Tires skidding

[Milo]

wondering if this is normal.... I have a 95 and whenever I'mgoing about 15mph and I roll over a dip bump (opposite of speed bump) my tires chirp a little and if I dont gas it the truck jerks aswell. Any idea's?

[Mike Hippert]

hmmm, the difflock is not engaed right? Do you have lockers? What year, auto or stick?

[Milo]

No, diff is not locked and no lockers. Its a 95 5-speed stock with 285/75 tires

[Mike Hippert]

Well, most 90s have a bit of "slop" in the drivetrain, what I am guessing is happening when you hit a dip bump is you are slowing down and the drivetrain is not under load so it is allowed to jerk back and forth a little causing the chirp and jerk. Next time your going through one of these dips try to move throught it with a smooth steady motion in gear and the engine above 2000 rpm, that way the drivetrain is under the load of the engine.

[Milo]

Thanks I'll try it tomarrow

[Milo]

Well I played around to get a feel and its pretty consistent, it happens when in normal driving while pressing on the gas around 10 to 15mph and feels like the rear tires, also I noticed it on a dirt trail doing the chirp and jerk. My concern is something is wearing out, I know I need new U-joints in front being that in 5th going about 70 if I slowly let off the gas it vibrates under my feet. Any help would be great. Thanks

[Mike Hippert]

First off if you need new U-Joints GET THEM! If one breaks when on the highway it can do allot of damage or it could flip you if it breaks and catches the ground.

Now for the skidding, does it do it when you are coasting? I am a bit confused myself.

[Milo]

Mike, yes it does it when im coasting any speed over about 12mph. I know its confusing but it sounds like its trying to catch either one sometimes both rear tires!I'm stumped. Was I right about the signs for replacing U-joints?

[Mike Hippert]

take off the driveshatft and lock the center diff then take it for a spinn, if the vibs are gone then I bet it's your U-joints.

[Milo]

Thanks Mike

[RickM]

Is it a chance that it is your pitman (sp?) arm (the front arm which aligns the front end). I recently was hearing this chirping noise myself and I started to notice unusual wear on my front tires. Turns out it was the pitman arm. This could be causing your front end to come down out of alignment after hitting speed dips. However if you are not seeing unusual tire wear, than I am waisting your time. Good luck.

[Milo]

Mike, anyone please help this is driving me nuts! I replaced front and rear U joints, adjusted RS9000 shocks, lowered tire preasure and tightened just about everything.
When I hit speed bumps, dipsand sometimes loose gravel when I do u-turns my tires chirp either front or rear. I'm stumped, its almost feels like driving with the the diff lock

[Mike Hippert]

This started recently right? Have you tried playing with the T-case, you know take it in and out of low and diff lock. Also is there plenty of gear oil in it? Did you try driving it without the front shaft to see if the problem went away? It is more then safe to drive with only one shaft trust me I have done it before (it handles very oddly though especialy with 35s and soft springs).

[Milo]

Mike, maybe I'm streching but is there any way it could be bushings i.e. radius arm, A-arm. I have 85k mi OME MD springs, rubberized spring spacers and 285/75 tires. Could this haveanythingto do with it? Thanks and sorry if this seems like a waste of time

[Mike Hippert]

Not a waste of time, the radius arm bushings may be a problem but I am not to sure. Just to eliminate the Drivetrain, try coasting through one with the T-case in Neutral. I don't think your tire setup has much to do with it but it could be making things worse.

[Milo]

can I put the T-case in neutral while moving? I've never tried

[Mike Hippert]

Actually you can shift from high to low while moving as long as you don't lock or unlock the center diff. The manual recommends this for when towing a heavy load from a start uphill. You just need to push the clutch in like you are changing gears. Like I was saying earlier it would be easier to remove one of the driveshafts and drive around for a while to test out rather then try to shift into neutral on the road and slowly roll over a bump.

[Red90]

Putting it in neutral won't affect the center diff. Sounds like it is locked.

1) Put hand brake on.

2) Jack up one front wheel.

3) Tranny in neutral and you should be able to spin the tire. If not, the center diff is locked.