Recently bought a 96 Formula with the factory LT1 and 4L60E. The car has a weird transmission related issue that I’ve never come across before, and I know very little about automatic transmissions, so bear with me. Basically, you can start the car up and it’ll run fine, but in Park or Neutral it feels like there’s a load on the engine. Then, if you put it in Drive (or any forward gear) it will creep forward and you need to give it a lot of gas to get it to move forward, basically feels like you’re on the brakes, but the brakes are not on. In reverse it’s worse and the car will barely move at all with throttle applied. If you let off the gas in reverse it sorta rolls forward, suggesting there’s some type of tension.

I don’t have much history on the car, motor is not stock (obvious mods like cam, headers, nitrous, etc) and sounds very healthy, so I’ve gotta believe it was pushing some decent power before something broke.

As I said, I am not all that good with transmission/driveline stuff….Any advice or thoughts on what to look at here? Or do I just bite the bullet and take it to a trans shop?

 

Swore I answered this allready but what you are describing is an internal mechanical issue, Its either trans time or trans shop time, Could be many of an assortment of internal causes.

 

OK, little update here. I took a chance and drove the car home from where it was when I bought it, about 20 miles, starting out in Drive it was sluggish (like the brakes were on) but once moving it upshifted through all the gears OK, and once it had run up through all 4 gears once or twice, everything free'd up and the transmission has been working fine since. Goes into reverse normally, moves normally, shifts normally, works great really. I ran it around my neighborhood a few times over the last couple weeks as well, and every time it's driven fine, no issues at all with the trans.

Finally got tags for it and ventured a little further from home, car did great until I had stopped in a left turn lane to wait for traffic to clear and then made a quick sharp left into a Sonic parking lot; as soon as I gave it gas while turning sharp I felt a little nudge in the driveline and that same strange behavior was back - resistance in forward gears and heavy resistance in reverse. I shut the car off, got my food, and went to leave, same weird behavior and needed a lot of throttle to get it to back out of the parking slot. Got it going forward again and the weird behavior continued in the parking lot until I got out to the main street where I could get up to speed and let it run through the gears, once it did, the issue was gone again and its back to normal.

Thoughts? The basic symptoms sound like I've got a crossleak internal to the trans that's somehow keeping forward gears engaged (and reverse and/or multiple forward gears) at all times. However, if that were the case I'd expect it to behave like that all the time, the fact that letting it run up through the gears temporarily solves the issue seems very strange.

Could it be Differential related somehow?

 

I had a similar problem 5 years ago. I found the problem in the rear differential. The bearing on the yoke had disintegrated causing the yoke gear to meet the diff carrier. There where witness marks all over.

 

Cool thanks, I really need to get this car on the lift and give it a good once over. Been putting it off as I have another car on it right now, but I should probably make the effort and move things around to get it up in the air,

 

If that’s ur problem it was pretty easy to repair. Wheels of, drain diff, remove c-clips, remove axle shafts, remove diff carrier, remove driveshaft, remove yoke, install new seal/bearing; throw it all back together with a new crush collar, set lash to .25 and done. Took 2 hours with beer.