Shimming gearbox layshaft (2014)

Spent a frustrating afternoon trying to shim layshaft per Old Britts instruction using rear iso shims
First attempt dry gasket, bolts to torqued to 15 ft/# same for all attempts, dial indicator read around .040 free play.
Second attemp dry gasket, added .020 and .010 shims, now no free play
Third attempt dry gasket , .020 shim only, still no free play
Fourth attempt dry gasket, .010 shim only, about .008 free play. Figure this is good and add new gasket with cement
Fifth attempt gasket cement, .010 shim only, now no free play
Stip stud disassembling again, get pissed, call it a day
Has anyone been able to do this. It seems to me and I just guessing that the gasket is getting compressed differently each time. It seems like if the gasket is around .020 it would be hard to get it to compress identically every time.
On my previous gear box rebuild, I just checked it after it was assembled and it was right at .010 and I left it alone.
I have a BSA bottom end to do. Hope it goes better than this.

Did you trim the shim to fit flush on the face of the kick shaft. There is a machined radius that does not allow the shims to lie flush. This is your mystery dimension.

He's right as rain. Gotta trim the shim.

I did not trim it. It seemed like it was fitting flush. I'll give it a haircut tomorrow just to issure it is fitting flush.

htown16 said:

I did not trim it. It seemed like it was fitting flush. I'll give it a haircut tomorrow just to issure it is fitting flush.

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That's the prob, spring back. I.D. Must be ground out to clear radius.

Some day most may do like I was taught by NOC-UK garden shed mechanics, leave a gasket or two out.

Okay, relieved the id of the shims just a bit using a grinding drum on my dremel. Inner cover back on and torqued down. Started out with .040 float and added .01 and .02 shims. Float now measures .010, so all is well.
Thanks for the tips.

Saw this thread. Good info. I am reassembling the gearbox this morning. Measuring the end float without shims, I have .074" on the dial indicator. Is this within the realm of what can be expected?

Thanks.

~998cc

998cc said:

Saw this thread. Good info. I am reassembling the gearbox this morning. Measuring the end float without shims, I have .074" on the dial indicator. Is this within the realm of what can be expected? I have enough isolastic shims (from AN) to get to .005 to .010", though the thicker ones (.030") are zinc plated and may be soft. I assume soft shims would be ill advised in this location? Otherwise it will be a stack of thinner shims.

Thanks.

~998cc

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That seams like more than just standard parts dimensional deviation. Gasket thickness? Bushing damage? I’d double check stuff.

concours said:

That seams like more than just standard parts dimensional deviation. Gasket thickness? Bushing damage? I’d double check stuff.

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All new parts. The Andover roller bearing kit with gaskets, bushings, etc. Bearings all went in with good interference. Interior of the box looks good.

Also, from time to time, check that you still have a small bit of free play by pulling on the kickstart lever. I have thought of having custom shims made with the correct I.D. There are plenty of shops that can make them. I had to do that on a BSA A-10 gearbox.
Careful with leaving out a gearbox gasket, it might make shifting a little stiffer.

Gasket is .018" uncompressed location.

seattle##gs said:

Also, from time to time, check that you still have a small bit of free play by pulling on the kickstart lever. I have thought of having custom shims made with the correct I.D. There are plenty of shops that can make them. I had to do that on a BSA A-10 gearbox.
Careful with leaving out a gearbox gasket, it might make shifting a little stiffer.

Click to expand...

It seems leaving out the gasket has been done on occasion. A gasket came out of mine, so one goes back in.

Going to reassemble again and check end float then make up the shim stack.

~998cc