Ok so I have an LS swap with place mounts. Sometimes when I am driving and take off I get this thud and rocking motion which feels like it is the engine. It is really bad when i launched it hard without slipping the clutch (i was in a burnout contest with some friends, so I just dumped the clutch). I thought I might have a broken mount but if I put it in first with the parking brake on and watch the motor is doesnt move at all. My tranny is about to go, do you think it might be the problem? thanks

 

its probaly your mount. look at them and see if they are torn or if there is cracks in them. a bad trany shouldnt make the car jump.

 

Well that would have to be one messed up tranny to hear a thump everyime to get on it!!
I would agree with what he said check out all your mounts to double check if one is broken. I would assume since you have a motor swap that you most likely have poly motor mounts right? I would check them all over and if anything stick a prybar in-between the best you can and move it around that way and check it.

 

Yeah I have the place racing motor mounts. Maybe they are just so stiff that it feels this way.

 

I checked the mounts as much as possible without taking them out. They look fine, I didnt see anything that looked like a broken mount. I also tried to move the motor by using the intake manifold as leverage and pushing and pulling on it, no movement at all. I still have no idea of what it could be. Any ideas?

 

Check out your ball joints, axles, bearings, bushings, all sorts of the front end stuff to look at just look for things that are loose or dont seem right.

 

I still cannot find the problem.

 

Do your axles shake when you let the clutch out? Mine did and they just broke today. I think I know what your talkin about.

Blaze

 

Ill have to check the axles out. Thanks