So You Just Bought a Near Mint Condition Commando?

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cliffa said:
So, which is the preferred replacement bearing, ball or roller ?
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Just to clarify, "ball" is the FAG 6203TB.P63 (or P6.C3) phenolic cage (so doesn't break up) bearing as recommended by the late Mick Hemmings in preference to the roller bearing and is the one I fitted.

Gearbox layshaft FAG ball bearing

Hi All. I am usually to use the FAG 6203TB.P63.C3 balls bearing, those sugest by Mike Hemmings. Bought new one but they havent the final code .P63.C3. Bought one time also FAG 6203TB.P63 without C3 final. Question is if they are really the same or only seem. Thank you. Piero
www.accessnorton.com www.accessnorton.com

So You Just Bought a Near Mint Condition Commando?

Edit: Note that the 6203TB.P63 was also marked 'Portugal' which isn't a problem (the latest ones are now made in Korea).
 
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Mick Hemmings used and sold the 6203TB bearing as 'The Solution', as it positively locates the layshaft as opposed to relying on shims to manage end-float which was never the design intent.
I initially used a roller, but found that the end-float had increased over time. It also meant that when I 're-re-shimmed' it there was less kickstart shaft protruding from the casing, so my RGM kickstarter would no longer fit.
Mick was pretty scathing about the roller bearing when I discussed it with him.
Triumph layshafts have substantial bronze thrust washers and highly finished thrust faces on the gears to maintain the correct clearance, whereas Norton gearboxes do not.

I note that the roller bearing is cheaper.
 
B+Bogus said:
Mick Hemmings used and sold the 6203TB bearing as 'The Solution', as it positively locates the layshaft as opposed to relying on shims to manage end-float which was never the design intent.
I initially used a roller, but found that the end-float had increased over time. It also meant that when I 're-re-shimmed' it there was less kickstart shaft protruding from the casing, so my RGM kickstarter would no longer fit.
Mick was pretty scathing about the roller bearing when I discussed it with him.
Triumph layshafts have substantial bronze thrust washers and highly finished thrust faces on the gears to maintain the correct clearance, whereas Norton gearboxes do not.

I note that the roller bearing is cheaper.
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That's interesting
I never knew this , I've had no issues with shimming but but if I ever have reason to open up the box again I think I'll go for this option
Cheers
 
Mich Hemmings is probably right but I think a roller bearing is reliable for road use only.
 
And presumably shimming the end float is much more difficult with the gearbox in situ?
 
Thanks all. So according to Jim's video it should be shimmed regardless of the type of bearing being used?
 
Alerted to the problem I changed mine (MKIII) in situ with no problems at all. Original ball bearing showed no signs of distress and the rest of the gearbox looked as new. Bike had less than 10k at the time.

Thanks to this forum for the alert. I can imagine the consequences of a rear lockup at speed!
 
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kommando said:
I fixed mine in the street, was a student at the time so no garage. Torch on the box and a clout on a piece of hardwood sitting on the outside of the gearbox under the primary and the bearing outer popped out of the housing. Still have the bike and nothing other than new rings, upgrades and a new harness in all those 35+ years.
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I built a box in the '70s using an old shell....to get the layshaft bearing out I went to the local blacksmith, he struck an arc on the outer race with his big welder, and it popped right out!
 
I wasn't real happy with less splines exposed on the kicker shaft after shimming, chose to for go the gasket, shims and use 518 on the inner and outer.
Brought it within tolerance.
 
MichaelB said:
I wasn't real happy with less splines exposed on the kicker shaft after shimming, chose to for go the gasket, shims and use 518 on the inner and outer.
Brought it within tolerance.
Click to expand...
IMHO, something sounds wrong. Over shimmed, fourth gear lay installed backwards, covers installed without gaskets before and gaskets used now? The difference should to very small and I doubt that I could see it before and after.
 
marshg246 said:
IMHO, something sounds wrong. Over shimmed, fourth gear lay installed backwards, covers installed without gaskets before and gaskets used now? The difference should to very small and I doubt that I could see it before and after.
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I agree
Doesn't seem right
Shims are usually only a few thousandths ?
 
Ok, what's the downside on for going the gasket and using 518?
The box is shifting perfect BTW.
 
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