HELP!! 4L80E Issues

[jvest]

I just built and installed a 4L80E in my 68 Camaro. Yesterday was the 1st time to try it out. It has a major problem. When it upshifts it locks the rear wheels. Using the Baumann controller, I've got it set to upshift to 2nd gear at 20mph. As soon as it hits 20mph, it'll lockup then down shifts back to 1st and starts turning again. I was able to pull the shifter down to 2nd and it started off in 2nd, but when it upshifted to 3rd it did the same thing. I pulled the rear servo and shorten the pin to the shortest length, but that did'nt phase. Does anyone have recommendation on where to start looking?

Thanks,
Jim

[Jake's Performance]

Jim,
Pull the main harness connector off and see what it does.

[jvest]

Jim,
Pull the main harness connector off and see what it does.

Jake,
What should it do when disconnected?

Jim

[critter]

Jake had me do this on mine as well.

It will default to "limp" mode and give full line pressure, only in second and reverse. Those are the only 2 gears you'll have. Did I get it right, Jake?

[jvest]

I’ll try that when I get home tonight. Since it’s sitting up on jackstands, I’m also curious what happens when I push the brakes while in 2nd gear. If it starts slipping could it actually be the intermediate sprag in backwards. It would be nice to have an idea where to start looking if I have to tear back into it.

Jim

[MarkB]

When you put it in manual 2nd, could you tell if it started in 2nd or 1st? It sounds like you probably have the intermeidate sprag installed backwards. Good luck.

Thanks,
Mark

[jvest]

When you put it in manual 2nd, could you tell if it started in 2nd or 1st? It sounds like you probably have the intermeidate sprag installed backwards. Good luck.

Thanks,
Mark

Mark,
The Baumann software was showing 2nd gear and the MPH was higher than 1st. While in 2nd manual and limp mode I held the brakes and increased the throttle and it was overriding the brakes. It sounds like the intermediate sprag is in backwards. I'll tear it down this weekend and check it.

Thanks for the help,
Jim

[Jake's Performance]

Chris,
Yes you are eliminating the controller from the equation and it should default to 2nd gear.

He was having issues with it locking up on the shift from 1-2 and 2-3.

A misassembled intermediate sprag won't cause it to lock up in 2nd but will in 3rd.

You would have 1st gear as normal, 2nd gear will work on jackstands due to the intermediate band holding, and it will lockup on the shift to 3rd and will remain locked up in 4th.

I had him do a wiring trick to eliminate the controller but test each gear and 1 and 2 were fine under those conditions, so it does seem to be the intermediate sprag.

Locking up on a 1-2 shift would usually be caused by a too tight low band.

[critter]

I continue to learn.

[jvest]

The intermediate sprag was backwards. I'm not sure how I missed it since it's clearly in the manual to verify rotation. I guess I got my clockwise and counterclockwise mixed up. I really like to 4th gear with my 4:10 rear gear. I need to do somehting to firm up the 2-3 shift. 1-2 is good, but 2-3 is a bit sluggish.

Jim