Gearbox shimming?

[Lammer205]

Now i'm in the middle of a complete engine rebuild, ussually i have shop built motors but doing this myself(nearest dealer 150 miles) so i have sticks spanner book and here really , my question is this when checking with a feeler guage after shimming up the gearbox, on the under side of the endplate there are two raised rings one round the layshaft and an outer one and this may sound stupid but which am i shimming to, i have also just put a magnet onto first gear and can give it a fair shake which is not filling me with joy to be honest! So any input, help and advise will be very welcome.
Thanks Lammer205.

[robert gilchrist]

is it from scratch the engine your building or with original gearbox and shim?, when shimming i measured feeler by touching or resting on the layshaft underneath the endplate

[nsaints]

I appreciate this doesn't really answer your question, but lots of play as you describe sounds similar to how mine was..this is what I did

1st thing you should check is, is that your gear stack is higher than your layshaft (Stickies 2nd edition, page 74)

Mine was not. My layshaft was higher on an original SX200 gearbox, of which there is no option to go out and 'buy a new SX200 gearbox' that I know of.
In this situation shimming is difficult

I therefore measured the difference between the gear stack and the layshaft
it was 0.3mm, I then shimmed as close to the raised part of the end plate that I could 0 I got to 0.05 of a mm

This gave me a total end float of 0.35mm...outside tolerence & not perfect, but what was the option to retain SX200 ratio's other than try and find another less worn G/Box, or grinding the layshaft maybe (has this been done before?)

Anyway I struck lucky and found someone with brand new 2, 3, and 4 JET200 gears - which made my stack higher than the shaft. I then shimmed to 0.15mm not to the raised portion of the end plate
gear box & shim spins freely and no more rattling gears as you describe

Hope the above ramble helps in someway

Good luck!

[HxPaul]

Now i'm in the middle of a complete engine rebuild, ussually i have shop built motors but doing this myself(nearest dealer 150 miles) so i have sticks spanner book and here really , my question is this when checking with a feeler guage after shimming up the gearbox, on the under side of the endplate there are two raised rings one round the layshaft and an outer one and this may sound stupid but which am i shimming to, i have also just put a magnet onto first gear and can give it a fair shake which is not filling me with joy to be honest! So any input, help and advise will be very welcome.
Thanks Lammer205.

The raised ring around the layshaft isn't part of the endplate,its the layshaft bearing track.The feeler gauge should be inserted between the endplate and the bearing shim to get the desired measurement.