63 GMC front disc conversion questions

[62CustomBurb]

I have a 63 GMC Suburban in nearly 100% stock configuration. I have become aware of the importance of converting to a dual master cylinder for braking safety. I am also exploring the possibility of converting to disc brakes, with the possibility of towing a vintage camping trailer. Two questions:

1) The truck has OEM PB and I had the Midland booster rebuilt; will that work with discs or would a different unit (with proportioning valve) be needed?

2) I have obtained original vintage 6-lug wheels and covers in excellent shape. One swap kit site (Stainless Steel Brake) states that with their unit "stock wheels will not clear". Is that typical? The original wheels are a deal-breaker for me.

I haven't ruled out a 73-87 front crossmember swap either; I could part with the original booster if needed but not the wheels. Wise input appreciated!

[The Rocknrod]

So as far as disc conversions there are numerous companies that make them for our trucks, I know POL (performance online) make the six lug disc brake kits. However everyone I have found says they dont fit stock 15" drum wheels. Maybe someone else has better info for on this.
* ECE (Early Classic Enterprises).
* POL (Performance OnLine).
* CPP (Classic Performance Products).
Here is a thread on the subject - http://67-72chevytrucks.com/vboard/s....php?p=4450757

[cwcarpenter98]

For the master, you would need one that is a disc front drum rear (if you aren't going disc all around) that will bolt to your stock booster. I don't believe the stock master was different between manual and power brakes. My aftermarket master bolted up to the stock spot in the firewall. I still have manual brakes. The proportioning valve that came with my master has a bracket mounting it to the master. The biggest issue will probably be getting the correct push rod that goes between a factory booster and an aftermarket disc brake master.

On the wheels, I ran into the stock wheel problem. My original wheels were drum brake wheels, so the inside of the drum was more at a 45* angle from the center of the wheel to the barrel. That's the part that doesn't clear the caliper. I found this picture from an old for sale thread on here:


You can find 6 lug disc brake wheels in a 6 wide or 8 wide. Should clear the caliper if the barrel looks like this:


On my truck, I chose to go with 15x8s because I like the look a little better that way.
I'm still stock height, but I did not do the whole squarebody front end swap. I did this awhile ago before the aftermarket offered spindles drilled to the stock, 63 specs, so my truck is running squarebody ball joints in the stock control arms and a tie rod adapter sleeve to go from squarebody outer to stock inner

[The Rocknrod]

Did you mean?:

Originally Posted by cwcarpenter98

For the booster (Master), you would need one that is a disc front drum rear (if you aren't going disc all around) that will bolt to your stock booster. I don't believe the stock master (Booster) was different between manual and power brakes. The biggest issue will probably be getting the correct push rod that goes between the booster and the master.

If you use the stock booster which you can, the pushrod will not be an issue.

[cwcarpenter98]

Whoops, I forgot to proofread I have corrected original post to what I wanted to say

[62CustomBurb]

cwcarpenter98, my wheels are definitely for drum brakes; those pics are very helpful. Thanks!

For now I expect I'll stick with all drums but switch to a later 60's dual MC to use with my refurbished Midland booster.

Apparently the later MC needs a longer pushrod from the brake so I'll have to sort that out.

[The Rocknrod]

Originally Posted by 62CustomBurb

...

Apparently the later MC needs a longer pushrod from the brake so I'll have to sort that out.

You can buy either a deep or shallow bore master cylinder. Depending on which Booster you have will depend on which master cylinder you want to buy.
https://techtalk.mpbrakes.com/how-to...r-cylinder-gap

[cwcarpenter98]

Happy to help! If your hubcaps are for the nub style wheels, then you can run any 15x6, 6 lug nub wheel from 71-87 or any 71-87 5 lug nub style wheel if you wanted to go 5 lug. You can also use the 15x8 nub wheels from 71-87. There's also aftermarket wheels that are designed to work with the factory hubcaps. I was able to source a used set of the aftermarket 15x8s, and they work great with a set of original 61-63 nub hubcaps that I have

[62CustomBurb]

So two separate issues; one is that I remembered that my covers are clip type rather than nub; good luck finding more great wheel covers, but this time nub style! Two, my vacuum booster is factory fender mounted rather than combined with the MC on the firewall. Not sure if that makes it harder or easier, and also would welcome specific MC source/item recommendations.

[cwcarpenter98]

Bummer on the hubcaps. I'd probably run the drums to keep the hubcaps as well.

Got any pictures of your brake setup? I haven't heard of what you describe, so some pictures would help us help you

[The Rocknrod]

Originally Posted by 62CustomBurb

So two separate issues; one is that I remembered that my covers are clip type rather than nub; good luck finding more great wheel covers, but this time nub style! Two, my vacuum booster is factory fender mounted rather than combined with the MC on the firewall. Not sure if that makes it harder or easier, and also would welcome specific MC source/item recommendations.

Oh wow, the Hydrovac booster (as opposed to hydro-boost). Here is a thread that was started some time back on that - http://67-72chevytrucks.com/vboard/s...d.php?t=747457
And someone split the brake lines, see post #9 here - http://67-72chevytrucks.com/vboard/s...d.php?t=742780
Some info on those here (if you have a midland) - http://dave78chieftain.com/MidlandRoss.html
There are people who say it can't be done - http://67-72chevytrucks.com/vboard/s...d.php?t=709718

[62CustomBurb]

Here's a pic taken before the booster came out for rebuild.

[62CustomBurb]

Here is the illustration of the original setup from the Maintenance Manual Supplement; It is a hydraulic rather than pushrod connection to the MC.

[The Rocknrod]

If you have a Hydro-Vac - http://dave78chieftain.com/HydroVac_brakes.html

[62CustomBurb]

No, this is a Midland vacuum booster. I had it rebuilt, intending to do a pretty straight-up original approach but I'm having second thoughts, considering discs.

[62CustomBurb]

After some counsel and chatter over at the 6066 GMC forum, I've learned that a second booster would have to be added to my setup to convert to dual MC. So for now I'm going new booster/dual MC, 4 drums and new brake lines. Anyone have insight as to whether 9" of 11" booster is better in terms of space needed and stopping power?

[theastronaut]

What tires will you be running? It doesn't do any good to have really good brakes unless you have tires that grip enough to use them. I see aircooled VW guys do this all the time; they do all they can to upgrade the brakes but limit their ability to stop by running hard compound 145/80-15 front tires that have been on the market with no updates for decades. Meanwhile mine has 100% stock manual drums with modern tires and it will brake harder than some modern cars with four wheel discs and abs.