Author Topic: I have an idea re: shims  (Read 617 times)

Offline smartsx1x

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I have an idea re: shims
« on: 21.06. 2018 17:45 »
Hi i'm new to this board thank you for letting me join
having bought a goldflash 1959 i soon found out that all that glitters is not necessarily gold,
so i am in the process of removing 9 peoples worth of hobby time from the engine etc,
my question is has any one thought about shimming the outer race on driveside roller bearing this would eliminate the need to fit those flimsey shims that i hear alot of horror storys about,the outer race would only stand proud an extra .05mm i would remove .05mm from the outer race protruding side to keep a good gap from crankshaft to allow oil flow ,the inner roller has a lot of clearence to the outer edge so dont see any problems .
has this been done before ? your thoughts advice would be appreciated
regards martin  *smile*

Online Greybeard

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Re: I have an idea re: shims
« Reply #1 on: 21.06. 2018 18:25 »
Hi Martin  *welcome*

Offline smartsx1x

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Re: I have an idea re: shims
« Reply #2 on: 21.06. 2018 18:46 »
cheers
ps 62mm od shims same as bearing od available on a well known website

Offline berger

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Re: I have an idea re: shims
« Reply #3 on: 21.06. 2018 19:33 »
hi and welcome, *welcome* the answer from me is no. the inner race must be tight up sandwhiching the shims to the web by means of the engine sprocket sleeve etc. if you do it the way your thinking it will tend to dance with vibration causing problems. my two penneth anyway. edit,

 engine sprocket bearing I keep calling it a sleeve cos well, to me  its long like a sleeve

Offline smartsx1x

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Re: I have an idea re: shims
« Reply #4 on: 21.06. 2018 19:36 »
thanks for advice

Offline smartsx1x

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Re: I have an idea re: shims
« Reply #5 on: 21.06. 2018 19:54 »
just looked at it again i see what your saying but the sleeve would push inner race tight up against crankshaft and the .05mm clearence would be taken out by shimming outer race the only thing i can see might need extra shim to lift cus drive cog up to align up with clutch
with respect thats how it looks to me i could be wrong  *conf*

Offline berger

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Re: I have an idea re: shims
« Reply #6 on: 21.06. 2018 20:01 »
I have not been to the pub, you are still giving the inner race a license to dance on the crank shaft . I thought out your idea many moons ago.  be careful *warn* if you go with your idea .... when moon come over mountain white man die. edit there will be some wise people along to speak on this but I do see what you mean, so who's done it this way over the years? ignore me i'm going to the pub cos i'm now talking shite with a house full of loons doing my head in, cheers

Offline smartsx1x

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Re: I have an idea re: shims
« Reply #7 on: 21.06. 2018 20:07 »
i here you :)  will tread very carfully

Offline Servodyne

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Re: I have an idea re: shims
« Reply #8 on: 21.06. 2018 20:32 »
Sorry to jump in, but I can't really see to advantage of what you are trying to achieve. If the correct shims are fitted to the inner race, the whole assembly is clamped up solid to the crank by the retaining nut.
If you delete these shims and shim the outer race, the crank assembly will still be clamped up solid, but you will need the same shim you deleted, fitted between the crank seal spacer and the shock absorber sleeve, in order to keep your sprockets in line.
It seem to me you are trying to fix a none problem.
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Offline smartsx1x

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Re: I have an idea re: shims
« Reply #9 on: 21.06. 2018 20:37 »
having heard a lot of storys about the shims being found in bits in the sump i just thought this could stop that but wonder why so many stories of shim breaking whats the root cause
thanks for your input

Offline Servodyne

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Re: I have an idea re: shims
« Reply #10 on: 21.06. 2018 20:49 »
Possibly incorrect shims (ID too big or wrong material) or slack retaining nut?
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Re: I have an idea re: shims
« Reply #11 on: 21.06. 2018 21:55 »
some bsa engine builders used to recommend the shim behind the bearing outer to case as small shims can be spat out from the crank webb at high revs. finding the size of shim is the major problem. the next one down is the bloke who posts a picture of his engine post explosion and blames this mod and me who recommended it.

Offline smartsx1x

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Re: I have an idea re: shims
« Reply #12 on: 21.06. 2018 22:02 »
i have seen suitable ones on UK Bearings Ltd i do like the idea  but not heard any thing on reliabilty just thought i'd throw it out there never hurts to ask

Online chaterlea25

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Re: I have an idea re: shims
« Reply #13 on: 21.06. 2018 22:04 »
Hi All
You guys are thinking too hard   *conf*
once the cush drive nut is tight, shims or no the bearing inner will be clamped solid
The sprocket alignment is secondary and needs to be addressed no matter where the shims are fitted
The downside of shimming the outer race is that it might require several attempts to get correct
this means heating the cases to release the bearing, this could lead to the interference fit being lessened
BSA picked shimming the inner bearing for a reason  *ex*

John

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Offline duTch

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Re: I have an idea re: shims
« Reply #14 on: 21.06. 2018 22:16 »

 Hiya smartsx1x , there was a discussion of this not very long ago- if you do a search you should find it....might save carbon-copying the stories  *smile*
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