63 GMC front disc conversion questions

[62Burb]

I posted this on 67-72 chevy trucks also (on the appropriate sub-forum).

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. Auto tranny. 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!

[Funky61]

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.

From my research, this is typical, and you would need steel wheels from the 71 to 87 trucks, to work for the disc swap. I believe they come in 15x6's and have the 4 nubs.

The early steel wheels with 3 nubs will not fit a disc brake application.
Do your wheels have clips or nubs?

You can add clips to the later wheels so you can keep your hubcaps and the stock look, if that be the case.

[AZKen]

What does "deal breaker" mean? Does it mean you won't convert if stock wheels won't fit?

[62Burb]

Funky61, I have the nub version of wheels and covers. Do you know if the 63 covers fit the later 6 lug nub wheels?

AZken, my preference is to keep the original style; having acquired the hard-to-find wheel covers in great shape I'd love to be able to use them. If they fit the later wheels I'd be fine using them up front. My interest in discs is somewhat theoretical since I don't have a vintage trailer at this point, and for the casual driving I'd be doing, well-functioning drums should be fine.

Which brings me to a crucial question; will my OEM booster work with a dual master? How do I select one?

[AZKen]

You will have to post some good clear pictures of your booster with master cylinder. It is hopefully just a plumbing issue. The shop that rebuilt it may have the info for you.

If you are wondering about stock wheel fitting a disc kit, use this downloadable gauge. https://techtalk.mpbrakes.com/drum-t...y-rides-wheels

[Funky61]

Funky61, I have the nub version of wheels and covers. Do you know if the 63 covers fit the later 6 lug nub wheels?

I found this answer on the 67-72 Forum. Yes, was the answer but best to read it through.

http://www.67-72chevytrucks.com/vboa...t+later+wheels

[62Burb]

This is a pic of the setup prior to booster removal for rebuild. I'm deep in snow and cold here in the NE and this is one of the things I'm prioritizing to get ready for the eventual return of seasonal driving weather.

I have read that a '67 and up dual master works but I want to be better informed since I'm a rookie to vehicle restoration/modification.

[62Burb]

So my memory is more like a sieve than a vise; my wheels are clips, not nubs. Had to go check them in storage since I obviously forgot! That could cement the deal in terms of sticking with drums for now; although IF I could find the appropriate later wheels AND matching 63 covers I could consider discs again.

Meanwhile the 67-72chevytrucks.com site seems to be down so I'll keep watching.

[Funky61]

I have become aware of the importance of converting to a dual master cylinder for braking safety.

Just doing that upgrade is a great move and there are great write-ups in the FAQ section of the other forum. You have time now to research and plot your next move. You could do it with or without the power booster.

[62Burb]

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