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Proportioning valve?

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    Posted: 17 Mar. 2019 at 11:12am
I will be installing a Suzuki disk brake conversion on my Willy’s. I was wondering if it would be wise to put a adj. proportioning valve in also. I read that it may not be needed with the weight distribution of the JEEP. What do you think? I have a $20 coupon for Summit and wondering if I should use it for other parts.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 17 Mar. 2019 at 4:37pm
Well on a normal vehicle 60% of the braking is done by the front wheels. In a hard stop the weight leans forward. This causes the rear wheels to loose traction if your brakes are applied with the same amount of force front to rear then the greater weight on the front and the reduced weight on the back will cause the rear wheels to skid. A tire in skid has NO CONTROL if you are on a corner or even a road with a decent super (OK the public would call it a crown) then the ass end of your jeep will slide down the slope while the rear tires are in skid.

Brake systems without a Proportioning valve will bias the front to rear by having different sized wheel cylinders. I would assume your disc brake set up dose not have smaller pistons on the rear.

You also need to put 2lb residual pressure valves in a Disc brake system one in the front line one in the rear line. Drum brakes should use 10lb valves.

YES YOU SHOULD USE A PROPORTIONING VALVE.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote rocnroll Quote  Post ReplyReply Direct Link To This Post Posted: 17 Mar. 2019 at 6:03pm
Originally posted by Siskiwit Siskiwit wrote:

I will be installing a Suzuki disk brake conversion on my Willy’s.


Just fronts or front & rear?



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Siskiwit Quote  Post ReplyReply Direct Link To This Post Posted: 17 Mar. 2019 at 6:45pm
All four corners
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Post Options Post Options   Thanks (0) Thanks(0)   Quote otto Quote  Post ReplyReply Direct Link To This Post Posted: 17 Mar. 2019 at 8:57pm
Did Suzuki fit the donor vehicle with a valve? If one was used on a Sidekick or Samarai you could just use a factory part.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Siskiwit Quote  Post ReplyReply Direct Link To This Post Posted: 17 Mar. 2019 at 10:50pm
I think I will install one. I just read that it probably wasn’t needed or hasn’t been needed on a cj2a by the guy that made the conversion kit if I remember right. I haven’t set up a brake system before so everything is new to me and want to do it right the first time. I’m going with a Wildwood dual master with a remote resivoire. One more thing I understand I will need a couple of 2 psi. Residual valves, where are they plumbed in? I am guessing after the proportioning valve going to the front and rear. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stev Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 12:45am
Sikiwit,

I put a proportioning valve in after I did the Geo Tracker disc brake conversion because the rears (still drums) were locking up before the fronts and --- the rear end of the Jeep was coming around when the rears locked up.

I also have a dual master cylinder from Herm.  




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Post Options Post Options   Thanks (0) Thanks(0)   Quote Siskiwit Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 12:48am
Thanks for the info.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 2:09am
Residual pressure valves go between the pistons and prop valve they are ment to stop leak back in disc brakes and to keep the springs in a drum brake system from pushing fluid back to the MC.


Edited by Mark W. - 18 Mar. 2019 at 3:10am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Siskiwit Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 2:53am
Thanks for the exact info I was looking for. Like I said before I don’t know shat about brake systems other than the obvious. . I know now what parts to order. Thanks a lot.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 3:09am
Siskiwit you only need one per circuit so put the Residual pressure valve between the Tee where your line splits right and left and the Proportioning valve.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick G Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 5:43am
Siskiwit,
I have 4 wheel discs (the large GM calipers) and I don’t use any proportioning valves or residual valves.  I originally installed the residual valves fore and aft, but have since done away with them.  I have had zero problems with my brake system without either type of these valves.  I’ve been wheelin pretty hard with this setup for 4 years now.  I never have to worry about my brakes.

HTH,
Rick
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Post Options Post Options   Thanks (0) Thanks(0)   Quote chasendeer Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 5:52am
Rick 
What master do you have?
Thanks
Jay

Originally posted by Rick G Rick G wrote:

Siskiwit,
I have 4 wheel discs (the large GM calipers) and I don’t use any proportioning valves or residual valves.  I originally installed the residual valves fore and aft, but have since done away with them.  I have had zero problems with my brake system without either type of these valves.  I’ve been wheelin pretty hard with this setup for 4 years now.  I never have to worry about my brakes.

HTH,
Rick
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick G Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 6:40am
Originally posted by chasendeer chasendeer wrote:

Rick 
What master do you have?
Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Metcalf Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 2:24pm
With 4-wheel disc brakes, I don't think a proportioning valve is required on a flat fender. The weight distribution is close enough front to rear it doesn't seem to be an issue. Most of the tires used on early jeeps can't really generate a ton of brake force before they lock up and slide. I installed one on mine when I designed and built my Sidekick/Tracker conversion. I have played with a lot, and I don't see much difference. It does create another leak point or three which is annoying, because most aftermarket units use NPT threads and adapters.

With discs on just the front axle, a proportioning valve seems to be required more often to keep things more balanced between the different braking systems.

A residual valve helps keep LIGHT pressure on the piston to help deal with any lateral concentric runout of the rotor to the caliper. The caliper can typically float in it's mount inboard and outboard, but the rotor can push fluid out of the piston depending on the force required. The residual valve helps this. Without one, you basically just have to push more fluid ( more pedal travel ) before things can lock up. This can cause a softer pedal feel at the top of the stroke.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Siskiwit Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 5:20pm
That’s why I considered not installing one, extra leak points. I think I’ll plumb the brakes without one first and if I find I need one I’ll put one in. Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpet Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar. 2019 at 5:25pm
Originally posted by Siskiwit Siskiwit wrote:

That’s why I considered not installing one, extra leak points. I think I’ll plumb the brakes without one first and if I find I need one I’ll put one in. Thanks
That's a good idea. I did not need one in my system because I found that my brakes were already bias to the front without it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LesBerg Quote  Post ReplyReply Direct Link To This Post Posted: 02 Apr. 2019 at 2:10am
OK. I guess I'm going against the grain.

I installed a proportioning valve on mine after completing the four-corner Suzuki disk brake conversion.

I found that panic-braking on dirt/gravel without it caused the rear to lock up well before the front. I want to be in full control on mountain roads.

That said, I'm still running the factory master cylinder on a jeep with a two-foot stretch, powered by a 225 Dauntless. Given that my wheelbase is 24" longer with a slightly lighter engine, my weight distribution is doubtlessly different from stock.

If your line-flare skills are up to par (mine aren't) then potential extra leak points shouldn't be an issue.

I guess the best advice would be to go drive it for a while. If you find that the back locks up unexpectedly or more often than you'd like, install a proportioning valve.
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