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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: st3vomettler on June 05, 2015, 10:06:28 pm

Title: Th400 rebuild
Post by: st3vomettler on June 05, 2015, 10:06:28 pm
Is it hard to rebuild a th400?
Title: Re: Th400 rebuild
Post by: Engineer on June 05, 2015, 11:51:44 pm
No. Not hard at all.

Probably the easiest automatic transmission ever.

One of mine survived for a couple of years in a mud truck where the owner never hooked up the fluid cooler........for real.
Title: Re: Th400 rebuild
Post by: st3vomettler on June 06, 2015, 10:14:43 am
Ok I had to take it out because the output shaft is messed up. I took the valve body off and the output shaft had a lot of play in it to were it shudder so bad it slowed down while going 63
Title: Re: Th400 rebuild
Post by: st3vomettler on June 06, 2015, 12:48:42 pm
How do I get the last bit of gears out of the transmission
Title: Re: Th400 rebuild
Post by: Engineer on June 06, 2015, 04:41:24 pm
If you took the valve body off there should be a 12-point headed bolt with a hole through the middle of it that holds the center support in. Take that out and the entire gear train should just slide out.
Title: Re: Th400 rebuild
Post by: st3vomettler on June 06, 2015, 08:10:56 pm
Is ether of the shafts on this move at all
Title: Re: Th400 rebuild
Post by: Engineer on June 06, 2015, 10:41:43 pm
There is a big snap ring that holds the rear output shaft into the planetary ring gear. Take that snap ring out and that all comes apart.
Title: Re: Th400 rebuild
Post by: st3vomettler on June 07, 2015, 09:26:10 am
Is there a way to tell if it's going bad?
Title: Re: Th400 rebuild
Post by: Engineer on June 07, 2015, 06:56:07 pm
Visual inspection would be a reliable and cheap method.

If it all looks ok it probably is.
Title: Re: Th400 rebuild
Post by: st3vomettler on June 07, 2015, 08:55:46 pm
It looks ok but when I got it apart I notice some big pieces of metal in it