vibration

[Stern]

i have a 1992 XJ with the NP231 and i lifted her 3 inches using Rusty's lift and added the 1 inch drop crossmember at the same time. i noticed a vibration right away. my mechanic took a temp gun to the u joints at the rear and said they were fine but i wasnt convinced. i took it to a 4 wheel drive shop and he looked at my driveshaft and said the angles were fine and he thought i needed new control arms to align the font end properly. i put the lift on at christmas time and i havent gone through any u joints... any ideas?? not sure what the angles on the drive shaft are or the caster....maybe if i took off the one inch drop?? thanks for your help!

 

[jtszymano]

Its very important that you try to measure the angles. Eyeballing wont be good enough. I suspect that the angles may be off...but the mechanic said they were ok. Hmm...Im not sure what it could be from. You say the ujoints are okay?

 

[ChuckD]

You need to describe the vibration better. Does it occur at certain speeds or all the time. Is it mild or shaking your rear view mirror? If you could take a picture it would help us to. Also what axles tranny do you have? If we get this info we most likely can point you in the right direction.

 

[Stoney]

dude u r spending way to much money and time on this!! first of all relize that u have a JEEP and at that a lifted jeep! second of all say u get this vibration fixed in two months it will come back or if u ever want to lift ur jeep again u will get it so so look at it as a free massage! unless u feel like ur u joints are crackin off!!!

stoney:angel:

 

[Stern]

i have the AW4 tranny with dana 35c in the rear...the vibration is mild and it comes in at 35 then goes away at 40 but is constant from 55 on...it is a very mild vibration that u can feel slightly, i have put about 6,000 miles on it since i put on the lift....so far i have spent NO money on finding the vibration..i just had the two guys look at it but cost me nothing...thanks for any help

 

[ChuckD]

It sounds like the rear should be fine, unless it's the Slip Yoke engagement. You may need the extended slip yoke.

Does the front axle have the vacuum disconnect? If it doesn't then you may try removing the front drive shaft and drive around. If the vibes go away, it might be a simple fix to replace the front U-joints.

 

[Stern]

I thought the rear was fine to but i am new to this, i was thinkin about purchasing an extened slip yoke from Rustys but wanted to get some opinons on here. Rusty's lift didnt come with new lower control arms and when i got her aligned after the lift was put on i didnt get the numbers on the caster and camber which i should have. im not sure if it is a vaccum diconnect but i will try the front drive shaft idea..thanks

 

[Uni]

Do you have a t-case drop bracket/spacer? 3" does not seem like a lot of lift, however The angle may be a bit steep for the shaft. You can make your t-case drop brakets out of 1" square tube. Just drill holes on the tube where the crossmember bolts on, and place the tube between the chassis and the cross member. That lowers the t-case a bit.

 

[ChuckD]

Do you have a t-case drop bracket/spacer? 3" does not seem like a lot of lift, however The angle may be a bit steep for the shaft. You can make your t-case drop brakets out of 1" square tube. Just drill holes on the tube where the crossmember bolts on, and place the tube between the chassis and the cross member. That lowers the t-case a bit.

He has Rusty's 1" drop crossmember, first thread.