vibration problems

hi guys. i was wondering if anyone can help me. i just put an aftermarket tranny in a 94 gt. everything went in perfect, but when i am accelerating or rolling period the car vibrates really bad. almost as if the driveshaft is out of balance. a long time ago i put a clutch in a 300zx and it did the same thing. later i found out that there was a certain way the driveshaft lined up to the output shaft( i had a 180 degrees out). i was wondering if the mustangs were the same way; if not then what would cause the problem? the mustang vibrated a little before the tranny swap, but now its terrible. thanks in advance

Yeah, I would definitely rotate the driveshaft and try it again before leaping to any other conclusions. My Dad's Dodge van did the same thing (he didn't change the tranny though).

What tranny did you changed to? A 5.0 Stang Driveshaft has some balance but not enough to cause what you are talking about.

Also check the transmission mount. Other thing to consider is the tranny itself, tail shaft or input shaft. Was the tranny new, used or rebuilt and what kinda?

the tranny is a tremic that he had built for him. everything in it is brand new and it seems to be working great, but like i said the vibration was there before we installed the tranny. its just worse now, also we put a new tranny mount and a new throw-out bearing in it. the clutch was installed about 2 months prior to this and looked good.( clutchmasters stage 2). is suppose i can take the driveshaft out and rotate it 180 degrees to see what happens

Just for shits and giggles, when you go to rotate the driveshaft 180*, start the car and accelerate through the gears without the driveshaft in place. Post back the results.

will do

What kind of transmission mount did you put on there? There's one (forgot the name) that doesnt have that rubber piece to absorb some of the jerking from the tranny, its more expensive b/c it supposed to last longer. (Put one on a Camaro, did the same thing). Just my idea...

Where the vibration was there before the tranny was changed you may be looking at the wrong part for answers.

First I don't know what is up with the clutch because if the guy switched in a tremec a T-5 clutch will not work. I don't know about clutchmasters but everyone else uses different clutch/pressure plates. I don't know if this means they can't physically bolt together but this may be where your first big problem is.

This goes w/o saying but make sure all your tranny/bellhousing bolts are tight(doesn't hurt to check). Also I would have to go back and look to make sure some1 can correct me but a tremec to T-5 swap needs a different driveshaft or a spacer to work(I think).

All this is assuming you did a T-5 to Tremec swap. Maybe u just swapped Tremec for a different Tremec. Which goes back to my original point you might be looking at the wrong part for the vibration. The rear-end can be the culprit. It could be anything from a bad carrier, busted gears, bent axles, bad bearing etc.., etc..,

Check the U-joints?? When you swapped tranny's did you inspect the U-joints on the driveshaft?? Factory U-joint's don't have the grease fitting's on them, They could be bad. Pop off the cap's carefully and see what the tiny needle bearings look like. If you did have the driveshaft in wrong ( which I've never heard of but not saying that it can't happen) if the U-joint's were bad you may have caused pessure on them and worn them out evenmore so.

This goes w/o saying but make sure all your tranny/bellhousing bolts are tight(doesn't hurt to check). Also I would have to go back and look to make sure some1 can correct me but a tremec to T-5 swap needs a different driveshaft or a spacer to work(I think).

I think that's right. I believe the Tremec uses a different splined yoke, then the T5.

Also he said in a previous post, that the vibration was there before the new tranny. I think he needs to determine if it's speed sensitve or rpm sensitive.

thanks guys for all the help. the car will be back at my shop tomorrow,so i will have all day to figure it out. i dont know much about these mustangs and the differences in the tranny's, but i do know that the splines were the same on the input shafts. the shaft on the tremec tranny was a bit longer than the original, but the bell housing made up the difference. which makes me assume that the clutch kit worked fine, but i will double check. im going to raise the car on the lift and run through the gear. i will post back to inform everyone of the problem. thanks again!

thanks guys for all the help. the car will be back at my shop tomorrow,so i will have all day to figure it out. i dont know much about these mustangs and the differences in the tranny's, but i do know that the splines were the same on the input shafts. the shaft on the tremec tranny was a bit longer than the original, but the bell housing made up the difference. which makes me assume that the clutch kit worked fine, but i will double check. im going to raise the car on the lift and run through the gear. i will post back to inform everyone of the problem. thanks again!

Well it does sound like you swapped a T-5 for a Tremec if you needed a different bellhousing. So I'll tell you right now i bet even clutchmasters uses a different clutch/pressure plate for tremecs and that would definetly cause a serious issue.