front d/s vibe...i think?

2000 xj, 4" DPG hybrid RE3.5" superflex kit. AA SYE and tom wood d/s....in 2 wheel drive at highway speeds i still have some vibes...around 70 they sound just as bad as my stock d/s that i had that was BENT before i lifted the truck...can this be the front r did the guy that installed my new d/s mess up some measurements? Next question, in 4 wheel drive, get vibes that are even worse and they occur when i'm doing any faster than 30. Must be the front d/s? b/c of a lp dana 30 that newer xj's like mine have? I did a search and it says that would be the cause...how do i fix it...adj upper control arms?? Thanks for any info.

upper adj CA might help. But that will mess with your caster angle... And is your rear shimed correctly?

On the later models at about 2100 rpm there is an exaust drone that might be confused w/ vibes. You have to redo the exaust to fix it. I forget from what point back, maybe the converter. Might be part of it, just a thought.

-Marisha

deff. not the exhaust, i didnt hear or feel anything like this before i did the lift. aside from the bent d/s but i know what that feels like and my g/f's 98 has no problems like mine....the performance jeep shop that installed my d/s and sye put 5 degree axle shimms in...i assumed he knew what he was doing hence why i paid him to do it. How do guys that do more than 4" take care of these vibes??

First make sure your u-joints are in good shape. Then check to make sure your tires are balanced. If that doesn't cure your problems, i would take it back to the shop that did the work and explain your problem. I am running a MJ with a lot more lift and probrably bigger tires, and I dont have the problems you are describing.


Patrick

remove the front d/shaft and drive it.. see if it goes away.. it's really a process-of-elimination thing...

so am i not supposed to have any vibes up front? or do we just not know a way to fix it IF i do have vibes up front? I already brought it back to the place that did the work, he said get a front end alignment and that should take care of 90% and the other 10% he agreed was the front and said there was nothing i can do about it...is this true? I'm going to try to get the front end done tomorrow before work but i cant see how an alignment has anything to do w/ vibes?

Ive got a 2000 and have been thru this,its a real compromice between castor a and pinion angle.

RCP Phx said:

Ive got a 2000 and have been thru this,its a real compromice between castor a and pinion angle.

Click to expand...

Ron's correct, as usual. It's tough to find a balance between pinion angle and having enough caster to track correctly. I never could fix it after I put the 5.5" lift on until I went to a manual hub kit.

I am here to tell you, IF everything else is right, you should not have any vibration problems. An alignment affects the way your jeep travels down the road. If it is off it can cause your tires to drag or push, causing vibration to be transmitted to the vehicle. It is possible a bad u-joint or wheel bearing could be causing your vibration. It is also possible that a bad steering stabilizer could cause it. Basically youneed to go through the whole jeep and use the process of elimination.




Patrick

I have been reluctant to give advice to you as you took your Jeep to a shop and therefore I am not sure what your expertise is in wrenching and diagnosing these issues. Process of elimination is the right road. I'd start with what is easy and probable and doesn't cost you anything to check first. That would be removing (as suggested) the front driveshaft and seeing if the problem goes away. If it doesn't, then do the same with the rear driveshaft,.... assuming that your T-case output is sealed. Is the vibration coming through the steering wheel or the seat? The steering wheel suggests a front end problem. The seat suggests a rear end problem. Do a search on line for how to measure and adjust pinion angles using shims under your rear springs to ensure that your rear axle and pinion are at parallel angles. I believe that Tom Woods website shows how to do this but don't remember. That way you'll know if the shop set you up right. Good Luck

I've got a 2000 and my daughter has a 2001. She has a RE 3.5" lift.After the lift she had some problems with front vibes. Since the DS wasn't changed it was easy to trace to the LP Dana 30 front axle. I put the Warn disco kit on it and it pretty well disappeared.
Mine has 8" lift and the D30 had to be replaced with a HP D44.
Jeep went to the LP D30 in about 1999/2000 depending on when the vehicle was made. Dumb ass move in my opinion. Since the front axle comes with a CV joint axle....it needs to have the pinion pointed at the tcase. That will align the axle with the tcase and DS. It will be a compromise with the caster angle however.
That said, then with 4" you should be able to eliminate about 75% of it eventually. Never will get rid of all of it unless you go with a disco kit.
I wrestled with this problem with mine for several years before going to a HP. It was a good excuse anyway!