crankshaft questions

Hi , I am in the process of reassembling the crankshaft of my '73 850 - when I took it apart I removed the 12 nuts ( 4 of which were slightly longer) along with the studs and 2 tab washers. After cleaning out the crank I ordered a crankshaft reassembly kit - this consisted of 12 nuts all of the same shorter length ,2 tab washers and the studs. Does it matter that it would not be a like for like replacement? would you still use the tab washers?
Also I noted on disassembly there were no shims on my crank is it likely that I will not require shims on reassembly ? I phoned a leading supplier on this and was advised that they only shim about 1 in a 100 of 850 cranks - does that seem right ? the forum seems to have lots of stories of people needing to shim up their cranks so I was expecting to do he same. If I do require shims I would prefer to use the larger ones that sit in the crankcase behind the main drive side bearing (apparently this is an easier process than removing the inner race repeatedly to get it right) can anyone advise where in the UK these can be purchased. Thanks in anticipation for any advice given.

You probably don't need shims, the vast majority of C-do engines do not. Consider using a modern high capacity ball bearing on the timing side instead of a pair of superblends, then you for sure will not need shims.

The change in hardware does not make a difference...use the tab washers, loctite the threads, and stake the nuts down with a punch.

All of the above goes right out the window if you're building a competition race engine.

builder said:

You probably don't need shims, the vast majority of C-do engines do not. Consider using a modern high capacity ball bearing on the timing side instead of a pair of superblends, then you for sure will not need shims.

The change in hardware does not make a difference...use the tab washers, loctite the threads, and stake the nuts down with a punch.

All of the above goes right out the window if you're building a competition race engine.

Click to expand...

This is really funny, I would just do the opposite!

Do need shims 9 out of 10.
Won't use a ball bearing (unless for racing, less resistance, change every season)
Also use the tab washers only to lock the centre dowel, no need to bend the lips (standard 850)
Don't centre punch the nuts (ruins threads) but use strong loctite

Different strokes for different folks.

agreed!

I find that I generally have to add some shims. Norton spec is .005" to .015" end play, but I generally go for .005". That usually requires shims. My only caveat is that these are all race engines. I've seen street bikes that work fine with all sorts of end play. My preference is also to use shims behind the outer races, not on the crankshaft, but either way works. I get the shims from a US industrial supply house, MSC, but there should be something similar available in the UK. They are generally available in .005" thickness increments. Years ago I used to cut my own shims out of brass stock, but I've seen them get torn up when the bearing starts to spin in the case. That could lead to a whole new thread on how to lock the bearings into the cases, couldn't it?

Ken