I just replaced my wcT5 with another one. after getting on the freeway and taking her up to 65 i noticed a vibration coming from the back of the car, and could feel it while holding the shifter. I let off the gas and at 60 vibration dissapeared. I dropped down to fourth gear and took it up to 65 with the same result no vibration at 60 and once at 65 and higher the vibration kicked back in. Since coming up with the problem i checked my u joints, they looked good. balanced both rear tires, and tried flipping the drivline one turn and bolting it back in. Nothing has stopped the vibration. Im gonna pull the drivline and take it to a shop, to make sure its balanced. Its just weird cuz before the swap i had no vibration at any speed, and ive taken her to 115. Has anyone run into this before? any more trouble shooting ideas?

 

I've been having the same type of problem. Haven't been able to find the cause yet. Didn't change the trans though. Vibration started over time and has slowly gotten worse. If you didn't have the vibration before the swap I would think it may be a problem with the trans or something you changed at the same time. Have you check the tail shaft bushing to make sure its not worn to bad?

 

I inspected that bushing when i replaced the tranny seemed fine. Ive searched and it seems a lot of people have run into this problem. But they never seem to post what solved their problem. I guess they got so frustrated they must have just given up lol

 

If the u-joints are fine, my guess would be that your driveshaft needs to be balanced.

 

Just curious if you guys ever found a solution to your problem. I have the same thing going on, and just rebuilt my T-5 hoping to resolve it, but to no avail. Just wanted to see if anyone had the solution yet.

 

my car was doing the same exact thing, 4 new tires, good to go ^^, can also be caused by worn wheel bearings

 

Balance ur driveshaft bud, that's what it is.

 

this can also be caused by bad pinion bearings and or a tail shaft bushing in the trans. even though your U joints are "good" they may still be binding. take your shaft out and move the yoke side to side, not all around. if it "hangs" the smallest abount this can cause vibrations as well.
i went thru this on my S-10.

 

I have this problem in my 87 Fbody also. Had a 2.8 and T5, and swapped in a 350SB and a T5BW. Shakes shakes through the shifter. If your u-joints are new, but slightly (and i mean a HAIR) offset int he yoke, one side or the other, they can shake, but the faster you push it, the tighter the shake will be.
Also, balancing the D-shaft is crucial, and I think that may be MY problem. Funny since the diff and shaft were left alone, but apparently, the rotating weight of the engine and it's balance has to match the shaft.
Let me know how you make out.
Thanks.

 

Does the driveshaft have to match the diff yoke? I remember the service manual mentioning that you had to mark the driveshaft relative to the diff yoke so that they went back together the same way, else you may get vibration. I never did do it and it didn't seem to make any difference on my car, but it would be easy to try. Also maybe taking the driveshaft back out of the transmission and rotating it 180 deg and reinserting it?