I did a quick search for this problem and didnt find anything. Well here it is. When Im cruising with the car at like 60 etc, and then let off the gas or lightly tap on the brake to slow it down, then let off the gas, once the car gets to about 45mph or especially 35mph, it starts to buck like a wild bronco and its extremely annoying and embarassing. Im assuming its something transmission related and was wondering if anyone else had this problem or has solved this problem before. Ive got an idea of what it is but Id rather not taint possible suggestions so I'll leave it at that and hope someone else has some input for me. Thanks!

 

Not speed, but what RPM is this happening at? On decel of course your RPMs fall, and if you've got that TSP 231 cam in there it could be cam surge (usually too much fuel at part throttle and decel which can be tuned out).

Another thing to consider, I have a VERY slight bucking, but its at low RPMs (probably a little cam related), but I didn't feel it until I installed my poly trans mount, so if you've got one that could be adding to it.

Otherwise something might be out of balance (converter, driveshaft, etc).

 

It is beacuse the converter is locked at those low speeds and low rpm.. My car does the exact same thing.. Once I get HP Tuners and and going to disable TC lockuo under 50 MPH in OD and disable in 3rd. AS long as the TC is not locked at low speeds and RPM's ( under 45 or so) my car runs smooth.

Joel

 

There we go, this is what I thought it was, and thats the answer I was looking for.

Its definitely not surging, Ive had that alot before which is tuned out now. This is an actual, buck, that you can feel the whole vehicle like clunk.

 

Hehe, If i don't tap the brakes to unlock the verter when cruising to a stop or slowing down my car bucks like mad. It's happens at a lot higher speeds since the cam has gone in. I had the lock up points moved up, but it still does it occasionally.

 

There's a table for downshifting (and maybe one for unlock...I don't remember)...those might need to be tweaked....but my car will do it too. I don't think it's as bad as yours...I'll only get it if I've been slowing down, and then get back into the throttle right around the mph where the converter will lock but it's definitely that same buck that you're describing.

 

Yep definatly the TC not locking/unlocking properly. I had the same thing with my car. I also have a SSF3500 w/ a similar size cam. We set the lockup for 55 and it would still kind of do it. Set it for 60 and it was fine.

 

I dont have this problem... what do you guys have done to your car to make this happen?

 

A good size stall will make that begin to happen. Add a cam to the mix and it is tough to get the converter to lock at lower speeds. The converter lock will need to be set higher. The bucking can get pretty violent, sounds like the tranny is gonna fall right out. This bucking only occurs around the speed where the converter is set to lock/unlock

 

Would you be so kind as to direct me to what exact table and where you have changed the lockup?

Thanks alot!

 

I honestly don't remember the actual name of the table. I don't have Edit, but I'll look around and see what you need to change. I'll see if I can find some exact #'s. It's all based on MPH vs. %TPS. I think when we did it we just used HP tuner which just gives us a Transmission tab where you can alter A4 TCC.

I think there are two tables starting at $L8311. One for 3rd and one for 4th