2001 4.5" RE w/VIBRATION!!!! HELP!!
 

Gents, I am new here so THANKS

I am the owner of a 2001 with a 4.5" Rubicon Express lift with a SYE eliminator and stock rear axle.
The previous owner lifted this did everything gears tires etc...
And never properly chased down this problem.
When I test drove it there was a HORRible drivleine vibration almost walked but I drove all the way to Vegas from San Diego to but it and it was clean so i bought it.
I hate to admit it but this has been a thorn in my shoe and more difficult to get rid of than i thought.
Its making me have thoughts of selling my jeep... i know i know
I bought the Jeep a year ago and have been screwing around with the rear axle shims swapping them out several times improving the vibration problem but still have vibration over 55 mph.

I got a new job so commuting on the freeway is a regular thing.
No local shops have the insight on this and I don't wanna spend hours and hours on their lift ($$) trying to figure this out.
They literally told me they had a customer with a XJ "just like mine" and they never figured it out what the vibration was:blush:
I cant be the only one with this problem.
Adams driveshaft was on the rear and it was prematurely destroyed from driving with vibration!
SO:
Brand new driveshaft on now
4.5 degree shims
33" tires with 4.56 gearing
Autotrans
SYE eliminator
The only unknown variable for me at this moment is the transfer case lowering kit.
Not sure if it has that...
ANY SUGGESTIONS?!
Thanks

First I would take the front driveshaft out and drive,, See if vibes are gone. If the vibes are gone that would be a clue the front needs to have the pinion angle adjusted (that's if you have adjustable control arms). If the vibes are still there with the front out, put the the driveshaft back in. Now you know its not the front shaft..
Now take the rear drive shaft off. Put the Jeep up on jack stands, put the Jeep in gear and slowly give it gas, are the vibes there. If no vibes, then you can start looking for other possibility's.
If you have the np242 transfer case. Just stick the Jeep in full time four wheel drive and take it for a spin with just the front shaft in(no back Driveshaft) see if the vibes are gone. If they are gone then you know it truly is the rear driveshaft.

My 2000 is at 4.5-5"lift 33"tires 4.56gears.. I have 5 degree shims Adams DriveS front and rear. No transfer case drop. I can take the Jeep too 100 with no vibes.


Also a case drop is just a band-aid. The drop puts too much stress on motor mounts and other components.

How is the back of the jeep lifted? With just leafs or with leafs and shackles. Is there shackle relocation kit on there. Need a picture of trans crossmember to see if there is a tcase drop for some reason.
When I out on my SYE I didn't need shims. Depends on how the jeep was lifted.
Down load a angle finder app and Google how to measure pinion angle.
With a SYE your pinion should be pointed up at your t-case. If do a visual check our better yet take a picture and post it
Also have you had your tires balanced?

Driveshaft vibration
 

I had a terrible vibration at 65 and up. Finally after balancing all tires, new u-joints in rear and front drive shafts, both front axles, new wheel bearing I decided to pull the front drive shaft off and run the Jeep. Smooth as glass without the front shaft in. Took the shaft to a local place to get balanced. They rebuilt the drive shaft and had it balanced. Put shaft in and vibration was back. Ran without the shaft in all Summer but now it is getting cold and snow likely soon decided to put the shaft back in and took off the weights the shop put on it. Vibration back at 65-75. Got two 2 inch hose clamps, took one of the weights and secured it to the shaft with one hose clamp and put the other clamp on as counter balancer without any added weight. Drew 4 marks each 1/4 around the driveshaft and numbered them 1-4 right behind the front differential. Raised Jeep on jack stands put it in 4 wheel part time. Started at mark one with the clamp tightened around the weight slowly rotated the clamp from position 1-4. At the 3-4 mark Jeep ran smooth. Took it out for a test ride and runs like a new Jeep. Of course each time you run it on jack stands to adjust the clamp, put car in Park and I turned the engine off then rotated the clamp then started it up to test again. On jack stands I had to run it up to 90 to 95 to get the vibration due to no load. HOSE CLAMPS DO WORK I was skeptical........ I had the vibration for over a year and dreaded driving high speed, now 65 and up runs as smooth as my Fusion.