- Location
- Southern Maryland
A couple of years ago, I installed a RE 4.5" lift with JKS adjustable lowers. I had to set the caster pretty steep to get rid of vibes, like 15" on the lowers with stock 1/4" shims in the LCA buckets. Steering was awkward but it did get rid of the vibes, highway driving was very smooth.
I got some 32" tires on the jeep this winter. The tires rubbed the inner fender on sharp turns, so I bought some adjustable uppers and set all four links to 16" (LCA buckets still had the 1/4" shim), so basically it moved the axle forward by 1" (maybe some slight changes to geometry). The tires no longer rubbed but I picked up some vibes in the 55-65 MPH.
While I was chasing some noises, I stuck a video camera under the jeep and noticed that the pinion was above the driveshaft most of the time. I thought, well, I changed angles a bit, let me set the pinion angle again, so I measured a bit and extended the JKS LCAs by another 1/4". That puts the uppers at 16" and the lowers at 16.5" (including the shim). The driveshaft is 9-degree at rest, and the spreader mounts on the D30 are also at 9-degree angle, so it should be dead on. But I am still getting vibes 55-65 MPH and its different from what before, its a rapid vibration, a chatter, and it makes the whole jeep buzz and rattle, whereas the other vibe was more mellow.
I am thinking that I should go back to the steeper angle and get the tires rebalanced. Alternatively, I could try extending the LCAs a little more, since I suspect the driveshaft angle becomes shallower when I sit in the seat. At this point I am looking for some input.
I got some 32" tires on the jeep this winter. The tires rubbed the inner fender on sharp turns, so I bought some adjustable uppers and set all four links to 16" (LCA buckets still had the 1/4" shim), so basically it moved the axle forward by 1" (maybe some slight changes to geometry). The tires no longer rubbed but I picked up some vibes in the 55-65 MPH.
While I was chasing some noises, I stuck a video camera under the jeep and noticed that the pinion was above the driveshaft most of the time. I thought, well, I changed angles a bit, let me set the pinion angle again, so I measured a bit and extended the JKS LCAs by another 1/4". That puts the uppers at 16" and the lowers at 16.5" (including the shim). The driveshaft is 9-degree at rest, and the spreader mounts on the D30 are also at 9-degree angle, so it should be dead on. But I am still getting vibes 55-65 MPH and its different from what before, its a rapid vibration, a chatter, and it makes the whole jeep buzz and rattle, whereas the other vibe was more mellow.
I am thinking that I should go back to the steeper angle and get the tires rebalanced. Alternatively, I could try extending the LCAs a little more, since I suspect the driveshaft angle becomes shallower when I sit in the seat. At this point I am looking for some input.