Brake proportioning

[Joris69velle]

Hey guys.
Im running a 1 1/8 wilwood master
C7 corvette front brakes
C5 corvette rears
Can that go thru the stock proportion valve of my 77 firebird. Im under the impression that the front is not getting all the fluid it needs.


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[79 Camaro]

On my C5 front/rear disc brake swaps into my hot rods I always use a Wilwood adj prop valve. Pic of my 80 With C5 brakes. Prop valve just below the master. 213241

[Vimes]

Came with drums, right? The answer is yes and no. Yes, you can use it as a distribution valve so as to not have to replumb your brake system but no, you can't use it as is. A disk/drum prop valve will send a lot less fluid to the drums as the brake cylinder is a lot smaller than a caliper. Gut the prop valve and it sends the same amount of fluid out all the lines. There's a very nice discussion about it on how to do it on this thread. There's also a residual pressure valve that you'll want to remove as disk brakes don't need it. You could try running it without a prop valve at all, but if you don't like how the rears engage a variable prop valve would be the next step.

https://www.pro-touring.com/threads/71511-Gutting-a-proportioning-valve

[ryeguy2006a]

When I had C5 front / LS1 rear brakes on my 2nd gen, I gutted my stock proportional valve and installed an inline adjustable valve since I didn't want to remake all of my lines. It worked great as a distribution block. I also added a 2lb residual valve to the rear.

[Joris69velle]

Thanks for the very helpful answers all.
Ill gut it as soon as i get a chance

[cdrod]

Inline Tube sells a combination valve that was used on '70 Cutlass models (A-body) disc-drum cars and '70-'72 drum-drum brake cars. This valve does not have the proportioning function built-in. The '70 disc-drum cars used a secondary valve at the rear of the car to handle the drum proportioning for the rear wheel cylinders; the '71 and later valves were called combination valves because they were both a distribution and proportioning valve.

I don't know if this part is similar to the 2nd gen F-body so do your homework, the part number is PR107 and sells for around $80. I'm using this valve along with a rear proportioning valve at the master cylinder on my '72 442 convertible project; C5 front w/13" rotors and '01 Blazer w/11.6" rear discs.

Here's a pic of the valve from Inline Tube.

Rodney

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