Brake problems on 87 XJ

It seems like my back brakes hardly work at all. I've replaced my wheel cylinders and master cylinder. The flow to the rear brakes is good while bleeding but they hardly seem to apply at all while stopping. Anybody have a solution for me.



Leith

Leithmc said:

It seems like my back brakes hardly work at all. I've replaced my wheel cylinders and master cylinder. The flow to the rear brakes is good while bleeding but they hardly seem to apply at all while stopping. Anybody have a solution for me.



Leith

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First can you explain how you are determining how effective they are?


Cherokee rear brakes arent known to be very effective and they are supposed to do only about 30% of the braking.
there are a few things to check.

id be looking at the drums and shoes..
are they new also? if not, have the drums been machined recently?

if they have, are they oversize?

if they are new.... I know some brands back east come painted to inhibit rust...did you clean the new drums of all oil and paint?

are the shoes in good condition? no cracks or uneven surfaces...no brake fluid or previously soaked in rear end grease (never try to clean a shoe that has 90 weight on it. You are only making yourself dangerous to other people on the road)

Adjustment is important...

proper adjustmet is turning the adjuster until you cant turn the tire by hand...then using a small screwdriver to release the auto-adjuster foot (the clicky thing), back the aduster off about 10 notches. Do both wheels the same and you are good to go.
-or-
tried and true method is to turn the adjuster until you hear the shoes start to drag...go pump the pedal a few times and check to see if the drag is the same....repeat until there is a slight drag turning it by hand.

Not very effective becuase I can apply the brakes while the vehicle is off the ground and spin the rear wheels freely after the fronts have locked up. Also I can slide backwards down an icy hill with the brake pedal fully depressed and the rear wheels are still turning while the fronts are locked up. One thing that is strange though, After I've been in the mud the back brakes seem to over power the front ones for a while, slightest touch and they just lock up. Shoes are near new and not soaked. Drums were machined when the wheel cyls were changed last month and still have 10 and 12 thou left to go.Everything else on your list has been gone over as well. I should probably have mentioned that I manage an automotive shop and my tech has done all the work on this. What I'm leaning towards is the proportioning valve. I was just wondering if anyone has had this prob.



Leith

I´d lean towards towards stuck adjusters and/or the adjusters in the wrong sides, there are a left and right adjusters.
Pry the adjuster away from the star wheel (a little) and try turning the star wheel by hand, if you can´t turn it by hand, the little lever of the adjuster really doesn´t have much chance.
Have also seen the adjuster lever, so rusted, it was thin and bent some. And the adjuster lever spring in the wrong hole, on the shoe.
On most models there is a cable connected to the adjuster lever, half way up the shoe there is a curved guide, that often pops out of the hole in the shoe, during assembly.
There are a number of things that can go wrong with the adjusters (which other than air) is a major cause of poor performance.
Next on my list would probably be lost prime and/or poor seals in the master cylinder and/or junk stuck in an orifice in the master cylinder.
Try closing the bleeder, until it´s just slightly open (a little more than some drops, but not totally open) and have someone stomp on the brakes, fluid should shoot out of there. Put a big "C" clamp on the shoes (with the drum off) and have someone work the brakes, you can see if they are getting pressure.

The proportioning valve gets weird and hangs-up on these XJ's. It's located in the brake line manifold under the master cylinder. If everything else checks out okay as others have suggested, try removing the propotioning valve, clean it and re-bleed the brakes. That helped mine after rebuilding the entire brake system and the drums still didn't work with the rear off the ground.

8Mud said:

I´d lean towards towards stuck adjusters and/or the adjusters in the wrong sides, there are a left and right adjusters.....................

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I have done an extensive search on this topic of stuck/frozen adjusters and have have learned a few things. Before anyone advises to just upgrade to disc brakes or how poor the drum brake setup is let me remind them that it worked fine before the disc brake came along and rear discs came along much later than the fronts due to parking brake issues.

I had a few muscle cars in my day and was able to work on the rear drums fine. It's been 30 years and I am having a tad bit of trouble with a '92 XJ that I recently acquired. It was originally owned my a college man who performed a lift and swapped a 8.25" replacing the original D35 and negating the ABS.

My question is based upon the fact that I didn't realize that there is a right and left star adjuster. Is this a dealer item only? I searched some online oem aftermarket part suppliers but, wasn't successful.

I am new to Jeeps and apologize beforehand if someone tosses out 83 eleven links to show how much better that their search capabilities are compared to mine.

F9K9 said:

I have done an extensive search on this topic of stuck/frozen adjusters and have have learned a few things. Before anyone advises to just upgrade to disc brakes or how poor the drum brake setup is let me remind them that it worked fine before the disc brake came along and rear discs came along much later than the fronts due to parking brake issues.

I had a few muscle cars in my day and was able to work on the rear drums fine. It's been 30 years and I am having a tad bit of trouble with a '92 XJ that I recently acquired. It was originally owned my a college man who performed a lift and swapped a 8.25" replacing the original D35 and negating the ABS.

My question is based upon the fact that I didn't realize that there is a right and left star adjuster. Is this a dealer item only? I searched some online oem aftermarket part suppliers but, wasn't successful.

I am new to Jeeps and apologize beforehand if someone tosses out 83 eleven links to show how much better that their search capabilities are compared to mine.

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Drum brakes work relatively well until you add bigger tires. More rotating mass on already not so good brakes=not stopping so well obviously. "self-adjusting" isn't one of the strong points of XJ drum brakes, converting to discs makes this point null since there is no adjustments to be made. When I converted to rear discs on my 8.25 rear end when I still had it, the difference in braking was night and day, a very worthwhile mod.

As far as the adjusters, I was able to pick ones up for my d44 from Autozone. 6 bucks a pop if I remember correctly. Some grease inside of them and they seem to be working well for now.

gregmondro said:

....................As far as the adjusters, I was able to pick ones up for my d44 from Autozone. 6 bucks a pop if I remember correctly. Some grease inside of them and they seem to be working well for now.

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Good info and thank you! There is definitely a "passenger", "driver" side difference in them? I would have thought that flipping them would help but, then it's been a time lapse of 30 yrs between my wrenching sessions:cheers:

I believe so, its been a while since I messed with mine, but It'd pretty apparent the way they go since the little lever that the adjuster star catches on will pretty much tell you if you have them on the correct way or not

F9K9 said:

I have done an extensive search on this topic of stuck/frozen adjusters and have have learned a few things. Before anyone advises to just upgrade to disc brakes or how poor the drum brake setup is let me remind them that it worked fine before the disc brake came along and rear discs came along much later than the fronts due to parking brake issues.

I had a few muscle cars in my day and was able to work on the rear drums fine. It's been 30 years and I am having a tad bit of trouble with a '92 XJ that I recently acquired. It was originally owned my a college man who performed a lift and swapped a 8.25" replacing the original D35 and negating the ABS.

My question is based upon the fact that I didn't realize that there is a right and left star adjuster. Is this a dealer item only? I searched some online oem aftermarket part suppliers but, wasn't successful.

I am new to Jeeps and apologize beforehand if someone tosses out 83 eleven links to show how much better that their search capabilities are compared to mine.

Click to expand...

I bought new adjusters at Autozone, they had them in stock, so they should be easy to get just about anywhere. I now wish I had lubed them with antisieze or graphite as the new adjusters are not much better that the rusted/siezed ones I replaced.

Actually I am in the same boat (XJ) replaced everthing brake wise except the Prop valve and still haviing week rear brake activity. I am even wondering if the Prop valve problem is affecting the rear drum adjuster perfromance. We are not the first with this rear drum / adjuster brake problem on XJ's.

I am even wondering if the brakes would not work better with out the prop valve???? None of my older cars had a prop valve!

I have one frozen and the other freed up and working nicely. Since I was rather ignorant in storing my parts out of the weather I don't recall which was which when I removed them. I did take a lot of pics to assist me in me replacng the old shoes but, they are all on the driver's side. Guess I will try to get both tomorrow and try to finish it up. Thanks for the insight.

They also counter adjust to each other, but I don't remember which one goes where. I think that the one that rotates normaly, goes on the drivers' side.

Adjusters are side specific!!!!!!!! The adjuster lever is outside of the star wheel. Downward movement (on outside) will cause adjuster to extend. Check that the adjuster lever is good, not rounded off. If it is suspect replace it. Any parts house can get them, if not leave and NEVER go back. I have always put a little anti-seize in the treaded area and a little in the cup end. Verify that everything works smoothly.

Most community colleges have a brake class, students can often be bought cheaply to do brake jobs as part of their class. Some repair shops have free brake inspections also (Midas).