Series Gearbox Selector Seals Leaking

Grandaddylow · Mar 20, 2021

Hi,

I rebuilt the S3 box a while back. I replaced the selector for seals in the process. When I'd finished, the gearchange was really tight (way too tight), but no leak. Now the gear change is normal, but it leaks a *lot* from those seals.

I might see if I can get hold of some genuine ones this time, but any other tips for getting it leak free without being difficult to change gear?

Thanks, GDL.

boguing · Mar 20, 2021

I fitted genuine when I rebuilt mine, and when I finally got round to trying to find the fairly significant leak - well, you can guess! I had a spare length of brake servo hose and cut some lengths of that and they work perfectly.

Actually, just thought - my leak were the two side seals over the detent/ball springs - are your front ones the problem?

jamesmartin · Mar 20, 2021

Grandaddylow said:
Hi,

I rebuilt the S3 box a while back. I replaced the selector for seals in the process. When I'd finished, the gearchange was really tight (way too tight), but no leak. Now the gear change is normal, but it leaks a *lot* from those seals.

I might see if I can get hold of some genuine ones this time, but any other tips for getting it leak free without being difficult to change gear?

Thanks, GDL.

is it dripping on the floor or just wet under the selectors

Grandaddylow · Mar 21, 2021

On no - it is dripping fairy well. The gearbox looks like new as the oil has cleaned it so well. I assumed it was the selectors seals, but I didn't think of the detent ball seals. I'll pull the middle seat and have a look.

Blackburn · Mar 22, 2021

Gearbox and selector shaft cover are line bored when made so tops are not inter changeable check numbers stamped at front corners match up.

nickjaxe · Mar 23, 2021

It will still leak with gen seals.....just a very poor idea.

Kiwi Landie · Mar 24, 2021

I used two thin double lipped seals on the front end of each shaft. These are much better than O rings. They make the selection a little tighter but not too bad.
I cut up some 5/16" fuel line to make the two side seals and packed the springs with grease before reassembling. Been pretty good so far.
This is a really terrible design and I'm not surprised it leaks. Would've been much better to have a little screw cap on each side like the centre detent.

ORJIP · Dec 13, 2022

I too have the typical selector rod leak, more of a weap. Is it leaking all the time whilst driving - or, is it due to residual gbox preassure once switched off? I get a 2pence sized dash of oil on the garage floor each and every time I go out. Gbox was rebuilt in 2021. Would you chaps just live with it - keeping an eye on gbox oil levels - or seek to replace the seals. I dont think I had a leak for about 4 to 5 months, so assuming the selector rods are ok and not burred or pitted - but the seals have failed (3rd time). Its a significant improvement, but oh so annoying after the efforts I've gone to in keeping oil where it should be. Might be worth dropping 500ml out of the box to see if that reduced pressure build up.

Any thoughts on this ol` chesnut of a deffect?

nickjaxe · Dec 13, 2022

I would prob live with it....carpet on the floor in my garage were the gearbox drips it oil.
Bought my S3 in 1975 leaked then....they are agricultural.

boguing · Dec 13, 2022

ORJIP said:
I too have the typical selector rod leak, more of a weap. Is it leaking all the time whilst driving - or, is it due to residual gbox preassure once switched off? I get a 2pence sized dash of oil on the garage floor each and every time I go out. Gbox was rebuilt in 2021. Would you chaps just live with it - keeping an eye on gbox oil levels - or seek to replace the seals. I dont think I had a leak for about 4 to 5 months, so assuming the selector rods are ok and not burred or pitted - but the seals have failed (3rd time). Its a significant improvement, but oh so annoying after the efforts I've gone to in keeping oil where it should be. Might be worth dropping 500ml out of the box to see if that reduced pressure build up.

Any thoughts on this ol` chesnut of a deffect?

There shouldn't be any pressure in there (there's a breather on top) but the oil is flung around pretty efficiently and the dynamic pressure would overcome a dodgy seal. Do make sure it's those seals though, I've seen more from the rod end caps and detent ball retainers.

Series Gearbox Selector Seals Leaking

Grandaddylow

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boguing

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jamesmartin

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Grandaddylow

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Blackburn

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nickjaxe

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Kiwi Landie

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ORJIP

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nickjaxe

Well-Known Member

boguing

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