89build66

89 xj 3” lift no more rear vibes after transfer case drop. Now I have a thumping noise in the floor or in the front suspension (maybe?) only when making left turns. All steering components are new. All bushings are new. Motor mounts and transmission mount is new. Rear driveshaft u- joints are new. Steering gear box is new. Adjustable track bar new and no movement at axle side or bracket. No movement in the ball joints. New drag link, new tie rod, new sway bar bushings. New steering stabilizer. The thumping may have been present, but just not felt due to the rear driveshaft noise being so pronounced before the t-case drop. I’m at a loss guys. Any ideas?????

89build66

I know there have been no reply’s to my post, but I just wanted to update what I found in case it may help someone else in the future. My knocking sound in the floorboard was not the control arms, track bar, track bar bracket, ball joints, axle u-joints or motor mounts (all NEW by the way) . It ended up being a transmission mount that was also new. The brand was Anchor and it has sagged considerably. Well, it was only 6.95 so you do get what you pay for. The transmission mount sagging caused the exhaust to thump against the cross member for the transmission. It was temporarily resolved by a transfer case drop of one inch Due to driveshaft vibrations and I could not figure out why it started again. Well, upon inspection I found that the Anchor transmission mount continued to sag and the exhaust was yet again resting on the cross member causing the unusual thumping that led me to believe, after much research and questions to other xj owners that I was gracious enough to share their experiences that it was not related to the above listed suspension components.
After speaking to a local and very experienced Jeep xj enthusiasts he recommended going with a Mopar mount as they are more prone to holding their height and taller than the Anchor mount I installed. He didn’t carry the Mopar mount so I went to the local Dodge dealership and ordered one. I will report back on if I’m fact the Original Mopar part is in fact taller than the Anchor brand mount. I know this to be the problem as I placed a piece of 3/4 inch of wood in between the cross member and the transmission mount and did a quick test. It did in fact solve the problem I was having. Another note to be taken here and this is one stated by a local 4x4 shop not trying to sell me anything is that a 1” t-case drop is Not going to be any harder on a lifted xj due to the fact that the xj motor already sits high and is naturally hard on motor mounts to begin with. Take it for what it’s worth. I’m not interested in getting into a debate over whether or not a t-cast drop is an equal alternative to a sye. I personally will be getting an sye in the future. Just my experience up to this point.

fb97xj1

Anchor transmission mounts have always been trash. You will be good to go with Mopar.

89build66

Thank you for your reply, I just finished installing the Mopar mount and OMG what a difference in quality! It is much more firm and heavier. It’s about 1/8-3/16 taller. I could push on the Anchor mount with my hand and compress it almost 3/4 of an inch and it is new.