Driveshaft Problem?

[RJB44]

I am noticing on my recently aquired 1991 GMC Jimmy that there is a vibration throughout the truck at low speeds or when you acclerate from an intial stop. It's usually between 10-25 Mph then starts to smooth out. Pretty smooth at 40-45 mph and higher. Very smooth at highway speeds 65-70MPH.

The prevoius owner added a 4 inch lift and 35 Inch tires on 15x10. Could this vibration be in part to these new mods? I am also thinking a possible u-joint issue? This is my first truck with lifted suspenion, so I thought I would get some feedback.

Thanks

 

[4X4HIGH]

If there has been no driveshaft angle correction after the lift then i would say that is your problem and a place to start would be a t-case drop. You will find some spacers between the crossmember bolts and the crossmember, remove the bolts and spacers and install the spacers BETWEEN the frame and crossmember and this should cure your problems unless it has already killed a U-joint. This is effectively dropping the T-case down about an inch making the U-joint angle better.

 

[Jason4x4]

http://coloradok5.com/forums/showthread.php?t=195486&highlight=transfer+case+drop
check this, don't use those to drop the t-case. it will make the front shaft angle worse.
might look into shims for the rear axle to tilt it up though.

 

[4X4HIGH]

Don't worry about the front shaft angle as you are only at low speed when using 4WD.

 

[imiceman44]

I am noticing on my recently aquired 1991 GMC Jimmy that there is a vibration throughout the truck at low speeds or when you acclerate from an intial stop. It's usually between 10-25 Mph then starts to smooth out. Pretty smooth at 40-45 mph and higher. Very smooth at highway speeds 65-70MPH.

The prevoius owner added a 4 inch lift and 35 Inch tires on 15x10. Could this vibration be in part to these new mods? I am also thinking a possible u-joint issue? This is my first truck with lifted suspenion, so I thought I would get some feedback.

Thanks

The problem you are describing is the same I am having now and it's a transmission issue on mine.
You say it smothes out once the truck is at highway speeds, or under light load.
Acceleration puts stress on the trans.
The reason might be bigger tires with no gear change.
Check your gear ratio and tire size, you need to match them up to have less strain on the tranny.

 

[skyyk5]

i had the same problem when i lifted mine 4" in front and 5" in rear. i had to made 1 1/4" spacers for between the frame and t-case member. it helped alot. but the slip yoke is junk on my 241 so i still get a little when i let of the gas (465 trans). if you have the $ get rid of the slip yoke and get a nice driveshaft.