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Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here!ZJ (93-98), WJ (99-04), WK (05+)
All ZJ/WJ/WK specific tech questions asked here!
There's a pulsing (or surging, or heaving) sensation as my 2000 WJ Ltd. approaches full stop. It is not felt through the pedal, instead the whole vehicle heaves repeatedly as it comes to rest. It appears to occur mostly when pedal pressure proportions more force to the rear brakes. The sensation is not prevalent under light braking when coasting. If I get into the brake pedal hard for any reason then it really shows up big time scary.
During a brief under car inspection I observed oil staining on the inboard side of the left rear brake backing plate. This is the only obvious visible defect - at this point - as I have not yet disassembled for deeper inspection. It made me suspect that I am experiencing left rear axle run-out perhaps due to a seal/bearing, leading to this brake "condition". I imagine that, while the pads and rotors in the car now appear to be very healthy, they will need to be replaced due to the affectations of run-out and I want to do the rear brakes once when replacing the axle bearings/seals. Does this sound like a correct line of reasoning?
Four new Raybestos rotors have been waiting on the shelf in my garage. I still need to get new pads, rears first (obviously) based on the assumption that they were contaminated with the same oil that stained the backing plate. What is the OEM stock recommended lining material, semi metallic?
Last edited by Cherryokee; 08-27-2016 at 05:46 AM.
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
ok sounds like either loose wheel lug nuts, contamination of pads, warped rotors, and or worn suspension components such as ball joints. I would first check the lugs then the ball joints then the brakes, including axle seals. When I worked for a brake chain in Dallas (Bill King's Brake O) we did a lot of axle work. They had a machine to arc the shoes into the drum on drum brakes!
Last edited by 97grand4.0; 08-27-2016 at 09:01 PM.
A leaking rear axle seal will coat the inner side of the rotor with fluid and will cause the "slip/grab" you are referring to. The axle bearings in the WJ are caged ball bearings in a cartridge and are held in place by the outer retainer. No need to pull the c-clips anymore. The bearing is a light press fit on the axle with a softer collar behind it that can be drilled and split with a chisel.
DON'T FORGET TO INSTALL A NEW SEAL BEFORE SEATING THE BEARING!!
I installed the new bearings (I did both) with a piece of water pipe that slid over the axle. Just make sure the pipe is clean inside before you go wailing on it. I used Timkin cartridges 50K miles ago.
OEM are Timkin, Mopar #5012825AA bearing $50.79 each, seal Mopar #5012824AA $27.99 each at rockauto.com
Dave, thanks. I got the bearing, retainer and seal. I started into the job today. I'm having a bad time removing the brake rotor but, thankfully, have time to leave it up on the stands and work at it in spurts this week. The rotor is so close to minimum thickness (8.53mm vs. 8.5mm min.) already, and is suspected for slight warpage anyway, I will not try to preserve it as a shelf-unit (per my original plan). The PB Blasting and beating has begun. Reluctant to go to the torch - heard too many horror stories. And oh yeah, almost forgot, I already backed-out the e-brake shoe adjuster too. Any other viable solutions?
Should I hit it here...
...and here?
Last edited by Cherryokee; 09-25-2016 at 06:21 PM.
Reason: pics
That's a nice hammer you got there. I would hit it on the sides front and rear to try to move it sideways on any clearance it might have. You could try heating the rotor, but keep it away from the axle flange itself. A standard propane torch ain't gonna cut it. you'll need a Mapgas torch or acetylene, AND you're just warming it, not turning it cherry. After it's hot, try shocking it by spraying it with PB Blaster again. Turn the torch off before you do that so it won't flash.
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
Is that a rubber mallet? You need a metal hammer. Either way it looks a bit too big, but it will work, ...what you don't want to do is give it dead blows with a metal sledge, and rubber aint gonna cut it either way. Try to set up high speed vibrations by giving it repetitive, low impact sharp blows, alternating one for one from top to side or top to bottom or some combination. Don't repeatedly hit in the same place. Also no need to try to drive it off by hitting the back. That and plenty of blaster should do the trick. Eventually it will just pop off. Very common problem. Very simple solution. Try to squirt it in where the lugs come through too as that is where the rust on the other side is. Let it sit a while. Hit it a few times and blaster it again. It actually wouldn't hurt to warm it up a bit too, and I think propane is fine for that, I use propane all the time and it always helps to heat stuff. Like Dave says you don't want it cherry. Lather rinse repeat.
Last edited by 97grand4.0; 09-25-2016 at 08:23 PM.
No, that's a drilling hammer, originally designed for drilling holes in rock with a chisel to plant charges in mines. It's sometimes called a "pocket sledge" for use by one man. Very handy when working on a jeep! Sometimes one good sharp whack and it pops off. Sometimes it takes a while. Swearing at it helps!
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
Drilling holes in rock to plant charges for mines, eh. Hate to be the guy whose job that was.
By the way, those jack stands look a bit flimsy there, I always roll the tires under the vehicle "just in case". Be careful there with the amount of force involved you dont want to smack it with that explosive hammer and it falls off on your leg.
Last edited by 97grand4.0; 09-26-2016 at 07:03 AM.
[QUOTE=97By the way, those jack stands look a bit flimsy there, I always roll the tires under the vehicle "just in case". Be careful there with the amount of force involved you dont want to smack it with that explosive hammer and it falls off on your leg.[/QUOTE]
Drilling holes in rock to plant charges for mines, eh. Hate to be the guy whose job that was.
By the way, those jack stands look a bit flimsy there, I always roll the tires under the vehicle "just in case". Be careful there with the amount of force involved you dont want to smack it with that explosive hammer and it falls off on your leg.
You're not seeing the whole picture. Both front wheels are planted and chocked, passenger rear still has the wheel mounted, there's a heavy duty jack stand set at the driver side frame rail (the side of my current struggle, it is just forward of the wheel in-picture) and then there are those two flimsy jack stands (upon which, with a set of four of them, my '70 GTX perched unshod for a couple months in 1990). My tools and methods have kept me and my work-pieces safe for nigh on 50 years, my friend, but thanks for your concern and good advice for this fellow motor-head, and any others who may be watching.
Ayuh, yeah and verily! You are a funny flatulist, Dave. Old farts indeed! Forsake and forsooth! The poet in me uses many old english colloquialisms, bastardizations, slang and dialect-variations that come to mind as I write. I found a bunch of very old crossword puzzle books and have been slowly filling them, and the words I've learned appear to be carrying-over into my everyday manner of speech. If it hurts that you recognize the words I use then, is it because I have gutted you with sharp-tongue or because you are in denial of your well-seasoned wordsmithing abilities? It must be oblious (that's my bag-word for obliviously obvious, or obviously oblivious) that the latter is the only truism.
I must confess (please be gentle) that I bought the bearing, seal and retainer at the stealership the day after you fed me those numbers. One of my compadres dragged me over hot coals for dropping about $160 for the one set. Sadly, I'm still a long way from getting that first rotor off the rear axle (or so it seems). Today is make-or-break day for me as I'll be going to the "heat-wrench" since nothing else seems to be working. Before I do, I plan to return those "gold-plated" parts to the dealer in-favor of same parts with lower prices because now I really want/need to do both axles. This after the admonishments of my "pals" who reminded me that you can't do just one side in a sixteen year old puff. I know they're right when they tell me "one tight seal will make the other older one leak and then your new brake assembly on the passenger side will get contaminated". Now THAT realization, my friend, was the proverbial knife twist.
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
Repeated blows with the steel hammer will do it.
Worked in a brake shop and that is how we did it.
Hit on the outside edge, (from the front only, not the back so you can get a good swing on it) alternate 180 and 90 degree blows one after the other, not so hard that you deform the axle or drive it to china, but you need to hit it like 50 times. You will eventually notice it moving ever so little, then more.
Also spray PB Blaster around where the lugs come through and around the center!
**Are you sure there isn't a bearing an nut holding it on under that cover?** if not proceed as above.
Last edited by 97grand4.0; 10-01-2016 at 08:22 AM.
(4) Remove caliper and anchor as an assembly.
(5) Secure caliper anchor assembly to nearby suspension
part with wire. Do not allow brake hose
to support caliper weight. (6) Remove retainers securing rotor to axle studs.
(7) Remove rotor off axle studs.
Please see photos in earlier post. There are no visible retainers (as suggested in the FSM). I will return to the PB Blasting, cursing, pounding, swearing, heating, cursing, drinking, spewing vulgarities and spitting.
After tripping to the dealer to return the over-priced articles...
The last time I saw "retainers" they were on an old Ford truck with drum brakes! They were just flat pieces of spring steel that screwed onto the studs. I left them off because I figured they'd cause the wheel to ****.
08-26-2016, 09:13 PM
Is "pulsing" the right word to describe this?
