Proportioning valve on stock master cylinder (1g awd)

[mini zilo]

Has anybody done this before? I have an ABS car, and I was wondering if when I eliminate my ABS, I could just run a proportioning valve for the rear brakes, and run the front's unregulated.

It seems I would just run a T from the front brake outlet on the MC to both of the front calipers. Then run the line from the rear brake outlet on the MC to the proportioning valve, run a T on that, and connect each of those to the rear lines. It probably wouldn't be too difficult to run the lines because I have a bunch of stainless steel braided lines.

Thanks!

[lowell]

You can definitely hook it up as you described. What kind of proportioning valve are you going to install? Driver adjustable?

[jtmcinder]

If you're going to use to an adjustable prop valve, then I guess you could plumb it the way you described. But keep in mind that a corner-to-corner split is much safer and should be used if the prop valve remains near the MC.

(A corner-to-corner split, which is how 99% of all cars are set-up from the factory, has one output from the MC go to the front left and rear right, and the other output from the MC go to the other two corners. This way, if one of the seals in the MC goes out, you have two opposite corners that still work, instead of both fronts or both rears.)

[eclipsegsx1736]

Originally Posted by slow_matic

Has anybody done this before? I have an ABS car, and I was wondering if when I eliminate my ABS, I could just run a proportioning valve for the rear brakes, and run the front's unregulated.

It seems I would just run a T from the front brake outlet on the MC to both of the front calipers. Then run the line from the rear brake outlet on the MC to the proportioning valve, run a T on that, and connect each of those to the rear lines. It probably wouldn't be too difficult to run the lines because I have a bunch of stainless steel braided lines.

Thanks!

I did this exact thing last year. I took the front MC outlet and T'ed it off to both fronts using SS lines, and the rear outlet directly to a prop valve and then to a T fitting, utilising the factory rear brake hardlines.

I used this prop valve because it already has an integrated "T" for the front lines so it made that part a lot easier. For now, the valve is mounted in the engine bay. Mounting it in the cockpit would have necessitated running new rear hardlines, which in hindsight I should have done if I had known I was taking the car to the level it is now. I'm considering running a cable adjuster to the cockpit, depending on how often I find myself needing to adjust it throughout the season. I'll get some pics if you need it, but it's not anything too complicated to do.

As a side note, I used Wilwood checkvalves right at the MC to keep a slight amount of pressure in the system to reduce pad knockback.


I've only driven the car a few miles on the street since the install and to bed in the brakes, as the car is no longer driven on the street. Soon, I'll have the car at the track to dial in the brake balance and test out the system. I can say though, the pedal pressure and feel is certainly improved, and I can definitely say the propvalve is working. I had it adjusted about mid-way for starters, and almost spun the car around on the freeway when I started to bed in the brakes from having a bit too much rear bias!. I'm waiting until I hit the track and get the pads up to temp before setting the final bias, as of course that will change will pad and tire temperature.

Beau

[mini zilo]

Originally Posted by eclipsegsx1736

I did this exact thing last year. I took the front MC outlet and T'ed it off to both fronts using SS lines, and the rear outlet directly to a prop valve and then to a T fitting, utilising the factory rear brake hardlines.

I used this prop valve because it already has an integrated "T" for the front lines so it made that part a lot easier. For now, the valve is mounted in the engine bay. Mounting it in the cockpit would have necessitated running new rear hardlines, which in hindsight I should have done if I had known I was taking the car to the level it is now. I'm considering running a cable adjuster to the cockpit, depending on how often I find myself needing to adjust it throughout the season. I'll get some pics if you need it, but it's not anything too complicated to do.

As a side note, I used Wilwood checkvalves right at the MC to keep a slight amount of pressure in the system to reduce pad knockback.


I've only driven the car a few miles on the street since the install and to bed in the brakes, as the car is no longer driven on the street. Soon, I'll have the car at the track to dial in the brake balance and test out the system. I can say though, the pedal pressure and feel is certainly improved, and I can definitely say the propvalve is working. I had it adjusted about mid-way for starters, and almost spun the car around on the freeway when I started to bed in the brakes from having a bit too much rear bias!. I'm waiting until I hit the track and get the pads up to temp before setting the final bias, as of course that will change will pad and tire temperature.

Beau

Excellent info, thanks! I had actually ordered that exact same "combination proportioning valve" before I saw you post this, now I'm glad I did. I like how it has the integrated "T" for the fronts.

[mini zilo]

Everything is installed. I ran new hard lines from the master cylinder to the wilwood valve, and I also ran new hard lines to the front calipers. Then, I ran T-fitting on the bias valve outlet, and connected the T to each of the rear brake lines. I mounted the wilwood valve on the firewall towards the passenger side, since this was the place where it would easiest to reach and adjust the bias knob.

[mschlanglv]

What is the red stuff on the threads?

[jtmcinder]

Most likely it's Loctite 271. Brake lines are flared, so they don't need a sealant, but thread-lockers are your friend.

[mini zilo]

Originally Posted by jtmcinder

Most likely it's Loctite 271. Brake lines are flared, so they don't need a sealant, but thread-lockers are your friend.

Yep, it's loctite.