I'm in the process of trying to remove the front main seal on my TH400. I've tried to get it out without getting too aggressive (using pliers and small screw driver), but have had no luck. Before I try more drastic measures, I figured I'd come and check to see if there are any tips from people who have done it before. I did a search and couldn't find anything.

Could somebody give me a few tips (if there are any) for removing and installing the front seal? Am I being to gentle with it?

Are you taalking about the seal on the timing cover? just lay it flat on your bench face up, (I think, Can't remember which way the seal goes in) Put a screw driver on the seal and give it a good wack. just be a little more gentle installing the new one.

I'm talking about the seal on the transmission that is around the transmission shaft that goes into the stall converter. Sorry, I'm not sure what the real name for that is..?

Sorry, Didn't see the TH before the 400. If I remember correctly, that is a press in. Should just pry out.

Okay, I'll give it another shot and come back inside with the results...

No luck. I can't pry it out. All I'm doing is bending the metal/alumin on the seal Gotta be done for the night. Should I hit the seal with a heat gun next time I get a chance? Any other suggestions?

I'm starting to regret the decision to replace the seal when it wasn't leaking...but I've also heard that it's a good thing to replace any time you have easy access to it...

Get a seal puller from sears. I just did the input and output seals on mine.

I'll make a trip to Sears today. Any tips on installing the new seal? I'm assuming that I will need a few soft hammer blows to get it in all the way.

I used a seal puller and damaged my bushing, I had to have m tranny shop pull the front pump to replace it. Be careful, it only takes a second to damage it.

just get a small screwdriver, catch it behind the metal lip that seats against the pump. tap it with a hammer. you'll distort the seal, when the lip bends out. grab it with some vice grips and pull. you just want the seal to crush in on itself. when you install a new one. just lay it flat, get a 1x2 and hit the block of wood, just make sure you work your way around it so it doesnt go in cocked. dont forget to lube the new seal rubber with some tranny fluid, if not, the dry seal might get damaged when the converter starts to spin. jim

I used a seal puller and damaged my bushing, I had to have m tranny shop pull the front pump to replace it. Be careful, it only takes a second to damage it.


How did you know you damaged your bushing? If you can't tell by my postings, this is the first time I've done this. :confused:

I looked in it and saw the scars on it. The bushing is pressed into the front pump behind the seal and it allows the converter to ride inside the pump. I knew it as soon as I did it.