Sorry- another rear disc brake question

[77 K20]

Is this thread over?
Total cost?

Recommended? Would you do it again and if so, what would you do different?
How could one improve upon your efforts?
Whew! That's a lot of questions but I feel like you kind of left us hanging...

Everything on the brakes is working great. I've used them in deep snow, on freezing rain, pavement, gravel, mud. They work great- better than my old drum setup.

If I was to do it again:

Don't buy the fixed proportional valve that was supposed to be for front and rear disc brakes. That thing was worthless. That was $67 absolutely wasted and made me have to replace it with an adjustable one and then re-bleed the brakes.

The larger master cylinder. Not really liking that. Sure- it has more capacity. The lid is not very tight on it. It is so big it contacts the vacuum connection on the brake booster behind it. Also the brake lines didn't fit on the larger one. The ports were reversed. I went with adapters instead of cranking the lines around to swap them. I think I would have been happy with my stock master cylinder. This was $74 I don't think I needed to spend.

I didn't like the DIY disk brake brackets. I had one that was so twisted I couldn't run a bolt thru it to hang the disc brake calipers. Anytime you are putting bends on a bracket then welding on it, things are going to warp and twist. This caused me problems. I'd buy the ones thru Off Road Design. It is a big washer you stack next to a flat bracket. Nice and easy. More expensive... but the cheaper ones cost me more labor, and waiting another week and a half to get one that wasn't screwed up.

So if I did it again, this is what I'd get:

ORD disc brake brackets. $150

ORD braided stainless lines to each caliper. $89

Raybestos RC4072 Professional Grade Remanufactured, Loaded Disc Brake Caliper $57.48 (Amazon)

Raybestos 5014R Professional Grade Disc Brake Rotor $40.06 (Amazon)

Baer adjustable brake proportional valve. $50 (Amazon)

$386.54 grand total. (well, you need to buy brake fluid)

 

[Rusty Nail]

Excellent! Thank you and congratulations.

How exactly did you add that valve? Cut the factory line(with what?) to add/make flare fittings, installed valve and left it chillin?

These are the same rotors/ calipers/ pads on the front, right? If I understand correctly, it's the same rubber lines too? THAT is what I'm after... thanks again!

 

[77 K20]

Excellent! Thank you and congratulations.

How exactly did you add that valve? Cut the factory line(with what?) to add/make flare fittings, installed valve and left it chillin?

These are the same rotors/ calipers/ pads on the front, right? If I understand correctly, it's the same rubber lines too? THAT is what I'm after... thanks again!

The adjustable valve was mounted right after the stock one on the single rear brake line. (under the engine, mounted to the cross member). The knob for it points down, so I can just reach under the front bumper and adjust it without getting dirty.

Yes, the disc brake rotors and the calipers are the same as what is on the front.
The braided lines for the rear are very similar to the front- I think they are a slightly different length.

 

[Rusty Nail]

I am two weeks away from pulling the trigger on converting my C20. This is research. Prior to finding THIS thread, I had in my head that I would buy a Delco disc/disc valve. I cannot help but wonder if your master cylinder swap is the reason it didn't work. All Gm parts used...does not compute. I will avoid an adjustable valve if possible, I now am curious about the Cadillac valve. 2wd truck disc in the front, 4wd discs out back...not trying to hijack your thread, good job. Rep given for posting part numbers.

 

[77 K20]

In theory any master cylinder should work. All it is doing is just forcing brake fluid thru the lines when you hit the brake pedal. I'm not sure why it didn't work... I researched everything again and again, and it just didn't work out. With my disc/disc valve I got full lockup on the rear end doing a medium strength brake check on dry pavement. On gravel roads it was even easier to lock up... it was fun for a few miles though being able to do "Dukes of Hazzard" style drifts around every corner. Just hit the brakes a bit going into the corner and wait for the back end to come around.

No problem at all with your posts. There is limited info out there on this swap, and for some reason everyone seems to have a different story. This was just how mine turned out.

 

[NOPHO84K30]

Doing this soon any problems with your studs being to long or short. I think ive got the rest figured out..

 

[77 K20]

I have steel wheels- so I just pounded out the stock studs and re-used them. I heard that if you have aluminum wheels they are thicker and the stock studs would probably be too short.

 

[77 K20]

Figured I'd update this thread. I'm going to replace that master cylinder I bought. The lid on it will not seal. That and the reservoir was so big it prevented me from unplugging the vacuum brake booster line the other day.
I'm thinking to order this one- it is still for front/rear disc brakes.

http://www.summitracing.com/parts/rsd-dbmc05/overview/year/1977/make/chevrolet/model/k20

 

[77 K20]

So another update: Ended up ordering the ACDelco 18M91 brake reservoir. This was one off of an older Corvette with 4 wheel disc brakes and power steering. The bore size is the same as the stock master cylinder that was in the truck.

The brake pedal feels very soft compared to the other master cylinder that I replaced- as it had a very firm pedal feel (which I prefer).

The brake port sizes were the same as the one I replaced- meaning if you have a stock master cylinder your brake lines will not plug right into this unit.

Seems like it is working well, and most importantly it isn't leaking.

http://www.amazon.com/gp/product/B000C9JDUC?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00