Has anyone successfully replaced the felt seals for the selector rods in a 120 gearbox?
Where did you obtain the seals and did they fully seal?
Very few people do replace them I believe
One person I know who did his mechanic used some sort of modern lip seal.
Part of the problem on leaking is I think the build up of pressure in box due to relief vent hole being to small
I’ve pulled the top of the box off and removed the seals. The do appear worn so am having some A Grade felt cut and see how they go.
Cant be any worse than what was in there.
I do see SNG Barratt do have them listed part number C.929.
Hi Graham,
Yes, I’ve just replaced them as part of a full gearbox rebuild. I used the SNG parts listed above, and they don’t quite fit. They are slightly too large to be able to be compressed enough to fit into the recesses. The outcome is that the metal cover that clamps them in place sits slightly proud.
Now, they do seem to give a decent seal around the shafts. I plan on modifying the ridiculously small breather to prevent any pressure buildup. Time will tell!
Simon.
Hi Simon.
Thanks for the info on the SNG seals.
I’ve also found the retaining plate isnt strong enough to retain compression on the seals and just bends. I may look at fabricating something stronger.
Regards
I’ve been thinking about this for a while, as my MKV box leaks like a sieve…
Could a thin line (like a distributer advance tube) be run from the breather into the inlet manifold to provide a bit of vacuum?
Graham,
Bear in mind that you are inserting bolts into soft aluminium, so even with a stronger plate, you probably can’t apply more pressure!
I’m sort of surprised it is an area that proves to be very leaky; as long as there is no internal pressure buildup, any oil pushed up into that extension should verb quickly drain back into the gear case??
Simon.
Certainly clean the vent on top, that should be all you need in the way of venting to keep these things at atmospheric pressure.
How much of a leak are we talking? A drop per week or a drop per minute?
We should not expect these old things to be as leak free as modern cars.
Leaks are generally at gaskets and shaft seals lower down, not much at the shifter rods. Or case bolts not tight.
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Hi Rob. Enough to leave oil on the ground everytime it is parked. On inspection of the seals it is evident they are the originals, that have probably leaked for the last 50 years, and should have been replaced when the gearbox was rebuilt.
Then there is this leak. About to attempt to replace front crankshaft oil seal. Engine was also rebuilt.
I recently tried replacing my selector rod seals. They still leak as badly, if not worse! The felt seals supplied via Coventry Auto Components seemed to be a much “looser” consistency than the old rather dense ones, and were also too big in diameter. There was no way I could stuff them into the recesses and so I had to trim the OD. They were also too thick, so the retaining plate is now “cocked”. All in all, a rather unsuccessful excercise! I checked the breather which was perfectly clear, and there are no leaks from elsewhere, just from the selector rods. I originally replaced the output shaft seal, thinking that was the cause, before I discovered it was the felt seals. At the moment I’m just living with it… I toyed with the idea of using modern X profile O-rings, which might work better, although the notch in at least one of the rods moves in and out of the seals, anyway. Guy Broads told me they just force a lot of grease up into that area. I don’t know how effective that would be…
Hi Chris.
I dont know why these companies bother to produce goods unfit for task.
You have given me an idea though.
I might try working something into the seals, like Vasolene, before installing.
Once compressed this might help keep the oil on the inside.
Or is there another lubricant that would actually repel the oil?
Cheers, Graham
I replaced them recently.
First I bought some replacement but they looked nowhere near as good as the original (actually they wouldn’t even fit properly — too thick — so the clamp plate couldn’t sit properly.
I suspect the felt seals provided are just generic felt seals, not tailored for the XK120 gearbox
In the end I used nice rubber square section seals I already had in a drawer. Cheap and so much better than the bad reproduction felt seals anyway (simple o-rings would fit too, and as for the material the gearbox oil is not very hot so I think there is no need to buy special fluoroelastomer seals)
Thanks Julian.
I will be collecting the seals I’ve had made today and fit them tomorrow.
I found a product on line called SINOPEC 7903 which is an oil resistant grease which looked ideal for working into the seals before installation however it is unavailable in Australia.
I may try further afield.
Regards