do they swell? because after putting in my rebuilt trans with a new gasket i filled it with 8 litres of dexron for a starting point and i had dribbles coming out for 2 or 3 spots around the pan. after waiting 5 minutes then topping of the fluid and having a drive its all sealed.

 

Nothing conclusive here but I've always had good luck with cork valve cover gaskets by just installing then snug- as long as the entire gasket's periphery is contacting the head (however slightly) they don't leak. I never had your luck with those !!@%!? transmission pans though. The last time I did the one on my Vette it wound up with a Muncie in it about 6 months later!!

 

Shouldn't you be using a neoprene rubber gasket? Felpro or the likes? I was under the impression that the cork gasket's weren't that good. Maybe I'm wrong.

 

im agreeing with both of you cause it kept leaking , even though it almost came to a stop. i know not to tighten them too much but gave them all a little bit more torque after the first drive but no joy .

my problem is im running a cheapish chrome cover and mixed with the cork gasket its no good. im going to bight the bullet and order a nice solid pan and felpro gasket.

is there any harm in adding a little red gasket goo to the 2 surfaces of the gasket just for extra security?

but man o man did this rebuilt transmission sure bring my gear changes to life. solid changes chirping when just cruising.

 

get an aluminum pan and you'll forget everything about fluid dripping on the floor!, thats what I did for my both cars after almost losing all my hair!

 

I've read that the cork gaskets work better. I had to replace mine (neoprene) again, but they didn't have cork at the parts store I went to. I didn't shop around though and used the Felpro neoprene. I have a cheap chrome pan too. Make sure the pan mating surface is flat. They get bent real easy at the bolt holes. I hammered out as straight as I could. This time I wire brushed the gasket surface of the pan then cleaned the pan and tranny surface with alcohol thoroughly. I used Gasgacinch gasket sealer on the pan only to hold gasket in place. I wouldn't use the red gasket sealer (I've tried and failed) based on what I've read and only use the Gasgacinch on the pan side. The other thing I tried was torquing to 95 in/lb in two steps. I found in the past that the more I tightened, the more it leaked. I'm hoping that torquing to spec will be the trick. If you have any bolt holes that are stripped, you need to helicoil them. The last bolt that I tightened was in a stripped hole, so I had to undo everything, drop in a helicoil and put it all back together. I knew if gambled on it not leaking there that it would. One thing I'm learning is to make sure you do it right the first time or you will be doing again. I don't know how many times I've tried to fix that tranny leak, but I'm as optimistic as ever that it won't leak this time.

 

The chrome pans are so slick on the pan rails that the gasket can't "bite". It slides around and will leak. Solution is to take some 80 grit sandpaper and rough up the rails on the pan.

 

By "red gasket sealer" I presume you're talking about RTV. If you must use RTV, use the GRAY Hi-Temp stuff. Over the years I have used all of them and finally settled on the gray stuff about 10 years ago. It WORKS, and I use it on anything that I use to seal gaskets. It also works very well AS a gasket, as in sealing a cast aluminum tranny pan to your TH400. The only thing that I've seen that is superior to it is MIL-S-8802 polysulfide aircraft fuel tank sealer which is what the military uses to seal nearly anything on an airplane that needs sealing. I think about taking a tube home sometimes but God says NO! so I don't.