Thought this would be good info for rear disk conversion on the fluid side.
I ran my disk rear converted car (98-02 s10) about 5 miles last night and noticed by rear brakes get HOT. I still have stock 1986 G body proportioning valve and master. I thought I could get away running the stock stuff but I have a 150 mile round trip to the hot rod power tour sunday so didnt want to play around with crap brakes.
Its semi common knowledge but the drum prop valve puts too little pressure to the rear for 4 wheel disk. A 4 wheel disk car does not need a prop valve due to it having the same brake system (in the same way a disk drum needs pressure split). Yeah, an adjustable one helps for the fine tuning but the large difference proportioning valve we are all familiar with for disk drum isn't needed.
You can convert disk drum stock parts to disk disk for free BUT I wasn't able to. The firewall side of the master has a 10psi check valve in to keep the rear drums pumped up. The issue is it drags the rear pads and gets hot. Need to get rid of that. My stock master also had really crappy feel, 7/8 bore just isn't enough for s10 rear disks. I had decent feel for the first 1/2 of what you expect but there wasn't enough flow and it bottomed out. The brakes were awesome when it had disk drum. Went disk/disk and it got crappy.
The prop valve that is easy to covert is a bendix style, cpp has a chart online PDF you can download that shows you what to remove, it's just a plastic check ball or something on the rear side. The little black thing in the top drawing below.
A g body has a kelsey hayes prop valve which (from what I know) isn't convertible like bendix one.
If anyone can see what to gut on the kelsey hayes let the world know.
https://www.musclecarresearch.com/1979-gm-kh-combo-valve-autopsy
Master I want to get is a 96 impala SS with 4 wheel disk. I looked and a 3rd, 4th gen f body or 98+ s10 master won't work (even if they are all disk) since the ports come out the engine side of the body not the fender side. Unless you want to redo your brake lines gotta stay with a 2nd gen 4wheel disk car, C3, or G or B body. Problem is a 2nd gen is the big ugly cast iron one. Can't go very new because you go from old G body standard SAE flare to bubble flare metric.
The caprice SS has metric bubble fittings not standard G body SAE flare. It also might need a different push rod? Not sure.
https://www.gmbbodyforum.com/t153p25-gm-8-5-10-bolt-swap-from-a-96-impala-ss
You are supposed to be able to convert the stock G body master to disk disk by removing the rear male brass press fit flare fitting inside the master by putting a wood screw into it and just pulling it out. Then pull the spring and check valve and put the flare back in. Also can put a machine screw after drill and tapping it. I would suggest that, it broke the screw flush in mine and its shot now after broken fitting extractors and broken drills. Oops. Now my master is junk.
Is there an aluminum/plastic GM SAE flare fitting master that has at least 1" bore diameter that bolts on with correct line output location available? I think the impala SS is the easiest one. I also read they use a different pushrod for the pedal, is that true?
I ran my disk rear converted car (98-02 s10) about 5 miles last night and noticed by rear brakes get HOT. I still have stock 1986 G body proportioning valve and master. I thought I could get away running the stock stuff but I have a 150 mile round trip to the hot rod power tour sunday so didnt want to play around with crap brakes.
Its semi common knowledge but the drum prop valve puts too little pressure to the rear for 4 wheel disk. A 4 wheel disk car does not need a prop valve due to it having the same brake system (in the same way a disk drum needs pressure split). Yeah, an adjustable one helps for the fine tuning but the large difference proportioning valve we are all familiar with for disk drum isn't needed.
You can convert disk drum stock parts to disk disk for free BUT I wasn't able to. The firewall side of the master has a 10psi check valve in to keep the rear drums pumped up. The issue is it drags the rear pads and gets hot. Need to get rid of that. My stock master also had really crappy feel, 7/8 bore just isn't enough for s10 rear disks. I had decent feel for the first 1/2 of what you expect but there wasn't enough flow and it bottomed out. The brakes were awesome when it had disk drum. Went disk/disk and it got crappy.
The prop valve that is easy to covert is a bendix style, cpp has a chart online PDF you can download that shows you what to remove, it's just a plastic check ball or something on the rear side. The little black thing in the top drawing below.
A g body has a kelsey hayes prop valve which (from what I know) isn't convertible like bendix one.
If anyone can see what to gut on the kelsey hayes let the world know.
https://www.musclecarresearch.com/1979-gm-kh-combo-valve-autopsy
Master I want to get is a 96 impala SS with 4 wheel disk. I looked and a 3rd, 4th gen f body or 98+ s10 master won't work (even if they are all disk) since the ports come out the engine side of the body not the fender side. Unless you want to redo your brake lines gotta stay with a 2nd gen 4wheel disk car, C3, or G or B body. Problem is a 2nd gen is the big ugly cast iron one. Can't go very new because you go from old G body standard SAE flare to bubble flare metric.
The caprice SS has metric bubble fittings not standard G body SAE flare. It also might need a different push rod? Not sure.
https://www.gmbbodyforum.com/t153p25-gm-8-5-10-bolt-swap-from-a-96-impala-ss
You are supposed to be able to convert the stock G body master to disk disk by removing the rear male brass press fit flare fitting inside the master by putting a wood screw into it and just pulling it out. Then pull the spring and check valve and put the flare back in. Also can put a machine screw after drill and tapping it. I would suggest that, it broke the screw flush in mine and its shot now after broken fitting extractors and broken drills. Oops. Now my master is junk.
Is there an aluminum/plastic GM SAE flare fitting master that has at least 1" bore diameter that bolts on with correct line output location available? I think the impala SS is the easiest one. I also read they use a different pushrod for the pedal, is that true?
