I've been looking at ways to upgrade the rear brakes on my XJ (short of a disk conversion). Back in high school, I used to take GM HD brake slave cylinders and swap them with what was found on dodge HD's for a low budget brake upgrade. Anything similar that can be done on a XJ?

Also, what is the best way to adjust the brake bias on a XJ?

 

Use the search for rear disc conversion, there's more than one write up
Using the rear brakes from a certain Grand Cherokee seems to be the easy way

 

What do you mean by brake bias?

 

Changing amount of pressure that's givin to each wheel.

 

If I'm not mistaken, the brake system has a proportioning valve built in which determines the strength of front/rear brakes. You should technically be able to put anything in back without worrying about it...

although, I have to wonder why.

My Jeep still has the factory drum brakes in back (big ones, to be fair). Properly adjusted with good pads/shoes and rotors/drums, my XJ stops on a dime. VERY good braking ability. Unless you're running massively oversized tires or pulling trailers/hauling heavy loads, a good drum brake overhaul should be more than enough to bring you to a stop.

 

Certain models of XJ came with a 10" rear drum brake setup...........Most have 9" drums. I am not sure what models had the bigger brakes, but you could search the junkyards for the hardware and backing plates.........
I honestly don't think you would notice much difference though.........

If your brakes don't feel that strong? and if it's never been done, I would suggest flushing the system of all the old fluid. You would be amazed how much firmer your brakes will feel after replacing with fresh fluid!
If you brake fluid looks even slightly brownish, it's long past due!

 

Excellent advice.

Adjust the rear shoes while you're at it.

 

AFAIK the stock valve cannot be adjusted. There have been threads through the years about modifying brake components (not disks necessarily) and swapping in adjustable valves. A Google search might turn up something as well as a search in Mod Tech. Perhaps someone will chime in.

I agree with 77olds and feel that most braking "problems" with stock rear brakes stem from misadjustment or worn components. Still doesn't mean that they can't be improved but I suspect that most will say that if you are going to go to the trouble, just swap in disks.

 

The valve cannot be adjusted. Fluid needs to be clean and shoes adjusted, after inspecting them.

 

I don't think I've ever got the rear end to stop spinning due to a brake lock up. The front locks on dry, wet, snow, ice, dirt, mud. Maybe I just need to adjust the rear shoes a bit.

 

I had a similar problem when I first got my XJ. Fluid looked like mud. Did a backyard brake fluid flush (speed bleeders make life easy for a one man rodeo) and it cured my problem. have you inspected your drums/shoes? check the adjustment on them as advised from other members. Also if you are lifted and/or running bigger tires remember you must compensate in braking for your added weight. It is also important to use quality replacement parts. Brakes are especially important for your saftey and the saftey of every other driver on the road.

 

I'll tell you this:

If you haven't done it, it needs it.

 

Definitely do a flush. These old things run DOT3 which is essentially good for 3-4 years. After time the oil soaks up water and becomes compressible - which does not a good hydraulic fluid make. Properly adjusting the rear brakes will make a tremendous difference.

Regarding adjusting pressure: It's non-adjustable in the sense that there are no ***** to turn. There are different springs that can be loaded into the front/rear proportioning valve but you don't want to do this with drums out back as these springs are for 4-wheel discs. Discs and drums have different operating pressures; you'd end up locking the drums up very frequently or just burn through shoes.

As far as upgraded hardware goes, just install discs. That's the upgrade. Some XJs have 10" drums but if you're replacing everything anyway why wouldn't you install the good stuff? I went discs when I swapper my rear axle and I am very happy with it. Afterwards you CAN do the proportioning valve swap for better F/R balance. Lookup some of the many writeups. It's worth the time.

 

This ^ I have less then $125 in my rear disc swap. Junkyard backing plates and calipers off a ZJ. New Pads/Rotors.

 

I just have to take the time to do a disk upgrade. Previous owner put drilled and slotted rotors with different pads up front but I haven't ever really checked on it much. Long story short, college student who's DD is starting to have transmission and engine problems so it's really a case of getting the Jeep ready to be a daily driver so I can sell my Trailblazer and find a pickup.