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Another Brake Booster and Master Cylinder Thread (with links)

noahrob

noahrob

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I have read almost every thread that I can find on this site and here is what Ive learned. The general consensus is that there is no general consensus. Opinions vary wildly as to how to upgrade your brakes after converting to 4wheel discs. Here is the closest I could get to a plan based on what I’ve read. I also tried to curate my notes a bit so the next guy (or gal) can save some time.

  1. Me = 1975 K5 with tons on 40” with 4wheel disc brakes (Stock D60 + Ruffstuff rear conversion kit)
  2. The plan - 1982 booster (has 6 holes so should bolt up) and C3500 MC with a proportioning valve.
  3. I don't want to go hydroboost with the hydroassist.
  4. The only thing I'm not sure about is if the pushrod is the correct length.

Here is some of the info I jotted down as I read thread after thread.
  1. Great thread with a ton of info. Here is another really good one (https://ck5.com/forums/threads/4wheel-discs-found-perfect-master-cylinder.174038/page-9)
  2. Cardone Part Number 102754 (adapters that go with it Edelmann makes them, their part #'s 258306 and 258307)
  3. Some folks run 1978 K30 MC on stock booster annd seem pretty content
  4. I read about a cool setup with a 1985 k20 booster. 2000 Tahoe m/c, with s10 reservoir
  5. To make sure you don't get a hydroboost MC (assuming you want vaccumm boost) master/booster to a k30 one with a 5.7
  6. This is close to the setup I want, but I want an earlier booster so it fits my firewall. '99 C3500 master cylinder (vacuum, 4 wheel disc application) '91 vacuum booster (might be Part Number 102754)
  7. Here is a link to the vacuum and hydroboost C3500 - https://www.autozone.com/brakes-and-traction-control/master-cylinder-brake-system/chevrolet/c3500hd
  8. I can't figure out what this is from, but several folks reported using it P35 - https://www.autozone.com/brakes-and-traction-control/master-cylinder-brake-system/gmc/p3500
  9. Another part number, for the raybestos brand version master cylinder MC390278

Anyway, I thought I'd share what I learned today and any feedback, especially if my plan is dumb, is greatly appreciated. Otherwise, hope it helps...
 
How do you like the way it stops now?
On my 84 K10, when I did the 3/4 ton swap (8lug 10bolt/ FF14bolt) and added the rear ruff stuff disc kit, the brakes were the best I ever had on this truck. Later when I added the front D60, the brake feel actually when down a notch. I run the stock vac booster, mc and proportioning valve.
 
Right now I cant drive the truck, well I mean I can drive it just fine, I just cant stop it in anything approaching a reasonable or safe way:yikes:
 
Only thing you kind of need to change is the proportioning valve, sounds like you have something else going on.

Charlie
 
Push rod should be adjustable at the booster/master. To check adjustment, on the bench,slide master onto booster if master cyl piston hits before flush, shorten rod. If m/c goes flush up to booster lengthen rod till it doesn't, then turn back in 1/2 turn or so. You just want the smallest little bit of play.
Lots of other ways to do it, modeling clay, special gauges( only know of for oem applications)
I'm not sure the master cylinder cares what booster it is bolted to, as long as it fits.
I put a 97 Dodge B van vacuum m/c
on a 91 P30 hydro boost, in a 67 f250 front disc rear drum works great.
 
CharlieC said:
Only thing you kind of need to change is the proportioning valve, sounds like you have something else going on.

Charlie
Click to expand...
Yeah, it might be a lot of things, but part of my hypothesis is that the 46 year old is shot so if I'm going to replace it, I might as well update it at the same time. New pads up front probably won't hurt
 
Wes Harden said:
Push rod should be adjustable at the booster/master. To check adjustment, on the bench,slide master onto booster if master cyl piston hits before flush, shorten rod. If m/c goes flush up to booster lengthen rod till it doesn't, then turn back in 1/2 turn or so. You just want the smallest little bit of play.
Lots of other ways to do it, modeling clay, special gauges( only know of for oem applications)
I'm not sure the master cylinder cares what booster it is bolted to, as long as it fits.
I put a 97 Dodge B van vacuum m/c
on a 91 P30 hydro boost, in a 67 f250 front disc rear drum works great.
Click to expand...
Yeah, I think the only question about the booster is whether it bolts to the firewall. Once that happens, the next question is whether the outside diameter of the mc fits the inside diameter of the booster. As long as those two things work, then it is just about brake line fittings.

Love the Dodger mc!
 
noahrob said:
Yeah, it might be a lot of things, but part of my hypothesis is that the 46 year old is shot so if I'm going to replace it, I might as well update it at the same time. New pads up front probably won't hurt
Click to expand...
I picked up one of these proportioning valves from Summit, but once I got the truck together I found I didn't need it. If you want it you can have it just pay for shipping.
Check out this page from Summit Racing https://www.summitracing.com/parts/sum-760185
 
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