I recently put a 4.5in RC lift kit on my 99 xj. For some reason my rear drive shaft makes this grinding sound when I let off the gas at 40 mph or above. I have replaced Ujoints. Also took off the front drive shaft to make sure it wasn't coming from that. And have tried putting different angled axle shims under my leaf springs. Looking for what to do next cause the sound is annoying and sounds horrible.
transmission mount/ motor mounts, Do you have a sye?
An SYE comes highly recommended with that kit.. The transfer case spacers are a band aid at best.. And you can still have problems as you're finding out..Get the SYE kit...
Check you angles with an angle finder. You may be able to shim your axle to the correct orientation, but a slip yoke eliminator (SYE) aka fixed yoke conversion is highly recommended. If you get a SYE kit, you can use a stock XJ front driveshaft in the rear.
I recently put a 4.5in RC lift kit on my 99 xj. For some reason my rear drive shaft makes this grinding sound when I let off the gas at 40 mph or above. I have replaced Ujoints. Also took off the front drive shaft to make sure it wasn't coming from that. And have tried putting different angled axle shims under my leaf springs. Looking for what to do next cause the sound is annoying and sounds horrible.
Just like everyone said above, you need an SYE (Slip yoke eliminator) and new driveshafts to take care of your vibrations/grinding/ etc. Before I put on my SYE, I had a transfer case drop and mine even made noise with the transfer case drop. After the SYE, smooth as butter, no issues.
I agree with the poster above, after your SYE and driveshafts are put in, measure your pinion angle and see if you need shims. You most likely will.
I wouldn't recommend using a front driveshaft if you have a few extra dollars to get a new driveshaft made. The new driveshaft can be made to your exact XJ and what measurements you need. Plus, it's new!
