C4 Troubles

[tannerc91gt]

For starters, everything that happens inside an automatic transmission is voodoo magic as far as I'm concerned. Posting this for a friend as we're a little stumped.
C4 trans, mild rebuild (bought 2nd hand)
The trans pulls great in 2nd and third but revs freely in first.
This happened both with the standard valve body and with the RMVB we swapped in.
Shifts into all the gears correctly. Fluid appears to be correct level.
You can feel it shift into 1st and it's like it wants to go but then revs freely. No problems with other gears.
Put it on stands and it does turn forward in 123 but in first you can hold the wheel and it revs freely.

As a bonus it shifts hard as into r. But that's a secondary issue.

 

[tannerc91gt]

Anyone?

 

[FoMoCo17]

Couple of things come to mind though I dont have my c4 book w me. Adjust the low/reverse band and Intermediate band while your at it. It can be found online easily. You adjust them the same by backing off nut on outside of case a few turns ... then torqing inner stud to 10 ft.-lbs. then low/reverse band toward the rear of the case gets gets backed out three turns .... then lock down the nut and torque it to spec. The Intermediate gets backed out 1 3/4 turns after torqueing to 10 ft.-lbs. and then its nut is locked down and torqued to spec. these nuts are supposed to be replaced (recommended) so if they leak replace them cuz their is an inner rubber seal that seals around the inner stud threads.

Make sure you have vacumm to the modulator and or replace the modulator on back of the transmission.

Also make sure you verify fluid level hot idle in park and in between the arrows.

If these items do not fix it ... I'd say your gonna have to pull it and look into it deeper ... or it could potentially be a converter problem.

Also ..check to make sure kickdown lever pops back when depressed from under the hood ... it should pop up and stay up when depressed down.

Hope this helps!

 

[tannerc91gt]

Thanks for the reply! We will try adjusting the bands as that seems to fit our issues.