400 auto gearbox problem

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Joined:Tue Sep 03, 2002 6:35 am
Location:St Albans, UK
400 auto gearbox problem

Post by simonc » Tue Aug 08, 2006 1:43 pm

I have rebuilt the GM400 gerabox in my 400 and was very careful to follow the GM workshop manual to the letter. New seals, bearings, clutches and band were fitted. I have refitted the box to the car and have a major problem. When I put the car in reverse it does not move properly, it just creeps very slowly backwards plus it pumps gearbox oil out of the small overflow pipe on the top of the box. I have drained the oil out and it seems a little black-ish and smells of burnt clutch. The clutches and band were new and the box was filled with new ATF oil. Obviously it has done zero mileage since the rebuild.

I obviously have managed to get something wrong. Does anyone have any idea what this might be?

Simon in London
Simon in the UK

1973 246GT Dino
1976 365 Boxer
1977 400 Auto

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