bad vibrations...

i get unbelievably bad vibrations when i go above 55 and they come down a bit when i make it to 75... they feel like they are coming from the front diff, but i dont really know, i'm very knew to the whole working on your own rig thing as i am pretty fresh in the sport. the vibrations are so bad that my middle review mirror is completley unfunctional due to the vidbrations shaking it so bad

by the way i checked the other threads and found nothing that compares to my situation

also i have a 4.5" lift and there seems to be nothing else wrong with the rig, and it is definatley not tire vibrations, and the pinion angle seems correct

note: to any of you who have read my other thread on death wobbles; this was happening before all that and i am assuming the problem hasn't left since i haven't been able to drive my rig for months now.

thanks alot, jordan

Sounds like your Front D-Shaft, I'd start there

What year? Disco- or non-disco? Yes, it makes a difference.

I just disconnected my front DS, to change out the u-joints, and I cannot believe what a difference the shaft loss has made. My front wheel u-joints are junk, and I can now see them rocking, and falling into themselves, when I yard on the empty front yoke. I'm taking a 3k trip at the end of the month, but my 1st job on return will be front axle bearings, and end shaft u-joints. I can still hear them "clunk" as I slow down to red lights... once they're up to speed, they find a "natural" balance, and just stick out there, wherever the "natural" point may be. If there's a lot of play, they'll ride out to their optimum point, and you'll still have some vibes- but not like the whole DS DRIVING them to an unbalanced point. You'll definately feel the vibes up front, but lessened alot.

The front DS is one beefy unit, compared to the rear DS. It only takes a few minutes to rule out the obvious- just pull the front DS, and see if there's any positive changes. If so, then you have some u-joint issues to resolve. This will also give you the chance to crank on the empty yoke, and see how bad off your individual shaft joints are- I think you'll be seriously suprised. I sure was!


It will surely tell you where to invest your $$$ first.

I forgot to ask Jordan- is your 4.5" lift "new"?

If it is, you might need to shim the back end, or add a 1" drop to the transfer case, to get the rear angles right. After a 6" lift, I needed a 6 degree shims set, and a "hard yoke" modification to make the rear end happy again.

Before the new driveshaft and yoke, I couldn't even get the poor thing out of my driveway, without shaking the occupants to death.

The shims and xfer case drop allowed me to drive on for 6 months, before "completing" the job. At anything more than 3", your looking at some mods, for the vibes to get settled, and everyone to be happy. You might be able to buy some time with an Xfer case drop, and some shims- but we all face the eventual solution in the end... a "double-cardan" driveshaft, and some degree shims, to finish the job.

thank you very much, i will definetley try your idea about the drive shaft, but i dont know the difference between disco and non-disco, i'll assume it refers to the axle shafts because i just bought some tj axle shafts that are non disco, by the way i have a 6 inch lift with a slip yoke eliminator and cv drive shaft, do you know what degree my shims should be? (i originally had an old 4.5inch lift with stock upper control arms and know sye and no shims and havent been able to drive my rig since i have done this) all i did was add 1.75inch spacers and rusty's 6 inch springs