TH400 Help
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Instructor
Joined: Aug 2004
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From: Highlands Ranch CO
TH400 Help
I have a '68 with a TH400 transmission. If the car has been sitting for awhile it will take a few minutes for the tranny to engage. Once it warms up there are no other problems and it seems to shift fine. Any idea what would be causing this problem? I've had one guy tell me this is serious and I should have it rebuilt immediately and another guy tell me its not a big deal. Any help would be appreciated!
Mark
Mark
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Joined: Aug 2004
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From: Highlands Ranch CO
The fluid level seems fine. It is leaking a little and I'm sure that is contributing to the problem. I'm pretty ignorant when it comes to transmissions but isn't there a front seal that could be the cause...requiring the whole transmission to be taken apart to get to it?
Melting Slicks
Joined: May 2002
Posts: 2,431
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From: Florida
with age, the lip seals internal to the transmission harden and will cause the problem you described. Since it's fine once warmed up, it's highly likely the lip seals are to blame. The overhaul kits have all the paper, rubber and cork gaskets needed to refresh unit. They also sell an additive which I believe is only a temp. fix which softens the internal rubber seals and cures this sometimes. This softening agent is kinda risky though since it may cause leaks and over soften seals. New trans. fluid might help since it too contains agents to condition the rubber parts but it probably isn't enough to soften them substantially. It's probably due for an overhaul including clutches and bushings....IMHO.
Jim
Jim
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Joined: Aug 2004
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From: Highlands Ranch CO
Originally Posted by jimvette999
with age, the lip seals internal to the transmission harden and will cause the problem you described. Since it's fine once warmed up, it's highly likely the lip seals are to blame. The overhaul kits have all the paper, rubber and cork gaskets needed to refresh unit. They also sell an additive which I believe is only a temp. fix which softens the internal rubber seals and cures this sometimes. This softening agent is kinda risky though since it may cause leaks and over soften seals. New trans. fluid might help since it too contains agents to condition the rubber parts but it probably isn't enough to soften them substantially. It's probably due for an overhaul including clutches and bushings....IMHO.
Jim
Jim
