C4 1-2 shift problem

[Guest]

[q4blind]

The transmission will not shift in to second gear when it is cold but after driving a couple miles and the fluid warms up it shifts in to second perfectly. Then park the car for an hour or two and no second gear till it warms back up.

This was a brand new trans from redneck performance. I got in a hurry when wiring the trans brake and got it ass-backwards so the trans brake was engaged when not touching the button and disengaged when holding the button. Fired it up and knew right away what was up but I had to leave, my cousin (which is a pretty good mechanic when it comes to sbf's)  came over while I was gone and attempted to drive it around with the trans brake stuck ON  , the temp gauge was pegged by the time he figured there was something wrong and parked it.

Rewired the trans brake and didn't have second till the trans fluid warmed up. Drove it around and there seemed to be no problems other then the 1-2 shift. A day later i drove for about an hour and every thing was fine, so i brought it up on the trans brake and launched it shifted to second, heard a pop and lost all gears. Sent the trans back to Redneck performance and explained what happened they said the pump exploded, they then fixed it and shipped it back for free i didn't even have to pay shipping.

Still had the 1-2 problem so i air checked it and found that one of the servo seals melted some and was leaking, changed the seal and every thing air checks but i still had the problem. I then took it to a local transmission guy who took it all apart and said every thing still looks new, cant find any thing wrong. Had the trans in for a few weeks while trying to figure it out and make sure it wasn't going to break again but could not figure it out. So i put the t5 in and the c4 has been sitting ever since. Drag strip opens near the end of the month so i was planning on putting it back in probably next week and trying to get it sorted out in time. Also i was using mercon 5 with dexron 3 tranmission fluid like redneck performance recommends.

Any one ever had this problem or have any ideas?

[69 Merc]

 

[BirdMan]

I would check the 2nd gear (front) servo piston for sticking or smooth movement, also take the valve body down and check for sticking piston/pistons as I am lost as to what moves when you shift to 2nd.  I figured out what did what a couple of years ago and have since forgot

[jimbob]

I am lost as to what moves when you shift to 2nd.  I figured out what did what a couple of years ago and have since forgot

It only applies the front band when shifting to 2nd.