Can you use gasket sealant?
Turbo Mini Forums

Ive recently taken apart my diff and reassembled, but there was no gasket between the gear box case and back plate, just sealant.

Do you need a gasket in between or can you use sealant on its own instead?

Cheers Matt

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1/4mile in 13.2sec @ 111 terminal on 15psi

yes, some gearboxes had no gasket

if theres no gasket there, then your just supposed to use sealant

Ah nice one at least I don't need to take it apart again.

It doen't say anything about that in the manual ive got though, strange 'cause its kind of important!

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1/4mile in 13.2sec @ 111 terminal on 15psi

It's pretty std to put the gearbox casing on with silicon gasket sealant nowadays, but you should use paper gaskets for all other mating surfaces...

Edited by Tom Fenton on 11th Sep, 2006.

I read this as 'gearbox casing' ie - onto the engine? Even that i thought sounded bizarre?

If unsure with the diff housing - a check with a set of decent digital calipers or internal micrometer in the diff bearing bore will yeild the right answer I'd have thought - given a typical gasket thickness it should be VERY obvious if it's meant to have a gasket or not...

This is even more confusing - Surely you're not suggesting that on an older transmission that originally used a paper gasket, that you can just use RTV or whatever sealant instead of the gasket?????
I pretty much hope I'm mis-understanding what you're saying...

Edited by turbodave16v on 11th Sep, 2006.

I was informed that if there were gaskets there original you used gaskets!

simple as that.

Certainly with the diff output shaft covers you can check by measuring, and as said measuring the diff housing is fairly easy :)

Never had a leaky diff housing with either type.

As for the gearbox to engine, I would imagin modern RTV sealant would do a better job than just paper.

Alex

AlexF

my gearbox is a mixed bag of nuts, i couldnt tell you whether it had gaskets orginally, and the casing has been changed.

It has bolts to hold the diff covers on, but i used gaskets with a smidgen of sealant on it

is there actually any disadvantage of using gaskets to hold on a gasketless casing, or vice versa?

The pre load on the diff will be wrong if you get the gasket on the diff side covers (output shafts).

Alex

AlexF

bolt the diff housing on with no diff,then check it for roundness

If it's round then assemble with sealer

If it's smaller at 90 degrees to the join then gaskets are req'd to make it round

Metro turbo weekend driver,Mini turbo in the making again!

eek,im scared now

saying that, its been holding up with no leaks

The type im using uses bolts instead of studs to hold the diff casing together.

The one ive just taken off has studs and DOES use a gasket!

Dave-I am talking about the plate the holds the diff bearings in.

Just Mic'd the gasket and it measures .22mm (new), when fitted they must compress to .15mm I would of thought?

Are the tolerances that precise, as it is very unlikely that each individual would apply the same amount of sealant as each other?

I would of thought it would be best too tight (within reason) than too loose!

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1/4mile in 13.2sec @ 111 terminal on 15psi

I did it in my very first ever gearbox build. You're not the first or last i'm sure!!!

Yea ive made sure the side plates have paper gaskets and an O ring.

Ive missed out the one between the engine and gear box before though, thankfully i'd only got as bolting the transfer casing before finding it amongst some other gaskets!

I thought the O ring on the diff side plate was the source of my oil leak, turns out its VERY likely to be my primary gear 0.45mm of play! The outer trust washer has taken a caning!

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1/4mile in 13.2sec @ 111 terminal on 15psi

It sounds like a few too many emergency starts have taken their toll! However axial clearance on the primary gear wouldn't usually cause an oil leak past the seal, although it is not great news for the life expectancy of your drop gears!

its been in the car 2 1/2years untouched and done over 8000miles at 12psi. its done well!

Got some SC drops now ;0

what with moving house etc haven't had chance to do a rebuild 'till now. Theres loads of oil in the clutch housingi assume its the primary seal as i read on other threads?

Im changing all gaskets,seals and O rings just to make sure.

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1/4mile in 13.2sec @ 111 terminal on 15psi