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Are any of you with disc brakes on all 4 wheels still running the stock proportioning valve?


Interested in hearing from you CJ7 and YJ owners about your brake setups.

Mine is an 85 CJ7 with twin dana60's. The front has been converted down to 1'2 ton disc brakes and the rear are explorer disks. I have a dual diaphram brake booster and will be running 38" tsl's.

Im wondering if the stock proportioning valve can handle this setup.
 

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I am still running the stock one in mine. And I don't even have power brakes. It seems to be working fine.

I read once that you are supposed to remove a check valve. I think it was in the stock proportioning valve, and I haven't even done that yet. I thought I would run it and then if I had any trouble, then try that.
 

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I'm running the stock MC with four wheel discs on my YJ. Works very well. I'm sure I could squeeze more out of the system, but so far, so good. I know for YJ's, a MC out of a 79 Grand Marquis with four wheel discs is pretty much a bolt on set-up that supposedly works awesome. I don't know if this would work for CJ's though.
 

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There are several reason's you shouldn't run the stock disc/drum m/c or combination valve with a 4 disc conversion:

M/c - the rear resevoir is smaller, and should be larger to have sufficient fluid reserve after the larger volume the rear calipers require.

The rear output includes a 10lb residual valve that is required to keep the shoes close to the drum, but with discs will cause the pads to drag

Combination valve - the stock valve is not just a proportioning valve, but also a metering valve.

"A metering valve or "hold off valve" is used in the disc portion of a disc/drum system to hold off the application of the front discs slightly allowing the slower reacting rears to catch up. This provides rear stability on wet surfaces and reduces excessive pad wear. "

again - not required or good for rear discs. The proportioning is also set ofr rear drums, not discs, and also some include the residual valve here (not in m/c).

Having said all that - it will work, but you sure won't get the braking you paid for with your 4 wheel disc swap.
 

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i ran 4 wheel disc's on my old d44 front/ 60 rear combo and it worked fine with the stock p/valve. they sopped well and never gave me a problem. i say try it and then is you have a problem fix it. now with the 1tons and stock brakes my stock system sucked! i just swapped in a hydroboost from a 1ton truck.
 

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I just installed rear discs and a hydroboost system. I bought a proportioning valve but didn't install it till I could try out what I've got. After running all weekend it works awesome. I have it set up with 3/16 line feeding the front and 1/4" feeding the rear with no proportioning valve of any kind. It has tremendous braking power with the rear locking up just a split second after the front in a panic stop situation. I think the proportioning valve will hang on the wall till another project comes along!
 

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as of right now yes... i havn't finsished the new motor and tranny swap yet so i havn't tried the new hydro system out yet. i have it all wired but i am waiting on my new pcm (tommarrow) and i need to remake my tranny mount/cross member (my rear d/shaft was at too much of an angle). hopefully i'll be able to give her a spin in a few weeks to find out.
 
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