ok well about 4mths (5000mi) ago I had my tranny rebuilt because the main shaft was bent. and either something is wrong w/ my setup or the guy really didn't know what he was doing. because now when I get on the highway and hit about 60-65mph I get a really bad vibration. I put it on a jack and ran it in gear and it's making noise from the tranny. is there something in there that could have come loose? or mayB I'm just low on fluid? I can't check cuz the fill hole was rounded out by the last owner so I guess I could drain and fill again. but if this tranny is blown I'm gettin rid of the car. All the gears go in fine I have no loss of power and no noise of grinding of any sort. thnk for you input.

 

Bump

 

Vibration at 65 mph. Try another gear at the same speed and report back if the vibration stayed or changed.
You want to isolate the vibration to drivetrain related or engine related.
Also try running the rpms from 1000 to about 4500rpm in neutral.

 

nothing in neutral. I turned the engine off and it's still there. reved in neutral, nothing. 3rd 4th and 5th gear vibrate at that speed and in neutral at the speed.

 

im nuetral at that speed wouldnt that cancel out the trannys and put it to the drive shaft maybe a u jion or some wheel bearings?? bad pinon gear in rear?? jsut osme idea for ppl to think about

 

if it could be the rear someone else confirm benz660rs idea and I'll switch it out w/ the rear from my project car.
I was also thinking the rear and 1st cuz when I bought it there was an intermitten hum comming from the rear after 80 but I don't wanna go that fast to C if it's still there. I just kinda wish something would happen so I could know exctaly what it is. and I've already checked the Ujoints with the shaft in the car. should I pull it out tomorrow?

 

is there a simple way to test the rearend?

 

Most likely it's the driveshaft or driveshaft related. Common problem with low geared cars. Next probable is the tires and or wheels.

The driveshaft spins 4 times faster than the tires. Use this on your guess as to which one it may be.