Vibrations at 3000 rpms

AdirondackFox08

AdirondackFox08

Member Plus
#1
#1
Alright guys, I can't seem to figure this out. My car is a 1990 5.0 with 150,000 miles, a T5 with a short throw shifter, and exhaust from headers back done. The vibrations happen at about 3000 rpms and get worse as the rpms increase. Once I shift to the next gear they go away until 3000 rpms again. In neutral the car can be revved up past 3 grand with no vibrations. The clutch, pressure plate, u joints, and pilot bearing are fine. I took the transmission down to the tranny shop and had them check things over and found nothing wrong with it, everything was in good shape and clean. The guy said he thought it could be the rear end or the driveshaft. I don't think it's the driveshaft since the vibrations are at 3000 rpms in every gear. I'm lost as to what it could be. Any help would be highly appreciated, the good weather is coming and I want to drive the mustang!! :)
 
fiveohhfox

fiveohhfox

Bronx Coordinator
#2
#2
that is puzzling its something that words cant descibe it would be something you would have to feel for your self well not you lol some1 else to get a better idea
 
AdirondackFox08

AdirondackFox08

Member Plus
#5
#5
I thought it was the input shaft, but the transmission guy said everything was good in it. He suggested to have my mechanic drive the car going down the hill and shut the car off with the transmission in neutral to see if the problem is behind the transmission. Needless to say, it might find where the problem is, but can be dangerous, lol.
 
SSChris NY.

SSChris NY.

Member Plus
#6
#6
Someone changed the position of your Drive Shaft, mark the drive shaft position on the flange at the rear, Rotated it on the Rear end 180 degrees and then drive it, check to see if the vibration is gone or has lessen, if it has lessen then crack it to the next position at the Rear, you will find that there's 4 different possible spots the drive will fit on to the Rear flange, till the vibration stops
 
Last edited:
H

HOOT

Active Member
#8
#8
SSChris NY. said:
Someone changed the position of your Drive Shaft, mark the drive shaft position on the flange at the rear, Rotated it on the Rear end 180 degrees and then drive it, check to see if the vibration is gone or has lessen, if it has lessen then crack it to the next position at the Rear, you will find that there's 4 different possible spots the drive will fit on to the Rear flange, till the vibration stops
Click to expand...
+1^^^ i had to do this with my one piece on a 240sx very similar problem.
 
Timspony

Timspony

Capital District Coordinator / Super Moderator
NYM Staff
#11
#11
I have a driveshaft that was taken out of my 1991 Mustang GT with only 5k miles on it if you want to try/buy it! :D
 
AdirondackFox08

AdirondackFox08

Member Plus
#13
#13
The vibration is just about gone! There is a little bit, but from what I heard about the T5s is there is vibration with those anyhow. The guy at the trans shop said he "cleaned" the transmission up a little bit, but the shifts are a lot smoother and not as notchy. I didn't do anything to the drive shaft, so it must've been something with the transmission. All's I know is that I'm excited that it's finally fixed and can actually be driven!! :headbang:
 
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