Crankshaft shims

[Mark_smugglers]

Hi. My disassembly of my 1972 750 combat engine continues and I split the crankcases at the weekend.
Can I ask: if I need shims when I reassemble it, do they go underneath the bearings?
I haven’t come across any yet, but then I haven’t pushed the bearings out of the cases yet.
I’ve read some old threads where it seems some place them by the flywheel and some place them under the bearings, but wondered what they would have done on manufacture?
Also, are the ones sold by Andover Norton for the flywheel end or under the bearings?
Thanks

 

[swooshdave]

I did not have any shims and did not need them. When you are ready fit the crankcase and crankshaft and see where your float is at.

 

[outawack]

Andover shims go on the crank, the shims that fit behind the bearing in the cases can be hard to come by depending on where you live. i am in Australia and had them cut localy. You wont no if you need them until you check your crank end play. End play should be between 10-24 thou.

 

[robs ss]

BTW - I my opinion, only shim between the outer bearing and the case. You don't want a "slinging cutter" potentially doing damage to your crankshaft, which is a possibility if you shim between the bearing inner and the crank cheek.
I got a kit of outer shims from oldbritts.

 

[outawack]

BTW - I my opinion, only shim between the outer bearing and the case. You don't want a "slinging cutter" potentially doing damage to your crankshaft, which is a possibility if you shim between the bearing inner and the crank cheek.
I got a kit of outer shims from oldbritts.

How long ago did you get the old brits kit, they no longer ship to AUS.

 

[Time Warp]

I never found any shims even on the 850 (with 0.029 and 0.031" from the factory)

I got a set of stainless steel shims from Bodger Engineering after buying the AN shims, not doing my homework and finding they went at the crankshaft journal.

End float set at 0.012", cases together with Wellseal.

 

[robs ss]

How long ago did you get the old brits kit, they no longer ship to AUS.

Yeah - it was a while! ... although this company in Sydney sells them (ex-AN I think) - they have 3 and 6 thou

Crankshaft Main Bearing Shim, Large, Commando » Classic Bike Spares

Crankshaft main bearing shim, large. Thickness: 0.006" This shim fits into the crankcases prior to fitting the bearing. It is used to reduce crankshaft end float. Clearly it will slightly reduce the bearing engagement, and so should probably not be used on racing or high performance engines...

www.classicbikespares.com.au

 

[outawack]

yeah they say that the shims are the bearing race type but they aren't there the Andover shims that go on the crank.

 

[HRD]

yeah they say that the shims are the bearing race type but they aren't there the Andover shims that go on the crank.

Not sure what you are meaning,spell checked/auto corrected maybe ?.The seller does say these shims fit in the crankcase.This is where the shim/s should be placed and not on the crankshaft behind the inner race,there has been lots of info posted about this.

 

[olympus]

I fitted shims behind the outer race purchased from old Britts.... now they don't ship ouside the US and and retiring a new source is needed

 

[robs ss]

I mentioned above they're available in Australia - https://www.classicbikespares.com.au/product/crankshaft-main-bearing-shim-large-commando/
Says "Made in England" so... someone must sell them over there!

 

[Mark Savage]

Buy some shimstock and make your own.

 

[concours]

"I haven’t pushed the bearings out of the cases yet."


OP, you know they fall out, right?

 

[olympus]

Buy some shimstock and make your own.

Cutting 0.003 & 0.006 thou may be pleasurable to some but it's a real pain in the arse especially cutting the inner circle even with proper snips
For the price I know what I'd be doing

 

[grandpaul]

"I haven’t pushed the bearings out of the cases yet."


OP, you know they fall out, right?

If they "fall out" with no heating and tapping, they are too loose, and can destroy their apertures...

 

[grandpaul]

Cutting 0.003 & 0.006 thou may be pleasurable to some but it's a real pain in the arse especially cutting the inner circle even with proper snips
For the price I know what I'd be doing

The don't have to be cut perfectly, and the OUTER circle is the more specific cut that needs to be made, to keep them as close to centered as possible. They are fit to space the outer race to/from the case face.

 

[olympus]

I know.. but it's like making your own puff pastry isn't it

 

[Mark Savage]

Cutting 0.003 & 0.006 thou may be pleasurable to some but it's a real pain in the arse especially cutting the inner circle even with proper snips
For the price I know what I'd be doing

Yes, I would have prefered to just have them sent but from where?
I stuck the shimstock to some plywood with contact adhesive and used a hole saw to cut the outer size then another hole saw for the inner. Soak in contact adhesive remover to release or run a thin blade under it.
I cut two of differing size but only used one. What size do you need?
The one I have left over is .010" though so quite thick.

 

[concours]

If they "fall out" with no heating and tapping, they are too loose, and can destroy their apertures...

I was attempting to stimulate thought/research by the OP, re: HEATING THE CASES. Carry on.
Nothing to see here.

 

[ludwig]

In another life I used to work on Bedford trucks.
The shims to adjust the tapered bearings in the rear axle had the right size. ( still have some)
Each bearing came with a set of shims.
There must be plenty of other small trucks with the correct size.
Go talk to your local truck shop, or google 'differential shims'