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Brake Question with Usual Suspects Already Checked

98NWCherokee

NAXJA Forum User
Location
Portland, OR
1998 XJ
2wd
4.0
AW4
8.25 rear axle with 3.55 gearing
165K
non-ABS

It's been a rough couple of weeks for the XJ. I made it through the PCM diagnosis and replacement, but now I have a new issue......the brakes.

Now, I know the braking system in our XJ's is not "cutting edge," but I'm having a strange issue. The brakes are "grabbing" and the pedal feel isn't what it used to be. I've adjusted the rears several times to no avail. Last year, the front rotors, pads, rear shoes, wheel cylinders and harware were replaced. The rear drums were turned as well.

I brought the Jeep into the shop today and did a full brake inspection. There's an awful lot of drag on the front wheels.....is this normal for a 2wd XJ? The wheel does not make a complete revolution before the drag stops it. At this point I was leaning towards perhaps a bad phenolic piston in my caliper or even a failing proportioning valve. I threw a set of gauges on the front and rear and I'm getting 1000 psi at the front caliper and 500 at the rear drum, which I interpret as normal.

So at this point, I'm leaning towards sub-par rear linings and perhaps aging calipers. The Jeep stops and I'm not worried about an accident, but it just doesn't feel the right. Any thoughts are greatly appreciated.
 
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I've had grabby brakes from rust on drums/rotors. Vehicle put away wet and sit for a few days makes for rust.

I've had grabby rear brake shoes just from bad/wrong/substandard material.

I've heard of grabby rear brakes if the rear shoes are installed backwards. (Leading shoes have less material length)

My Euro-sedan (2WD) wheels won't go a full revolution due to bearing & brake drag.

Just some thoughts to work with....
 
Thank you very much for the suggestions 2X_01_Jeeps. I think you might be on to something when talking about substandard materials. I did check and the primary and secondary shoes are installed correctly. Also, there's no rust on the rotors as the Jeep is driven daily and spends the night in a garage.

Glad to hear the drag on the front may be normal....

I think I'll just continue to monitor and think about replacing the shoes....I hate to do it because they have nearly 90% material left.
 
If I remember it right, the grabby material was black semi-metallic rear shoes but I could be mistaken.

I prefer the softest linings in order to get the longest life out of the expensive parts (the rotors/drums).
 
I am not sure how bad the drag is but all disk breaks have a drag on them. Unlike drum breaks, there is no mechanism in disk breaking system to push the disks back off the rotors. Having said that, my XJ had one wheel sticking on the front. It was easy to tell because that wheel would grab when the breaks were applied. In addition, that side generated a lot more heat than the other side with the non sticking breaks. It was a bad piston in the caliper. After a drive do a touch and see if they are excessively hot. Also, a pungent smell is always a give away that the breaks are sticking.
 
Just a longshot thought. There are two types of brake shoes in a set, the leading and trailing. I have seen people get them installed in the wrong position. After a while they start grabbing.
 
Thank you techno1154. I appreciate your suggestions. I know that drag is an inherant part of the disc brake system......this just seemed like a lot of drag. I've done brake jobs on other vehicles and could get 2 rotations of the tire before the drag stopped the wheel.

Neither rotor is heat checked or scored and I have zero runout. The rotors actually look brand new still and the braking is even with no pull. I have touched them after a drive and they're not what I would call scorching hot......I have no smells either.

I did an impromptu test where I drove the XJ on a very slight incline. As soon as the Jeep stopped, I bumped it into neutral and the Jeep immediately began to roll backwards. I would interpret this as normal drag....

On the plus side, I didn't have the lockup issue today after driving 10+ miles. The pedal still doesn't feel great but the brakes are definitely there and feel a bit less grabby.....Maybe the bleed was all I needed....

I'll continue to monitor but please keep the suggestions coming.
 
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