Hello everyone, my 99 jeep cherokee was sagging really bad so I bought 3.5in full leaf packs and rough country shocks for up to 4.5 in lift. I just got done installing the rear leaf packs and shocks (seems more like a 4.5-5in lift) and took it out for a drive, the rear end vibrates like crazy anything over 15 mph! its pretty much undriveable right now and this is my daily driver, so I really need all the help I can get! Noitce: only the rear is lifted not the front, and I am running 32's all the way around.
EDIT: the rear packs did come with angled shims which I beleive should have helped

I heard it is because of my driveshaft angle? I probably need a TC drop but how much?

Main questions is, WHAT IS IT? and is it safe to drive around or will I damage something? i need to get to work tommorrow morning.

 

Don't get a t case drop.. You're better off with an SYE or a hack n tap. A t case drop twists the angles of the engine, tranny and transfer case which doesn't help the life of the mounts.

 

I had the exact issue when I installed leafs with degree shims.The TC drop will not remedy what the shims are doing to the driveline angle.
The shims are not always compatible with the stock rear driveline, they tilt the pinion upwards and place the u-joints 'out of phase', hence the vibrations.

You have two options to be able to drive it immediately.
1) Remove rear driveshaft and drive the jeep as FWD in 4-PartTime. This will not damage anything but jeep will behave slightly different. This will be until you get a SYE and driveshaft just like the front shaft (double cardon, C.V. type).

2) Remove shims (easier said than done). Than test drive, not guaranteed to be 100% but it will be better.

Edit; if it is vibrating bad at 15mph than it will eventually damage something if you drive it around. Bearings, seals, mounts, u-joints etc.

 

Thank you! I will try to remove the degree shims and see what happens, should I remove the shims AND do a t-case drop?
I drove it to work this morning avoiding the freeway, the vibrating is bad from 20 to about 35 and then pretty much completely gone after 38 till like 45, comes on a bit after 50 more of a humming
EDIT: there are horrible grinding and clanking noises when I let off the gas and roll to a stop, hope im not damaging parts :/

 

Do not use a t case drop.