freddy

Got a vibration after installing new crown leaf springs in the rear and new coil springs in the front .I did level the stance with a 3/4 inch spacer in the front as well.my tc yoke is 7 degrees down and my pinion reads 3 degrees up.should I shim the axle with 2 or 4 degree shim? 4 degrees seems a lot for such a small lift.

jordan96xj

Right after a modest lift like this, the U-joints will be unhappy. They have been spinning and wearing-in at a certain angle for a long time. All of a sudden they are spinning at slightly different angles.

I had brand new u-joints on shafts and axles before lifting (almost identical to your lift). And they still complained for about 100 miles (rumble/vibe especially under load or acceleration). Then they settled in to the new angles and smoothed out.

You can give them a little time, but if some of the u-joints are older and were already a bit marginal, you may have to just replace them.

If I were in your position, I would just make a day of it, and replace all of them in one shot.

Even if the vibe ends up being more complicated, you'll want to do this first as it will help to rule out the u-joints as you continue to troubleshoot. But I did almost exactly the same lift you did, and worked through the exact same issue. (I had the dorman springs and used spacers up front).

freddy

ive been driving for a week and a half,maybe 250 miles or so.the driveline angles of 7 down 3 up make me wonder if I need to shim the rear. I understand you want equal degrees between the two.my u joints are about a year old.i keep them greased. it didn't vibrate before so I'm sure my angles are disturbed. 2 degree shim doesn't seem enough and 4 seems too much.with such a modest lift I didn't expect much trouble.oh well. I guess trial and error will figure it out?im not going to lower tc. that seems a cop out to me.