Have you opened the drums yet take apart, and clean with brake cleaner and reinstall. by the engine not being able to hold you from rolling back, i meant that on large inclines, when you release your gas, you shouldnt roll back right away.

 

I haven't, but I will this weekend. As far as the engine holding me in place, this all came about during a recent trip to the Sierras when I tried to make it up an ever increasing hill. I got to a point where forward progress was impossible and wanted to engage 4WD but as soon as I shifted out of gear to engage the front diff I started rolling backwards (not sliding, rolling) despite full pressure on the brake pedal. I had no way to stop so I quickly pumped the brakes a couple times to slow my decent but still couldn't completely stop. Again, I was rolling, not sliding, the wheels were turning. Some of this has to do with my relative off-road inexperience, too. I should have been in 4WD before ever starting up that hill but I thought I could make it in 2WD. That's what I get for thinking.

I'll pull my drums this weekend and have a look.

 

pumping pedAL increased system pressure same as booster upgrade does

 

Everything else aside you should be able to lock the fronts, forward or back. On the hill you describe it should be easy. Try repeatedly hitting the F1 key. Bleed the fronts and test that they grab? Bleedm' and check the lines, especially the flex lines. I've had them blow. (better to pressure test them in the driveway than in traffic!)

I did read that the proportioning valve can be reset by applying allot of force. (that would be to the petal!) It might have been in the FSM, a psi was even mentioned.

Yea, rears backwards? Might not work so well, but your fronts should grab pretty easy on dirt.

What I mean, (to be clear), is your rears might be fine, and your proportioning valve just might be flipped?

 

On the XJ's the small pad goes in the front, large one in the back.

 

Dammit Freegdr, you're trying to make me do a project!

F1 F1 F1 F1 F1 F1 F1 F1 F1 F1 F1 F1 F1. Nope, still won't lock.

 

Fluid is up. Engine idling. Foot hard on the brake. Front still turns? Master cyl, or proportioning valve/blown line.

I've never seen a flipped proportioning valve. I'd think you couldn't bleed (your fronts) if it were flipped?

I'm curious. Say you blow a front flex line, and the thing works. So you then stop with the rears. Then you replace the blown line and bleed it. NOW...can you feel it with your foot when the thing flips back to give you all four again?

F1 F1 F1 F1 F1 How old is your master Cyl? that might do that. Get a little sideways on gravel and lockm' at 20 or so, then get out and look at the gravel. (leave the dog out for this)

 

No just do yourself a favor if you end up doing a master upgrade and be amazed at the difference .

 

Master cyl or a blown line/proportioning valve. "boosting" nothing won't help!

Bleed it. Check the flex lines. If the piston in the caliper is clamping the pads on the rotor, it won't turn ether way.

I sure would bleed those fronts if it was me.

 

I'm going to replace the pads and shoes this weekend and I'll do a full bleed when I do. I might even look for the booster Freegdr recommended.

 

Found this article on the booster swap...

http://www.jpmagazine.com/techarticl...s/viewall.html

 

That's a characteristic of old, glazed "lifetime" shoes and pads.
Brake parts people have forgtten brqkes are a friction device. They make them super to last, but get glazed too fast.

Use the el-cheapo linings, they are softer, stop better, and last almost as long. The lifetimes are hard and wear the drums/rotors fast.

 

Not to disagree with anyone. These guys know them well. I've used Cherokees on a "noteworthy" hill since the mid 90's. I don't can pads or shoes when they are OK. Grooves in drums don't bother me. Rotors need to be good. I haven't had any brake lines rot/burst, or flex lines blow. Couple master cyls, and a few wheel cyls leaked. Rings in the calapers, for me expanded, and "bound", and caused rotor heat and wear, never saw leaking from the pistons in the calipers. Those rings are cheap.

Shorter story. Take the rotors in. Pass on the drums. If they look OK run'm.

Front pads...Got a 1/4 inch ? Even 1/8-3/16? Yea they are not too spendy, guess you get about 3/8.

* A rotor that is normally fine will distort, and show it needs turning, (by pulsing your pedal), right away when it gets hot, like 30 seconds going fast on a real downhill. *

Anyway F1 F1 F1 F1.....I'd bleed it, clarify that I have pressure out all four first, was me. Even totally worn to toast, those fronts should grab, or leak.

 

 

Fast forward about a year... There were many issues with my braking system, a complete overhaul has fixed all of them and adjusting the parking brake has resolved it's holding issues.

This was most likely the primary contributor. When I removed the pads and shoes they appeared to have been wet sanded and polished to a pristine glossy finish, as were my drums and rotors. I don't think my brake fluid (about the consistency of pudding) was helping, either.

Thanks for all the advice and patience.