dhoge88

So I just put a 2" lift and 30's on my xj. 2" spacer, 2" ome leafs. BFG a/t's. So I hear noise on the road when I have the gas on but when I let the gas off it's as quiet as can be. Are these just the tires or are they vibes? Are vibes only apparent during acceleration or would they also be there during coasting? As of now my tires are getting remounted on different wheels and getting aligned. Maybe it will go away?

kyledye25

I have vibes like that as well. After installing new leaf springs after sagging for so long. I believe mine are my u joints. I guess after changing the drive shaft angle after sagging so long caused me to have very light vibes. They are starting to go away now....but I know I should get new u joints. Just not looking forward to the install.

Chex_Mex

Check your rear pinion to drive shaft angle. When you accelerate, it causes the pinion to raise up due to the torque applied. the softer the springs (and i know ome springs are soft because they offer such a nice ride) the more the upward movement. just my .02

dhoge88

What is the ideal angle?

dhoge88

So I still have minor vibes from 25-40 mph. I'm home for spring break for this week. Is it ok to drive with minor vibes for a week to see if the leafs settle and the vibes go away??

dhoge88

Repost

dhoge88

Anything?

kyledye25

Like I mentioned....I put new leafs on. Only been two months but already they are starting to settle. Slowly but surely. Vibes are going away. Still there tho. I have been told I'm ok to drive it for awhile but I am getting a whole bunch of new parts to finish the lift...plus u joints, transfer case drop and more. Hopefully it rides smooth when I'm done.

Chex_Mex

depends on how flexy the leaf packs are, but i couldn't tell ya.

If you were to draw a line from the u-joint from your slip yoke (assuming you haven't installed a sye yet) to your axle, you would want your pinion to be slightly below that line (like a few cm) so that when you accelerate, the pinion comes back up in line with the drive shaft. you don't want it too far below though, because then you will have vibes when you are coasting, so it has to be in that happy medium of the two.

freegdr

this should splain it fur ya....http://www.4xshaft.com/driveline101.html

Chex_Mex

excellent explanation

nice rig btw freegdr