Hey all,

I'm rebuilding my gearbox, and I have a second gearbox for parts (since this box was recently rebuilt but has had the box damaged).

Looking at the two diffs, the bearings are quite different. The old one seems to have a plastic cage that has collapsed. The newer bearings seem to have a metal band as part of the cage, and they are still thrust bearings.


The upper one has been rebuilt (I believe - the rest of the gearbox had been). The lower one hasn't seen the light of day since 1978.


The old diff close up with it's cage falling out.

So the question: do I treat the new bearings the same as the old type i.e. preloading shims and the like? Are these bearings the right ones for the job?

Edit: I suppose you might want some numbers:
The old bearings have the number 2LJT34.9
The new bearings have 17LJT13/8

Original diff bearings were a deep groove ball bearing, both sides looked the same and you could fit them either way round. Preload on these was only .001".

Later type are angular contact bearings, and are marked `thrust' on the outer ring. These only can fit 1 way and are preloaded .005".

I have been told this 2nd type is NLA now, most places are selling the early type again- which are a standard size ball bearing.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Chuck a 4 pin in there while youve got it all apart.

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Simplify and add lightness

This must be to handle the monstrous torque delivered by my unmodified 998 :)

Now, another question related to the gearbox: The threaded rod that attaches to the actual box and holds the levers that controls the selector forks spins when I try to turn the nut. This is the threaded rod that is attached to the circle at the bottom of the box. When I dismantled the last box, the nut came straight off, but with this one, it's turning the whole lot. Any suggestions on how to get the nut off, and will this cause the box to leak in the future?

Depends how long you want it to last

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Simplify and add lightness

A single competition pin from Karcraft would be more than sufficient for and unmodified 998.

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Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

I was thinking that a broom handle...

Foget the pin, fit a CIG limited slip )

To answer your question,
Yes Both these Bearings you have pictured can be treated as the same.

They are both THRUST type bearings.

The thinner bearings in the lower part of the photo are in fact the newer of the two...

The bearings in the upper photo are the first of the THRUST type, not to be confused with the very early deep groove ball bearings used in early cars.

Hope this helps,
Dave

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