Layshaft ball bearing versus roller bearing opinion

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nortonspeed

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Why should you use a ball bearing in the first place if you can get the best available layshaft bearing around: a roller bearing with E specification (like the superblend 306E crankshaft roller bearing). For example a FAG NJ203E layshaft bearing will take far more load then any other ball bearing (or roller bearing without E specification), provides easy removal of the layshaft/gears and some (possible) side float of the layshaft/gears for smooth engagement.
 
I don't know. I guess I trust what Mick says.

Dave
69S
 
Well it might be friction reduction as a ballbearing has point contact while a roller has line contact. Of course a roller is more stout re load the original issue ballbeArings had qc problems and could deteriorate to catastrophic failure at speed w/ the only warning an abnormal movement of the kick start lever often unnoticed.
 
The E on a roller bearing part code stands for Extra load capacity which is achieved with barrel shaped rollers and this has the added benefit of coping well with flexing layshafts and cranks. I doubt there is much difference in performance between the 2 but I have always used E rollers with no issues so will continue to use them.
 
Flo said:
I believe the ball is best for layshaft flexing.
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That's where the 'E' specification comes in!
Norton started using crankshaft (staight) roller bearings to cope with increasing power of their growing twins. These roller bearings reached their limit in the 1972 Combat engine. The roller bearings couldn't cope with the crankshaft flexing at high rates. From that moment Norton succesfully used the famous 'superblend' roller bearing. This roller bearing with 'E' specification has 'rounded edges' to cope with flexing shafts.
 
Wish I had known this before I put my Hemmings ball bearing in, I probably would have used one as I would trust a good roller bearing more if it could stand flexing.
The split roller I took out was knackered on the inner race, but it could of been a straight roller type.
 
Flo said:
Wish I had known this before I put my Hemmings ball bearing in, I probably would have used one as I would trust a good roller bearing more if it could stand flexing.
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Mick always recommends the 6203TB ball bearing, and he fits them in preference to any roller, even in the race bike gearboxes he builds, and, as he says in his NOC gearbox rebuild DVD, he has never known one to fail. So I don't think you need to worry.
 
The ball bearing is going to cope with end float loads better than a roller. And on the layshaft, there is only the one bearing and that layshaft has end float. Having said that, last weekend I reconned my box with an SKF roller and the old one that came out was still in servicable condition. If Hemmings is using a particular ball bearing I would be quite confident of using it as well.


Mick
 
All the gears in the box are straight cut so the end float loads are low and well within the roller bearings capability, if the gears were helical cut then the loads would be higher and the ball becomes the better option.
 
I just wish I could get my layshaft bearing to quit spinning in the case even with using a perma tex loctite on the race my kickstart is still moving back under hard use. How much would the bushing in the kickstart that supports it have to do with that?

I tried heating the race with a torch while the tranny was in place I will taking it right soon because I want to change sprockets and chain at the same time.

My question is the newer roller type bearing have a slightly larger o.d than the ball to make it a tighter fit?

thanks
 

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The roller bearing od is same as ball, but if you go for a N203E instead of a NJ203E (all 3 spot) you will have the rollers intergral with the inner ring instead of the outer, you can then take the outer ring to a plating shop and have the OD copper plated with the required thous to give back an interference fit in the housing. The plating shop will varnish the inner track on the outer ring so only the od will be plated. As its copper plating with no polishing it should be cheaper than chrome plating.

On second thoughts you can also consider NJF203E (3 spot again), the rollers are in a cage and the inner and outer have 1 flange on opposite sides so you have one way float control. For a full list of the possibilities go here.

http://www.skf.com/portal/skf/home/prod ... ink=1_4_2b
 
you may have to have the bearing staked in place.
Contact oldbritts.com
Fred does this or can tell you what's involved right over the phone.
Good luck
Marshal
 
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