Author Topic: Crankshaft side play/shims etc  (Read 3952 times)

Offline BSA500

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Crankshaft side play/shims etc
« on: 05.11. 2015 16:03 »
I posted this in the clutch etc forum....

A bit of an odd one on a A7SS. It sounds like the chain rubs on the inner primary side case if you lean the bike to the right while the engine is running. I think there is side play on the chain anyone else had this?

Well took off primary side case and found as per title the crank has loads-by loads I mean loads-of play side to side(no up/down). I recently rebuilt the bottom/top ends so new bearings/bush/big ends/small ends and pistons. I set the play using a dial gauge to 2 thou.
It now has more play than what I started with. The strange thing is there is NO broken shims at all the oil screen is spotless, even the magnetic plug has minimal swarf on it.
Now I have taken these engines down many times so that's no problem other than I don't want to  *sad2*. My actual question is about a post a while back about stripping down without disturbing too much of the rest of the lump can anyone point me in its direction I ahve a pretty good idea how to approach it but would like to check my thinking.
The bike always plays up when I start to work on the car project jealous cow

Online Topdad

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Re: Crankshaft side play/shims etc
« Reply #1 on: 05.11. 2015 16:19 »
yes they are like that, mines sulking cos a Honda VFR is sharing the garage at the moment,  *smile*. RichardL will be around soon ,he had a problem with shims so should be able to shed some light on this,sorry I can't as I opted for SRM conversion when I last restored mine, Bob
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Offline BSA500

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Re: Crankshaft side play/shims etc
« Reply #2 on: 05.11. 2015 16:24 »
The times I have reshimmed over the years its the main source of issues for my bike. I suppose I shouldn't use it all year round  *sad2*(We have been together 25 years)

Offline BSA500

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Re: Crankshaft side play/shims etc
« Reply #3 on: 07.11. 2015 11:22 »
Have started to remove the lump and I did find the post on removing it intact. Looks easy enough. Also the bit about not removing the top end etc to sort out the shims. Did a quick and dirty end crank measurement with the dial gauge and got 22 thou *eek* *eek*.

Offline edboy

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Re: Crankshaft side play/shims etc
« Reply #4 on: 07.11. 2015 12:35 »
i was told many years ago to place any shims behind the main roller bearing outer race so they cant be spat out. unfortunately i ve never tried this because i ve never had right size shims. however bsa500 have you tried this method?

Online bsa-bill

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Re: Crankshaft side play/shims etc
« Reply #5 on: 07.11. 2015 13:01 »
If you've had these engines down a few time BSA I'm going to be telling you how to suck eggs - apologies but this might be of help to another reader.
In theory the bearing inner rotates with the crank, the outer should not rotate at all, so shims clamped between the bearing inner and crank web should
 be safe, in practise if the bearing inner rotates at all the the shims will suffer, shims placed between the bearing outer and the crankcase must be large enough to not touch the bearing inner as edboy infers I think.
Not sure I'd be happy with that method, the relationship between the thickness of bearing inner and outer has to be within spec for this application also,
Make sure you source the bearing from a knowledgeable BSA A dealer
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online RichardL

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Re: Crankshaft side play/shims etc
« Reply #6 on: 07.11. 2015 14:17 »
Andy,

First, could you point us back to the thread about bottom-end disassembly while leaving the top end intact?

With at least 0.022" play, as you've mentioned, it is really surprising that you did not find shim bits in the sump. If the shims are intact, it makes me think that either the outer race or timing-side bushing was not fully seated when you last assembled the bottom end and now it's pushed into place. That said, I think you'll probably find the shim bits somewhere down there and we all want to know where. The last time I went through this I did find the bits in the sump.

In my case, I found that the inner race was finger-loose on the crank. That loose and there is no guarantee that the friction between the inner race and the crank will be greater than forces applied to the inner race by the rollers (others may disagree, but this just seems to make sense to me). If you're buying it, the inner race can spin and wipe out the shims. I used Loctite 641 retaining compound to keep the inner race in place on the crank and so far (about 1000 miles) it seems to be working. (I am about the furthest you can be from superstitious and still looked for wood to knock.)

Please let us know what you find down there.

Richard L.

Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline BSA500

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Re: Crankshaft side play/shims etc
« Reply #7 on: 07.11. 2015 18:07 »
Andy,

First, could you point us back to the thread about bottom-end disassembly while leaving the top end intact?

With at least 0.022" play, as you've mentioned, it is really surprising that you did not find shim bits in the sump. If the shims are intact, it makes me think that either the outer race or timing-side bushing was not fully seated when you last assembled the bottom end and now it's pushed into place. That said, I think you'll probably find the shim bits somewhere down there and we all want to know where. The last time I went through this I did find the bits in the sump.

In my case, I found that the inner race was finger-loose on the crank. That loose and there is no guarantee that the friction between the inner race and the crank will be greater than forces applied to the inner race by the rollers (others may disagree, but this just seems to make sense to me). If you're buying it, the inner race can spin and wipe out the shims. I used Loctite 641 retaining compound to keep the inner race in place on the crank and so far (about 1000 miles) it seems to be working. (I am about the furthest you can be from superstitious and still looked for wood to knock.)

Please let us know what you find down there.

Richard L.

I will try to find it but in a nutshell loosen the barrel studs put the pistons TDC  and slide the barrels up. This should give enough clearance to take the drive side crankcase off and do the shims etc. A bit heavy and fiddly but better than having to remove rockerbox/head/barrels and all the gaskets etc.
I will tell/pictures of what I find but again the oil screen was spotless. I am going down the drive side bearing not properly home

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Re: Crankshaft side play/shims etc
« Reply #8 on: 07.11. 2015 18:52 »

I will try to find it but in a nutshell loosen the barrel studs put the pistons TDC  and slide the barrels up. This should give enough clearance to take the drive side crankcase off and do the shims etc.

I think we mostly got that. I just thought there might be some amusing pictures.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline BSA500

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Re: Crankshaft side play/shims etc
« Reply #9 on: 08.11. 2015 10:20 »
I think the amusing pictures will come when I try this   :!

Online RichardL

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Re: Crankshaft side play/shims etc
« Reply #10 on: 08.11. 2015 16:04 »
 *smile* Looking forward to it.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline muskrat

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Re: Crankshaft side play/shims etc
« Reply #11 on: 08.11. 2015 18:57 »
You won't be able to renew the base gasket and the pushrods will fall out of their cups when the followers drop.
Cheers
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Offline edboy

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Re: Crankshaft side play/shims etc
« Reply #12 on: 08.11. 2015 20:28 »
yes and the base gasket will tear easily when you lift or move the barrels around. the method of top end removal mentioned does sound interesting and a jig to take the weight would make it easier to lift the top end but then again replacing the barrels, head and rockerbox is sunday afternoon stuff so not really worth the aggro. shiming the outer bearing to the crankcase oil seal face isnt my idea,  i was wondering if others were using that method .i.m looking forward to seeing what caused all the excess end float within 2,000 miles.

Offline BSA500

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Re: Crankshaft side play/shims etc
« Reply #13 on: 08.11. 2015 21:53 »
Base gasket can be glued together  ;) always ends up leaking any way. Going to wedge the followers. I just going to give it a go, The worst is having to remove the rockerbox while the engines out of the frame. That has got to be better than doing the limbo to get the rods back in when the engine is back in.
It has only done 1400 miles so yes its a little....disappointing  *sad2*. If the shims are intact then who knows???

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Re: Crankshaft side play/shims etc
« Reply #14 on: 08.11. 2015 22:46 »
 
Hi  *smile*

I have also just found out, that the crankshaft on my 1960 A10 have about 0,3 mm sideways endplay (no play up and down). Is that normal? I suppose not  *conf*

See a short video of the problem here: https://www.youtube.com/watch?v=7MdP7AL_DHM

Regards Frederik, Denmark.