69 brake help, please

Frosty69 · Jan 10, 2013

First I'm sorry, I know this info is in these threads somewhere but after an hour+ of searching and reading I've gained a lot of knowledge about some basics and even more questions on some of the details.

I have a 69 Camaro that originally came with a 350 (not an SS), TH350, AC and power drum brakes. The front brakes were converted to disc brakes (from an acceptable but unknown donor car) but the power booster and master cylinder were never switched out and no proportioning valve was ever installed. We are now replacing the booster and master cylinder, nothing fancy just a nice stock style look. I'm gathering a standard 11" stock style booster and 1 1/8th" master cylinder are a good way to go. Now the confusing part is the valves. A great article at pozziracing says the 69 Disc Brake cars had 3 valves. Looking at the Delco stamped replacement booster/master combinations it says they come with a correct style proportioning valve but is that enough? Is there a separate proportioning valve in the rear of the car? Do we need one? Are there different styles or dimensions for the valves? My head hurts.

Vintage 68 · Jan 10, 2013

nsaneblk said:
... I'm gathering a standard 11" stock style booster and 1 1/8th" master cylinder are a good way to go.
... Now the confusing part is the valves. A great article at pozziracing says the 69 Disc Brake cars had 3 valves.
... Looking at the Delco stamped replacement booster/master combinations it says they come with a correct style proportioning valve but is that enough?
... Is there a separate proportioning valve in the rear of the car? Do we need one? Are there different styles or dimensions for the valves?
... My head hurts.

Let's take this a little at a time to make it easier to understand :thumbsup:

Sure, an 11" booster and 1 1/8" master are usually fine for most retrofit/upgraded Disc-Drum set-ups.
But there are exceptions ...
I often select a 1" master based on pedal feel or desired performance of the system.
Either size has sufficient capacity for almost any stock (or stock replacement) caliper.
The 1 1/8" is often the choice of 'repoppers' due to it's more relaxed response to avoid the system acting 'grabby' in some conditions.

Yes, OEM 69 (and other year) GM vehicles factory Disc. systems often had two(2) or three(3) 'valves' in the system to perform multiple functions.
These were later re-engineered into a single 'valve' (commonly called a "Combination/Combo" valve*) that performed the same functions in a compact and easier to plumb system. This single 'valve' block performs all the needed distribution, proportioning and monitoring that you'll need, so no additional valves or blocks should need to be installed to get a correctly functioning system.
* - I believe that is most likely what would be supplied with the new booster you are sourcing for your car.

My head now hurts also :beers:

robbys67rs · Jan 10, 2013

I'm in the middle of a front disc conversion and am installing the 8" booster, MC and combination valve kit from Right Stuff Detailing.

I was confused about the valve stuff too which is why the kit with the combo valve was nice. You can get the valve separately here:

http://www.camarocentral.com/1971_1977_Combo_Proportioning_Valve_and_Bracket_p/brc-232.htm

I'm assuming you still are running drums on the back,but they also make a combo valve for disc/disc cars if you have switched to disc on the rears too.

I will say this about the valve though, of the 3 outlets (1 to front pass, 1 to front drivers, 1 to rear) only the front pass outlet mated up correctly with the stainless brake line kit I got from Camaro Central. I'm going to have to cut and install the "correct" fittings to match the valve.

Good luck!
Robby

Vintage 68 · Jan 10, 2013

robbys67rs said:
... only the front pass outlet mated up correctly with the stainless brake line kit I got from Camaro Central. I'm going to have to cut and install the "correct" fittings to match the valve.

Good luck!
Robby

Remember that ALL brake system line flares are the "Double-Flare" type and require the correct tooling to make them!
Do not for any reason try to shortcut this design

robbys67rs · Jan 10, 2013

Vintage 68 said:
Remember that ALL brake system line flares are the "Double-Flare" type and require the correct tooling to make them!
Do not for any reason try to shortcut this design

I've got it covered. :thumbsup: Thanks for the reminder though, I should have mentioned that to the OP.

Gbauer · Jan 10, 2013

Vintage 68 said:
Remember that ALL brake system line flares are the "Double-Flare" type and require the correct tooling to make them!
Do not for any reason try to shortcut this design

I did the double flare on my rear brake line when I did the conversion (fronts were already flared) but why wouldn't a single flare be acceptable?

It was something I was curious about when I bought the flare kit. I went for the double just because that's what the old line used.

Vintage 68 · Jan 10, 2013

Gbauer said:
... but why wouldn't a single flare be acceptable?
...

Brake lines and connections constantly flex (and even 'balloon' - although very minimally hopefully) with repeated pressure application(s), as well as vehicle flexing/stressing, and the single flare with fatigue and crack/fracture in a very short time during service.
A properly done 'Double-flare' will keep this fatigue cracking from happening via it's forgiving 'spring' type action at the flare junction.
This is design SOP for all vehicles manufacturers when designing and fabricating brake system connections and also very common in industrial small pressure lines that are prone to flex flare termination failure.

I've run into this quite often when looking over vehicles that have had brake system modifications by a 'shade-tree' during their life :sad:

Gbauer · Jan 10, 2013

Thanks for the explanation.

Steiner · Jan 11, 2013

Your setup will look something like this if you're doing the stock type. The square one is the distribution block and the round one is the metering block that delays pressure to the front discs to give the rear drums time to activate. (Image from Matt's Classic Bowties $284 setup)

The prop valve in the rear brake line....well...who knows. It seems it was dependent on options. I had a four wheel manual drum small block a/c car with it and a power disc/drum small block non-a/c car with it so go figure. Take a look on the frame rail under the driver side door and it would be there if you have one. Both of mine now have a Right Stuff four wheel disc setup with the single combo valve and no valve under the door. I threw everything I pulled off away or else I'd give it to you. Sorry.

Here are the details on all the components that may clear up some of the confusion:
http://www.getdiscbrakes.com/knowledge-base/main/GM_Classic_Car_Valve_Configurations

69 brake help, please

Frosty69

Vintage 68

robbys67rs

Vintage 68

robbys67rs

Gbauer

Vintage 68

Gbauer

Steiner

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