Reducing laygear end float

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Reducing laygear end float

Postby 69Midge » Sat Jan 09, 2010 5:25 am

Hi,

I'm rebuilding a ribcase gearbox out of a 69 Midget and the laygear has quite a bit of end float, 0.021", and the manual says it should have 0.003-0.005" for the MK3 midget. The running surfaces in the hosuing look ok so I'm not sure why it has so much. I'm putting a new laygear and shaft in it and both the old and new laygear have the same problem. The shims in the front and back are both 0.125". I know I can get a thicker rear shim up to 0.0131" but this won't be enough to fix the problem. Is there something else I can do ? Can I get even thicker shims?

Thanks,

Greg
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Re: Reducing laygear end float

Postby Charlie Tolman » Sun Jan 10, 2010 1:49 am

Is the available thicker rear shim 0.131" (0.0131" typo ?) ?

Would you be able to make some shims from thin material, around 0.008", to add to the front and rear 0.125" shims?
I have made shims for the output shaft, and this exercise would be similar.

Some machine shops have a variety of valve spring shims, in different thicknesses and inside diameters, which might work.

Charlie Tolman
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Re: Reducing laygear end float

Postby 69Midge » Sun Jan 10, 2010 7:11 am

Yes typo, 0.131". I was thinking of putting a shim in between the spacer and the housing but wasn't sure whether this would be ok as the factory spacers have oil grooves on both sides to keep lubrication between them and the housing and if I put a shim in it it obviosuly won't so if the shim spins the side against the housing could wear the housing? or perhaps there'll still be plenty of lubrication around with a shim in and I'm worrying about nothing?

Greg
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Re: Reducing laygear end float

Postby Charlie Tolman » Mon Jan 11, 2010 1:30 am

If one used two shims fabricated from #10 gauge mild steel, with a thickness of 0.1345", the net end play should be close to 0.002". With a little "polishing" on a flat board with 180 or 240 grit wet-or-dry paper, the shim thickness could be reduced slightly, and the end-play could be increased to 0.004". A few shallow radial slots could be filed into these shims, for oiling purposes.

Using one shim of #10 gauge mild steel, and the available 0.131" rear shim, would change the 0.021" end play to approx. 0.005 to 0.006". The gears on the layshaft might not align perfectly with the gears on the main shaft. ??

Aluminum #8 gauge, at 0.1285", appears to be slightly thin for this shim application.

Just a couple of suggestions.

Charlie T.
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Re: Reducing laygear end float

Postby wworks » Tue Jan 12, 2010 9:03 pm

Greg,
You have a PM.
Dug
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End float fixed

Postby 69Midge » Fri Jan 21, 2011 7:33 am

Well my end float problem is fixed!! :D

Doug (wworks) made me a shim to order. The workmanship was 1st class and when I put it in it was spot on at 0.004" end float, instead of the 0.021" it had. Having a fellow enthusiast make it made it a lot easier for me because he understood my problem and how to fix it. If I had to go to a machine shop, explain what I needed I'm sure it would have been hard wiork. Thanks Doug!

I suspect my endlfoat may have been there from day one. When the car first came of the road in about 1984 with its previous owner the gearbox had already been apart and the laygear needle rollers had been replaced with bronze bushes and the shims had been centred punched on their edges in a futile attempt to make them fatter. This didn't fix the endfloat. It would jump out of gear now and then when dabbing the power on and off and I now wonder whether the laygear floating back and forth may have been the cause of it because apart from general wear I've found no other faults with the box.

I've bought a lot of parts for it and its cost me quite a lot but I'm now confident that I've have a good gearbox for many years to come.

Greg
Greg
Tasmania,Aus
'69 MKIII Midget
69Midge
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