Brakes very biased to the rear?

Hi,
The brakes in my 95 XJ (4.0 5sp) seem to be VERY biased to the rear. When I brake, the rear locks up very easily, and if I'm downshifting and braking at the same time, it gets even worse. Driving on wet roads is quite an interesting experience... This is my first XJ and I'm not sure if the brakes are supposed to be like that. Is there a proportioning valve somewhere that needs to be adjusted?
Thanks.
Mikel

The brakes are not supposed to be so biased to the rear.

If you search the archives here, you're likely to see a lot of posts regarding the tendency of the rear brakes to lock up. The exact cause remains somewhat elusive, but the first suspect is bad adjustment. The self-adjusters on these are notorious for failing, and oddly enough, when the brakes go out of adjustment, they often grab, espcecially when wet. Other theories include needing new wheel cylinders, ridges on the drums, bad shoe material, and bad springs.

I'd recommend as a first step opening up the brakes and looking to see if the adjusters are intact (the little cables often rust off, and the star wheel adjusters often rust solid). Look also for bad or missing springs, loose shoe edges, etc.

There is a proportioning valve, but it is not adjustable. It might also be worth looking at that, though.

I had the same problem recently on my 95 after a complete rear brake job (but without drum work) and it seems now to have gone away after I got the rears adjusted and seated in well. Frequent adjustment does seem to help.

As a further dose of confusion here, I'll just mention that years ago I had this problem on an 87, and it went away, at least for a long time, after I replaced the warped FRONT brake rotors. I figure perhaps the pulsation was affecting the rears, but then again maybe it was just placebo effect or the phase of the moon.

What i have found-

There are many variables involved here. I doubt there is a porportioning valve problem. Front to rear balance is tough to keep. Generally is best to use stock shoes and pads. The engineers have worked hard to use materials designed for proper balance. There are a plethora of diff designs and friction coefficients out there with aftermarket. With each you will change the balance.

I have seen indicators of what happens when wet roads: The front rotors will get wet easily, the rear drums stay dry. When hit the brakes, the rears will grab more than the wet front rotors at first. Have seen this in many diff vehicles. Nothing helps but even less bias to the rear...generally not good. 4-whl disk help with this occasional imbalance problem.

Careful adjustment and scrutiny of rear brakes in total. Adjustment there can make a world of difference. If continues, turn drums and new shoes, maybe new hardware.

Thank you both!
I will have a look a the brakes next weekend. My front rotors are starting to warp, so it's probably been a while since the brakes were worked on.
Thank you again.
Mikel