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Old 09-10-2019, 12:48 AM
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Unhappy Death Wobble or front unit bearing

OK - Just found I problem I didn't want. At about 60/65 MPH I hit the brakes and it starts slowing down then goes into a wild shake on the left front. Did it 3 times today coming home. 50 mph and below there is no shake and it stops straight. It feels like it is only the 1 wheel.


FYI In the past I had an issue where the RF wheel/tire went into a shake while slowing down and going around a right corner. I searched Death wobble and found shock problems, track bar problems, etc. I checked the track bar it didn't seem loose but I tightened up the track bar bolt tight enough to break it - surprise. I replaced it with a little bit larger true grade 5 bolt and got it good and tight. I also replaced the shocks with new Bilsteens that were standard to 1 1/2 longer gas charged - they seem to be a bit too long and hold the body up on the springs - gives a little wiggle until there is some weight to sack it down some. I also found at that time that the air gauge I was using - dial type- was reading at least 10 psi higher then what was in the tire. I have E rated stiff side wall tires 265/75-16 on it- they came with it. I was airing them down to 20-22 per the gauge that was actually 10-12 psi - on the road. I figured that was too low and caused the right turn wobble. I had them checked for balance - they had been run for a few thousand miles with no issue at higher pressures. Every tire was out of balance but were able to be Rebalanced OK. So I thought everything was OK.


Jeep has been parked for a couple of years while I did things to it - new Ujoints and greasible CV joint on Front Driveline, water pump, idlers, belt , etc.


Finally got it up and running again then this. The only other thing that may be an issue is that I had it up on jack stands with wheels off for that couple of years while life got in the way and the rotors rusted up some. I was going to sand them off/clean them up before running it again but I forgot and went ahead and stuck the wheels on (at night) and dropped it down. I know I probably affected the pads while they rubbed off the rust. I ran it while holding down hard on the brakes to clean them off - ran it around using the brakes hard , etc and ordered a set of new pads front & rear. Haven't installed them yet. Seemed to be stopping better and better no pull, hard pedal - push harder and stop better.



Finally getting to the questions. Would a bad unit bearing allow the wheel/disc to start shaking badly under braking only the way I described it. No shake or wobble while running up to 70mph - just when I hit the brakes at that time. Is there any way a brake pad would be slick enough to not clamp ( not wore out - still plenty of pad) and start a wobble - the other 3 wheels not reacting badly - clamping and slowing down.


Any Ideas appreciated!


LBM

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Old 09-10-2019, 07:32 AM   #2
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I would think that a bad unit bearing would give you a vibration/shimmy at all speeds and would be speed sensitive as to the degree of vibration/shimmy. When I recently had a lot of work done on my TJ, replaced all brake pads/rotors/calipers as well as most of the hoses, I also had the ball joint, unit bearings and axle shaft u-joints replaced. I figures while in there get it all out of the way. At 130,000 miles, the unit bearings were still good but had to be removed for the ball joints and u-joints anyway. Why put old ones back in?

DW will not rear it's head when braking. What does is a warped rotor. I have had warped rotors on two vehicles. A '90 light duty W250 which had 3/4 ton axles with 1/2 ton brakes (brilliant!) but Dodge was not the only one, Ford had a F250 like that only it had 7 lug wheels. All three manufacturers discontinued those models. The other was a 2008 Chrysler Town & Country when I had the front rotors turned (not recommended by Chrysler) and the rotors wound up too thin.

Warped rotors can also be felt in the brake pedal that will tend to pulse a bit rather than be steady. All rotors (and brake drums) will rust when sitting for a while, even if the wheels are on the vehicle. Within a few miles and brake applications the pads (or shoes) will scrape off the rust and be back down to the bare metal.

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Old 09-10-2019, 03:59 PM   #3
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dry steer test the front end, wobble is from loose or worn front end components, or bad tire balancing.
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Old 09-12-2019, 12:34 AM
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Cool Wobble & Brakes

Thanks! Definately do not have an issue running at speed on the highway until I hit the brakes then the LF starts a bad scary shimmy/wobble - that only seemed to be that wheel. I slowed down to 50-55 mph and then pushed the brakes hard to stop and there was no wobble. Probably the brakes and possibly the tire.


I have the pads for all 4 wheels and I just ordered the 4 rotors from Rock Auto. Just going to do them all while I'm there and I'll look to see what ever I can see on the rest of the components. I just checked the mileage 183300. I think most is on the highway miles - bottom of jeep does not look at all like it has been off road much. Probably with that mileage the ball joints and tie rod ends are loose????? Except for the way underinflated tires on the asphalt wobbling which was the bad gauge I haven't had any drive-able issues until now - well except for that squeeling front driveshaft CV joint that drove me nuts until I figured out it was the problem.


I paid a premium for this Rubicon because it was so clean top to bottom. Been learning Jeep Lessons I never wanted to learn ever since.






Quote:
Originally Posted by rgreen65 View Post
I would think that a bad unit bearing would give you a vibration/shimmy at all speeds and would be speed sensitive as to the degree of vibration/shimmy. When I recently had a lot of work done on my TJ, replaced all brake pads/rotors/calipers as well as most of the hoses, I also had the ball joint, unit bearings and axle shaft u-joints replaced. I figures while in there get it all out of the way. At 130,000 miles, the unit bearings were still good but had to be removed for the ball joints and u-joints anyway. Why put old ones back in?

DW will not rear it's head when braking. What does is a warped rotor. I have had warped rotors on two vehicles. A '90 light duty W250 which had 3/4 ton axles with 1/2 ton brakes (brilliant!) but Dodge was not the only one, Ford had a F250 like that only it had 7 lug wheels. All three manufacturers discontinued those models. The other was a 2008 Chrysler Town & Country when I had the front rotors turned (not recommended by Chrysler) and the rotors wound up too thin.

Warped rotors can also be felt in the brake pedal that will tend to pulse a bit rather than be steady. All rotors (and brake drums) will rust when sitting for a while, even if the wheels are on the vehicle. Within a few miles and brake applications the pads (or shoes) will scrape off the rust and be back down to the bare metal.
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Old 09-13-2019, 08:02 AM   #5
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If you decide to replace ball joints, I would go ahead and replace the front axle u-joints and unit bearings while you are in there. You have to remove the unit bearing to get to the ball joints so why reinstall unit bearings that have 183K miles on them? While you have the unit bearings out, the u-joints are right there.

I had mine done recently. I bought the ball joints and unit bearings and while the mechanic was in there I had him replace the u-joints. Since he was an independent and honest, he did not charge for remove/replace the unit bearings.

My project started as a brake job, replacing the pads, rotors and calipers. I went with the Powerstop Calipers (S4339 front and S4754 rear) since my originals had 129K on the at the time. I had all the parts assembled and a weekend blocked out with a friend when fate intervened. On a charity Jeep run, I had a friend driving my TJ and I was in my Chief when the left front caliper on the the TJ failed and every time my friend had to apply the brakes it would swerve to the right. When we got to the end of the run, he told me about it. We were thinking of limping back home with it when I realized we were a half block from my mechanics shop. So we simply dropped the Jeep off there and let him do all the work.
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Old 09-13-2019, 11:47 PM
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Man - always something - have to remove the unit bearing to get to the ball joints. Now I have 2 questions - well probably more then 2.



I tried to order the Powerstop # you included - when I plug it in the Rock Auto it defaults to 2 but it doesn't say it includes a left & a right & doubles the price - did you get a left and a right???


I've been looking at ball joints and Rock shows a bunch of OFFSET ball joints as well as "standard" ball joints.- any idea if there are problems w/ Rubicons that require Off set ball joints????? First time I've seen "offset" ball joints offered?????




What kind of $$$$ am I looking at do do a front end right??? Any Ideas. Ball Joints, tie rod ends, Unit bearings, Front drive shaft U joints ( are they greasible??) track bars, control arms or bushings, etc, etc??????


Thanks - LBM
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Old Yesterday, 02:39 AM   #7
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It sounds as through you are getting ready to throw a whole bunch of money at your Jeep, perhaps unnecessarily. Also: unless you are compensating for an issue, you do not need offset ball joints.

First, I would say confirm what's worn before replacing. You're probably at the end of the useful life for steering links and u-joints, but everything else should first be confirmed to be worn out.

For ball joints and all u-joints use OE Spicer. The u-joints should also be sealed (NON Greaseable) as they are maintenance-free and stronger than u-joints with zerk fittings.

Denny's Driveshafts has everything Spicer that you'll need, likely at the best price.

For the track bar and steering links, use Moog and upgrade to the ZJ tie rod.

The control arm bushings are nearly impossible to replace. It's better to just buy the OE Mopar control arms from Rock Auto.

For wheel hubs, I would recommend Timken.

I've done just about everything you are considering in the past year, except for hub assemblies, control arms and rear brakes. Total cost was $669.23. If you are not doing the work yourself, I would expect labor to be 3X the cost of parts.
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Old Yesterday, 05:58 AM   #8
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Quote:
Originally Posted by motovate View Post
What kind of $$$$ am I looking at do do a front end right??? Any Ideas. Ball Joints, tie rod ends, Unit bearings, Front drive shaft U joints ( are they greasible??) track bars, control arms or bushings, etc, etc??????
I did all of my front end parts last year. Ebay has the best prices. I went with Detroit axle wheel bearing/hub assemblies and ball joints, Spicer axle u-joints and Moog tie rods and draglink. Hub assemblies and ball joints were $110, axle u-joints were $50 a pair and the tie rod ends ran about $130 (including draglink end). I also replaced the upper control arm bushing that are pressed in ($22 for both). Stock control arms with bushings are $25 each. I also bought all new Detroit Axle brakes and rotors for $130 (front and rear).
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Old Yesterday, 07:12 AM   #9
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i don't recall having to pull the hubs to change the BJ's, but i'm old and forgetfull.

only at higher speed and only when you hit the brakes and you think you know which wheel it is................. swap it to the other side and see if you have the same results, if it moves with the wheel it's the wheel....... if it stays where it is, it's the front end parts. if you suspect the rotor swap it as well see if the problem moves.
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Old Yesterday, 09:25 AM   #10
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i don't recall having to pull the hubs to change the BJ's, but i'm old and forgetfull.
Definitely a recollection issue. Removing the steering knuckle with the axle installed would be a bit problematic.
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Old Yesterday, 09:43 AM   #11
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It sounds as through you are getting ready to throw a whole bunch of money at your Jeep, perhaps unnecessarily.
No kidding. $20 spent getting the front rotors trued up might well solve the immediate problem.
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Old Yesterday, 10:44 PM   #12
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I got my calipers from Amazon and they come in pairs.
Front:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Rear:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

They are OEM refurbished with new internals and powder coated exterior. They also have the original cast in CDJR part numbers.

You have not mentioned model year and level, but since you mentioned rear rotors I have to assume it's a 2003-2006 Rubicon. All owners of that series Rubicons have to hope that we never have a leaking rubber brake hose in the rear. The hoses for Non Rubicons are vastly different as the rubber brake hoses for the Rubicon rear brakes are clamped onto the hard line from the center of the axle out to the brakes. That part is unicorn teeth and about as expensive. When I did my brakes I was going to replace all the rubber brake lines. I did the front and the center rear but not the ones at the rear wheels because if you can find them, they are about $300 as side. My plan is if they ever leak, have my mechanic fabricate new hard lines to new rubber hoses that screw onto the new hard lines.

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