Benefits of roller bearings

[Skeeve]

OK, when I was down with quite a few other types of riders and had a Harley afficianado/mechanic friend (riding a BMW R60 at the time) he was always talking about so-and-so HD guy who'd "spun a bearing." This I presumed at the time to be a roller bearing of some sort that had seized a race (inner/outer) and spun it.

 

Your mechanic friend wasn't using the slang properly, or didn't know what he was talking about. Roller bearings are always spinning. "Burnt a bearing" might have been appropriate; Evos were known for blowing out the stock crank bearing (left side?) at one time, when the factory bean counters subbed a less suitable part (1/2 the # of roller, rollers only 1/2 width instead of the old full-width Torrington part.) H-D, to their discredit, tried to deny there was anything wrong w/ the new sub-standard part instead of just fixing the problem [the 'fix' being firing the accountant who'd pressured the parts dept. to switch to the substandard bearing to save $1 a unit, at the cost of $1000s/failure, and switching back the to original part during construction!]

 

I would think that if not lubrication failure, then improper tolerances, uneven expansion/incompatible metals, or just a poor quality bearing would result in deterministic catastrophe for a bottom end.

 

Exactly. W/ plain bearings, it will be the first one; in Harley's case as outlined above, the last. The middle case tends to be sorted out in initial product development, which is why newly-minted mechanical engineers aren't put in charge of new product development, but assigned more suitable tasks like kickstand design... this gives them time to absorb "real world" engineering skills from the old guys.

 

Plain bearings, OTOH, may cut you a little more slack, since the oil cushion would take up whatever additional machining tolerance might be there, one way or the other.

 

Au contraire: plain bearings flat out require mo' betta' production machining standards to function properly: why do you think that up until the late 60s or so, almost all motorcycles had built up cranks & roller or ball bearings? Cars didn't get shell plain bearings until what, the 50s? Model T's had plain bearings: you poured the bearings in situ, to get the correct tolerances! CNC machining really changed the engineering, since it opened up a whole new realm of possibilities available at the same product price point...

 

It has not been my experience that Guzzi, BMW, Ducati, Kawasaki, or any of the plain bearing machines I've owned had sloppy machining. Try this with a Guzzi valve cover: tighten one of the screws to spec with all others out, then try and finger screw one in, and it won't thread. Even when their machining was done by hand it was tight.

 

This is about the most specious example I've seen on the forum yet, altho' it's an excellent example of why you should always sneak up on your torques evenly across the board... even for something with as loose of tolerances as the hole locations on valve covers!

[luhbo]

....

Your mechanic friend wasn't using the slang properly, or didn't know what he was talking about. Roller bearings are always spinning.

....

 

I'd say roller bearings are only spinning as long as you hold them in your hand or have them stuck on a finger. Somtimes they spin when built in, then the inner ring would spin on its seat. It's a very bad situation and usually caused by improper tolerances between shaft and bearing.

 

Hubert

[Ryland3210]

Timkins are a type of caged roller bearing, actually. More expensive than ball bearings, but better able to absorb shock-induced loads normal to the axis of rotation. AKA "tapered roller bearings."

 

Ride on!

 

Timken is the brand name. Timken is practically, if not literally, the grandfather of the tapered roller bearing. They make all three types mentioned: ball, roller, and tapered roller.

 

Rollers, with line contact over the entire length of the rollers, instead of the relatively small contact of ball bearings, withstand a much higher load, size for size. Tapered rollers are more expensive, but used where there is an axial thrust in addition to the radial load, such as in wheel bearings. Ball bearings are also used in radial/thrust combinations for relatively light load applications. Cages and seals are used or not used on all three types, depending on the application.

[John in Leeds]

Sadly some friction in the bearing discussion.

 

However thank you all for shedding some light on my problem. FYI Highland are taking the engine back to Sweden for a rebuild and I hope to get their analysis and also any updates that are currently available. In the meantime Rock and Road have given me a Hyper Motard for use until the rebuild is complete. What a top outfit

[GuzziMoto]

In relation to your engine failure, I have heard of issues with the use of the newest spec car oils in engines with bearings other then plain bearings. Supposedly the decreased friction properties of the oil don't get along with roller and ball bearings. How big an inpact this really has I don't know. But I have heard that it is a reason to avoid the new spec car(they use mainly plain bearings) oils in bikes(lots of roller and ball bearings, especially in european bikes). I would be curious what experts say.

[John in Leeds]

In relation to your engine failure, I have heard of issues with the use of the newest spec car oils in engines with bearings other then plain bearings. Supposedly the decreased friction properties of the oil don't get along with roller and ball bearings. How big an inpact this really has I don't know. But I have heard that it is a reason to avoid the new spec car(they use mainly plain bearings) oils in bikes(lots of roller and ball bearings, especially in european bikes). I would be curious what experts say.

 

Used Mobil 1 15-50w. There may be something in what you say, be interesting to hear Highland's comments. The specification of Mobil 1 exceeds that of the oils required by the manufacturer. I do hope good intention has not caused the problem

[pete roper]

Harleys are long stroke, 360 degree crank motors, that is, both pistons move up and down/fire in unison. That's a hell of a load on the bottom end. The same is true for the earlier Triumph/Norton parallel twins I believe.

 

Errrr? I dunno where you got that idea from. Harleys are a what? 75 degree twin so the firing interval s will be 360 minus 75 degrees = 285 degrees and 360 plus 75 degrees = 435 degrees of crankshaft rotation. Pommy twins, and in fact most parralel twin four strokes have 360 degree firing intervals, one cylinder will fire as the other one is at the end of the exhaust stroke and on the beginning of the induction stroke with the valves on overlap and visa-versa. The exception to this is machines like the Yammy 850 twins (TDR 850?) which use offset crankpins to provide good primary ballance.

 

Pete

[Ryland3210]

Errrr? I dunno where you got that idea from. Harleys are a what? 75 degree twin so the firing interval s will be 360 minus 75 degrees = 285 degrees and 360 plus 75 degrees = 435 degrees of crankshaft rotation. Pommy twins, and in fact most parralel twin four strokes have 360 degree firing intervals, one cylinder will fire as the other one is at the end of the exhaust stroke and on the beginning of the induction stroke with the valves on overlap and visa-versa. The exception to this is machines like the Yammy 850 twins (TDR 850?) which use offset crankpins to provide good primary ballance.

 

Pete

 

Harley was only 15 degrees away from having primary balance, and with the connecting rod arrangement, zero rocking couple. I have to say, though, the 90 degrees of the Ducati's never looked as aesthetically pleasing as the Harley layout.

 

In the case of the parallel twins, the distance between the pistons provides spacing for the crankpin offset, but then leaves a rocking couple. I have wondered why the offset crankpins weren't always used. Perhaps some cost factor was involved.

 

All reasons why I love the Guzzi layout. 90 degrees, connecting rods only 24mm apart, and good looks.

[Skeeve]

All reasons why I love the Guzzi layout. 90 degrees, connecting rods only 24mm apart, and good looks.

 

Hard to beat that with a stick!

[GuzziMoto]

Errrr? I dunno where you got that idea from. Harleys are a what? 75 degree twin so the firing interval s will be 360 minus 75 degrees = 285 degrees and 360 plus 75 degrees = 435 degrees of crankshaft rotation. Pommy twins, and in fact most parralel twin four strokes have 360 degree firing intervals, one cylinder will fire as the other one is at the end of the exhaust stroke and on the beginning of the induction stroke with the valves on overlap and visa-versa. The exception to this is machines like the Yammy 850 twins (TDR 850?) which use offset crankpins to provide good primary ballance.

 

Pete

All H-D's are 45 degree Vtwin's except the V-Rod bikes that have the new(for H-D) 60 degree Revolution engines. Have not ridden a V-Rod, but the 45 degree H-D's vibrate like crazy. That's why women love them. And for vertical twins, while most fired the cylinders 360 degrees apart, some old british twins fired the cylinders at the same time( nick-named Twingles ). And some jap twins used 180 degree cranks.

[pete roper]

All H-D's are 45 degree Vtwin's except the V-Rod bikes that have the new(for H-D) 60 degree Revolution engines. Have not ridden a V-Rod, but the 45 degree H-D's vibrate like crazy. That's why women love them. And for vertical twins, while most fired the cylinders 360 degrees apart, some old british twins fired the cylinders at the same time( nick-named Twingles ). And some jap twins used 180 degree cranks.

 

I stand corrected. Dunno where I got 75 degrees from? Still it holds true that both cylinders on a Harley dont fire simultaneously, just means that the intervals are 315 degrees and 405.

 

As for the 'Twingle' term? I thought that was used as a description of split single two strokes? Quite happy to be wrong on that though.

 

Pete

[Skeeve]

I stand corrected. Dunno where I got 75 degrees from? Still it holds true that both cylinders on a Harley dont fire simultaneously, just means that the intervals are 315 degrees and 405.

 

As for the 'Twingle' term? I thought that was used as a description of split single two strokes? Quite happy to be wrong on that though.

 

Pete

 

75deg is the Yammie a/c 2v v-twins that used to power their 535, 750 & 920-1100cc bikes starting back in the 80s thru to about 2k1? or so. Or was that 72deg? Anyway, pretty close. Harley guys everywhere are straining at their dog-collars to string you up for missing that 45deg v-twin thing about H-D, but hey, they hate the Guzzisti (or anyone not of the fold!) anyway, right?

 

Does anyone know why Harley's are 45 deg v-twins? Anyone? Anyone? Bueller?

 

Because that was the w-i-d-e-s-t angle that would fit in the original converted bicycle frames their first models were based upon!

 

As far as the "Twingle" term, it was originally used to describe the split (siamesed-pistons] single 2-strokes, but has also been used to describe the changing of a 360deg firing order to a 0deg firing order to get traction dynamics similar to those of a Harley for dirt-track racing...

[quazi-moto]

My old A65 sure could use a roller bearing on the timing side. That and a conversion to end feed lubrication.

[mike wilson]

Guess I should check my responses by doing some Internet searches beforehand, perhaps like other folks.

 

Here we go: http://en.wikipedia.org/wiki/Harley-Davidson#The_Big_V-Twins

 

Harley-Davidson engines

 

 

 

So, I'm completely unreliable concerning information about the Harley Davidson 45 degree twin firing order.

 

It's quite logical when you think about it. The firing interval gives the distictive "potato potato" sound we know and love. If they fired together it would go "spud spud".

 

Happy New Year.