M6 crankshaft end float

Information relating to Matchless and AJS Models built prior to 1939
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Tim K
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M6 crankshaft end float

Post by Tim K »

Hi Everyone
What should the crankshaft end float be on a 1929 M6 (plain bearings). When I disassembled the engine all the shims were on the drive side, is this correct or should I split the shims across both sides?
Cheers
Tim
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Duncan
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Re: M6 crankshaft end float

Post by Duncan »

Hi Tim, unfortunately I don't know what the end float should be for your engine but early 50's singles were between 0.020" and 0.050" (service limit) http://archives.jampot.dk/book/Workshop ... ndards.pdf see page 7. From other makes of pre-war engines I have worked on the required shimming should be positioned between sides to ensure that the conrod is running central to the bore/piston.
Tim K
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Location: Nsw AUSTRALIA

Re: M6 crankshaft end float

Post by Tim K »

Hi Duncan
Thanks for that. Splitting the shims between the sides makes sense as having it all on the drive side could misalign the big end oil feed through the drive side bush.
Cheers
Tim
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Taid
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Re: M6 crankshaft end float

Post by Taid »

Rather than simply splitting the shims equally, should they not be divided such that the big end journal is central ..

I know it sounds like the the same thing ... But if shims are needed, you can't assume the same amount is needed each side ..
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Now sold ... 1956 AJS 16MS Bitsa .. HSU 414 .. rebuilt/re-registered 1987
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Duncan
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Re: M6 crankshaft end float

Post by Duncan »

Taid wrote: Sun Apr 02, 2023 7:41 am Rather than simply splitting the shims equally, should they not be divided such that the big end journal is central ..

I know it sounds like the the same thing ... But if shims are needed, you can't assume the same amount is needed each side ..
Correct, but stated clearer than I managed to.
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