[Celestine]

my 91 trooper was lift 3" about month ago since then it has vibration whenever start to drive forward (and reverse) from stop. Already tried independent4x.com's shims but it got worse after installing it? anyone have any ideas?

 

[bigpoppax2]

Some disagree with the fact that you can go with a one piece driveshaft and cure your problems. I did it to mine not a problem since. For whatever reason it's commonly thought that the trooper doesn't need to go to a one piece. Well unless you want to change the center bearing (rubber bushing part, not really the bearing) then one piece is the way to go.

I had mine done using my parts and just retubing it to a one piece with DOM tubing for $140. It's a center bearing you'll never replace again, and one less universal joint to think about.

 

[ShowMeDave]

Did you install the shims correctly? They should be installed with the fat part to the rear, which will lower the pinion in the front. If you installed them with the fat part in the front you made your pinion angle worse instead of better.

I had to do the same thing to mine when I lifted it. The shims helped A LOT!! If your u-joints are not in tip-top shape that will add to the problem too. At the very least, make sure they are greased.

A word of caution...... I have no problem with Matt or his stuff but I would caution against the use of the aluminum shims he(or anyone else) sells. I was stranded about 100 miles from home when mine broke in half and fell out. The problem with them is that they are so thick that they have no flex and will crack when you tighten them down. The curve of the top of the leaf spring will bend/crack the shim when you tighten down the u-bolts. I replaced mine with steel shims so I don't have to worry about it any more.

I previously had used some thinner 2º aluminum shims that apparently had enough flex that I had no problem with them. The thicker 4º shims I got from Matt just had no flex and thus broke in half.