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Old 02-20-2020, 11:55 AM   #1
MASTERBrian
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Master to proportioning valve question

Ok, I completely redid the brakes on my 60 burb 3yrs ago when I got it. Problem it's I've forgotten since things and I have a friend that's trying to fix the brakes on his 63 c10.

I ran a dual 9" booster and a master from a 90 c1500. I hung it from a captain fab bracket. The proportioning valve is a ssbc adjustable valve A0730. I have CPP discs up front on drop spindles and factory drums in rear. My suburban stops on a dime and squats perfectly doing so.

The questions that have arisen are does the large reservoir on master, which is towards firewall, go to the drums or the discs? Then dies the proportioning valve turn pressure down to the disc or the drum? Logic tells me discs have more stopping force, thus large reservoir to them and you turn ther discs down. For some reason I keep thinking that the sins are what is being adjusted.

Originally, looking back at pics, I had the large reservoir plumbed to the R, rear, of the valve, but i changed it and now the large reservoir goes to the F, front, of valve. Most people's pictures seem to show my original layout, but maybe their reservoirs are different.... mines the plastic body with black lid. Unfortunately, my truck is in driveway covered with snow so I can't crawl under to confirm that the large cylinder is for certain feeding the front discs, but it appears this way from looking at the valve.

Again my truck is stopping fine, just trying to explain to him the setup. I've attached a pic of the setup pre install with the large reservoir going to the rear of valve. Then another pic of it as im running it now, with the large reservoir going to the front.
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Old 02-20-2020, 12:08 PM   #2
SCOTI
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Re: Master to proportioning valve question

As long as there's enough fluid to the brake piston/cylinder, which 'pot' it comes from is irrelevant. The unequal size reservoir (pot) are for allowing adequate fluid reserves when wear occurs @ the pads/rotors/shoes/drums.

The prop valve is intended for adjusting the brake bias. Normal bias is a 70(F)/30(R) split; or 70% of the braking force is on the front brakes. You don't want the rears locking up @ a different rate vs. the fronts. Adjustable prop valves allow just that. You can tune the bias so the rear lock-up is better matched to the front.

Tire diameter plays into the bias as well when it comes to OE set-ups.
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Old 02-20-2020, 07:30 PM   #3
Keith Seymore
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Re: Master to proportioning valve question

Just to be clear:

The larger reservoir is for the discs.

The adjustable prop valve goes in the rear system.

K
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Old 02-20-2020, 08:24 PM   #4
MASTERBrian
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Re: Master to proportioning valve question

Quote:
Originally Posted by Keith Seymore View Post
Just to be clear:

The larger reservoir is for the discs.

The adjustable prop valve goes in the rear system.

K
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