I'll give alittle rundown of what I have done to the tranny so far. I had the tranny rebuilt about a year ago with new Kevlar clutches, band. 5 pinion planetary gears, the"beast" sunshell, hardened input and out put shafts,a nd corvette servo. I also installed a new EDGE 3400 Stall. I have put about 5000 miles on it with around 20 track passes, other wise all street driving.

Recently it has started do develop a problem that was intermitted, but now happens all the time. I cannot hold the RPM in any gear, 1,2,3,or 4th. It feels like the sprag is broken but the tranny guys I've talked to said that if the sprag goes you will know it from all the metal chunks and ball dancing around inside the transmission. The tranny sounds fine.

For example, I can be crusing down the street with the selector in 4th (OD) going 45-50 MPH and the tranny is in 3rd gear, I can pull the gear shifter down to 2nd and it will do nothing, just kindof free wheels

The tranny performs geat just shifting through the gears, and can't feel any slipage. But if you start from a dead stop with the selector in 1st it will take off up 4500 RPM or so and when you let off the gas the RPMs drop down to about 1500 instead of slowly falling as the car slows. You can then get back into the trottle and the car won't try to move forward untill you reached the RPM where you let off(I know it sounds F@#ked up!) but If any one has had a problem or has any ideas please feel free to inform me. Thanks for the help guys!

 

No one?

 

It sounds like you have a few problems, one being your over run clutches aren't engaging.. When you had it rebuilt you mentioned kevlar clutches, but were the steels upgraded? Also what cluctes, I assume the 3-4, are kevlar because they ripped you off if everything is kevlar.. Plus Kevlar is too hard, you need a little give for longevity. Raybestos Blue clutches and Koleen coated steels are the best combo to hold pwer and retain longevity. Also was the band kevlar, was it standard width? I would say the sounds of it that your kevlar wore the steels down and now you have too much slack in the clutchpacks..

BTW, I also don't like the corvete servo you have, but I don't think it is causing this problem.. What else was done during the rebuild? Pump slide springs? Was a single cage sprag put back in, or was it upgraded? Larger boost valve? Shift kit?

The better picture of what was put in will help with trouble shooting, but either way it sounds like you are going to need it rebuilt, good luck with it..

 

Did the old tranny blow up? If you didn't flush the cooler out, you washed contaminents back into the good transmission.

 

You've either got complete over-run clutch failure, a broken apply piston, your lugs are broke off the over-run part of the sprag, or the sprag itself has failed.
When the transmission was built was the weak (stock) SKF "single cage" input spag replaced with a stronger Borg-Warner "double cage" sprag?

Frank

 

The old tranny didn't blow, it was getting weak. I wanted to install a different torque converter so I thought I would have the tranny strengthened while it was out. I can't remember what type of clutches were all installed, I just remember some were kevlar. And yes new steels were put in. I just contaced a performance tranny shop and asked what parts would be needed to up grade. They gave me alist and I ordered them. I had a friend that rebuilds 4L60E's at a local chevy dealership put it together for me.

I know a new sprag was put in but don't believe it was a Borg-Warner unit.

When the tranny first started to have the problem it was intermitted, it would work one day and not the next. I would think if the sprag failed mechanically it woun't work at all once it failed. I guess I'll have to drop the tranny and take it to a shop and see what they say.