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Turbo 400 slipping issue

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Turbo 400 slipping issue

Postby AK Motor » Thu Oct 14, 2010 7:15 pm

I have a fresh rebuilt turbo 400...what the issue is that in low gear it slips...if you gun the throttle it will not even spin the tires on gravel...revs up...

It does move when in low gear if you provide light throttle....you can acutally get enough speed to get it to shift into 2nd and 3rd....which are fine w/o slipping. Reverse works fine too. It has a TransGo 400-2 shift kit in it. Stall converter of 4500...behind a 454.

Below are the line pressure I get in each gear
Park..145#
Rev...210#
N.....140#
Drive... 145#
2nd... 180#
1st ....180#

any ideas???
Steve
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Re: Turbo 400 slipping issue

Postby whitehendrix » Thu Oct 14, 2010 11:33 pm

what little i know about auto trans... i would surmise a toasted clutch pack for first or sticking valve and/or solenoid.. i know some trans operate off applied and released bands around a planetary.. some operate clutches.. pretty sure the TH400 is a clutch-style trans..
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Re: Turbo 400 slipping issue

Postby TRN » Mon Oct 18, 2010 5:25 pm

Low gear reaction element is the one way roller on the back of the center support. Only the forward clutch is required for first gear.

Does the car move in manual low? Manual low engages the low/reverse band.
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Re: Turbo 400 slipping issue

Postby AK Motor » Tue Oct 19, 2010 7:23 am

Yep it moves forward in low gear..but if you smash the throttle like yur leaving the line..the RPM's shoot up and the car moves...but not like it should. Instead of lauching it moves forward. Another thing that happens is that when you put the car in drive 3rd...it takes off in drive....and it does not have a manual valve body...just a shift kit....
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Re: Turbo 400 slipping issue

Postby Alan Roehrich » Tue Oct 19, 2010 11:05 am

Check the line pressure. It sounds like it is down about 50 psi or more. If you put the spring behind the modulator valve, take the spring out, smash it with a hammer, and throw it in the trash. Check to see if the governor valve is sticking inside the body, that's a common TH 400 problem.

I don't use anything TransGo makes. Try a Fairbanks kit, it is far better. Or try a Superior kit.
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Re: Turbo 400 slipping issue

Postby TRN » Mon Oct 25, 2010 12:58 pm

So here's my GUESS:

There's an issue with the low roller/sprag. It's probably starting in 2nd when the selector is in 'D'.

Did you rebuild this yourself? If so, do you remember checking the low roller/sprag? If not, have you asked the rebuilder?
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Re: Turbo 400 slipping issue

Postby AK Motor » Mon Oct 25, 2010 2:13 pm

Yes I did the rebuild myself..roller locked up fine and was in good condition. I also put in the 34 element sprag. I did more testing this weekend...this occurs in all gears not just low.

I put the line lock on and rev it to 6000 and the tires never moved..then put it in 2nd..tried the same thing...no tire movement...3rd same deal.

Under a light throttle it will back up and move forward and get up to speed 60 mph...

I am thinking that its the stator in the converter...even though its a new converter :twisted:
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