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Vibrating noise during takeoff/ slowing

3K views 30 replies 6 participants last post by  Dmactampa 
#1 ·
Ill tell you what I have first. 2013 jk Sahara. Put on RK 2.5 stock mod lift and 35 tires. Well the RK lift was a lot more than what it was suppose to b and I ended up buying a lot of extras that if I would have known in the first place could have saved some money. I got a vibrating noise coming from the jeep when i was taking off at low speeds and also when i slowed to a stop

So first thing i think is the ds is in a bind. I bought the rear adj track bar to make sure rear was perfectly centered. Then I bought the front lca's and rear uca's. Got the angled matched perfectly put it back together last night and went on test drive and vibration is still there.

I'm out of ideas on this one. Any suggestions?
 
#8 ·
No no engine ping thank god. I'm not sure of the exact numbers of caster and things. When I first put the uca's on I set them to the length in the instruction book but when I stepped back and looked it turned the rear end so much I had to much angle now in the opposite direction. So I took them off and jacked differential until it was even with the angle of the driveshaft. No measurements I just used a straight edge between the two.
 
#11 ·
Hold up.... You should have your rear lowers set to around RK's spec and uppers so that the pinion is minus 2 (-2") below the DS.
The pinion pulls up slightly under acceleration.

The front is a fine mix of caster/pinion. You want enough caster where pinion/DS angle is not a problem.
I am at 4" of lift and have it set up for +3 pinion which is more then stock. My caster is low and the jeep handles poorly.
I have a aftermarket shaft so pinion angle is important.

Check you DS rzeppa jjoints and the front u-joint for any damage.
 
#13 ·
Depending on the tires you chose and how knobby they are I would say that's the issue. Is it happening at 5mph or less? If so I would bet that's it. My brother lifted his truck and put 35s on it an I asked him what the hell was wrong with it when he was coming to a stop. He said it was the tires. I feel the same thing in my jeep now after the lift and 35s
 
#23 ·
Quote from RK

"Our rear upper arms are designed to be used with our "longer set" of rear lowers to allow pushing of the rear axle back a little bit. It makes clearing 37's on 2.5" or 3.5" of lift with flat fenders a snap and will have no issues trimming the pinch weld seam..."

RK
 
#28 · (Edited)
DCR-13JK said:
Not sure what u mean here. Also not sure what pushing the rear end back would do besides make me need a longer ds. But don't get me wrong I don't know a lot that's why I'm asking.
The more involved kit moves the axle back 1". When you lift, the axles are drawn in. The factory DS has a slip joint which enables it to expand.

What I am saying is. You do not want to run your pinion even with the DS. You want the pinion -2 below the DS.


Those uppers are not intended to be used by themselves (w/o adj lower CA's) because of their length.
I was wondering if you could adjust those arms back enough to actually achieve that -2
According to RK you can't.
 
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