gimme a brake!

My 89 4WD XJ with 130K miles is beginning to pull when braking. Just replaced front pads, the rear shoes were OK. I am thinking I should rebuild the 4 wheel cylinders and the master cylinder. Braking power is not what it used to be. Will this return the jeep to contollable solid stopper again? Is the project hard and time consuming? Does it pay off? Thanks Guys!!

Wheel cylinders are cheap, and rebuilt calipers are fairly cheap. I've rebuilt both in the past, but it's not worth the effort involved.

Loss of braking power overall is more likely due to the combination/proportioning valve assembly than to a bad master cylinder. I know people who have replaced literally everything in their braking system and still had lousy brakes ... until they replaced the combo valve.

The master cylinder should be fine, if the brake pedal doesnt slowely sink while holding it down then it should be fine.
~Joe~

Eagle said:

Wheel cylinders are cheap, and rebuilt calipers are fairly cheap. I've rebuilt both in the past, but it's not worth the effort involved.

Loss of braking power overall is more likely due to the combination/proportioning valve assembly than to a bad master cylinder. I know people who have replaced literally everything in their braking system and still had lousy brakes ... until they replaced the combo valve.

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Okay, where the heck is the combo valve..or even, what is it. I've got the same thing going on..I'm standing on the brake pedal until my thigh muscle is jumping, and still moving forward. Its not just the weight of the 33's, this thing ain't right. (replaced adjusters, pads on front/back, front rotors, new fluid, new wheel cylinders, and rehoned the drums), was thinking of the brake booster and master cylinder, but the MC is 169.00... Never heard of a combo valve... And the pedal doesn't slowly lose pressure. Did find some fluid in the leaking wheel cylinders, so switched 'em out, just in case.

Every one forgets brake hoses...can make it pull or hard to stop or keep front brakes from releasing.

The combination valve is located directly beneath the master cylinder. It serves two functions: (1) It's a proportioning valve that reduces pressure to the rear wheels; and (2) it's the "thingie" that turns on the BRAKE warning light if either the front or rear brake circuit loses pressure.

Eagle said:

The combination valve is located directly beneath the master cylinder. It serves two functions: (1) It's a proportioning valve that reduces pressure to the rear wheels; and (2) it's the "thingie" that turns on the BRAKE warning light if either the front or rear brake circuit loses pressure.

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Ah, okay. wonder if that was included in the $169.00 price they quoted me today for a Master Cylinder..Needs to have something done, and hell, bleeding the brakes is about all I've ever done without someone beating me over the head with a brake spoon...

http://www.napaonline.com/cgi-bin/n...lts_cat.d2w/report?search_string=&org_string=
Napa has the safety stop MC for $66......

or $20 for a reman.... alot better than ure price

Joe R. said:

or $20 for a reman.... alot better than ure price

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Aye, I vaguely remembering turning pale, and wandering out into traffic. Had the other stuff done, running out of time before our moab trip, but passed on the MC, don't think mine's messed up. The fluid was sure gunked up, though. Moot point, had all that work done today, and blew a hole in the block coming home..it stopped okay once all the oil and coolent fell out. Unfortunately, people stopped to help, rather than just run over me.

Did you resurface or replace the rotors? If not, nice flat new pads up against grooved rotor may take a few miles to wear in. Pads will only contact the high spots worn into the rotor until then.

I'm one of those that chased the mystery of the deteriorating brakes on a XJ. Part of the problem is the XJ brake system is marginal at best ... then you compound the effects of larger tires and aging components that are subjected to harsh environments over 15 years of service ... the result is a slow deterioration of the brake system.

Mine stopped good until it reached 110K miles ... when the rear shoes were replaced for the first time---the brakes haven't been the same since. The only components that haven't been replaced are the rear backing plates. The rear auto-adjusters don't seem to adjust like they're supposed to ... that partially may be due to driving habits.

The combo valve was the second to last of the components I swapped out ... it seemed to help some ... but, I don't know if it was the new part or due to the system being re-bled again---it seemed to always revert back to its poor braking power. I took my old combo valve apart and could find any visable clogs or buildup of sediment. The most dramatic difference was new flex lines ... you may want to start there first.

Ultimately, I scrapped the idea of using any aftermarket pads (Raybestos semi-metallics) ... even after running them for several years with zero problems. A dealer finally convinced me to use "stock" OEM pads and shoes ... stay away from the Mopar V-Line OEM replacements. The "stock" pads really improved low to moderate speed braking ... but high speed stopping power is still a challenge.

Good luck.