at it.

00:26:07Four of the six frame tubes joining the steering head

00:26:11had come loose because of this tremendous vibration.

00:26:17So, it would be good if a person's ability

00:26:23to tolerate vibration somehow gave heart

00:26:27to the welds in the frame

00:26:30and gave them a similar tolerance for the vibration.

00:26:34To my knowledge, it hasn't happened.

00:26:38Now, a second...

00:26:41Sorry, it makes me think of Dan Gurney's moment canceling twin.

00:26:46Yep.

00:26:46Yeah.

00:26:47Well, that's what Kawasaki did.

00:26:49They did the very same thing.

00:26:52Instead of having the pistons at 180,

00:26:54they made them at 360.

00:26:56And now what happens is,

00:26:59when the pistons are both up,

00:27:03the counterweights are down,

00:27:04pulling down at 100%,

00:27:06so no vertical force.

00:27:08And when the things turn 90 degrees,

00:27:11you have one counterweight going,

00:27:13yanking forward and one yanking backwards.

00:27:16Net zero.

00:27:18Smooth.

00:27:19Balanced primary.

00:27:21And that's what Dan Gurney built

00:27:23because he had tried a V-twin

00:27:25in one of his alligator feet-first bikes

00:27:28and he didn't like the vibration.

00:27:32Yeah, they were making a ton of power.

00:27:33They were using 45s of some variety

00:27:36and then applying all their hocus-pocus

00:27:39to the cylinder heads.

00:27:41I mean, the hottest single-cylinder engine

00:27:44I have ever ridden on

00:27:45is that 700-650.

00:27:49It was 700cc,

00:27:51but it was a Honda XRXL 650.

00:27:55And it was amazing.

00:27:58It really ran great.

00:27:59So they really knew how to make them breathe.

00:28:01The moment-canceling twin was 110 cubic inches

00:28:03and it was doing 280 horsepower

00:28:05and it was really smooth

00:28:07and it would have made

00:28:08quite the recumbent motorcycle engine.

00:28:11And you could have done a lot

00:28:12with that kind of power plant, frankly.

00:28:15Well, there are four ways

00:28:17to cancel vibration in a twin.

00:28:21That's one of them.

00:28:23The boxer is another one.

00:28:26And the 90 degree is another one

00:28:30because if you do the, you know,

00:28:32zero, 90, 180, 270

00:28:34and add up the numbers in your mind,

00:28:38it's, oh, comes out to zero.

00:28:40That's marvelous.

00:28:42And then,

00:28:47oh, what was the fourth one?

00:28:49Well, it's escaping.

00:28:51But at any rate,

00:28:52one of the best ways

00:28:54to balance an engine

00:28:55and get rid of external vibration

00:28:57because the internal loads

00:28:58will still be there

00:28:59because the pistons are experiencing

00:29:02those tremendous G loads.

00:29:04But to get rid of external vibration

00:29:06is to have one cylinder

00:29:08cancel the vibration of another.

00:29:12What's going on?

00:29:13Why are six-cylinder inline engines

00:29:15so smooth?

00:29:16Just move.

00:29:18Yeah, I mentioned

00:29:19that a three-cylinder,

00:29:20a 120 firing order

00:29:23three-cylinder,

00:29:25the center of mass

00:29:26doesn't move.

00:29:27It sits there

00:29:28serenely

00:29:29like one of Plato's ideals.

00:29:32But the engine

00:29:34makes that kayak paddle motion.

00:29:38So, why don't we hook

00:29:39two of those together?

00:29:40Mirror image.

00:29:41Now, we've done away

00:29:44with the rocking couple

00:29:45because one rocks

00:29:46against the other.

00:29:48We also have

00:29:49an immovable center of mass.

00:29:52What have we?

00:29:53A BMW, automotive,

00:29:55straight six.

00:29:56Others make them.

00:29:58But BMW is so persistent.

00:30:00They love that configuration

00:30:02because it is so self-balancing.

00:30:05Oh, K1600

00:30:06out of this world.

00:30:08I mean,

00:30:08just a fabulous motorcycle engine.

00:30:10Just wonderful.

00:30:13Great sound.

00:30:14You know,

00:30:14you've got

00:30:15all the combustion events,

00:30:16more combustion events happening.

00:30:18So, you get that kind of sizzle.

00:30:20And, you know,

00:30:22they tune that engine really well.

00:30:24They gave it a lot of heat.

00:30:27Really let it rip.

00:30:29And it's wonderful.

00:30:31But, yeah,

00:30:31inline six,

00:30:32you know,

00:30:32in a Jaguar or whatever.

00:30:33When you balance

00:30:34all your pistons

00:30:35and you balance,

00:30:36you know,

00:30:36ends of your connecting rods

00:30:38and everything

00:30:39and make sure

00:30:40your flywheel

00:30:41is tip-top.

00:30:42They are,

00:30:43you just rev them

00:30:44to 5,000

00:30:45even with a really long stroke.

00:30:47You know,

00:30:47something like

00:30:47an XK Jaguar engine.

00:30:50I mean,

00:30:51110 millimeter stroke,

00:30:53I think.

00:30:54And those trash can pistons.

00:30:55And these big pistons.

00:30:57This is a Jaguar.

00:30:57This is a stock Jaguar piston.

00:30:59This is heavy.

00:30:59I don't even weight it,

00:31:00but it weighs a lot.

00:31:03So,

00:31:03but there they go.

00:31:04Just smooth as,

00:31:05you know,

00:31:06rev it up

00:31:06and look in the rear view mirror

00:31:07and it's not,

00:31:07it's not buzzing at all.

00:31:10The rear view mirror is perfect.

00:31:11The image is crisp.

00:31:13It's very satisfying.

00:31:16And it just makes,

00:31:18well,

00:31:18let me just,

00:31:19let me say

00:31:19riding a twin cylinder

00:31:20Triumph

00:31:21is the opposite

00:31:23of an inline six.

00:31:25It's just shaking all over

00:31:26and they,

00:31:27you know,

00:31:27they put that

00:31:27four and aft vibration

00:31:28in because it does feel better.

00:31:30And when you sit

00:31:31at a stoplight

00:31:32on a 58 Triumph Trophy,

00:31:33the front,

00:31:34because it's on the fork

00:31:35and it's a pretty flexible fork,

00:31:37the front is shaking.

00:31:38Just like the Sportster.

00:31:39Yes.

00:31:39Yeah,

00:31:39the shaking back and forth

00:31:41and then you pull the brake on

00:31:42and then the bike shakes more.

00:31:44Yes.

00:31:45Well,

00:31:46what we have to realize here

00:31:48is that

00:31:48vibration by itself

00:31:50does not consume power.

00:31:52A tuning fork,

00:31:53bing,

00:31:54and it rings for a long time.

00:31:56Or a bell,

00:31:58doink,

00:31:59if you've got your hand on it,

00:32:01but bong,

00:32:02if it's free,

00:32:03and it rings for a long time

00:32:04because we have

00:32:07highly elastic material,

00:32:08namely metal in both cases,

00:32:10that is storing energy

00:32:12in a small deflection

00:32:13and that energy,

00:32:17it doesn't have any part of it

00:32:18except it's pushing

00:32:20a little air back and forth

00:32:21and there may be

00:32:23some molecules

00:32:24inside the metal

00:32:25that are a little uncomfortable

00:32:27and they eat up

00:32:28a little energy,

00:32:29but it's highly efficient.

00:32:30So vibration by itself

00:32:33is not a

00:32:36loss-producing mechanism,

00:32:40but

00:32:41back and forth

00:32:42piston shaking,

00:32:43the principal source

00:32:44of vibration

00:32:45on a

00:32:45IC engine-powered motorcycle,

00:32:48has all sorts of

00:32:50consequences

00:32:51that eat power.

00:32:53But

00:32:53I want to turn now

00:32:54to

00:32:56torsional vibration.

00:32:59And it's not so much

00:33:00that this vibration

00:33:01upsets people

00:33:04or

00:33:05promptly breaks parts,

00:33:10but

00:33:10if we imagine,

00:33:12let's just start

00:33:13with a crankshaft

00:33:14that we imagine

00:33:15to be perfectly rigid

00:33:16as it rotates

00:33:18a cylinder

00:33:20or cylinders

00:33:21fire,

00:33:22where does the energy

00:33:24of that

00:33:24power stroke

00:33:25go?

00:33:26It goes into

00:33:27speeding up

00:33:28the crankshaft.

00:33:29We're rolling

00:33:30along the road,

00:33:31so the rear wheel

00:33:32is taking

00:33:33whatever power

00:33:35it needs

00:33:35to overcome

00:33:36aero resistance

00:33:37and rolling resistance,

00:33:39so it's constantly

00:33:40taking something

00:33:41from the crankshaft.

00:33:43So what does

00:33:44the crankshaft do?

00:33:45It's RPM flutters.

00:33:48And the

00:33:49magnitude

00:33:50of the flutter

00:33:50is the effect

00:33:51of the cylinders

00:33:52firing,

00:33:54shoving energy

00:33:54into the crankshaft

00:33:56by speeding it up.

00:33:59And

00:33:59that

00:34:02causes

00:34:04power

00:34:05to the rear wheel

00:34:06to be

00:34:08less than smooth,

00:34:10which is a reason

00:34:12that there is

00:34:13a spring drive

00:34:14located usually

00:34:15in the clutch,

00:34:16and also

00:34:17there may be

00:34:18a second one

00:34:18in the rear hub,

00:34:19a cush hub.

00:34:20The purpose

00:34:22of this

00:34:22is to allow

00:34:23the engine

00:34:24to rotate

00:34:26in this

00:34:27non-uniform

00:34:29way

00:34:29without disturbing,

00:34:31creating high

00:34:32peak loads

00:34:33on the gearbox

00:34:33or possibly

00:34:35feeling

00:34:35chuggish.

00:34:37Take an old

00:34:38single,

00:34:39I had one

00:34:39for a year,

00:34:41and if you

00:34:42let the revs

00:34:43down and then

00:34:44open the throttle,

00:34:45you can feel

00:34:47you are being

00:34:49pushed down

00:34:50the road

00:34:50by those

00:34:51separate

00:34:52impulses.

00:34:54And

00:34:54the crankshaft

00:34:55is not rotating

00:34:56steadily and serenely,

00:34:58it is kind of

00:34:59being given

00:35:00a shot of energy,

00:35:01and then it

00:35:02smooths out,

00:35:03and it's given

00:35:04another shot

00:35:04of energy

00:35:05so that there

00:35:06is this

00:35:07unsmoothness.

00:35:08At the same

00:35:10time,

00:35:10if we consider

00:35:11crankshafts

00:35:12that are not

00:35:13rigid,

00:35:14but are able

00:35:15to twist,

00:35:17it's clear

00:35:18that the

00:35:20crankshaft

00:35:21is going

00:35:21to be set

00:35:22into twisting

00:35:23vibration,

00:35:25of which there

00:35:25are several

00:35:26modes,

00:35:27by cylinder

00:35:28firing.

00:35:29and this

00:35:31was discovered

00:35:32in early

00:35:33days when

00:35:34big six

00:35:36cylinder

00:35:37aircraft

00:35:37engines

00:35:38were built

00:35:39and the

00:35:40wooden

00:35:40propellers

00:35:41that were

00:35:41bolted

00:35:42between

00:35:42steel

00:35:43flanges,

00:35:44the bolts

00:35:44were carefully

00:35:45tightened,

00:35:46they would

00:35:47come back

00:35:48from a

00:35:48flight and

00:35:49the wood

00:35:49under those

00:35:50flanges

00:35:50would be

00:35:51charred.

00:35:53And the

00:35:54reason is

00:35:55that the

00:35:57crankshaft

00:35:57has natural

00:36:00modes of

00:36:01torsional

00:36:02vibration.

00:36:03There can

00:36:03be an

00:36:04end-to-end

00:36:04mode,

00:36:05there can

00:36:06be both

00:36:07ends going

00:36:08one way

00:36:08and the

00:36:08middle going

00:36:09the other

00:36:09way,

00:36:10and combinations

00:36:11of all

00:36:12these things.

00:36:13So that if

00:36:14you graph

00:36:14the excursion,

00:36:17the amount

00:36:18of twist

00:36:19versus

00:36:21RPM,

00:36:22you will

00:36:22get a

00:36:22thing that

00:36:23looks like

00:36:24a pretty

00:36:25unpleasant

00:36:25mountain range

00:36:26and there'll

00:36:27be one

00:36:28primary

00:36:30mode that

00:36:31really sticks

00:36:32up.

00:36:34And that

00:36:35may be the

00:36:35one that

00:36:36breaks your

00:36:37crankshaft.

00:36:38Because in

00:36:38the early

00:36:39days of

00:36:39six-cylinder

00:36:40automobiles,

00:36:43Napier

00:36:44had this

00:36:45terrible

00:36:47rattle.

00:36:47It would

00:36:48bounce the

00:36:49valve system

00:36:51and make

00:36:52quite a

00:36:53clatter.

00:36:53They called

00:36:53it power

00:36:54rattle.

00:36:55Power

00:36:56rattle.

00:36:57If you

00:36:58can't get

00:36:58rid of

00:36:59it, make

00:36:59a virtue

00:37:00of it.

00:37:01Yeah, make

00:37:01it a

00:37:01feature.

00:37:02So that

00:37:05ability to

00:37:07rattle the

00:37:07valve train

00:37:08is where

00:37:09torsional

00:37:10vibration in

00:37:11modern engines

00:37:12can, it

00:37:14doesn't, not

00:37:14that it

00:37:15absorbs power,

00:37:16but that it

00:37:17prevents it

00:37:17from being

00:37:18made.

00:37:19Because,

00:37:20first of all,

00:37:21the crankshaft

00:37:22is subject

00:37:23to these

00:37:24thumps from

00:37:25combustion,

00:37:26so its

00:37:26rotation is

00:37:27not smooth.

00:37:29Second, it

00:37:30is supporting

00:37:31vibratory modes

00:37:32that are set

00:37:33in motion by

00:37:34those combustion

00:37:35thumps.

00:37:38And metals

00:37:40respond to

00:37:42high stress

00:37:44applied in a

00:37:45cyclic fashion

00:37:46by eventually

00:37:48developing

00:37:49cracks and

00:37:50breaking,

00:37:51which is what

00:37:52those early

00:37:53six-cylinder

00:37:53crankshafts

00:37:54did.

00:37:55Where did

00:37:56they break?

00:37:56They broke

00:37:57where the

00:37:58smooth journals

00:37:59joined the

00:38:01as-forged

00:38:02crank cheeks.

00:38:04and they

00:38:06soon learned

00:38:07that that

00:38:07had to be

00:38:08a smooth

00:38:09radius there

00:38:10because having

00:38:12a sharp edge

00:38:13was like

00:38:14saying,

00:38:15crack here.

00:38:17And I

00:38:19remember hearing

00:38:20a story about

00:38:20an incompetently

00:38:23reground

00:38:23Ferrari

00:38:25crankshaft

00:38:25that broke

00:38:26the first day

00:38:27that it was

00:38:28put back

00:38:28into service.

00:38:30It probably

00:38:31had a crack

00:38:31in it,

00:38:32but makes

00:38:33a good story.

00:38:34Well,

00:38:34you know,

00:38:35that's one

00:38:36thing you

00:38:36can do

00:38:36with particularly

00:38:37a long

00:38:38crankshaft

00:38:39is you

00:38:40can hang

00:38:41it by a

00:38:41wire and

00:38:41make it

00:38:42ring usually.

00:38:43And if it

00:38:43doesn't ring,

00:38:44then there's

00:38:44a big

00:38:44problem.

00:38:46Same with

00:38:46crockery.

00:38:46That same

00:38:47test works

00:38:48very well

00:38:48with crockery

00:38:49to find a

00:38:50crack.

00:38:50Yeah,

00:38:51so,

00:38:52well,

00:38:53crank dampers

00:38:53came to

00:38:55the rescue.

00:38:57Early

00:38:57crank dampers,

00:38:58there's one

00:38:58on an

00:38:59inline-six

00:39:00that powered

00:39:00the Rolls-Royce

00:39:012025 in

00:39:02the 30s.

00:39:03That was

00:39:04what they

00:39:04called the

00:39:05small horsepower

00:39:05Rolls,

00:39:07and it was

00:39:07for this

00:39:08class of

00:39:08person who

00:39:09wasn't as

00:39:10classy as

00:39:11I can afford

00:39:12a full-time

00:39:12driver.

00:39:13I'm doing

00:39:14okay,

00:39:15and really,

00:39:16you know,

00:39:16modern people

00:39:16drive themselves

00:39:17anyway.

00:39:18So they had

00:39:19the small

00:39:19horsepower ones

00:39:20and they

00:39:20were inline

00:39:20sixes.

00:39:22Excuse me,

00:39:23the crank

00:39:23damper on

00:39:24that was a

00:39:24magnificent

00:39:25sandwich,

00:39:27big disc.

00:39:28it had

00:39:29pieces of

00:39:30canvas in

00:39:31it and

00:39:32then you

00:39:32had all

00:39:33these little

00:39:33discs and

00:39:35everything that

00:39:35you bolted

00:39:36together.

00:39:37Like a

00:39:38clutch.

00:39:39Like a

00:39:39clutch and

00:39:40you would

00:39:40put that

00:39:40in your

00:39:41vice and

00:39:42then you

00:39:42would take

00:39:43a torque

00:39:43wrench and

00:39:44you'd measure

00:39:44the breakaway

00:39:45torque.

00:39:47And it has

00:39:47to be something

00:39:48like what,

00:39:48I forget what

00:39:49the spec was,

00:39:49but it had

00:39:50to be like

00:39:5018 foot

00:39:51pounds for

00:39:51it to move.

00:39:53And you're

00:39:53like,

00:39:53oh,

00:39:54okay.

00:39:54And if it

00:39:55wasn't,

00:39:55take it all

00:39:56apart and

00:39:57then change

00:39:57the little

00:39:57springs.

00:39:58I mean,

00:39:59it's insanity.

00:40:00Now we just

00:40:01have bonded

00:40:02dampers,

00:40:02but everything's

00:40:04got one.

00:40:05And then

00:40:05now the

00:40:05Thames

00:40:06400E

00:40:08van,

00:40:08which has

00:40:09a Ford

00:40:10console 1703

00:40:11inline four

00:40:12in it,

00:40:12from the

00:40:13factory,

00:40:13those didn't

00:40:14have a

00:40:14crank damper

00:40:15on them.

00:40:17And I

00:40:18have one of

00:40:18those engines

00:40:19and in

00:40:21building it

00:40:21decided I

00:40:22wanted a

00:40:23crank damper.

00:40:23So we

00:40:24got an

00:40:24ATI

00:40:24crank damper,

00:40:26which is a

00:40:26company that

00:40:27makes crank

00:40:27dampers,

00:40:28performance

00:40:29racing ones,

00:40:30and got an

00:40:31ATI and

00:40:31adapted it

00:40:32to the

00:40:32crank.

00:40:32And one

00:40:34of the

00:40:34reasons I

00:40:35did that

00:40:35is because

00:40:36my friend

00:40:37Ray,

00:40:37who runs

00:40:38his,

00:40:40you got to

00:40:41understand a

00:40:42Thames van

00:40:42with a

00:40:431703 in it

00:40:44is like

00:40:45life on a

00:40:46dyno.

00:40:48So what

00:40:48you were

00:40:48talking about

00:40:49crank radius

00:40:49fillets,

00:40:50one of those

00:40:51things.

00:40:52So I'm a

00:40:52street guy.

00:40:53When you have

00:40:54a crankshaft

00:40:55that's like

00:40:55no undercut

00:40:58already,

00:40:58you know,

00:40:58it's not

00:40:5910 under,

00:40:59it's not

00:41:0020 under,

00:41:01you're like,

00:41:01oh,

00:41:01this is great.

00:41:02I hope it

00:41:03cleans up at

00:41:0310 because

00:41:04that means I

00:41:04have 20,

00:41:0530,

00:41:05and maybe

00:41:0640 for

00:41:07the future.

00:41:08But when you

00:41:09call the

00:41:10crank guy and

00:41:10you say like,

00:41:11hey,

00:41:11my crank

00:41:12flew apart,

00:41:12so the

00:41:13Thames van

00:41:13that didn't

00:41:14have the

00:41:14crank damper

00:41:15and was

00:41:15living life

00:41:16on a

00:41:16dyno,

00:41:16which was

00:41:17flat out

00:41:18on Interstate

00:41:205 hauling

00:41:202,000 pound

00:41:21loads north

00:41:22and south,

00:41:23which is how

00:41:23the guy used

00:41:24it.

00:41:25The crank

00:41:25came apart

00:41:26and it

00:41:26basically wrecked

00:41:27everything in

00:41:28that engine.

00:41:29So that's

00:41:30where the

00:41:30crank damper

00:41:32idea came

00:41:32from.

00:41:33And the

00:41:33next engine

00:41:33that he

00:41:34built also

00:41:34had a

00:41:35crank damper,

00:41:36but he sent

00:41:37it to his

00:41:37crank guy up

00:41:38in Idaho.

00:41:39And the

00:41:39crank guy says

00:41:40like,

00:41:40oh,

00:41:41how do you

00:41:41use this?

00:41:41And he's

00:41:42like,

00:41:42ah,

00:41:42flat out

00:41:42all the

00:41:43time.

00:41:43You know,

00:41:43he's like,

00:41:44okay,

00:41:44life on a

00:41:44dyno.

00:41:45Yep.

00:41:45Yeah.

00:41:46All right.

00:41:46We're going

00:41:47to turn it

00:41:4740 under

00:41:48and we're

00:41:48going to

00:41:48put huge

00:41:49fillets.

00:41:50Yes.

00:41:51And I'm

00:41:51like,

00:41:52what?

00:41:52No,

00:41:53you can't

00:41:53go 40,

00:41:54can't go

00:41:5440 under,

00:41:55but that's

00:41:56what you

00:41:56want to

00:41:56do.

00:41:57You get

00:41:57the big,

00:41:57big radius

00:41:58and the

00:41:58crank damper

00:41:59now,

00:41:59we hope,

00:42:01lengthens the

00:42:02life of

00:42:03the Thames

00:42:04400e on a

00:42:04dyno.

00:42:05Well,

00:42:05here's a

00:42:06tree growing

00:42:07out in the

00:42:07open.

00:42:09The trunk

00:42:10comes down

00:42:11and flares

00:42:12out into the

00:42:13root structure.

00:42:15What if

00:42:16instead of

00:42:16doing that,

00:42:17it just

00:42:17came down

00:42:18like this

00:42:18and stopped

00:42:20there and the

00:42:21root structure

00:42:22just grew

00:42:23out radially?

00:42:28A billion

00:42:29years of

00:42:30R&D,

00:42:33accidental R&D,

00:42:34has brought

00:42:35to us

00:42:36trees that

00:42:37have a

00:42:37graceful

00:42:38organic radius

00:42:39where the

00:42:40trunk becomes

00:42:41the root

00:42:42structure.

00:42:43That's one of

00:42:43John Britton's

00:42:44nice observations

00:42:45about nature.

00:42:47Yes,

00:42:48nature is

00:42:48worth

00:42:49observing

00:42:49because it

00:42:51is the

00:42:51product of

00:42:52intensive,

00:42:54long-lasting

00:42:55R&D.

00:42:57But the

00:42:59real problem

00:42:59with torsional

00:43:01vibration,

00:43:02other than

00:43:02that the

00:43:03crankshaft

00:43:03may break,

00:43:06which is

00:43:06not to be

00:43:08sneezed at,

00:43:09is that

00:43:10while the

00:43:11crankshaft is

00:43:12doing this

00:43:12and it's

00:43:13trying to

00:43:13transmit

00:43:14this

00:43:14up the

00:43:17camshaft

00:43:18drive,

00:43:19and the

00:43:19camshaft

00:43:20is having

00:43:21to lift

00:43:22valves against

00:43:23powerful springs

00:43:24or accelerate

00:43:25valves against

00:43:27powerful inertia

00:43:28in the case

00:43:28of Ducati's,

00:43:30the torque

00:43:32required to

00:43:33drive the

00:43:34cam is

00:43:34varying,

00:43:35and the

00:43:35torque,

00:43:36the motion

00:43:37that's being

00:43:37sent to it

00:43:38from the

00:43:38crankshaft

00:43:39is not

00:43:39smooth.

00:43:40So the

00:43:41camshaft

00:43:42itself is

00:43:43set into

00:43:43motion.

00:43:45And if

00:43:46as the

00:43:47valve train

00:43:48has just

00:43:50been accelerated

00:43:51and now

00:43:52it's on the

00:43:52part of the

00:43:53cam lobe

00:43:54that where

00:43:55it's going

00:43:56to start

00:43:57decelerating

00:43:58to go over

00:43:59the nose

00:43:59and begin

00:44:00to close,

00:44:01if at that

00:44:02point

00:44:02the wound

00:44:04up camshaft

00:44:05unwinds,

00:44:08its lobe

00:44:09is going

00:44:09to be

00:44:10moving so

00:44:10fast that

00:44:11it will

00:44:11just

00:44:11pit-tui,

00:44:12it will

00:44:13toss the

00:44:14valve train

00:44:15off the

00:44:15profile.

00:44:17And I

00:44:17know I've

00:44:17spoken of

00:44:18this before,

00:44:20you know,

00:44:20go to sleep

00:44:21while I

00:44:22deliver my

00:44:23little lecture,

00:44:23but in

00:44:25material from

00:44:26Honda on

00:44:26their Formula

00:44:27One engines,

00:44:28which you

00:44:28can access,

00:44:29you can get

00:44:30at on the

00:44:31internet,

00:44:32they describe

00:44:33developing a

00:44:34valve train

00:44:35for Formula

00:44:35One and

00:44:36finding that

00:44:37it could,

00:44:39that the

00:44:39float limit

00:44:40was x

00:44:40RPM,

00:44:41the highly

00:44:42developed,

00:44:43lovely valve

00:44:45train,

00:44:45lightweight

00:44:46parts,

00:44:46so beautiful,

00:44:47being driven

00:44:49by an electric

00:44:50motor with

00:44:51the heavy

00:44:51flywheel.

00:44:53Then they

00:44:53take that

00:44:54valve train

00:44:55and put it

00:44:55on the

00:44:56engine for

00:44:56which it

00:44:56was designed.

00:44:58Now the

00:44:59valves float

00:44:59at x

00:45:00minus

00:45:011500 revs.

00:45:03because that

00:45:06is the

00:45:06price of

00:45:07unsmoothness

00:45:08in rotation

00:45:09of those

00:45:09parts.

00:45:11So if the

00:45:12valves are

00:45:12floating,

00:45:14you soon

00:45:16will have a

00:45:16valve failure

00:45:17and in the

00:45:18meantime,

00:45:19the valves

00:45:20are not

00:45:20opening and

00:45:22closing at

00:45:23the times

00:45:23that were

00:45:24found to

00:45:25be optimum,

00:45:26so you're

00:45:27losing power.

00:45:28this is

00:45:30not an

00:45:31acceptable

00:45:32situation.

00:45:33And it's

00:45:33usual for

00:45:36new racing

00:45:37engine designs

00:45:38to have

00:45:39an arm

00:45:40wrestle in

00:45:42developing a

00:45:43stable cam

00:45:44drive that

00:45:46doesn't wind

00:45:47itself in

00:45:47pieces.

00:45:49Steve

00:45:49Scheibe at

00:45:50Harley-Davidson

00:45:51showed me a

00:45:53box full of

00:45:54twisted up

00:45:54cam chain

00:45:56tensioners

00:45:56that were

00:45:58destroyed in

00:46:00early in the

00:46:00development of

00:46:01the VR-1000

00:46:02superbike.

00:46:04So

00:46:04modern Formula

00:46:08One engines

00:46:09have to be

00:46:11lightweight.

00:46:12They want

00:46:12them to

00:46:13weigh

00:46:13110

00:46:15kilograms,

00:46:18120

00:46:18kilograms.

00:46:20I mean,

00:46:20that's something

00:46:21that if you

00:46:22were young

00:46:23and lively,

00:46:24you could pick

00:46:24up and

00:46:26move a

00:46:26short

00:46:26distance.

00:46:27It's not

00:46:28the giant

00:46:29700-pound

00:46:30monstrosities

00:46:31that you

00:46:31see dangling

00:46:32from those

00:46:33orange shop

00:46:34cranes.

00:46:35Oh,

00:46:35right out

00:46:36in the

00:46:37old Ford

00:46:37460

00:46:38out there.

00:46:41728

00:46:41pounds,

00:46:42they say,

00:46:43without

00:46:43accessories.

00:46:44Good one.

00:46:45I watched

00:46:45the crane,

00:46:46man.

00:46:46We'd start

00:46:46cranking the

00:46:47crane and

00:46:47normally just

00:46:48on the

00:46:48light stuff,

00:46:49it just

00:46:49lifts it

00:46:50up.

00:46:50And then

00:46:50this one

00:46:51kind of

00:46:51went,

00:46:52they got

00:46:56to really

00:46:56pull it,

00:46:57pump,

00:46:58and then

00:46:58it would

00:46:59go.

00:47:00So,

00:47:00to achieve

00:47:01that

00:47:01lightweight,

00:47:02they're

00:47:03going to

00:47:03make a

00:47:04very

00:47:04lightweight

00:47:05crankshaft

00:47:05that has

00:47:06hollow

00:47:06journals and

00:47:08everything

00:47:09reduced to

00:47:10the bare

00:47:10minimum,

00:47:11usually not

00:47:12by computer

00:47:13in the

00:47:14final analysis,

00:47:15but by

00:47:15running it

00:47:16until it

00:47:16breaks and

00:47:17then fixing

00:47:17it over

00:47:19and over.

00:47:19And this

00:47:22is a

00:47:22replay of

00:47:23what I

00:47:23went on

00:47:24when diesel

00:47:25engines were

00:47:26put into

00:47:26submarines.

00:47:28They went to

00:47:28the diesel

00:47:29company and

00:47:30said,

00:47:30well,

00:47:30a submarine

00:47:31is pretty

00:47:32small in

00:47:32there and

00:47:34people have

00:47:35to be able

00:47:35to walk

00:47:35between the

00:47:36two engines.

00:47:37Can you

00:47:37make something

00:47:38that will

00:47:38fit in

00:47:38there?

00:47:39So,

00:47:39long,

00:47:40slender

00:47:40engines,

00:47:41lightweight,

00:47:43with very

00:47:43lightweight

00:47:44crankshafts.

00:47:46Oh,

00:47:47the

00:47:48crankshafts

00:47:49have,

00:47:51if you

00:47:52graph it

00:47:52out,

00:47:52one of

00:47:53those

00:47:53expressions

00:47:55that shows

00:47:56where the

00:47:56torsional

00:47:57modes are.

00:47:58And we're

00:47:58out on

00:47:59sea trials,

00:48:00grinding

00:48:00along,

00:48:01leaving a

00:48:01heavy black

00:48:02trail of

00:48:03smoke behind,

00:48:04and there's

00:48:05a loud

00:48:06clunk and

00:48:06one of the

00:48:07engines stops.

00:48:08The

00:48:08crankshaft

00:48:08has broken.

00:48:10Oh,

00:48:10good thing

00:48:11we have

00:48:11two.

00:48:13Turn

00:48:14around and

00:48:14head back

00:48:15for base.

00:48:16Clunk!

00:48:17the second

00:48:18crankshaft

00:48:18breaks.

00:48:20Hmm.

00:48:22Then there

00:48:22was the

00:48:23case in

00:48:231948 of

00:48:25a

00:48:26Constellation

00:48:27airplane

00:48:28flying New

00:48:28York to

00:48:29Miami,

00:48:29and the

00:48:31pilots

00:48:31must have

00:48:34neglected to

00:48:34keep the

00:48:36engine

00:48:36operating in

00:48:37the safe

00:48:38zones.

00:48:39In

00:48:39between

00:48:40those

00:48:40peaks of

00:48:43vibration

00:48:43are safe

00:48:45zones.

00:48:45And in

00:48:46this

00:48:46case,

00:48:46it's not

00:48:47the

00:48:47crankshaft

00:48:47that's

00:48:48vibrating,

00:48:49it's the

00:48:49propeller

00:48:49blades.

00:48:51And the

00:48:52propeller

00:48:52blade is

00:48:53saying in

00:48:53a high

00:48:54squeaky

00:48:54voice,

00:48:55I feel

00:48:55fatigued.

00:48:57Oh,

00:48:58I feel

00:48:58cracked.

00:49:00And a

00:49:00piece of

00:49:01propeller

00:49:01blade,

00:49:0218 inches

00:49:03long,

00:49:04came through

00:49:04the fuselage

00:49:05and killed

00:49:06someone.

00:49:07Fortunately,

00:49:08they were

00:49:08able to

00:49:09land,

00:49:09and there

00:49:12was a big

00:49:12hoo-ha,

00:49:13as there

00:49:14ought to be

00:49:14when someone

00:49:15loses his

00:49:16or her

00:49:16life.

00:49:18But this

00:49:19is the

00:49:20nature of

00:49:21these systems

00:49:24that involve

00:49:25vibratory

00:49:27modes that

00:49:29must be

00:49:29observed,

00:49:30stay out of

00:49:31this area.

00:49:33With the

00:49:34Norton

00:49:35Cosworth,

00:49:36it was a

00:49:37parallel twin,

00:49:38with a

00:49:38Cosworth head

00:49:39on it.

00:49:40Formula

00:49:41One

00:49:41technology

00:49:42on

00:49:431937

00:49:44concept.

00:49:47Well,

00:49:48they found

00:49:49that the

00:49:51crankshaft

00:49:51would break

00:49:52if the

00:49:53engine were

00:49:53run steadily

00:49:54at 4000

00:49:55RPM on

00:49:56a good

00:49:58amount of

00:49:58throttle.

00:50:00Well,

00:50:01the answer

00:50:01is,

00:50:02train the

00:50:03riders not

00:50:04to do

00:50:04that.

00:50:06Well,

00:50:07riders have a

00:50:07lot of things

00:50:08to do,

00:50:09though.

00:50:11So,

00:50:12this

00:50:14torsional

00:50:14business in

00:50:16Formula One

00:50:17has been

00:50:17suppressed by

00:50:18putting multiple,

00:50:19not just one

00:50:20on the nose

00:50:21of the

00:50:21crankshaft,

00:50:22multiple

00:50:22dampers.

00:50:24Some of

00:50:24you have

00:50:25seen the

00:50:27Honda RC30

00:50:28superbike

00:50:28engines apart.

00:50:29some of

00:50:31those engines

00:50:31had fly

00:50:32wheels on

00:50:32the camshaft

00:50:33that were

00:50:34there to

00:50:35sort of

00:50:35put a

00:50:37restraining

00:50:37hand on

00:50:38the buildup

00:50:40of

00:50:40unpleasant

00:50:42action in

00:50:44the valve

00:50:44train.

00:50:46And

00:50:46lots of

00:50:48aircraft engines

00:50:49were supplied

00:50:49with dampers

00:50:51of one

00:50:52sort or

00:50:52another

00:50:52to prevent

00:50:54them from

00:50:55exciting

00:50:55metal

00:50:56propeller

00:50:57blades

00:50:57into

00:50:58fatigue

00:51:00generating

00:51:01oscillations.

00:51:02So,

00:51:03it's all

00:51:04very well

00:51:04to get

00:51:05nostalgic

00:51:05about

00:51:06vibration

00:51:06on those

00:51:07great old

00:51:08bikes.

00:51:09But

00:51:09you can

00:51:11see from

00:51:11examples

00:51:12that we've

00:51:12given

00:51:13that

00:51:15a little

00:51:16vibration

00:51:16such as

00:51:17what used

00:51:18to come

00:51:18from those

00:51:19beds,

00:51:20motel

00:51:21beds,

00:51:21you put in

00:51:22a quarter

00:51:22and it

00:51:23kind of

00:51:23buzzes a

00:51:24little bit,

00:51:24supposed to

00:51:25help you

00:51:25go to

00:51:25sleep.

00:51:28We could

00:51:29all put

00:51:29up with

00:51:29that.

00:51:31But

00:51:32severe

00:51:34vibration

00:51:34is going

00:51:35to break

00:51:36something

00:51:36eventually,

00:51:37and that's

00:51:37worth avoiding.

00:51:39What they

00:51:39did with

00:51:40the submarines

00:51:40is they

00:51:41looked at

00:51:41that graph

00:51:43and they

00:51:43said,

00:51:43here's a

00:51:44wide

00:51:44safety

00:51:45zone.

00:51:46Let's

00:51:47operate

00:51:47the engine

00:51:48in that

00:51:49zone and

00:51:50nowhere

00:51:50else.

00:51:52And we'll

00:51:52connect it

00:51:53to a

00:51:53generator

00:51:54and power

00:51:55the submarine

00:51:56with electric

00:51:57motors.

00:51:58On the

00:51:59surface,

00:51:59the batteries

00:52:00will be

00:52:01charging and

00:52:02the diesel

00:52:02engines will

00:52:03be generating

00:52:04and under

00:52:05the surface

00:52:06the whole

00:52:09system will

00:52:10operate on

00:52:10electric and

00:52:11the diesels

00:52:11will be

00:52:12shut down

00:52:12because there's

00:52:13no air

00:52:14under the

00:52:14water,

00:52:15of course.

00:52:16But that's

00:52:17why that

00:52:19diesel electric

00:52:20drive was

00:52:21developed to

00:52:22keep the

00:52:22crankshafts

00:52:23from breaking.

00:52:24Always

00:52:25operate the

00:52:26engine in

00:52:26this speed.

00:52:27It's

00:52:28governed to

00:52:28it and

00:52:31you'll be

00:52:31fine.

00:52:34So,

00:52:34so much

00:52:36for the

00:52:37usual

00:52:37sources of

00:52:39vibration,

00:52:39but there

00:52:40are more

00:52:40because the

00:52:42whole motorcycle

00:52:43itself is an

00:52:44oscillator.

00:52:46It vibrates.

00:52:47The motorcycle

00:52:48consists of

00:52:49two casters,

00:52:51a short one

00:52:53at the front

00:52:53and a

00:52:54longer one

00:52:55at the

00:52:55rear,

00:52:56joined at

00:52:57a common

00:52:57pivot,

00:52:58which is

00:52:58the steering

00:52:59head.

00:53:00Any of

00:53:01you who

00:53:02have pushed

00:53:02a shopping

00:53:03cart knows

00:53:05that twisted

00:53:06older shopping

00:53:07carts that

00:53:08have collided

00:53:09with automobiles

00:53:10in the parking

00:53:11lot a few

00:53:11times,

00:53:12one of the

00:53:13front wheels

00:53:14of the

00:53:14shopping cart,

00:53:15they are both

00:53:16casters,

00:53:17may be a

00:53:18little under

00:53:19loaded.

00:53:19And as

00:53:20you push

00:53:21along,

00:53:21it starts

00:53:22to swing

00:53:22back and

00:53:23forth.

00:53:24It can

00:53:25develop into

00:53:25quite an

00:53:27attention-grabbing

00:53:28oscillation.

00:53:31Same thing

00:53:32for the

00:53:34rear,

00:53:34which is

00:53:35from the

00:53:35steering head

00:53:36to the

00:53:37rear tire

00:53:37contact patch.

00:53:39That can

00:53:40oscillate.

00:53:42And

00:53:42modern

00:53:44motorcycles are

00:53:45carefully designed

00:53:46to prevent

00:53:47those oscillations

00:53:48from disturbing

00:53:50our pleasurable

00:53:51ride,

00:53:52but it was

00:53:52not always

00:53:53so.

00:53:55In the

00:53:55bad old

00:53:56days,

00:53:57this was

00:53:58something that

00:53:59was better

00:53:59not discussed.

00:54:01Head shake,

00:54:02buddy,

00:54:02watch out.

00:54:05So,

00:54:06and there's

00:54:08yet another

00:54:09mode,

00:54:10which comes

00:54:11from the

00:54:11tires,

00:54:12and it's

00:54:12called

00:54:12chatter.

00:54:13and it

00:54:16definitely

00:54:16does consume

00:54:17some power

00:54:18because it

00:54:18gets the

00:54:19tire,

00:54:20first the

00:54:21rear,

00:54:21then the

00:54:21front,

00:54:23bouncing

00:54:23and slipping

00:54:25and sliding

00:54:25in a way

00:54:27that is

00:54:28really

00:54:29disconcerting.

00:54:30The first

00:54:30time that

00:54:30Freddy Spencer

00:54:31encountered

00:54:32chatter,

00:54:33he came in

00:54:34and he said,

00:54:34Irv,

00:54:35the bike's

00:54:36doing some

00:54:36crazy stuff

00:54:37here.

00:54:38Irv sort

00:54:39of smiled

00:54:40and said,

00:54:41yeah,

00:54:41did you try

00:54:42to ride

00:54:42through it?

00:54:42Yeah,

00:54:43I did,

00:54:43I couldn't.

00:54:45And it

00:54:46just intensifies

00:54:47the more

00:54:48you try

00:54:49to push

00:54:50on it.

00:54:51Last year

00:54:51racing in

00:54:52Arma on

00:54:54the BMW

00:54:54Twin in

00:54:56Formula 750

00:54:57and Bears,

00:55:00I'm riding

00:55:00the executive

00:55:01director's bike,

00:55:02really well

00:55:02sorted,

00:55:02Dan May,

00:55:03meticulously

00:55:04well sorted

00:55:05bike,

00:55:05not one

00:55:06problem over

00:55:07the entire

00:55:08weekend.

00:55:08Lovely.

00:55:09And so I

00:55:10just did

00:55:12my best

00:55:13to be

00:55:13methodical

00:55:14and take

00:55:15the lap

00:55:15time and

00:55:16you know,

00:55:17it's best

00:55:18to discover

00:55:18for me,

00:55:19it's certainly

00:55:20best to discover

00:55:21these things

00:55:21incrementally.

00:55:23There are some

00:55:23guys who go

00:55:24on and like

00:55:25throw it in

00:55:25and the front

00:55:26slides and

00:55:27they're like,

00:55:27okay,

00:55:27and then they

00:55:28knew where it

00:55:28is.

00:55:28That's not me.

00:55:29I just step

00:55:30by step

00:55:31and last

00:55:33corner,

00:55:33turning on to

00:55:34the front

00:55:34straight downhill

00:55:35left,

00:55:35I was loading

00:55:37and I was loading

00:55:38and I was

00:55:38loading and

00:55:39then I was

00:55:39getting my

00:55:40lap times

00:55:40down and

00:55:41I turned

00:55:42in and I

00:55:42left the

00:55:43front loaded

00:55:44going down

00:55:44the hill

00:55:45for a little

00:55:46extra,

00:55:46just pushed

00:55:47it harder

00:55:47before applying

00:55:49the throttle

00:55:50and it

00:55:51chattered so

00:55:51much I

00:55:52screamed because

00:55:54it was the

00:55:54first thing

00:55:55the bike had

00:55:55done wrong.

00:55:56I was going

00:55:56fast enough

00:55:57to make it

00:55:57do something

00:55:58wrong and it

00:55:59chattered on

00:56:00that downhill

00:56:01and I screamed

00:56:02and I'm like,

00:56:03oh God,

00:56:03and I'm like,

00:56:04I didn't crash,

00:56:04thank goodness,

00:56:05and I did that

00:56:06and so the

00:56:06next lap,

00:56:07I could feel

00:56:08that nascent

00:56:09chatter coming

00:56:10and I adjusted

00:56:12the line so I

00:56:12could get on

00:56:13the throttle

00:56:13sooner instead

00:56:14of loading it

00:56:15in what I

00:56:16felt was a

00:56:16more ideal

00:56:17line.

00:56:18This is an

00:56:18excellent example

00:56:19of the

00:56:20motorcycle

00:56:20talking to

00:56:21the rider

00:56:22informing the

00:56:24rider that

00:56:24buddy,

00:56:26you're getting

00:56:26there,

00:56:27so go

00:56:28carefully and

00:56:30when people

00:56:31say as

00:56:32many MotoGP

00:56:34riders have

00:56:35said in the

00:56:35past,

00:56:36this thing

00:56:37has no

00:56:38feel in

00:56:39the front,

00:56:39what they're

00:56:40saying is

00:56:41they don't

00:56:41get any

00:56:42information from

00:56:43it,

00:56:43suddenly,

00:56:43you're gone,

00:56:45you're eating

00:56:46the gravel

00:56:47and this

00:56:50conversation

00:56:52between the

00:56:53rider and

00:56:54the machine

00:56:55is essential

00:56:56to going

00:56:57fast.

00:56:57their engine

00:56:59mounts are

00:56:59like these

00:56:59little blades

00:57:00now.

00:57:01Yeah,

00:57:01no resistance

00:57:02to lateral

00:57:03movement.

00:57:03Between the

00:57:03chassis and

00:57:04the engine

00:57:05they're mounting

00:57:05and it's

00:57:06allowing this

00:57:07flexure to

00:57:07happen.

00:57:08So that the

00:57:09upper frame,

00:57:10which has

00:57:11become quite

00:57:12attenuated,

00:57:13the upper

00:57:13frame is

00:57:14able,

00:57:15with carrying

00:57:16the steering

00:57:17head and

00:57:17keeping the

00:57:18front wheel

00:57:19in parallel

00:57:20to the

00:57:21plane of,

00:57:21the center

00:57:23plane of

00:57:23the motorcycle,

00:57:25is capable

00:57:27of moving

00:57:28from side

00:57:29to side

00:57:29like a

00:57:29lateral

00:57:30suspension.

00:57:31Not that

00:57:32way,

00:57:32that's right.

00:57:33Not the

00:57:33twist.

00:57:34Don't want

00:57:34that one.

00:57:36So the

00:57:39standard

00:57:39model on

00:57:40chatter says

00:57:41that it

00:57:42begins at

00:57:43the rear

00:57:44when slipping

00:57:46and gripping

00:57:46excites the

00:57:49ability of

00:57:50the whole

00:57:50tread band,

00:57:51which is

00:57:51quite stiff

00:57:52like a

00:57:53tank track.

00:57:54It can

00:57:55move laterally

00:57:56on the

00:57:57springs that

00:57:59are the

00:58:00much more

00:58:01flexible

00:58:01sidewalls,

00:58:02which are

00:58:03only a

00:58:03couple of

00:58:03millimeters

00:58:04thick.

00:58:05Well,

00:58:05more than

00:58:05a couple,

00:58:06but just

00:58:07a few

00:58:07millimeters

00:58:07thick.

00:58:09This thing

00:58:09has its

00:58:10own natural

00:58:10frequency.

00:58:13Well,

00:58:14what's going

00:58:15to happen

00:58:15is that the

00:58:16back end of

00:58:17the machine

00:58:17is going

00:58:18to go

00:58:18as you're

00:58:20pushing hard,

00:58:20leaned over

00:58:21in the

00:58:21corner,

00:58:22and that's

00:58:24going to be

00:58:24transmitted through

00:58:25the chassis

00:58:26to the front

00:58:26where the

00:58:28fork may

00:58:30have a

00:58:31bending or

00:58:33lateral

00:58:34frequency that

00:58:34is quite

00:58:35close to the

00:58:36chatter frequency,

00:58:36and that

00:58:37causes the

00:58:38front to

00:58:39build up

00:58:39into a

00:58:40tooth-chattering,

00:58:42confidence-destroying

00:58:44action that you

00:58:45won't forget.

00:58:46but this

00:58:48is just

00:58:49another form

00:58:50of vibration

00:58:51that a

00:58:52motorcycle can

00:58:53produce

00:58:55that can

00:58:56interfere with

00:58:58the application

00:58:59of power

00:58:59because you're

00:59:00thinking about

00:59:01something else.

00:59:03Namely,

00:59:04will I

00:59:04survive

00:59:05on to the

00:59:06next straight

00:59:07away?

00:59:07I hope

00:59:08so.

00:59:08But these

00:59:12things become

00:59:12familiar to

00:59:13people who

00:59:14push it,

00:59:15and so

00:59:16many

00:59:16motorcyclists

00:59:17are perfectly

00:59:18satisfied to

00:59:19have nice

00:59:21Saturday,

00:59:22Sunday,

00:59:23comfy rides,

00:59:24and I'm

00:59:25with them.

00:59:25That's fine.

00:59:26but it's

00:59:28good to

00:59:28know that

00:59:29these things

00:59:30exist,

00:59:32and that

00:59:33there are

00:59:33lots of

00:59:34people around

00:59:34that you

00:59:35can talk

00:59:35to about

00:59:35them if

00:59:36you're

00:59:36interested.

00:59:37They're

00:59:38experienced

00:59:38riders.

00:59:39Yeah.

00:59:40And a lot

00:59:41of times

00:59:41they aren't

00:59:42eliminated

00:59:42so much as

00:59:44they're moved

00:59:44out of the

00:59:45range.

00:59:46They're there,

00:59:47but you're

00:59:48not using

00:59:48the thing

00:59:49to generate

00:59:50that vibration,

00:59:52like you

00:59:53pointed out

00:59:53with the

00:59:54submarine

00:59:54engine,

00:59:55or we

00:59:55talked about

00:59:55with,

00:59:56the stints

00:59:56in 108,

00:59:57you avoid

00:59:58that band

00:59:58of RPM

00:59:59that causes

00:59:59the problem.

01:00:01Yeah.

01:00:01And you

01:00:02just carry

01:00:02on.

01:00:02It made

01:00:03me think

01:00:03of fins

01:00:04on air

01:00:06cooled

01:00:06engines

01:00:06because

01:00:07noise

01:00:09regulations

01:00:10tightened

01:00:11up,

01:00:11and as

01:00:12we wanted

01:00:12our

01:00:12motorcycles

01:00:13to be

01:00:13quieter

01:00:14anyway,

01:00:15we got

01:00:16little rubber

01:00:17cookies in

01:00:17between

01:00:18cylinder

01:00:18cooling fins

01:00:19to stop

01:00:20them from

01:00:21singing.

01:00:23And I've

01:00:23always wondered

01:00:24looking at

01:00:24the RD

01:00:25350 and

01:00:26RD

01:00:26400.

01:00:28It's got

01:00:28the great

01:00:29big cylinder

01:00:29fins on

01:00:30it.

01:00:31And then

01:00:32there are

01:00:33areas where

01:00:34there are

01:00:34gaps.

01:00:34And I

01:00:35always thought,

01:00:35well,

01:00:36that's where

01:00:36the cracking

01:00:36happened,

01:00:37either from

01:00:38heat expansion

01:00:39or vibration

01:00:41or both.

01:00:41and so

01:00:42that the

01:00:43fins were

01:00:43not,

01:00:43it wasn't

01:00:44a continuous

01:00:44saucer

01:00:45around,

01:00:45just take

01:00:46a single

01:00:46cylinder.

01:00:47It's not

01:00:47a continuous

01:00:47saucer.

01:00:48It had

01:00:49voids made

01:00:50into it.

01:00:51And I

01:00:51always thought

01:00:52that that

01:00:52was to

01:00:52change the

01:00:53mass,

01:00:53change the

01:00:54frequency of

01:00:54vibration.

01:00:56The OD

01:00:57of the

01:00:57fins is

01:00:58cool.

01:00:59Because it's

01:01:01mostly

01:01:01down at

01:01:03air

01:01:03temperature.

01:01:04And as you

01:01:04move in

01:01:05toward the

01:01:05hot cylinder,

01:01:06the temperature

01:01:06gets greater.

01:01:07So this

01:01:08is like a

01:01:08brake disc

01:01:09that is

01:01:11being heated

01:01:13more at

01:01:14the OD

01:01:14than it is

01:01:15at the

01:01:15inside edge

01:01:16of the

01:01:17friction

01:01:17track.

01:01:18And so

01:01:18the outside

01:01:21expands and

01:01:22stretches the

01:01:23inside.

01:01:23Should wish

01:01:24to cone.

01:01:25And then

01:01:25when it

01:01:25cools,

01:01:26the only way

01:01:27it can do

01:01:27so is to

01:01:28cone slightly.

01:01:30And that's

01:01:30what,

01:01:31when my

01:01:32rider came

01:01:33in complaining

01:01:33about there

01:01:35being no

01:01:36brakes,

01:01:37at the

01:01:38end of the

01:01:39straightaway,

01:01:39I got my

01:01:4012-inch

01:01:41straight edge

01:01:42out of the

01:01:42toolbox and

01:01:43laid it on

01:01:43the front

01:01:44discs and

01:01:44sure enough,

01:01:45they were

01:01:46coned.

01:01:48And I

01:01:48took them

01:01:49home that

01:01:49night and

01:01:51fixed them

01:01:52and brought

01:01:52them back.

01:01:55Don't try

01:01:55this at

01:01:56home.

01:01:59The industry

01:02:00soon came

01:02:01up with

01:02:01button floaters

01:02:03so that the

01:02:04disc ring

01:02:05itself was

01:02:05free to

01:02:06expand.

01:02:06They

01:02:07made the

01:02:07pad track

01:02:08narrower so

01:02:09the difference

01:02:09in heating

01:02:10rate was

01:02:10not great

01:02:11enough to

01:02:11cone them.

01:02:12So that's

01:02:13the way

01:02:13things are

01:02:14now.

01:02:15But that

01:02:15is learned

01:02:16by going

01:02:18as far as

01:02:19you can

01:02:19with the

01:02:20existing

01:02:20technology,

01:02:21discovering a

01:02:22problem,

01:02:23and then

01:02:23coming up

01:02:24with a

01:02:24solution

01:02:24over and

01:02:25over.

01:02:27Makes our

01:02:28present-day

01:02:28motorcycles

01:02:29pretty nice.

01:02:30Well,

01:02:31it's a good

01:02:31lesson to

01:02:32riders too

01:02:32is ride

01:02:36it until

01:02:37you actually

01:02:37discover a

01:02:39problem.

01:02:40If you're

01:02:40going to

01:02:40track days,

01:02:41have a safe

01:02:42motorcycle and

01:02:43do your

01:02:43safety wire and

01:02:44make sure your

01:02:45coolant is

01:02:45good and you

01:02:46have fresh

01:02:47brake fluid and

01:02:47all that

01:02:48stuff.

01:02:48Know how

01:02:49old your

01:02:50brake fluid

01:02:50is.

01:02:51It's a good

01:02:52test.

01:02:52Should I go

01:02:53to a track

01:02:53day, how

01:02:55old is my

01:02:55brake fluid?

01:02:56If you

01:02:56can answer

01:02:57that and

01:02:57it's not

01:02:57that old,

01:02:59sure, why

01:02:59not?

01:03:00But yeah,

01:03:01ride it until

01:03:01something tells

01:03:03you it's not

01:03:04happy and then

01:03:05try to adjust

01:03:05that specific

01:03:06problem.

01:03:07I mean,

01:03:08everybody wants

01:03:08to stick a

01:03:09fancy shock

01:03:09on and,

01:03:10you know,

01:03:11I've got to

01:03:11revalve these

01:03:12forks and I

01:03:12got to do

01:03:13this.

01:03:14It all

01:03:15helps, but

01:03:16ride it until

01:03:17there's a

01:03:17problem and

01:03:17then solve

01:03:18that problem.

01:03:19Because that

01:03:20brings understanding.

01:03:21You'll be

01:03:22better for it.

01:03:23Because otherwise

01:03:24you're just

01:03:25copying what

01:03:26you're seeing

01:03:27around you.

01:03:28Oh, that

01:03:28guy's got

01:03:29cartridge

01:03:31dampers in

01:03:32there.

01:03:32Oh, this

01:03:33fellow's, what

01:03:34make is that?

01:03:35I'm not

01:03:36familiar with

01:03:36those.

01:03:37I've got to

01:03:37look it up.

01:03:38But it's

01:03:40clear that

01:03:40you're never

01:03:41going to do

01:03:42anything

01:03:42outstanding by

01:03:43copying others.

01:03:46Right.

01:03:46Because getting,

01:03:48solving the

01:03:48problem that's

01:03:49holding everyone

01:03:50back is the

01:03:51biggie.

01:03:52Yeah, I

01:03:53mean, you

01:03:54have to admit

01:03:55to yourself

01:03:56as I, I

01:03:58had to admit,

01:03:59for example,

01:03:59okay, it's

01:04:00very easy to

01:04:01say I am

01:04:01not Mark

01:04:02Marquez.

01:04:03Mark Marquez

01:04:03is riding a

01:04:04motorcycle that

01:04:05I will never

01:04:05experience.

01:04:06I could get

01:04:06on his

01:04:07motorcycle and

01:04:08I will not

01:04:08have the same

01:04:09experience.

01:04:10I will not

01:04:10get the same

01:04:11information.

01:04:12There's no

01:04:13world where I

01:04:14can extract

01:04:14information from

01:04:16his motorcycle

01:04:16because it's

01:04:17outside of my

01:04:18functional range.

01:04:19Yep.

01:04:20And I, I

01:04:21had to admit

01:04:22that with

01:04:22Don Cane.

01:04:23Hey, you

01:04:24know, I

01:04:24went on my

01:04:25first press

01:04:26launch with

01:04:26Don Cane to

01:04:27the Suzuki

01:04:27Hayabusa launch

01:04:28because I was

01:04:29at Cycle

01:04:29News and I

01:04:32went pretty

01:04:33good at that

01:04:33press launch and

01:04:35then there goes

01:04:35Don and then

01:04:37just as I

01:04:39got faster, I

01:04:40got closer to

01:04:41Don but I was

01:04:42never the same

01:04:42speed as Don and

01:04:43you just have to

01:04:44say like, you

01:04:45know, we had

01:04:46same, we would

01:04:47have conversations

01:04:47about the way the

01:04:48bikes were behaving

01:04:49and we usually

01:04:50concurred and I

01:04:51felt good about

01:04:51that because he's

01:04:52got a lot of

01:04:53talent and he's

01:04:54paid attention and

01:04:55so I was happy

01:04:56that I could be in

01:04:57the ballpark but

01:04:58when Don was

01:04:59ready to push, he

01:05:01could put this

01:05:02amount of lean

01:05:02angle on street

01:05:04tires and with a

01:05:05soft seat, he

01:05:06was able to get

01:05:07information, which

01:05:09is vibration, I

01:05:10think, we're

01:05:11getting, we're

01:05:12getting a signal,

01:05:13yeah, we're

01:05:13getting a signal,

01:05:14he was able to

01:05:15get information that

01:05:16I would never get

01:05:17out of a bike and

01:05:18it's impressive,

01:05:20you know, it

01:05:21really is.

01:05:21So anyway, just

01:05:22don't throw parts at

01:05:23your motorcycle, make

01:05:24it safe and then

01:05:26when you notice a

01:05:27problem like, oh,

01:05:28it's pumping, oh,

01:05:29it's chattering, oh,

01:05:30whatever it might be

01:05:31or it clunks when I

01:05:32hit the brakes.

01:05:34Fix the thing that's

01:05:35holding you back.

01:05:36Yeah, exactly.

01:05:41Well, we've

01:05:41vibrated out,

01:05:43have we?

01:05:43You have something

01:05:44else you'd wish to

01:05:45shake us up with?

01:05:48Yeah.

01:05:48Well, no, that's

01:05:51we've covered a lot

01:05:54of ground here

01:05:55because there's

01:05:56there's the basic

01:05:57source of vibration,

01:05:58which is the

01:05:59piston moving

01:06:01back and forth

01:06:01in a straight

01:06:02line, experiencing

01:06:03very high rates

01:06:05of acceleration

01:06:05and deceleration.

01:06:07And because that

01:06:08force has reacted

01:06:09to the engine,

01:06:10the engine is

01:06:10moving back and

01:06:11forth slightly,

01:06:12and that takes

01:06:13with it the frame

01:06:14and everything

01:06:15attached to it,

01:06:16which is why

01:06:17you feel

01:06:18vibration

01:06:19in your feet,

01:06:21in your hands,

01:06:23and on your

01:06:24behind.

01:06:25And

01:06:26there are other

01:06:28sources.

01:06:29If something is

01:06:30not balanced

01:06:32that's rotating,

01:06:33I remember that

01:06:34there was a case

01:06:35of a

01:06:36TZ750

01:06:37clutch

01:06:38that was out

01:06:38of balance.

01:06:39I don't know

01:06:39how that would

01:06:40happen,

01:06:41but evidently

01:06:42it did,

01:06:42and the rider

01:06:43was being

01:06:44driven nuts

01:06:45by it.

01:06:45They finally

01:06:45found it.

01:06:48Then there's

01:06:49the problem

01:06:50of torsional

01:06:52vibration,

01:06:53which is not

01:06:54so much

01:06:54a power

01:06:55absorbing,

01:06:56but a

01:06:58form of

01:07:00motion that

01:07:01interferes with

01:07:02making horsepower

01:07:03because it

01:07:04destroys valve

01:07:05timing and lift,

01:07:06and maybe

01:07:07the integrity

01:07:08of the parts.

01:07:11And then

01:07:11we have

01:07:12the stability

01:07:13of the motorcycle.

01:07:14The whole

01:07:14motorcycle can

01:07:15vibrate as

01:07:16two casters

01:07:17with a

01:07:17common pivot.

01:07:19And then

01:07:20we last

01:07:20discussed

01:07:21chatter,

01:07:24which in

01:07:25MotoGP

01:07:27used to be

01:07:28called

01:07:28vibration,

01:07:29but now

01:07:30they're starting

01:07:30to say

01:07:30chatter again.

01:07:31Language is

01:07:32always changing.

01:07:33so I'm

01:07:37sure that

01:07:38you will

01:07:38find in

01:07:40your

01:07:40recollection

01:07:41of things

01:07:42that have

01:07:42happened to

01:07:42you in

01:07:43your riding

01:07:43career,

01:07:44evidence of

01:07:44some of

01:07:45these forms

01:07:47of vibration.

01:07:48It's just

01:07:48cool to

01:07:50know a little

01:07:51more about

01:07:52where it's

01:07:53all coming

01:07:53from.

01:07:54Well,

01:07:54you know,

01:07:54in the

01:07:54reference for

01:07:56certain riders

01:07:56is what it

01:07:57is.

01:07:58So we

01:07:58had a

01:07:59guy on

01:08:00staff who

01:08:00was a

01:08:00real fast

01:08:01road racer.

01:08:03And he

01:08:04liked to

01:08:05ride every

01:08:05kind of

01:08:05bike.

01:08:06I would

01:08:06say he

01:08:06was a

01:08:06good Cycle

01:08:07World guy,

01:08:08you know,

01:08:08likes to

01:08:09ride everything,

01:08:10puts the

01:08:10hat on and

01:08:11experiences cruisers

01:08:12and all that.

01:08:14Dirt bikes,

01:08:15you name it.

01:08:15And fast on

01:08:16everything,

01:08:17smooth on

01:08:17everything,

01:08:19sympathetic to

01:08:19the machinery,

01:08:21kept them

01:08:21clean,

01:08:23and could

01:08:23settle up

01:08:24time.

01:08:24And did a

01:08:25lot of

01:08:25inline-four

01:08:26riding,

01:08:26race 600s

01:08:27and thousands

01:08:27and all

01:08:28that.

01:08:29And then

01:08:29one day

01:08:30we got a

01:08:31Harley-Davidson

01:08:32with a

01:08:32135-inch

01:08:34crate engine

01:08:34in it.

01:08:36And it's

01:08:37great.

01:08:37The 135's

01:08:38stellar.

01:08:40It's amazing.

01:08:41Very big

01:08:41booms,

01:08:42a lot of

01:08:42power.

01:08:43I forget

01:08:43what we

01:08:43got on

01:08:44the dyno,

01:08:44but

01:08:44astronomical

01:08:45torque.

01:08:46I think

01:08:46140 pound

01:08:48feet or

01:08:48something like

01:08:48that.

01:08:49And he

01:08:50rode that

01:08:50bike and

01:08:50I was

01:08:51going to

01:08:51ride it

01:08:51on a

01:08:52long ride.

01:08:52He rode

01:08:53that

01:08:53motorcycle

01:08:53and he

01:08:54came back

01:08:54and said,

01:08:54something

01:08:55wrong,

01:08:56man.

01:08:56Front wheel's

01:08:57way out

01:08:58of balance.

01:08:59I'm not

01:08:59really sure

01:09:00what's going

01:09:00on.

01:09:00I'm like,

01:09:01oh man,

01:09:01okay,

01:09:02well,

01:09:02thanks for

01:09:02bringing it

01:09:02up.

01:09:04And so

01:09:04we sent

01:09:06it back

01:09:06to the

01:09:07fleet

01:09:07center.

01:09:08The guy

01:09:08up there

01:09:09is tip

01:09:10top.

01:09:11He's like,

01:09:12nope,

01:09:13wheels balance,

01:09:14everything's

01:09:14fine.

01:09:15He's like,

01:09:15steering heads

01:09:16loose,

01:09:16right?

01:09:17Nope,

01:09:17no,

01:09:18everything was

01:09:18perfect.

01:09:19And he

01:09:19brought it

01:09:20back and

01:09:20I rode it.

01:09:21And it

01:09:21was just,

01:09:22it was

01:09:22great big

01:09:23pistons moving

01:09:24through a

01:09:25great big

01:09:25stroke at

01:09:27high compression

01:09:28and just

01:09:28booming.

01:09:29It felt

01:09:30like a

01:09:30tapping in

01:09:32your hands.

01:09:33And those

01:09:34pistons are

01:09:34not heavy

01:09:35in comparison

01:09:36with the

01:09:37bore size.

01:09:38They look

01:09:39just like

01:09:39the piston

01:09:40you held

01:09:41up.

01:09:42And the

01:09:43ring pack

01:09:43on the

01:09:44135 is

01:09:45in fact

01:09:45the same

01:09:45as that

01:09:46used on

01:09:46the racing

01:09:48motorcycles.

01:09:49Yeah.

01:09:49The baggers,

01:09:51the king of

01:09:52the baggers

01:09:53bikes.

01:09:53So this

01:09:56rider had

01:09:56encountered

01:09:57real

01:09:57vibration.

01:09:59Yep.

01:10:00And it

01:10:01was fine.

01:10:02Get the

01:10:02grips with

01:10:02this.

01:10:03Yeah.

01:10:04Well,

01:10:05you know,

01:10:06it's been

01:10:07a while,

01:10:08but,

01:10:08you know,

01:10:09you ride a

01:10:10Velocet and

01:10:11you feel certain

01:10:11things.

01:10:12You ride a

01:10:12Norton

01:10:12Commando and

01:10:14you know what

01:10:14vibration is

01:10:15until ice

01:10:15elastics

01:10:16suddenly take

01:10:18it away.

01:10:19That'd be

01:10:19something to

01:10:20talk about

01:10:20one day,

01:10:21ice elastics.

01:10:21You touched

01:10:23on it.

01:10:24Well,

01:10:24thanks for

01:10:24listening,

01:10:25folks.

01:10:25That's it

01:10:26for today.

01:10:27We appreciate

01:10:28you riding

01:10:29with us and

01:10:30we'll see you

01:10:30down in the

01:10:31comments and

01:10:31we will catch

01:10:32you next

01:10:32time.

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