lonewolf411

I had bad rear vibes when i hit the gas hard with my 3.5 inch lift so i put in a 1 inch transfer case drop. Now when i hit 40 and above its like there is a low droning sound. Its sounds like it got alot less aerodynamic. Could it be the rear driveshaft u joints? It happened AFTER i put in the t case drop. It did not make this sound before. Would this make sense because putting the tcase drop lowers the stress that the driveshaft had on it?

jakbob

park the jeep. crawl under, grab your driveshaft, and try to wiggle it (use some muscle). that will tell you if you have bad u-joints. is it only on acceleration? coasting?

lonewolf411

Ok ill do that. Its on acclerating and coasting until it either goes above 40 or below

beerdriver1

I am working with the same exact issue. Just installed my 3.5 lift and did the transfer drop along with 6* shims. The pinion is alittle too high now so I have to order a 4* and it should be perfect but i have a good vibe from 25-40 or so and mostly under acceleration. Im hopeing the 4* will take care of it but I might have to go SYE

lonewolf411

The thing is my old leafs only measure to 2 inches in the rear so when I get my new leafs I will have to get like a 4 degree shim

98Plum Crazy

Keep in mind that tcase drops are a band aid and shouldn't be used to correct, it messes with the whole geometry. As for drone noise, probably is u joints because now the angle is different, the old ones were used to the old angle and got worn that way. After I lift a xj, I always replace u joints and always install minimum a hackntap sye for customer.

lonewolf411

It's def not coming from the rear, when I get up to speed its from the front, now I need a new front driveshaft so could that be it?

98Plum Crazy

Just new joints in shaft and new double Cardan joint also, a newer shaft won't fix it, unless it is brand new never worn, replace joints.

lonewolf411

Well my current shaft is weakend so I definitely have to get a newer one and so ill replace the joints on the newer one?

98Plum Crazy

Copy, that's where to start, 90% times that fixes problem