Parking Brake fail
 

https://cimg0.ibsrv.net/gimg/www.che...92387ff7d5.jpg

https://cimg1.ibsrv.net/gimg/www.che...de1d148456.jpg

I had the distinct pleasure of dismantling my rear axles and brakes October last year due to an axle oil seal failure. Brake lining contamination and rotor warping was assumed due to heavy surging/pulsations experienced when braking. Aside from calipers, all of the original equipment brake hardware was replaced with Raybestos Professional Grade components. The above photos are driver side original equipment parking brake shoes etc. (note the thickness of the linings) which would not hold against idle speed in Drive or Reverse beforehand.

Smooth braking action resulted after replacements were completed but the parking brake still would not hold at idle speeds. It passed inspection despite having parking brakes being unable to hold. The mechanic allowed the pass because he knew I had only just done the work and they were still getting dailed-in. Fast forward to this year's inspection (due before end of this month) for which the state now has stricter criteria.

The replacement parking brake shoe linings were and are thinner than the originals which were discarded. Additionally, the lining material on the original shoes cover greater shoe surface area (toward the actuators) than that found on the replacements. Adjusting to the point that the parking brake will work causes dragging brakes that overheat under normal driving. I fear that this already did or will cause warping damage of the top-hat rotors due to overheating at the drum surface.

Doubting my work from a year ago, I took it apart again to confirm parking brake cables were in-fact attached and actuating. They are but actuation travel is minimal (and probably should be) but I can't for the life of me figure out why they won't hold. What gives? Am I missing something? Can anyone point me in the right direction on this dilemma? I want normal parking brake action to pass inspection without over-adjusting the parking brake shoes.

Maybe the parking brake cable is stretched. Still actuates but doesn't provide enough pressure.

I take it you are adjusting that little star adjuster and not the brake cables to get the parking brake to work?

The actuator link in your second photo is what set up on mine. I drove it for 3 years without them until the springs rotted and the shoes started dragging. Then I took out all the parts. When I got my replacement rear axle, it came with good parking brake cables that worked and almost new shoes, so now I've got parking brakes. I'm currently setting the parking brake every night to keep them working.

Make sure the shoes are extending with the drum off. The actuator may be frozen on one side or one shoe on both sides.

This was one of my suspicions but the PO claimed to have rarely or never used the park brake since purchased in 2000. Would the cable(s) still have stretched if practically unused?

Yes, that is the only means for park brake adjustment (unlike prior years where adjustment was accomplished at the equalizer) which led to dragging shoes and heated rear brakes (both sides). Backed-off shortly after the assemblies cooled.

What do you mean by "set up"? Did your actuator link bind on one or both of its two outward directions of travel (upper vs. lower shoe)? Do the actuators articulate in that manner? Is my situation simply a matter of cleaning and lubricating the actuators? When my helper cycled the park brake lever I observed one (upper) shoe actuating (at each wheel) by as much as 3/16' travel but the other (lower) shoe did not move - except when I thumped my fist downward against the extended upper. I attributed that action (or lack thereof) as being due to having no drum there to counter the upward/outward push against the drum face, that if a drum was present then the force would be distributed equally to both shoes. Must both shoes actuate when no drum is present?

Good question. You could always try these to take up the slack and see if it works better.

Good concept but clearances are lacking for a piece like that. The only exposed cables are in the junction box beneath the rear seat. The cables are jacketed everywhere else. Assuming stretched cables, I pondered inserting (slotted-puck-like) shims/spacers to the cable ends where they key/couple onto the equalizer bar...or even inverting/reversing the equalizer if possible. You see, if I did something like that and I would have to set the star adjusters to minimum, then it might cause shoe extension anyway and subsequent shoe-dragging. I'm sure you've got the mechanical aptitude so, are you getting the visuals that I'm trying to describe?

What happened with mine was the actuators didn't move at all. The cables applied tension, but the handle in the cab only moved a tiny bit. The shoes never moved at all. IDK how the actuators are made or how they function internally. I would assume they move both shoes at once and with the drum off, only one would move until it contacted the the drum, then the other would move. The cables are braided steel and I doubt they would stretch enough to not function. I think your actuators are rusted enough to not move far enough. With the cables disconnected from the actuators, the brake handle in the cab should come up almost vertical.

Even the FSM doesn't show the actuator disassembled. All it shows is how to hook the cable up to it.

You can try lubing the **** out of the actuators in the hopes of freeing them up. Once you get them free, force some brake grease into them.

Y'see, now that's what I'm talking about. I think you just nailed it, Dave1123! You've definitely earned a top ten spot on Santa's "nice" list. Oh yeah, and thanks to you too, rgr4475, for your contribution. Valid input/concept for sure.

My park brake handle does move, but only as much as ~20 degrees (max guesstimation) from the down position. Pulling up really hard for a click or two beyond that will get you a very weak park brake action. And like I said before, there is a little brake shoe movement with no drum present. I'll dismantle them again to clean/lube/free the actuators and hope that it's the cure. Nothing else makes any sense based on what I've done and seen.

Let us know what you find. I'm interested to add to my well of knowledge LOL!

I replaced both actuators ($74) with a great deal of cursing but they did not resolve the issue.

I then found a wealth of info/discussions on this issue when I searched in the Jeep forum under the WJ sub-forum. Search parameters included "brake shoes", "Park brake", "emergency brake" and "rear brakes".

After all that reading I finally realize that I'm just plain screwed unless I try to fight city hall over the B-S test they demand for the parking brake to hold (in a 4x4 V8 Jeep with LS axles on Quadra-Drive at 1500 RPM in gear). A ridiculous test expectation even when new. We all know what you get when you try to fight with city hall or state authorities.

This is why my mechanic doesn't test above 1000 rpm. The total swept area of the brake shoes isn't large enough to stall that kind of torque. He says it's an inspector's judgement call anyway. No hard data gets sent to the state computer. The only data that NY demands is ready monitors.

I was wrong to say bad things about Raybestos, have retracted my statements and issued apologies. My complaints and bad-mouthing of their quality were posted out of frustration. Today I had the pleasure of working (via communication over phone and email) with their Customer Service, Quality Engineering and various other Technical Professionals, up to and including their very well-versed Vice President (who called me while on his vacation). Excellent people who take pride in their company and product, all from an excellent American company. I learned a great deal from them, including their discovery of a bad lot of shoe "frames" from one of their vendors. Apparently, I was the recipient of some of the "escaped" bad hardware that was shipped from off-the-shelf in a warehouse somewhere. The frames (the metal structure on which the lining material is attached) had been over-machined by the vendor. Too much material had been cut from the recessed notch where the brake actuator makes contact and THAT is the root cause for the insufficient travel of the brake shoes. The solution was verified by their quality engineering group on several WJ's. They are now overnight shipping new shoes and rotors (tophats) to me with doubly-verified dimensions/specifications. Once again, you get more bees with honey. Will advise (them and you all) with results after new hardware is installed and state inspection passed.

Okay then! I just checked mine and it holds up til 1200 rpm, then it creeps. That's a 4.0 in 4wd. I either have Raybestos or Bendix on mine. Can't remember which.

Both are top names in replacement brake hardware. I still think that the test is wrong, that 1500RPM creates too much torque for even a healthy set of parking brakes on a V8 QuadraDrive WJ. I will challenge the inspection mechanic to think on this at the right time. (QuadraDrive or QuadraTracII, eh, whatever.)