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Old 04-25-2008, 06:07 AM
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th400 slipping 3rd gear

Got a th400 tranny was rebuilt year and a half ago
worked fine for first 400 miles
1-2 shift is firm all good 2-3 shift is soft but after 30-45 seconds in 3rd
it starts slipping.
I can pedal it and get it to grab 3rd for a second or two then starts slipping again.

reverse gear and clutch is fine (this is the same clutch thar 3rd uses correct)
so I don't think it is the clutch
has to be a broken spring or stuck pistion for the 2-3 shift circuit?

can any one give me a diagram on where this is in the valve body
have put shift kits in trannys before but that all
willing to give this valve body fix a try if I know where to look

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Old 04-26-2008, 10:05 AM
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Quote:
Originally Posted by rolrandy
Got a th400 tranny was rebuilt year and a half ago
worked fine for first 400 miles
1-2 shift is firm all good 2-3 shift is soft but after 30-45 seconds in 3rd
it starts slipping.
I can pedal it and get it to grab 3rd for a second or two then starts slipping again.

reverse gear and clutch is fine (this is the same clutch thar 3rd uses correct)
so I don't think it is the clutch
has to be a broken spring or stuck pistion for the 2-3 shift circuit?

can any one give me a diagram on where this is in the valve body
have put shift kits in trannys before but that all
willing to give this valve body fix a try if I know where to look

IF you have troubles in 3rd gear , the frictions are burning.

Reverse gear does use the same clutch BUT the pressure in R is boosted . That will cover up a weak clutch pack for a while.

I would suggest a tear down to find and repair the problem... any thing else is a band aide repair IMHO.

IF you wish , A TransGo 400-2 shift kit has a triple plate separator plate.. this will dual feed the direct clutch without disassembly of the transmission.

good luck , post back when you can .

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Old 04-27-2008, 10:08 AM
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The tranny was rebuilt clutches were new
it has just sat around while I finished the rebuild of the car

I was thinking it was 2-3 spring broke or stuck piston in that circuit that was not letting pressure build up very much

sound reasonable??
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Old 04-27-2008, 01:20 PM
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Quote:
Originally Posted by rolrandy
The tranny was rebuilt clutches were new
it has just sat around while I finished the rebuild of the car

I was thinking it was 2-3 spring broke or stuck piston in that circuit that was not letting pressure build up very much

sound reasonable??
nope....... slippage is slippage. Frictions are thin and burn quickly.

I'd find the problem soon before you pay for a rebuild again

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