hey guys i've got this vibration coming from somewhere in my drivetrain, i just cant put a finger on it. it's only between the range of 15-20mph, and it happens both when i speed up and slow down right through that range. it's really bad when my truck's cold but never the less it still occurs when it's warm. as i speed up through first, i shift to second and as i release the clutch my whole truck damn near vibrates. also, the vibration seems to travel from the passenger side rear to right below the cab as the truck slows down and it fades away. ive got 2 new u joints in the rear, with a balanced d-shaft. any answers?

 

check alignment, tires balanced, Wheel bearings maybe, steering loose?. Theres alot it could be but those are a couple to check! My buddy is having a similar issue with his 83 SFA in his 94 pickup. His is more of a death wobble though not just vibration

Post up the specs of your rig too!

 

The vibration could also maybe be the main bearing in the tranny going! That would easily cause a vibration in the drivetrain

 

could be shocks too if you're getting some wheel hop

 

tires are balanced, not sure about the alignment. ya the steerings loose too but i just figured, hey its an old truck i didnt expect it to respond like a corvette. i wouldnt call mine a death wobble though (yet), but definetly a strong vibration. any way in particular to check the main bearing in the tranny?

 

how are the fluids in the diff/tranny?

 

push the clutch when the vibration starts and see what happens, if it vibrates at 15 -20 when it is just rolling(no load on motor) or clutch you may be able to isolate.

 

chuck,
i have done that. the vibration is there even with no load on the motor. only thing is, as i release the clutch it vibrates also. but to answer your question, yes the vibration is there at 15-20mph regardless of whether or not im in gear.

 

that rules out parts of the drive train. Your vibration is a constant velocity component, drive shaft, front axel, wheel bearing, rear end etc. Keep searching, we'll keep ponderin'

 

how do i know it is or isnt the tranny main bearing?

 

One thing to try if so inclined is to pull the rear drive shaft and test drive in front wheel drive (lock the front hubs and use 4H). If the vibrations go away, it is likely the rear shaft, if not, then you have eliminated the rear shaft. One thing to check on the rear shaft is the phasing of the u-joints:
- http://www.4crawler.com/4x4/CheapTri....shtml#Phasing

 

I know this is an old post but any chance you figured it out? I'm having the same problem with my '92 pickup.

 

Bump.... Anyone knows how this went ?

I have about the same problem, I have tried everything: replaced front and rear axel, check wheelbearing, wheel position control, tries two sets of wheels, checked propellarshafts and u joints, tried to take of propellarshafts in the rear and drove in frontwheel drive, even had the gearbox out to check the clutch, everything is ok. I have tried to take of both front and rear propellarshafts and run the engine, tried the gear box at differnt gears at different rpm's in low and hi gear... nothing. It apperars that everthing is ok intill ( I don't know the english word) it meet "resistance" ? "load" ?
I cant figure this one out..... i'm thinking tranny, but there is no noise and both outgoing axels are tight, no slack.....