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2006 4.7 V8 WK Limited
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Discussion Starter · #1 · (Edited)
I have a mysterious issue where sometimes my Jeep starts shaking (to the tune of the speed of the wheels, not engine) with the intensity increasing to the point that I have to stop at the side of the road (with the shake slowing down as I slow down but being felt all the way to a complete stop). Then, after being still for say 15 secs if I slowly get going again the issue is gone or at least so low in intensity that I can drive on. It's not shaking through the steering wheel, it's going through the entire vehicle. I tried to pinpoint the source several times but I could never tell it precisely enough. I think it comes either from the center of the car or the rear, possibly left rear quadrant.

Now for the "sometimes": where it happens virtually all the time is on freeway or more specifically after reaching freeway speed and then slowing back down to city speeds and e.g. taking an exit I start feeling it. Then I have one segment of the road where I almost always get this issue: I enter a small roundabout and exit it at the next branch (so basically a 90 deg turn but with a large turn radius) and speed up because it's a 4-lane road exitting a town. The road is slightly declined on the right side, so the car it ever so slightly leaning towards the right side during that entire turn and speedup maneuver. I'm describing this in detail because it's the only road segment where I was able to observe some consistency in this issue cropping up. Also, it never happens on a cold car. Most of the time it's a situation where I drive somewhere, get out to run my errands and then when I get back in a warm car and get going I get it.

My tires are balanced, the steering wheel is completely still. When this issue is not present the car drives nicely, no drifting to the side, nothing. Any idea what could cause this weird issue that only happens sometimes and can be mitigated by just stopping and going again?

Possible things I could think of:
  • AT shot - got oil changed some time ago, no change, shifting is perfectly OK, no slipping
  • 4x4 transfer case or one of the diffs -- changed fluids in all of them when I got the car, which is relatively recently, none of them have old fluid. Afaik I have eLSDs in both axles, maybe the rear is playing havoc?
  • Attachment of something on the underbody, some shock absorbing mount dead
  • Wheel hubs/bearings, probably rear -- but why would it only happen sometimes and other times let me drive ok? Tried wiggling the wheels when they were off the ground, no play
  • Driveshaft and/or U-joint(s) bent/eccentric - again, wouldn't that mess my driving up all the time? Also, I got under the car and tried wiggling the driveshaft and saw no play
EDIT: Just found WK Intermittent vibration by @Bob2008WK -- sounds like a very similar issue. Also forgot to mention brakes on all 4 corners were done fairly recently - rotors and pads are good.
 

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2006 4.7 V8 WK Limited
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Discussion Starter · #2 ·
Re rear emergency brake adjustment on WKs -- some posts here say there is a small hole on the back of the brake plate that let's you adjust them with a screwdriver, some say you have to take rotors off. Does someone know the definitive answer or do I just need to crawl under the car to have a look? :) Sounds nonsensical to me to adjust parking brake with the rotor off but dunno...
 

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Re rear emergency brake adjustment on WKs -- some posts here say there is a small hole on the back of the brake plate that let's you adjust them with a screwdriver, some say you have to take rotors off. Does someone know the definitive answer or do I just need to crawl under the car to have a look? :) Sounds nonsensical to me to adjust parking brake with the rotor off but dunno...
There is a plastic plug on the rear side. Star wheel adjustment is with a drum brake spoon (the old-timers know what I am talking about.). Take ID/OD measurements before re-assembly and note which way the wheel has to move to expand the shoes. Do this before installing the brake rotor. Re-assemble and adjust so parking brake works.

It should also self-adjust when backing up and braking to a stop.
 

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Discussion Starter · #4 ·
I found the hole on the back of the brake plate and messed with the star wheel yesterday, and today on my morning grocery run the problem was worse than ever... so I think I'm on the right track :) Will jack it up again and this time try to properly contract the shoes on both sides, even to the point that the e-brake would not function ideally, just to confirm my hypothesis. If that does not work it'll be time for the brake assembly to go off.
 

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Normally tighten until wheel is starting to get hard to turn then back off about 6-7 clicks.
Mercedes -Bmw - Volvo all use similar setups like this.
You may find the friction material has come off the shoe itself and is floating around the drum getting jammed up.
Use a digital temperature gun if you have one and check for a difference between both the rear wheels after a drive.
 

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You should also check the CV joints on your front driveshaft, it's very common for the rubber boots to fail at this age and allow grit into the joint. Usually it starts off with a whining noise coming from the center of the vehicle, and when it gets bad cause very bad vibrations. Carefully inspect the rubber boots on all of your driveshaft joints, if any of them are torn it's very likely this is your issue. You can find rebuild kits for the CVs on amazon or ebay. I had to do them on both of my WKs around 150k miles.
 

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Beginning to wonder if this could be a fuel starvation issue ??, possibly caused by a bad gas cap maybe .
Reading your first post where you say only on a warm engine and you can reach freeway speed before it occurs each time and a 15 second stop / idle diminishes it seems to point to fuel starvation issues
 

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How old are your front diff and suspension bushings?

Mine has done that a few times, but not recently. When it did it, I could stop the vehicle, then do a power-braked launch and that would fix the problem.

My WK also had one broken bolt in each of the front LCA rear pivot pillow blocks, which I recently replaced, along with the diff bushings. It drives MUCH better now.
 

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Beginning to wonder if this could be a fuel starvation issue ??, possibly caused by a bad gas cap maybe .
Reading your first post where you say only on a warm engine and you can reach freeway speed before it occurs each time and a 15 second stop / idle diminishes it seems to point to fuel starvation issues
I had some weirdness like this a few months ago. I replaced the wheel speed sensors and it fixed everything! I think I have a write up on that....
Here it is: 2006 WK - How To Change Your Wheel Speed Sensors (front...

I should clarify why this might be the issue. The wheel speed sensor triggers the abs system, and the traction control system. The computer goes a bit crazy when the sensors are working right, and it pulses the brakes. You don't feel it through your feet, possibly because your foot is not on the brake pedal, but the gas. But the Traction Control kills the throttle, and the brakes are clamping down and pulsing, causing the vibration or shuttering. Its not smooth like ABS though, because its going kinda haywire. I thought I was having bad fuel, failing fuel pump, or a faulty throttle body. Nope, it was just one wheel speed sensor. I replaced them both, and ever since then, no issues at all....until last weekend when my front diff locked and would not unlock. That turned out to be a failed solenoid in the locker (QDII), which was another inexpensive, though more mechanically challenging repair. Still possible to do in the driveway with basic tools.
 
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