Found a roller layshaft bearing in gearbox

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singring

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Progressed well for the layshaft upgrade, removed the layshaft and found that a Made in Japan KOYO 203 (no other markings apparent) roller bearing had been previously installed...was a bit of a surprise as there was no shim on the kickstart shaft. So a bit of a dilemma here:
I could remove the roller bearing and replace with Mick Hemmings recommended ball bearing ( FAG 6203TB.P63 ) that sits on my bench awaiting install into the gearbox case, or I could just leave the roller bearing in place, but get the recommended isolastic shim ( what size, and exactly where to place it, I don't recall ). From what I can tell, the roller bearing looks in perfect shape, as do all the gears and other components from the gearbox...I would say that anything that needed replacing in the past has already been done (bike has 10600 miles on it). The roller's outer race is still locked into the layshaft bearing gearbox housing, and the inner race is on the end of the layshaft...I would have to get a slide hammer to pull the outer race out.
Any suggestions appreciated.
 
Take the piece in hand and spray solvent all the lube out of it then slowly turn and turn and turn through many cycles and feel for a gripping sense or rough sense getting though every now and then when all the wear points line up for an instant. If nothing detectable then take the easy way out by shim and nip back up on to the next task. You can gain similar w/o shim by going sans gaskets which serve no purpose in tranny but squash down risk and less stable nip up and items to use up.
 
Giving the layshaft a closer look, I see that the bearing's inner race is not flush with the end of the layshaft...it sticks out roughly 0.142 inch (about as close as I can get with electronic caliper) from the layshaft end....is the inner race suppose to be flush, or has there been some end float compensation factored into the inner race's position? If I decide to use the existing roller bearing, it is going to be difficult to determine when the bearing's inner race is flush with the outer race, when positioning the layshaft. I guess I could push the lay 4th gear back as far as the inner race on the shaft, and ensure the 4th lay gear is up against the outer race, which would make the inner and outer race edges flush.....or am I just shooting in the dark? Might be easier to just use the ball bearing, then no shimming, or compensation, required.
 
Its been a while since my last tranny operation but do remember the laybearing inner race should seat pretty darn flush with end of shaft. You own peace of mind should choose what to do so thought don't get distracted to that area riding with the wind.
 
Just out of curiousity, how is it that a ball bearing is being supplied as an 'upgrade' here ?
 
Rohan said:
Just out of curiousity, how is it that a ball bearing is being supplied as an 'upgrade' here ?
Click to expand...

The high-spec. 6203TB ball bearing is an alternative fitment to the roller bearing, and Mick Hemmings certainly recommends the TB ball in preference to the roller.
 
L.A.B. said:
Rohan said:
Just out of curiousity, how is it that a ball bearing is being supplied as an 'upgrade' here ?
Click to expand...

The high-spec. 6203TB ball bearing is an alternative fitment to the roller bearing, and Mick Hemmings certainly recommends the TB ball in preference to the roller.
Click to expand...


But I have never figured out why. Jim
 
I'd suspect same as pre-superblend, round balls allows more shaft flex and twist before things bind, bend, break. In my own case I'd have to consider long term storage damage of a new in the box bearing as poor economy by the time the installed one became questionable. If the current bearing got stuck bound before full seated what's that imply on its clearance crush life expectancy? Is there a definitive way to determine why the current one is proud and if it could be seated that its ok to run a long time? How hard do stress the tranny?
 
hobot said:
I'd suspect same as pre-superblend, round balls allows more shaft flex and twist before things bind, bend, break. In my own case I'd have to consider long term storage damage of a new in the box bearing as poor economy by the time the installed one became questionable. If the current bearing got stuck bound before full seated what's that imply on its clearance crush life expectancy? Is there a definitive way to determine why the current one is proud and if it could be seated that its ok to run a long time? How hard do stress the tranny?
Click to expand...

So TC obviously knew how to stress one and he swore by the roller bearings. Jim
 
Ok get me up to speed, which roller bearings, the flatter originals or the more barrel shaped?

Somewhere in Capt Norton Notes is long and ancient discussion on crankshafts which had drag racer reports that got away with more rpm with thinner 750 cases and ball bearings. Best I could glean a decade ago made me build 1st Peel Combat with superblend and 11 ball on TS. Best I could glean only down side over advantages of TS ball bearing was superblend/roller might wear longer.

Found a roller layshaft bearing in gearbox


My pre-Peel Combat is still famous for being that decade's area hot rod and when I opened just for leaks both its original flat rollers were still pristine. I sent them to Michael Taglier in NY to mic em just to verify by a detail fanatic. It was never lugged that's for sure and I found out the hard way about valve float power lost passing semi's in tights.

Bearing and cases. rods, pistons survived serve over rev just fine, the rpm limits are bent crank with end flex damaging whats attached. So I can tell ya if you build a 10,000 rpm Norton crank and head, you also have to re-engineer its cam drive and charging system or lack of it. Your gear drive may allow it.

When ya study the Combat factory issues the initial AAU version was the biggest trouble maker d/t uneven firing loads on the poor bearings.

So kind of like an argument with my brother, which was worse or better .357 or .45, He won with - Shit Just Surprise Me!
 
hobot said:
Ok get me up to speed, which roller bearings, the flatter originals or the more barrel shaped?

I would suspect that with crankshaft bearings there would be a slight advantage in reduced friction loss with a ball bearing.
As far as how long they last the superblend main bearing or the roller trans bearing is far superior. Not to imply that the HD ball bearing is not adaquate in the trans. Jim
Click to expand...
 
I concur that Superblends are superior crankshaft bearings. I've had heavy-duty ball bearings fail on the timing side. I have never had a Superblend bearing fail in the engine or gearbox on my mega-mile Combat


Tim Kraakevik
kraakevik@voyager.net
 
comnoz said:
L.A.B. said:
Rohan said:
Just out of curiousity, how is it that a ball bearing is being supplied as an 'upgrade' here ?
Click to expand...

The high-spec. 6203TB ball bearing is an alternative fitment to the roller bearing, and Mick Hemmings certainly recommends the TB ball in preference to the roller.
Click to expand...


But I have never figured out why. Jim
Click to expand...

On all the layshaft ball races I've seen bust the primary cause was always pressed steel cage failure, the balls and ball grooves looked perfect under a magnifier. I believe the upgrade bearing has a solid brass cage. Perhaps the best of both worlds, but I haven't had a roller fail yet (Fingers crossed :| )
Cash
 
cash said:
comnoz said:
L.A.B. said:
The high-spec. 6203TB ball bearing is an alternative fitment to the roller bearing, and Mick Hemmings certainly recommends the TB ball in preference to the roller.
Click to expand...


But I have never figured out why. Jim
Click to expand...

On all the layshaft ball races I've seen bust the primary cause was always pressed steel cage failure, the balls and ball grooves looked perfect under a magnifier. I believe the upgrade bearing has a solid brass cage. Perhaps the best of both worlds, but I haven't had a roller fail yet (Fingers crossed)
Click to expand...

The failure-prone Portuguese layshaft ball bearing has a brass cage.
The "Hemmings" TB bearing is a high spec ball bearing, and it has a phenolic cage so presumably the cage can flex without eventually self-destructing.
TB ball
Found a roller layshaft bearing in gearbox
 
The failure-prone Portuguese layshaft ball bearing has a brass cage.
Click to expand...

LAB you're probably quite correct, I haven't seen one for years. The Portuguese cage is a "J" type and has the tendency to break up allowing the balls to run to one side.
The the first improved ball bearing I saw had a machined brass cage and I thought it was Hemmings who offered it. Nonetheless, Phenolic Resin retainers have to be a far better option than the original.

J-Type Ball Bearing Retainer

“J” Type: Two piece ribbon consisting of two halves that are assembled one half from one side, and the other half from the opposite side. Fold down tabs secure the two halves. This type of cage is guided by the balls. “Loose” clinch type provides lower torque. Material is type 302 stainless steel. Brass and carbon steel are also available. These types of cages can operate at low to moderately high speeds. Loose crimp is standard. Tight crimp (JF) is used for higher speeds. Extra loose (JL) is used for low torque applications.
Click to expand...



Cash
 
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