markcrain

I have a 99 XJ with only 21K driven miles. No idea how many miles it was towed behind a motorhome but it was used for that as it has a towbar. It had a little vibration when I bought it and I think the tires my be out of balance and\or flat spotted from sitting. Does towing these cause a problem? I installed rough country 3.5" lift and now I have a vibration that starts about 25mph but then it quits around 45 mph but only under power. Lift the gas and it quits. But that's only the half of it. When you lift the gas almost all the way off so the drive line is unloaded completely, no drive force and no engine braking I get a different hard to describe vibration. It almost sound like a metallic buzz. Sorry so wordy but I'm stumped. Any ideas?

cherokeefreak

There are a few possibilities. 1. your driveshaft angle may be to extreme and you're getting some driveline vibrations. 2. you have a tire out of balance. 3. you have a bad wheel bearing causing some odd vibrations(if it is the wheel bearing it would make noise throughout all speeds. 4. bad U-joint

When you say it vibrates throughout a certain speed and only while under power makes me think that its your driveline angle, but with only 3.5" of lift it shouldnt be making that much of a difference.

anyone else have any ideas??

markcrain

[QUOTE=cherokeefreak;422635]There are a few possibilities. 1. your driveshaft angle may be to extreme and you're getting some driveline vibrations. 2. you have a tire out of balance. 3. you have a bad wheel bearing causing some odd vibrations(if it is the wheel bearing it would make noise throughout all speeds. 4. bad U-joint

When you say it vibrates throughout a certain speed and only while under power makes me think that its your driveline angle, but with only 3.5" of lift it shouldnt be making that much of a difference.

I just had a friend go from D to R and back and I get a pretty good clunk from the TC when going into drive only. Also I have a little up and down play in the yoke going in. All this normal? No metal showing in oil.

cherokeefreak

there shouldnt be any play in your T-case output shaft if thats what you're saying. Im guessing you checked your U-joints on your rear driveshaft, if those are good, you shouldnt be able to move your DS at all when in park. If you are able to move it, take your rear driveshaft off (slip-yoke boot and everything) and see if there is any play with your output shaft from your T-case. If there is play, I dont know what to do to fix it, I would probably just get a new one from a junk yard, but you might be able to find someone on here that could help you.

offroadnut36

when you said this i immediately thought driveshaft vibration, maybe your drive shaft is out of balance
when you said this i thought tires, possibly the flat spots you mentioned, but that usually only happens with bias ply/nylon ply tires. not sure what kind of tires you have though. is it like a whirring noise?

markcrain

I replaced the rear ujoints today and it helped but still vibrating but not as bad. Output shaft is fine but there is a little play in the slip yoke on the output shaft. Not a lot but some. I also still have the high pitch vibration\grinding sound when I unload the drive train and thats worring me a lot. Going to go to home depot tomorrow to get stuff to make a TC drop.

cherokeefreak

is it shifting normal? whens the last time the tranny fluid or T-case fluid was changed?

shintastrife

sounds like a drive shaft is out balance. my step dads truck had that issue he droped like 900 bucks replacing parts and then we pulled both DC and took them to a shop and the read one was out of balance.

check your DC for any dents or nicks some times a small can throw it off is what i was told

markcrain

Well I dropped the TC and it all but gone. Can barely notice it and only under hard accel.