915 Gasket Seal ?

[GotaT]

After rebuilding my 915 box i've put in place the Very thin Paper gaskets that just didnt seem to fit exactly as desired. I have at this point put High Temp Red RTV on One side of the gasket on the box housing. It just seems the paper gasket was not cut exactly perfect and has some minor Kinks in it. Should I not worry about the kinks and just install the the boxes together OR put Gasket Seal on the other mating Surface as well?

[ChrisBennet]

I'm not a fan on putting sealant on gaskets - except for the transmission gaskets. I could be wrong but it seems like the paper transmission gaskets wick fluid it out resulting in "nose drips".

I put the sealant on my fingers and rub it into the gasket before I put the gasket on - think suntan lotion not frosting. I use Loctite 512 (clear red stuff) or Threebond 1211 (thin white non-hardening RTV).

Like any gasketed surface, the surface needs to be free of raised "dents" and old gasket material for best sealing. Don't pry on those surfaces.

I don't enjoy scraping gaskets off but when I have to I prefer to scrape them off the surface that doesn't have stud sticking out of it. To that end, I clean both the surfaces with BrakeKleen or something then I spray the surface that has the studs on it with some WD40 or just wipe it down with some oil. The result is the the gasket sticks better to the non-oiled surface better so next time I disassemble the transmission the gasket sticks to the surface that doesn't have studs sticking out of it.


-Chris

[GotaT]

I have 512, but i thought this was only to be used for Metal to Metal mating surfaces.. I have already put High temp Red RTV on one side as mentioned, should I coat the other side once I push the Cases on? Which would be recommended, high temp red rtv OR Loctite 512?
Thanks

[Roslin]

Not many are talking about the old Blue Hylomar (Rolls Royce Gasket)
but i used it a lot in earlier days on mini engines/gearbox paper gaskets with sucess.

[ChrisBennet]

Originally posted by GotaT
I have 512, but i thought this was only to be used for Metal to Metal mating surfaces.. I have already put High temp Red RTV on one side as mentioned, should I coat the other side once I push the Cases on? Which would be recommended, high temp red rtv OR Loctite 512?
Thanks

Sounds like you applied RTV without assembling. If so, that RTV now cured. It's not hard to seal these transmissions but I don't know they will seal with a bumpy uneven RTV gasket.
Personally, I'd pull the gasket and clean up the surfaces and get a new gasket and rub some 512 into the gasket and assemble.
I'd toss the HiTemp RTV in the trash but that's just me.
-Chris

[Jeff Alton]

Hylomar is what I have used in the past with success. I will find out again here shorlty if it worked this time too. I think I got that tip from either Hayded or Tyson, can't remember.

Cheers

[Roslin]

Thanks Jeff, look forward to hear about the result.

Roslin

[Jeff Alton]

Roslin, you can't go wrong with adivice from Chris, he has had a few more of these apart than I have!

Cheers

[john walker's workshop]

K&W coppercoat spray is nice. let it tack up a bit before assembling. beware of any gooey sealer on those newspaper thick gaskets. when you tighten the parts together, the sealer will be pushed out and it will often take the gasket with it.

[tagpower]

been using hylomar for about 30 year its great for this mating surface but you have to make sure that you re-torque the unit after 30 min of first hardwar torque.

cheers

[MBEngineering]

HI, Some guy's in Germany I think (but not to shure) designed and built gearbox's like these and I have seen a few in the UK , I have had the pleasure of taking the odd one apart and found only the gasket fitted, no sealer, (do you think that thay got it wrong ??and should have put RTV in there, then come to think of it they prob' did not have any RTV when they built, sorry designed it!!) as long as you use a good original or elring gasket's you should not have any prob's fitting the gasket dry, if the casing faces are not damaged and clean/dry like Chris says and if you must put some thing on there to hold the gasket in place a dab of grease/ Curil-K or hylomer, I have only had a leak from the gearbox gasket when the gasket has been damaged/torn with no sealer, my fault on assembly, have fun choosing what to do as it is your box and we are only giving you our advice/opinions on what we do.

regards mike

[GotaT]

I appreciate all the input and have ordered New gaskets. I think I will look into getting either the Permatex in the container, I forget the Name,.. something..Tac. Or the Hylomer. Where can it be purchased?