lt170chevelle

Just rebuilt my 4l60e and first time out there is no 4th or lockup for that matter.I can manually shift and feel 4th shift but when the gas pedal is applied, it just feels like it slips up to the point where 3rd gears rpms would be.I just installed a new transgo plate and matched the holes up to my old b&m plate.This is my daily driver and really need to get this figured out.Any of you guys have an idea whats causing the probem?

lt170chevelle

oh and forgot to mention that all the rest of the gears feels perfect.

Performabuilt

4th gear is just the 2-4 band coming back on so if seconds good bands good I would look at 4th servo and 2-4 band clearance .

lt170chevelle

I think it was a defective trans go plate that i had just installed.I replaced it with my old plate and it fixed it.The first thing i thought it might be was the servo but both the one for the band and the one in the case were perfect.I tore the valvebody apart and didnt find any stuck valves or anything.
The trans go plat on the other hand didnt have the machined look like the stocker..you know that almost mirror finish. It had more like the surface of a piece of steel flat..not rough but definitely not the optimum surface for a hydraulic unit i would think.
Anyways , thanks for the reply and works perfect now.

Pro Built Automatics

There are two holes that need to be blocked on the separator plate at a minimun on the 1988 and up units when installing this TransGo separator plate, otherwise you will have problems. This plate is used throughout the industry as a replacement plate. You could have had one that was missing a hole, or a wrong hole being blocked. The rough surface had nothing to do with it.

lt170chevelle

This exact problem came back in the past few days..I dont get it..Ok so it isnt the plate..What i did last time was go through the valvebody and the 2nd4th servo on the side of the case and it fixed it at the time. With that being said..should i do this again? I have no debri in fluid but is getting that burned odor.
What should i do to figure this out?1-3rd feel absolutely great ..just this darned 4th problem

Performabuilt

I would have to suggest again checking the 4th servo clearance while your 2nd servo may be fine because it has a larger travel capability the 4th servo could be colliding with the spacer/divider between them . The will cause it to slip in flurth and slowley burn the band

lt170chevelle

How much band clearance is ok?
The billet servo kit came with the press on tip that can extend the pin if needed.

Performabuilt

well and easy in the car check is remove servo and diassemble. Reinstall the washer and eclip then put the pin only with the 4th servo and cover with no seals . With the clip installed the cover should not be able to travel in more than the thickness of the clip.
Also of note if your using the sonax super servo in 4th discard the gold washer and replace with a washer the same thickness and diameter as the gray/black washer thats under the eclip

lt170chevelle

Well i checked the servo travel and sure enough it had a ton of travel. How did this not affect 2nd? I went ahead and installed the extended tip onto the pin and grinded it down till there was only the covers clip width of travel.
And i believe i did replace the gold washer per the instructions.
How hard is it to wear the band out? im kinda worried how much wear occured when it was partially applied.Also why would the band wait till a few months after rebuild before it started acting up?

AZ2ENVY

Did you have 4th gear when the trans was cold ? Did it only act up when warmed up ?

lt170chevelle

well see i rebuilt it a few months ago and first day out it did not have 4th hot or cold.Went through the VB and 4th servo and worked perfect. last week it was like partially engaging 4th , would shift but had absolutely no grip if i gave it gas, so i just ran around in 3rd. but no temp didnt seem to affect mine working or not.

Performabuilt

Well I have seen it a few times with that combo as we do use it though we no longer have the issue since we dont use the gold wsher that comes with the sonax servo anymore rather replace it with a black servo like is under the clip. But the band from applying will sprtech a little after running a while and then the 4th servo just cant travel far enough however the second servo starts out with much more travel so is unaffected by this.

lt170chevelle

Oh ok ..makes more sense now.So is the gold washer you speak of , just limiting the 4th servo's travel?
I didnt even think of the band stretching a little either.Well hopefully this is the last tranny problem i will have for a while.
Thanks for your help.