The WEIRDNESS of METALS is what makes them so GREAT--MELTY, MALLEABLE, M-AWESOME
Metals are absolutely key to our good times on two wheels. Steel, Aluminum, Chromium, Nickel, Copper, Brass, Magnesium ("electrified dirt") and all the alloys make up our most loved form of transportation and good times. As ever, CW Technical Editor Kevin Cameron knows a lot of key details which he shares with Editor-in-Chief Mark Hoyer and the rest of us. Thank you for all the support of the podcast and please let us know in comments what you like and what you don't--but leave Hoyer's headphones out of it... :)
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SportsTranscript
00:00:00Welcome back to the Cycleworld podcast. It's another week, it's another Wednesday,
00:00:05and we're here. We're really glad in the comments that everybody says Wednesday
00:00:10is their favorite day or TGIW, somebody said. I was delighted by that. We
00:00:16really appreciate all that. We enjoy hearing what you think and sharing your
00:00:22knowledge, which happens quite a bit. We have a super smart audience on the whole
00:00:27and this week we have a real barn burner for you. It's actually such a
00:00:35broad topic. I don't know what we're gonna do in an hour, but we're gonna give
00:00:40it a shot. The topic is metals, and boy is that broad, but we can't get around the
00:00:46fact that virtually everything that we really need to be tough and do things is
00:00:51made of metal. There's certainly great other materials, and boy we love plastics
00:00:56and carbon fiber and Kevlar and all these other things, but at the end of
00:01:01the day, steel, aluminum, titanium, copper, silver, that kind of everything that we
00:01:11love in the motorcycle world kind of starts with all those materials. You know,
00:01:16Kevin's gonna probably use the term asperities again, his favorite word.
00:01:22We'll just see if that happens naturally. I brought it up, and you know, we have
00:01:27some notes as we always do, and I'm looking at one part of these and it says
00:01:30delocalized electrons, and I'm like, oh that's interesting. So I think what we'll
00:01:35do is we'll start with some of the basics about what makes metals great in
00:01:42our world and fundamental to our love of movement, and then what those qualities
00:01:47are, what the metals are, and then specific applications, and if we got time
00:01:51we'll get into coatings and chromium and, you know, alloys and all that, so.
00:01:57Let's not leave out niobium for our friends in South America. Yeah, so where
00:02:06do we start, Kevin? You're good at this. Well, the thing is that early humans must have
00:02:12just been knocked over when they ran into what they call native copper, which
00:02:16is copper, not as a sulfide or an oxide or, you know, some kind of an ore
00:02:22where it's combined and it doesn't display metallic properties, but just
00:02:27regular old metallic copper, and you could bend it within limits. You could
00:02:37pound it in to make it thinner. You could, and if it began, when you pounded it
00:02:45enough, the metal got tired of all that and started to split, but if you put it
00:02:51in the fire and got it red-hot and brought it out, it was soft again. It was
00:02:57a mystery, and it went on like that for some thousands of years, a curiosity.
00:03:03I'm the big chief here. I've got the copper lump. I just want to sidebar that
00:03:09you can do that to your copper ceiling washers. You heat them up
00:03:13with your propane torch, and you dip them in water real quick, and you can
00:03:17reuse your copper ceiling washers. It softens them right up. RD-350 circular
00:03:22head gaskets. Yes. Same, same. Well, later on they found they could melt this stuff,
00:03:30and they could pour it into shaped cavities, casting. They could cast axe
00:03:38heads. They could cast all sorts of things, arrow points, out of this
00:03:43mysterious material, and the wonderful thing about metals is that they are
00:03:51malleable. You can bend them without having them snap like a piece of stone
00:03:58or substantial pieces of wood. This malleability comes from the fact that
00:04:08metals have full electron shells, and metallic materials are permeated by a
00:04:16gas of electrons, which are delocalized, and they have no permanent home. They
00:04:25circulate through the crystal lattice so that the nuclei are slightly positive,
00:04:34and they're in this negative gas. When you apply great stress to nonmetals, a
00:04:45fracture begins, and it quickly spreads through the material and click. That was
00:04:52the key to making flint tools, was knowing just how to strike the core to
00:05:00spall off a flake that you could use. Fracture. But with metals, if the metal
00:05:09started to yield, the atoms just rumbled past one another, but they were still
00:05:15well stuck together because they were still filled with the permeating
00:05:19electron gas. This is responsible for the high thermal conductivity of metals
00:05:29and the high electrical conductivity because those electrons are just buzzing
00:05:34around in there. They're very mobile, so energy is rapidly distributed through
00:05:42metals. Those with high conductivity, like a silver spoon, put it in really hot
00:05:47coffee, and very quickly it's too hot to hold the handle. Put a stainless spoon in
00:05:55there, it doesn't care. It never gets warm at the handle because there are so
00:06:01many other atoms besides iron in there. There's a lot of chromium and quite a
00:06:06bit of nickel that the structure becomes irregular, and the electrons are kind of,
00:06:13which way through here? This is the great thing about metals, is that
00:06:21they bend, they don't break. The next thing that we found, the humans early on,
00:06:30they found that they could forge it, as I described. They could cast it.
00:06:35When more advanced methods became available, you could make sheets out of
00:06:42this material. It could be rolled. You could form the sheets into shapes. You
00:06:47could press them between dies. Metals can assume virtually any shape. I know I can
00:06:55hear the additive manufacturing people rustling in the back of the room.
00:07:01Yes, we know it's a new field. 3D printing, folks. Yes, indeed. But these
00:07:08traditional methods developed very quickly after 1860 and rolled sheet
00:07:18steel and other sheet metals. Just had a million applications almost immediately.
00:07:26Of course, they rolled plates from which ships were riveted. They rolled
00:07:34iron rails at first, and then when they learned how to make steel in quantity,
00:07:39they found that steel rails lasted seven times longer than iron rails, because
00:07:46steel is so much stronger and tougher than iron. Might be a good time to talk
00:07:52about recipes, eh? Alloys and all that. Well, that was, I think a lot of
00:08:02chemistry was the work of gifted amateurs who had independent wealth. A
00:08:08lot of tabletop science went on in the late 19th century and the early 20th
00:08:15century, to the end that in about 1895, Winchester adopted nickel steel for gun
00:08:25barrels, because adding 5% nickel, one part in 20, to ordinary carbon steel
00:08:34resulted in a 40% increase in strength, which was just in time for the new
00:08:41smokeless powders, which burned at a much higher pressure than previous gun powder.
00:08:47And the other early application, under very high stress, was the side plates
00:08:55of roller chain for the bicycles, the safety bicycle, which became very popular
00:09:00around the same time, 1895. And also in that period, there was a German fellow
00:09:10who developed a ball grinder, and he found that by making little pellets of
00:09:19high carbon steel, they could be ground into balls. And Leonardo da Vinci's idea
00:09:27of the rolling bearing could be realized at fairly low cost. And within a short
00:09:33time, this fellow in Germany was making a million balls a week. And all this stuff
00:09:40was really super hot and happening scene around 1900. So in a way, the internal
00:09:50combustion engine, which was arriving at the same time from like 1876 onward,
00:09:59practical metal handlers, they weren't dignified with the term metal artists yet,
00:10:05were ready to take on a lot of these problems and come up with practical solutions that worked.
00:10:13It is said that the czar of all the rushes was presented with a set of aluminum dinnerware.
00:10:20And of course, it would have rivaled the gold dinnerware set that guaranteed
00:10:26that all those royal personages never got a hot meal.
00:10:30Because of that conductivity, heat conductivity of metals. So the easiest metal to work at the
00:10:39time that we're talking about, the turn of the century, 1900, was iron, because the railroads
00:10:47had used it for everything. And they were very adroit at casting complicated shapes.
00:10:54So you want a cylinder with fins on it? You want a cylinder with a valve chest
00:10:59cast on the side of it? No problem. And so iron was the material of early internal combustion
00:11:09engines. And iron, because it contains graphite, large areas of slippery carbon,
00:11:20it also gives it surface texture that holds oil, is an excellent friction surface. And that's why
00:11:27the iron liner persisted as long as it did. So those early engines, iron was a godsend because
00:11:36you could seat valves on it, didn't need a hard seat ring. Pistons could slide up and down in it.
00:11:43And it was strong enough structurally to contain the force of combustion.
00:11:49And aluminum didn't come as a piston material until really World War I, because
00:12:00there was W.O. Bentley, who started out wanting to be on the footplate. He wanted to be an engine
00:12:09driver. And he was caught up in all of this technology. And at one point, he was importing
00:12:18a little French car and he noticed on the desk of one of the executives of this French company,
00:12:25a little piston. What is this? Ah, this is aluminum. It's only a curiosity with a Gallic shrug.
00:12:36So old W.O. went home. He went to his favorite foundry and he said,
00:12:43what can you do along these lines? And at this point, internal combustion engines had
00:12:52cast iron pistons, as well as cast iron cylinders and cast iron piston rings.
00:12:59And they made the material very, very thin because they were so skillful at casting it. But
00:13:06cast iron pistons would sometimes become red hot in the dome and lead to what people called,
00:13:14with British understatement, misfiring. Deadly, deadly pre-ignition. And in a couple of cycles,
00:13:25the piston would be punched through, end of day, walking. So there's W.O. at the foundry.
00:13:33And the foundry guy said, well, we could start with a few percent of copper. Well, that's good.
00:13:42Fine. Make me a bunch of these. When he put these aluminum pistons into the engines he was importing
00:13:50from France, he found that the power went up immediately. How could pistons make more power?
00:13:58How can changing the metal make more power? Here's how it worked. Even if the pistons weren't
00:14:05red hot, they were very hot. When the air came into the cylinder on the intake stroke, it hit
00:14:11that hot piston and became hot itself. And it expanded in such a way that it sent a message
00:14:18out the intake valve, no more jobs are all taken. And so the charge density was low.
00:14:27But when they put in aluminum pistons, they transmitted heat so well that the center of the
00:14:34dome could run at an acceptable temperature because the heat was flowing from it outward
00:14:41to the cylinder wall so quickly. So that's how the power went up, just by changing the material.
00:14:48It was a lovely story. Of course, W.O. Bentley, his story was a long one, and he went on to
00:14:56manufacture very distinguished motor cars. So those early engines at Brooklands, there's a
00:15:06lovely little book about racing at Brooklands, and it has all of this antique stuff in it, people
00:15:12having difficulties that no longer exist. But during World War I, W.O. introduced aluminum
00:15:23pistons into the Bentley rotary aircraft engine, and they worked so well that everyone else just
00:15:29said, I give up, we'll make those too. So aluminum became the dominant material for making pistons,
00:15:37as it remains to this day. Even though at one point, Daring Dan Gurney decided to have some
00:15:46beryllium pistons made, because beryllium has good heat transfer qualities, very high stiffness,
00:15:55and it's sort of dreadful to work with because it's sort of sintered from powder. And if you
00:16:03inhale this dusty stuff while you're machining it, you contract berylliosis and farewell,
00:16:11you'll find all the insurance papers are in that box, and farewell again.
00:16:17Makes a good valve seat alloyed with bronze. Yes, yes, beryllium bronze has good strength
00:16:26and reasonable heat conductivity. Another invention of the period around 1895 was
00:16:38seamless drawn steel tubing. Now you can make steel tubing by curling up sheet metal and welding
00:16:45along the seam, but stress always finds the zones of maximum defect density, and as a weld cools,
00:16:59the cooling forces many of the impurities ahead of it, so that they end up in a line right down
00:17:05the middle of the weld, and that area is subject to fatigue failure. So seamless drawn tubing
00:17:13remains the desirable form of steel tubing to this day for that reason.
00:17:20As you can imagine, all these lessons were learned in little steps and with considerable pain,
00:17:31but the goal in view was tremendous. A material that transformed everything. When they started
00:17:37to make ships out of steel, they could really make some good-sized boats.
00:17:47So aluminum casting is something that has taken a step forward as recently as 25 years ago,
00:17:58because at the time that I was working with three-cylinder Kawasaki's in the early to mid-70s,
00:18:05if something needed welding, then the welder would invariably say,
00:18:12welding thing would exfoliate when you got the die-cast metal hot gas inside the metal,
00:18:20caused it to look like baklava. And you could see the welder poking at it with the rod and
00:18:30brushing it and carrying on, and eventually some kind of a weld would be achieved.
00:18:36You couldn't heat treat die-cast material for the same reason that when you got it hot,
00:18:41it would exfoliate. But they discovered, 25 years ago doesn't seem all that much to me at this point,
00:18:51that there was a better way to cast aluminum. What had been done in the past was you had a
00:18:59mold made in two or more pieces, an upper and a lower, and any cores that were required,
00:19:05for example, something to occupy the cylinder bore so that it didn't become solid all the way
00:19:10through when you poured the metal. And so other ways of supporting where there are going to be
00:19:18fins, they would pour the metal in and it would fill up from the bottom while they're pouring it.
00:19:28And the pouring of hot metal, you cannot stop atmospheric oxygen from forming an oxide layer
00:19:37on top of the hot metal. And the aluminum is avid for oxygen. And this method of pouring
00:19:47caused this aluminum oxide film, which is not soluble in aluminum. No, our instinctive model
00:19:55is based on pudding. Pudding forms a skin, you stir it, the skin goes away, but not so with
00:20:05aluminum oxide. So the problem that was discovered by this John Campbell working in a British
00:20:14university was that the aluminum oxide films were being entrained into the liquid metal and were
00:20:26cooling with it and formed an internal fail on dotted line entity. And
00:20:36foundries got around this and die casting designers got around this by just,
00:20:41we'll make it thicker. If it's not real strong, we'll make it thicker.
00:20:45So around the year 2000, these new methods of casting filling from the bottom and fairly gently
00:20:54so that it wasn't enough turbulence to mix the films in with the liquid. The films would
00:21:01stay floating on the surface and rise to the top of the mold and then out through the vents
00:21:08and leaving nice pure aluminum alloy behind to cool. And that was so outstanding, an advance,
00:21:19that I was told by a crew chief for one of the racing teams here in the US that
00:21:29their brand was a bit behind at the time because the Yamahas were 30 pounds lighter.
00:21:38Yamaha has always been really progressive with the casting technology, that controlled
00:21:44fill. I think they use a vacuum as well on some so that you don't have any, you know,
00:21:49you have no appreciable oxygen in the mold. If there is any, the aluminum will find it.
00:21:55Yeah, the frame on the FC-09, MT-09 is a beautiful example of,
00:22:04it's two cast pieces, it's two halves that are bolted together at the steering head. They use
00:22:08bolts that, you know, are permanent bolts. The part comes out so close to finished that there's
00:22:15virtually no work. There's a little bit of machining at the steering head for the bearings
00:22:18and then there's a minor amount of machining at the engine mounts. And so it can be made
00:22:23very inexpensively and very lightweight because it's just thick enough, as you say,
00:22:29no entrainments, no mark in his backyard, heating up a pan of aluminum and pouring into a mold and
00:22:34having it churn up and have those oxides separating the casting, basically. I mean,
00:22:39it's very small, but the metal is not joined there. And as you said, that's a place for
00:22:45failure. And the frame on the MT-09 was just so clever and really nice and very low labor to
00:22:53finish. The part comes out nearly done, the absolutely nearly correct size, not tons of...
00:22:59What they call that net shape.
00:23:01Net shape. And it's just, it was really, really something. And as you say,
00:23:07man, the lightness that we've seen in motorcycle engines.
00:23:11Engines, yes. For example, Ducati's V4 with the fuel injection sitting on top of it
00:23:17is like 140 something pounds.
00:23:20Imagine the specific output.
00:23:22That's what a TZ750 engine weighed, 140 pounds. It didn't have any cams or valves or any of that
00:23:28stuff. So that tells you that the TZ750 had way too much metal in it by modern standards.
00:23:37So engines and chassis weight just went...
00:23:41So this is, I think, a good time because what you said about castings,
00:23:47controlled fill coming out near strength of forging. We should talk about the difference
00:23:53between a cast piston and a forged piston or cast parts and forged parts and why
00:23:59we like forgings when we're getting fancy.
00:24:02Yeah. Well, whenever you're talking about a high fatigue situation, such as a connecting rod or
00:24:09a piston subject to all sorts of cyclic stress that quickly mounts up into the millions of cycles,
00:24:18you know that statistically there's damage occurring on every stress cycle.
00:24:25And one day it will result in a crack and how many thousands, millions of cycles more.
00:24:31And you'll have a failure. You're hoping that you can get it to the junkyard before that happens.
00:24:37And today they're very successful with this. Wonderful, wonderful materials. It used to be
00:24:45that truck crankshafts, racing, race car crankshafts and connecting rods are made from
00:24:524340. And when 4340 is vacuum remelted to allow impurities to
00:25:03evaporate from the hot metal, it becomes 300M, which is what the landing gear struts on 747
00:25:12were made of. And I think there's considerable stress there. Here comes that thing with its
00:25:19undercarriage dangling underneath it. It reminds me of those mud wasps.
00:25:24And then the wheel smashed down onto the runway, which by the way, has to be three feet thick at
00:25:31the touchdown point for those aircraft. And the passengers are already putting away their
00:25:40newspapers and their personal electronics and getting ready to look for a cab.
00:25:48I mean, at least on landing, they've already burned the 300,000 pounds or 400,000 pounds of
00:25:53fuel. So you got that going for you, but still not light. Yep. That's a fact. So,
00:26:01yeah, those airplanes burned 25,000 pounds per hour.
00:26:07And, but I, I love that, that 300M, those, those many of the metals that are in use today
00:26:16have fancy names, but they are directly related to materials that have been around a long time.
00:26:25So 8620 was a case hardening steel for making gears and for making Yamaha connecting rods in
00:26:37the two-stroke era, where all 8620, you can make a thin, hard case on that material that
00:26:45makes a good bearing race. And of course, gears where the teeth press against each other,
00:26:51the pressure there can, can be up to a hundred thousand pounds per square inch, which is
00:27:01marvelous that mechanisms can operate with pressures like that.
00:27:05So we would call that durability, right? That's not toughness. That's really...
00:27:10Well, it's a combination because the material in the gear
00:27:17requires toughness. That is, instead of failing, it yields.
00:27:23We want it to have a gooey center. Like you don't, you don't want to harden, you don't want
00:27:27to harden a gear all the way through because it'll crack. And you don't want to, that's why
00:27:31plasma nitriding of a crankshaft is useful because you bombard the surface and you
00:27:36compress the surface and you make the surface hard, but the inside of the crankshaft is still
00:27:42got some... It can take it. In the early days, in the early days of when carbon steel was king,
00:27:51which is sort of before 1900, you would heat a tool up red hot and then quench it,
00:27:59which would give it very high hardness, but it would be brittle.
00:28:04And when they came up with nickel steel, nickel removed some of that brittleness.
00:28:11And later they came up with the idea of case hardening, which you just mentioned, bombarding
00:28:16the surface or baking the material in a nitrogen rich atmosphere so that the nitrogen diffuses
00:28:25into the surface. There you can produce a very hard surface suitable for
00:28:33gear teeth meshing together or roller bearing to rumble over it.
00:28:40And yet the material underneath it has tremendous toughness. And what toughness is, you can imagine
00:28:48a Christmas candy. It just snaps the usual red and white candy cane. It's brittle.
00:28:58It may be strong, but it's brittle. And when it fails, it fails, click, you're done. Whereas taffy,
00:29:06you pull, you pull and pull and it gets thinner and thinner. This is what happens to ductile
00:29:13metals. Finally, bang, failure. What you've done is a lot of work, force that it takes to stretch
00:29:22it. Times distance is foot pounds. Foot pounds is work. And what you're trying to do to make a tough
00:29:32steel is to make it cost the force that's applied to it, a lot of foot pounds to produce failure.
00:29:43So you make the inside of gears tough. You make the surface very hard. The alternative for Formula
00:29:51One and other forms of racing where the gears will not do millions of cycles is a hard cut.
00:30:00The gear material is hardened enough to be so-so on tooth wear and maybe a little
00:30:08less tough than you might like it optimally, but it simplifies the process so much because the gears
00:30:16get heat treated and then the carbide cutter cuts the teeth. This reminds me of a conversation that
00:30:28you had with Byron Hines when we were at the test of one of the, I believe it was the first Harley
00:30:35drag bike that they did with the giant V-twin. And you asked him, he brought parts to show us
00:30:42and we were standing there and you asked him a question related to that. It was a gear, I think
00:30:47it might've been a gear, great big gears and the pistons were massive and the connecting rods were
00:30:52these giant aluminum forging. It's a 2600cc twin. Yeah. So you could imagine. It had to have push
00:31:01rods. It had all these limitations on it to make it Harley-esque for the effort. Harley-esque,
00:31:06yes. Well, there was no production part probably. No Harley parts at all in those things. But
00:31:14spiritually making the boom boom. But you asked him about that and you asked him about a surface
00:31:21treatment. He says, no, no, it doesn't need to last a long time. It just needs to be really tough
00:31:28and that they could just make it out. They didn't have to mess around with bombarding a
00:31:32surface or baking it in a nitrogen rich atmosphere, which I'm assuming is
00:31:37almost pure nitrogen because we are in a nitrogen rich atmosphere right now.
00:31:41Yes, we are. Just happens to have the oxygen we need.
00:31:48Thank goodness. Let's see, questions I have, as we talked about this podcast,
00:31:57you mentioned Yamaha showing up with plated aluminum cylinders. Yeah. And I think that's
00:32:05interesting because you have to do, you kind of have to do a lot, not a lot, but to make an
00:32:11aluminum piston work in an iron cylinder, certainly you have to make allowances. And then if you want
00:32:18to use an aluminum cylinder, which would probably expand at a very similar rate to your piston and
00:32:22give you the opportunity to make close clearance without seizure, but you want it to wear a long
00:32:27time. I think telling the Yamaha story that you told about showing up at GP is a good place to
00:32:35start. And let's talk about some of that low expansion. Okay. Just a little background first,
00:32:40which was that in the development of British singles for racing in the Isle of Man TT,
00:32:46cast iron, of course, was the first material and the engines were flathead side valve to Englishman.
00:32:53And as they develop more power, problems develop because iron could tolerate the heat,
00:33:03but in order to get rid of more and more heat, the iron had to be made hotter and hotter,
00:33:08which meant eventually the oil would boil. And so one of the first things they did was to make
00:33:14the cylinder head out of bronze and bronze has about twice the heat conductivity of iron.
00:33:25And so the famous Triumph Ricardo single had a bronze cylinder head for that reason. And I think
00:33:34there were some Vincent TT replicas that were made with bronze heads. The pre-war Triumph twins,
00:33:42you could get a bronze head. Yeah. A friend of mine owns one with a bronze head. It's
00:33:47option. Well, it's just so, you know, a sidebar on materials. It's just so beautiful.
00:33:53Just you, you see the color and you see the difference and it makes you have a feeling.
00:33:58And when I see really high quality valve springs that are made today where you can just,
00:34:03the sheen, the nickel, they're just, it's just gorgeous. But yeah, bronze, right? Bronze. Let's
00:34:08talk about bronze. Bronze didn't last long because they were increasing the horsepower of engines
00:34:15rapidly at the time. And so what they really needed was aluminum heads, but they couldn't
00:34:22make valve seat inserts stay in the aluminum because the aluminum would get hot and it
00:34:28would lose strength and the seats would come loose. And so it was necessary at that point
00:34:37that a certain invention took place in the state of Ohio when at the Army's Air Development Center,
00:34:48S.D. Heron remembered Y-alloy. Y-alloy was terrible, he remembered, because you couldn't
00:34:57cast it. If you cast it cool enough not to be filled up with porosity, it wouldn't fill the mold.
00:35:05It behaved like pudding with steel wool pieces in it. It just clogged up all those
00:35:16fine structures in the mold. So, okay, we'll heat it up more. And now it pours in nicely,
00:35:25fills the mold, but it's filled with porosity. So, you know, it came down to would you prefer to be
00:35:32hanged or shot? And so Sam Heron went to his metallurgist, E.H. Dix, Jr., who later became
00:35:46chief metallurgist at Alcoa, and he said, fix this stuff. It won't, it doesn't cast well.
00:35:56Make it act like there's silicon in it or something. So Dix went away and did his
00:36:03a bit of study, and he came back with what was, during the Second World War, was called
00:36:11alloy 142. And literally millions of radial engine cylinder heads were cast out of this material.
00:36:19And Harley-Davidson adopted it for the pan head. So once they had this material,
00:36:27which had high hot strength, it contained copper, like the original W.O. Bentley's
00:36:34first aluminum pistons, also nickel, also iron, and I think some magnesium.
00:36:45The alloying materials formed a variety of intermetallic compounds in the aluminum.
00:36:55That's why I used that steel wool fragments analogy, that it had a structure that when the
00:37:02material cooled was very strong, and it retained strength to a high temperature. This was the key
00:37:11to making it retain valve seats. I think Velocette were the first to use the new
00:37:16modified Y alloy. So that gets us to the point of about 1960. And the problem with seizing
00:37:27in a two-stroke is that the cylinder, particularly the fins, are relatively cool because all this air
00:37:36is passing through them. And the bore of the cylinder is cooler than the piston. Otherwise,
00:37:44the piston couldn't be cooled by contact with it. So the piston being aluminum and the cylinder
00:37:51being aluminum, and the piston being hotter and the cylinder being colder, means seizure.
00:37:57So they had to come up with a delicate balance between the materials for the cylinder and for the
00:38:04piston. And I took a bunch of pistons and put them in my first wife's oven, and furiously
00:38:13fetching them out with oven mitts and trying to measure them with micrometers and find out
00:38:18what the coefficient of thermal expansion was. But the new pistons contained a lot of silicon.
00:38:27And that not only made the piston stronger, but it reduced its expansion under heat,
00:38:34such that while Honda was enjoying their first flush of super success, in 1963
00:38:45at the Spa circuit in Belgium, two Yamaha riders, Sunoco and Ito,
00:38:53simply rode away from the Honda 4s on the Yamaha RD56, which had this new metallurgical phenomenon
00:39:06of matched piston and cylinder with a chromium bore. Now normally chromium doesn't wet very well
00:39:16with oil. If you find a chromium plated bumper, they're pretty rare nowadays,
00:39:22and give it a good rub and put a drop of oil on it. The drop of oil sits there like an egg on a plate.
00:39:29It doesn't spread out and wet the whole surface. So in order to make it hold oil
00:39:36and lubricate properly, they had to back, back etch it. They had to turn the polarity,
00:39:43the plating polarity around and etch pits into it. But that became the basis for all those
00:39:51TZ Yamahas that won so many races in the 1970s and early 80s, and with which
00:40:01now elderly men had such a good time.
00:40:06Fast forward to victory, and I've told this story before and I got the measurements a little bit
00:40:11off, but fast forwarding to victory, I'd been doing a lot of, you know, Velocette rebuilding and
00:40:17RD350 and some other stuff, and I was, you know, thinking about microns and piston clearance,
00:40:23and victory was introducing the, I believe it was the second generation engine. I was talking
00:40:30to one of the engine guys and I was like, hey, what's the piston clearance? He said it was 25
00:40:36microns. And I looked up in the sky and at the time I got it right. And it's about a thou,
00:40:42it's a little bit less than a thou. And I was just, I mean, this is an air oil cooled engine.
00:40:48I'm like, how do you, how do you get a thou piston clearance? Cause you don't want to,
00:40:51even in an alloy cylinder in a Velocette, you know, you're still looking at
00:40:55three thou and then with an iron cylinder, you're looking at maybe four, four and a half to really be
00:41:00safe. And how is, how is this even possible? And they were making the pistons and cylinders
00:41:07out of the same material and allowing them to have that clearance. It's just amazing.
00:41:15Yes, indeed. In the, in the early days of the water cooled Yamaha Road Racers, TZ250s,
00:41:22uh, people soon learned that the risk of cold seizure, which is water takes a lot of
00:41:30heat to raise its temperature a lot more than it takes metals. So if you started up your Yamaha
00:41:39rolled out to practice, you might not get very far because the pistons would heat up rapidly
00:41:45and the piston and the cylinders would heat up less rapidly.
00:41:51So you would see these people with their bikes backed up to a fence somewhere, uh,
00:42:02warming up until they could see it on the temperature gauge, then out to practice.
00:42:08And of course, Udo Giedl would have said, uh, of his BMWs that he
00:42:15arranged so that the piston would
00:42:21grow in contact with the cylinder wall as it, as it warmed up and expanded. And that greater
00:42:28contact would cause the piston to cool off and the temperature, that clearance would become
00:42:33self-stabilizing. But of course it might be that Udo had to be standing somewhere nearby to make
00:42:41it work like that every time. Yeah, I was going to say, boy, that is, that's some very refined,
00:42:46um, well, that's, that's what you do though. You refine your thinking and you pay attention
00:42:53fanatically to details. Yes. And once you've got it down, anyone else can do it by following the
00:43:00steps and that's our, the technology that keeps this race of humans alive. Imagine your disappointment
00:43:07as being the first water-cooled TZ person to start your bike in cold seas.
00:43:16But it was perfect. Why did this happen? Oh, disappointment.
00:43:23Well, luckily you can get the head off and the cylinder off in about
00:43:26four minutes, so. Yeah, didn't take long.
00:43:29But they were made for that. They were made to make this so you could get it off quickly.
00:43:34When Irv Canemoto was still involved with two-stroke GP racing, um, seems he had the
00:43:42pistons out after pretty much every practice, because he wanted to be able to read what was
00:43:48inside the piston, uh, and see the whole piston crown as well as the inside of the piston crown.
00:43:57And that's supervision. Yeah, happy Valisette pistons have a nice sort of, uh,
00:44:05under, under the crown, you know, they have a nice light kind of golden hue almost. It's really,
00:44:11uh, they would be pretty satisfying to, uh, because even though it's a lot harder to take
00:44:17apart a Valisette with great frequency, 500cc pushrod, uh, it's, it's, it's, it's, it's,
00:44:25400cc pushrod. Four-stroke, uh, I've still done it quite a bit. So, um, uh, let's see,
00:44:33I want to talk about, I think we're, so we've gone through quite, quite a bit of stuff on the engine.
00:44:40Of course, the stuff that really, really needs to be strong is generally made out of steel.
00:44:47Your crankshafts, your connecting rods, your gears, there are titanium connecting rods.
00:44:54Uh, and if you specifically design a titanium connecting rod to do the job of a connecting rod,
00:44:59then you're, you're in pretty good shape, but it still has a tremendous amount of, you know,
00:45:04the Young's modulus or the, you know, the, the spring ability we would call it. Yeah. And so
00:45:10if you're really trying to get your squish clearance really close using a titanium rod,
00:45:15you better, better be careful because it's going to, I mean, you should tell the story about,
00:45:21you know, let's talk about Young, let's explain the steel and, uh, titanium Young's modulus.
00:45:27It is confusing because we know by, you know, you can sit at your console and look these things up
00:45:33and find out that you can, there are titanium alloys out to over 250,000 psi yield. And there
00:45:44are steel alloys, a lot of steel alloys in that category. So
00:45:50steel and titanium can be made comparably strong, but steel is twice or three times stiffer
00:45:59than titanium. And here's the difference between strength and stiffness. We've got a concrete wall.
00:46:06We drill a couple of half inch holes into it. In one hole, we stick a three foot long piece of
00:46:13steel rod, heat treated to whatever spec we like. And in the other, a titanium rod,
00:46:19three feet long, and we start to hang weights on the ends. And if we're only interested in
00:46:26at what point the part fails, we're just looking at the mass. And eventually they both sort of
00:46:35fold down at about the same weight applied. But on the way to that, as we're hanging more
00:46:43weights on, more weights, we're finding that the titanium is being deflected by the weight
00:46:55two or three times as much as the steel. They're comparable in ultimate tensile strength,
00:47:03but one is stiffer than the other. It doesn't bend as rapidly under, doesn't deform as rapidly
00:47:10under stress. That's why Mark was saying that in Formula One, they found that if they had
00:47:18steel rods in an engine and they could run 27 thousandths of piston to head squish clearance,
00:47:25and they put titanium rods in it, they had to increase the squish clearance
00:47:29to keep the piston from tapping the head and possibly crushing the
00:47:35top land down on the piston ring, trapping it there and causing it to stop sealing.
00:47:44So there are weird, weird thing. Beryllium is quite stiff. I think
00:47:52manganese is amazingly stiff. But the general purpose metal that is the basis of our civilization
00:48:01is steel. Steel bridges, steel rails, steel ships, steel landing gear, cars are steel.
00:48:11Everything important in the office chair I'm sitting in is made of steel.
00:48:16Yeah. And at one point, you may remember that Audi was offering an aluminum car and they may still do for all I know.
00:48:24And the aluminum as a material for automobiles has many advantages. For example, it melts at a low temperature.
00:48:33So recycling it doesn't use a lot of heat and it doesn't rust.
00:48:41Well, when the aluminum people began showing signs of uppityness, the steel people just jumped right on it.
00:48:51And now we have all these fine grained, wonderful, high strength, low alloy steels so they can make car bodies even thinner to meet the EPA's latest guidelines.
00:49:05And the aluminum people had to sort of, yeah, well, our day will come and we'll see if we live long enough.
00:49:21So it isn't necessarily that one material is better than another. It could be that the marketing is better.
00:49:29And people who've tried to do bodywork on these new cars that have the high strength, low alloy stuff, some of that, yeah, it is just so stiff.
00:49:41Zero yield at all. I tried to help a friend with a car that was a modern car and you hit it with a hammer and between a hammer and a dolly.
00:49:49It doesn't do a thing. And that's one difference, you know, if you're hand working aluminum or steel sheet, you know, aluminum killed steel and, you know, the nice little thinness you want to make, hand make a gas tank or something.
00:50:03It's pretty buttery, works pretty well, but it does work harden over time. And the more you hit it, you know, by the end of the job, you've really, you can hear the difference between the hammer and the dolly.
00:50:15The sound that it makes and the feeling it gives with aluminum, you can just anneal it again. You just heat it up. You can put your sharpie on there. You hit it with some sooty acetylene and that gives you enough temperature to anneal it.
00:50:31And then it's butter again. And that's a, it's a real dream to work hand work. I mean, that's very, there aren't that many people doing that, but we could call Evan Wilcox and get a...
00:50:42Silversmiths know this whole thing very well. You're making a broach or a hair bar or something, and you're tapping away. Why is it splitting at the ends? I didn't want that. Oh, you didn't anneal it soon enough.
00:50:58You have to get all those atoms back into a low energy state. What's going on there? When you run the can opener around and don't quite remove the lid, and then later you want to put it in the trash and not have somebody cut himself on it, you bend it back and forth until click.
00:51:18The steel lid breaks off. What's happening there is when you deform metal, you are forcing atoms to give up the bonds that they have and move to form new bonds with adjacent atoms.
00:51:40And this process cannot take place massively. That is, if you imagine gluing marbles to two different surfaces and then putting them together, you can't slide one over the other very easily. And in, because you're having to break all the bonds simultaneously.
00:51:59So the way that metals yield and at a force far lower than theory predicts, what's happening is that little mistakes in the crystal lattice, they're called dislocations, an incomplete row of atoms, all sorts of... they've got wonderful words to describe all of this. Get yourself a metallurgy book. It's a kick.
00:52:30These little defects can be pushed through the metal to allow one atom, two atom, three atom movements. And these things, which are called dislocations, when you make the metal stronger, what you're doing is you're preventing dislocations from moving.
00:52:51So when iron becomes steel by being alloyed with carbon, the carbon distorts the lattice so that in the vicinity of a carbon atom, a dislocation kind of... I'm going to take the long way around here.
00:53:09And when you're bending the can lid back and forth, you're creating so many dislocations and driving them into tangles that the material becomes very stiff and finally it breaks off.
00:53:27There are people that spend their lives doing this, of course, and I'm not one of them. That's the only way you can get the really detailed knowledge. I have a glimmer.
00:53:37Yeah. Well, you recommended the Castings book a while back, I forget.
00:53:42Parts of it are readable, yes.
00:53:44Hastings, I think, is the author there. But it was a book on Castings and that's where my knowledge of entrainment came. But boy, I tell you what, for my brain, that was read the page seven times, get a headache, try to bust through that, and then the light would go on.
00:54:04But I don't have a metallurgy background either, so I didn't come to the table with any of the language or the thinking, but it's still nice to try that stuff.
00:54:16Sure. And it looks good on your bookshelf.
00:54:19It does. Let's talk about steel frames and how long we use steel frames and then transitioning to aluminum. We love aluminum. I think it's one-third the density, right?
00:54:32Yeah. And one-third the strength.
00:54:35Right. Is that a paradox? No, it's just a problem to solve. Let's call it a problem to solve. We're kind of getting back to steel. We like steel because it's low cost and it's pretty easy to manipulate.
00:54:51So there's plenty of more entry-level bikes getting steel frames again. The ZX4RR Kawasaki has a steel frame. We like it, but also aluminum can't beat it in a lot of ways.
00:55:09When Honda built the Hurricane, we all praised them for giving it a steel frame because what was happening in 750 was that everything was turning into a superbike.
00:55:20They all had to have the aluminum frame. They had to have the movable swing arm pivot and all those other racing features to homologate it for a superbike.
00:55:31Steel is wonderful stuff because you can take it to your local welder who can competently weld it. If you're a welder yourself, you can competently weld it. You don't need a shielding gas. You don't need all kinds of trick stuff.
00:55:53When it was discovered that the Soviet MiG-25 was made out of stainless steel, there was immediately a lot of sneering from people up high saying, oh, it's not even made out of titanium, these primitive Soviets.
00:56:15And then somebody said, but it's field repairable. Oh, well.
00:56:21And so their choices of materials can be motivated by a lot of different things. And field repairability is... I remember when Richard Chambers carried a gas welding outfit and he could have spent his whole time at the races welding other people's frames and never get to race himself at all.
00:56:47So it has its place. And the great thing about steel is that it has what is called a fatigue limit.
00:56:58If you'd never stress it above a certain level, which is called the fatigue limit, its lifetime is very long.
00:57:09Whereas aluminum remembers every insult, no matter how small. And it's as though it has a film badge for stress, and you can see it turning darker before your very eyes.
00:57:25And it used to be... Well, for example, fuel dragsters use aluminum rods, and they don't use them for long. A run nowadays is, what, 3.6 seconds, I think, in top fuel, but they only go 1,000 feet.
00:57:41But they liked aluminum because it seemed to have some shock-absorbing properties that steel lacked. I don't think anyone ever put their finger on that one.
00:57:54But the great thing about steel is that it lasts a long time. And when Kenny Roberts, beginning of the 1980 season, was given that first aluminum Yamaha with the square tube frame, he said, before we even race that thing, he said, we're testing and we're welding that thing every day.
00:58:19Welding, welding, welding. And finally, they made the wall thickness thicker, and they made the joins between tubes more organic, more flowing, more like nature.
00:58:31And eventually, they had something that would run 45 minutes. And it took time to work out what you could and could not do with aluminum. And at the same time, the marketing people were saying, you know, engines vibrate. Do they have to do that?
00:58:56Because so many people complained about it. After a long day in the saddle, various parts of the body, some of them not mentionable in mixed mix company, become essentially numb. And it's just a pain.
00:59:14So they got busy and they did away with a lot of vibration. Harley added the balancer on the big twin. They didn't take out all the vibration because they knew that people liked some. And they put counterbalancers. I think Honda put a counterbalancer in the Blackbird 4 in 1997.
00:59:40I think it had two.
00:59:42Did it have two?
00:59:43I think so, yeah.
00:59:44And it smoothed out all this vibration so that by the time aluminum frames were well along, low vibration engines were well along. Sort of like how the bicycle, the inventions for the bicycle came together. The seamless drawn tubing, the ball bearing and the roller chain in 1895.
01:00:11All these sometimes there are these beneficial clusters. And in this particular case, it made the aluminum frame possible. And with it came valuable weight reduction. Because although there are some people who say that they're comforted by a heavy motorcycle, when it comes to rapid maneuvering, the lighter, the better.
01:00:37And you have to design for aluminum. It is one third the density and also one third the strength.
01:00:46Well, that's another problem. That's another problem because you look at those one third the weight, one third the strength. Well, let's just make it out of steel. We'll just make it thinner.
01:00:59Well, the problem is that as frame builder Frank Amilleri explained to me, he said, yeah, we could make the frame out of two inch tubing with a paper thin wall. Then how do we attach the engine to it? How do we attach the steering head, the swing arm pivot, the foot pegs?
01:01:20We'd have to butter it with a layer of thicker material with long welds to feed that stress into a fair amount of tube of our lovely thin wall, two inch tubing with a wall so you could practically push it in like the wall of a soda can.
01:01:40Once the lids off and it would buckle. So the reason that these aluminum frames exist is that when you make steel that thin to make a tube that gives you the desirable stiffness, it's steel foil.
01:02:00And you can't attach anything to it and it buckles easily. So aluminum is three times as thick. So in that degree, it is self bracing. It's not just two dimensional. It has a little bit of a third dimension, just enough to keep it from being quite so easily buckled.
01:02:23Okay. Why not magnesium? Well, let's not get into that.
01:02:27Electrified dirt.
01:02:29Yes. When Elliot Morris was making the first cast magnesium wheels in the US back in the early seventies, he went to his friend at Lockheed and he said, I need some help. I'm trying to get these wheels cast in some kind of good way. And what can you tell me about it?
01:02:57And his friend said, and he said, we don't even mess with that awful metal anymore. We've got engines that'll lift anything.
01:03:10Well, that's one way to solve the problem.
01:03:12And that's why street bikes have aluminum wheels. Race bikes have forged magnesium wheels. Forging closes up internal defects. It orients the grain along the direction of stress if it's properly designed and is altogether quite a wonderful thing.
01:03:34What isn't so wonderful? I visited the Marcazzini part of the Brembo Red Mile factory. And when the forging comes out of the die, it looks like bread that rose. It's all puffy and bloated looking. What happens to all that metal?
01:03:59My guide pointed, there were all these bales of magnesium chips, which are being kept wet. Horrible stuff. I had a magnesium fire once.
01:04:10Oh boy. Yeah.
01:04:12I nearly burned my shop right down. And just as the flames, brilliant white flames were reaching the ceiling, it used up all its fuel and was done. We're just showing you what could happen, man.
01:04:28Years ago, training for the fire department, they used to talk about Volkswagens. I'm a volunteer firefighter and they used to talk about Volkswagens having magnesium engine cases. And if you had an engine fire, watch out. Now we're talking about electric cars because they make some pretty bad smoke when they catch on fire and they just don't go out.
01:04:53Yeah.
01:04:54All right. Well, another great show. It was good for food analogies. We had a lot of good puddings and et cetera. Food is primal. Kevin and I have had an email chain called the Excellence of Butter. It was a while ago. And we do occasionally talk about gravy.
01:05:14But really fun to talk about metals. And again, maybe not the most emotional topic like Goldwings or TZ750s, which we're very happy you guys like the TZ750 podcast because that's our biggest hit so far.
01:05:31We don't understand it because who knows from TZ750? What is it? Who cares?
01:05:38I know, right? Everyone seems to care about that one. It just really is.
01:05:41I have to tell you that there is emotion in metallurgy because of the time that I was seated next to a metallurgist at one of those rubber chicken dinners. I could see that this man was settling in.
01:05:56Sad. He's making a sad face. Spotify listeners.
01:06:00The speaker will start and I'll try to look like I'm awake. This man was a metallurgist, I've been told. So I decided to try something. And I turned to him and I said, what can you tell me about carbide segregation in the intergranular zone?
01:06:18And he just lit up as if I were the angel Gabriel. And I had a lovely conversation through dinner and didn't pay any attention to the featured speaker.
01:06:32It's always good when you can find someone who speaks your language. It's like going to parties. I'll be the guy alone on the bench in the corner and there's nobody to talk about welding.
01:06:45Dance card is all blank.
01:06:47Yeah.
01:06:49Well, thanks for listening, everybody. Again, jump down the comments. There's been a request to bring back the Kevin Cameron t-shirt a few times. It might be one guy commenting multiple times. Not sure.
01:07:03But we'll look into getting the design back in our t-shirt store. If you go underneath the YouTube description or underneath the YouTube video, there's a store where you can buy CycleWorld merch. I'm wearing the Norton Commando shirt. That's my actual former Norton Commando photographed by Jeff Allen and then laid on the t-shirt there.
01:07:24Anyway, thanks for listening. We'll see you next week. And jump down the comments. Let us know what's up.