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Discussion Starter · #1 ·
4-wheel independent brakes / poor man\'s locker

Well, I finally got around to doing it-- I now have electric valves for independent control of all 4 wheel brakes on my 79 CJ5. 4 pushbuttons, push any button or buttons, then hit the brake pedal, braking force goes only to the wheel(s) corresponding to the button pushed. Push no buttons, brakes work normally. A seperate switch to lock all 4 (push the pedal, hit the switch, release the pedal, brakes stay on).

And it works. Sort of. Definitely takes practice to use effectively, fortunately the CJ's pedals are well situated for heel-and-to action, and a hand throttle helps too. Went out in the snow and was able to walk a front tire up onto an 18" high rock with a vertical side by locking the opposite wheel. Couldn't have done that before. Less useful in generally slippery snow (or I presume mud) where all 4 wheels have no traction, you then just control which wheel spins. Ya gotta be real careful to let go the button if you start rolling backwards, or you'll have zilch for braking action.

Here's the "sort of" part: It's almost impossible to lock a rear wheel, but I'm not sure why. I can think of 4 reasons (comments, anyone?):

1. The rear brakes are badly out of adjustment or worn (seems most likely).
2. The proportioning valve prevents sufficient pressure from getting there (does anybody know exactly how the proportioning valve works?).
3. The proportioning valve is defective.
4. CJ rear drum brakes (the front are discs) aren't that effective anyway (question, not a statement, but the emergency brake does almost nothing-- OTOH the emerg brake on the 75 DJ5 I used to have would lock the rear wheels hard).

Anyway, I plan to go into the rear brakes next weekend (ran out of time today) and replace the shoes, adjust, etc., so we'll see.

As a parking brake it's limited; it won't hold on a real steep hill-- but then the valve is designed to hold full pressure only in one direction (and it does-- lock all 4 and hit the pedal and it feels like the pedal is welded to the frame!). The manufacturer couldn't give me a pressure rating in the reverse direction. I'll probably also change the electrical design so touching the brake pedal releases the park setting.

Total cost: Under $200 for four valves, fittings, switches, tubing, wire, etc. A helluva lot less than an ARB!

Possible future plans could be a power brake booster (does anybody know if that can be added to a 79 CJ5?). That would increase the rear brake effectiveness, and also it might be possible to add another valve to operate the booster, providing full braking action even if the brake pedal isn't depressed. Then wheelspin sensors and some fairly simple electronics would be all you'd need for true traction control like some of the real expensive vehicles. An alternative might be ABS components from some other car, but good technical information's dammnably hard to find.

-Dana

A goverment that fears arms in the hands of it people should also fear ROPE!
 

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Discussion Starter · #2 ·
Re: 4-wheel independent brakes / poor man\'s locker

Update:

New shoes in rear brakes, properly adjusted. Works much better now, though the rears are still much less effective than the fronts; I presume that's just the way it's gonna be with drums. Rear disks would be great! Or power brakes, or some other setup that would apply the brakes when I push the button, leaving my foot free.

A little more development, and I'll post more details on a web page.

-Dana

But daddy, if Clinton can lie, why can't I?
 

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Re: 4-wheel independent brakes / poor man\'s locker

i think you got a good idea going, i've thought about using dual rear parking park brakes (even front drum brakes using parking brakes also)
but anyway, about your proprtioning valve question, i once asked "how to choose a master cylinder" on this board and "Jaffer" told me to call this guy. he is definety an expert, told me exactly which master cylinder to use. i could tell he knew what he was talking about.
ask for "Van" @
Vanco Power Brake Supply
9738 Atlantic Avenue South Gate, CA 90280
(323) 563-1588

tell him a guy with a red 3/4 ton Jeep told you to call, i've been wanting to recommend him to someone.

3/4tonYJ
My Jeep Page
 

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Discussion Starter · #4 ·
Re: 4-wheel independent brakes / poor man\'s locker

I talked to him last week, his explanation was that the only thing the valve does is to maintain a little residual pressure in the rear line even when the brakes are off, which is what you want with drums. Certainly it does that, but I thought it also maintained a pressure differential between the front and rear to prevent the rears from locking.

-Dana

Great spirits have always encountered violent opposition from mediocre minds-- Albert Einstein
 
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