Any advice on a double master cylinder for my 65 C10. I don't seem to be able to find one on the major suppliers.

Thanks

Was the original equipment MC a dual line? If not, why change it?
Jerry

I would like to change for safety reasons only. It didn't come with seat belts either so I am putting them in for safety (also because of the law).

Everything else pretty much as stock as possible

It's amazing that we have any of these old trucks left to work on. If single line brakes failed as often as the gloom and doom purveyors say, they would have all been wrecked before they were 10 years old. Unless you're willing to install a complete dual line brake system, it's very likely you'll end up with something far more dangerous than an original system that has been brought back to "as new" condition.

I can understand the addition of seat belts- - - -even if you are a good driver, there are people like me on the road with you!
Jerry

Same could be said of certain wheels... joking.

I agree for a different reason. I've found that it works best for me to get everything working as it was originally intended prior to trying to modify or improve it. Getting the brake system working like it should will make it easier to identify faults vs deficiencies. Faults you fix. Deficiencies you modify. Always have a clear understanding what your are dealing with.

Thanks guys that is really good advice. But getting the single cylinder system working would require new brake lines, and since I have to buy them it makes more sense to me to go ahead and install the dual system.

However, and I should have clarified this in my initial post, what I'm looking for is a dual master cylinder without the booster. However I have not been able to locate a dual without a booster from the major suppliers. So I'm thinking I'll have to go with the dual with booster.

That is how I'm thinking. But as I said your posts make a ton of sense.

Brakes are engineered as a complete system- - - -master cylinder diameter and stroke, which controls the volume of fluid moved, and the pressure that's developed, plus the diameter and stroke of the wheel cylinders and/or disc calipers. Then there are such things as proportioning valves and other hardware and plumbing to be considered. To simply swap the master cylinder for a dual line unit without using the entire system it was designed for would require some pretty complex calculations of fluid displacement and system pressure to assure that the brakes would operate as safely as the original one. A drum/drum dual line brake system usually has a MC with equal volume fluid chambers. Those are a little hard to find these days. The last time I can remember owning a non-power dual drum brake system was on a mid-1960's Rambler station wagon.
Jerry

A lot of the after market stuff is based on a Corvette master.

If you're set on doing this, I would call Wilwood and tell them what you have for your outboard brakes and that you want a non-booster dual master cylinder They'll tell you which of their masters will work best for you.

Well it sounds like the simplest and safest approach is to go with the dual master cylinder/booster and brake lines specifically for that particular unit.

What would you guys do in my shoes?

I appreciate your advice.

Make sure your factory equipment is sound and unless you decide to go racing leave it be .
Don't forget the factory brakes were designed to stop the truck with 1000 lbs in the back , and did .

John

The single line master and original setup in my 2 ton does just fine, it's rated at 16,000 lb. gross, I'm not even running the Hydrovac yet, just manual stock hydraulic. I did pull the booster off the truck to get identification so now on the hunt to get it rebuilt or swap it.

"What would you guys do in my shoes?"

Not knowing much about how your truck is configured and your fabrication/engineering skills, I would advise going to people who specialize in brakes.
In my area (I have no idea how good they are):

MASTER POWER BRAKES
110 Crosslake Park Dr.
Mooresville, NC 28117
1-800-472-4181
info@mpbrakes.com

People have converted to dual non-power master cylinders on drum-drum trucks using newer generation master cylinders. Disc-drum started around 1971 and for this master cylinder you would need a proportion valve. If you have a drum-drum system, compare the size of your wheel cylinders and find/determine which master cylinder works best for those sizes.

I don't like giving advice on steering and brakes systems because they are extremely important for safety reasons.

I appreciate the advice. I thought it was a no-brainer to go with the dual cylinder system, and the dual cylinders come with the booster and proportioning valve, so I was pretty much sold on that system. One thing to consider though is the people telling me I needed the dual system were the ones selling it!

But these posts have got me to thinking. The original single cylinder system is not junk.

Thanks to all who replied.

I'm always just a bit suspicious of somebody who promises to solve all my problems by selling me something! He just might not have the purest of motives. That's especially true of the guys with the IFS suspension systems!
Jerry

Copy and paste:
Wagner Electric invented a dual-cylinder brake system in 1960. This system had a dual master cylinder separating front and rear hydraulic lines. In other words, if one line developed a leak, the other line could still work, and your brakes wouldn’t completely die. This safety measure was mandated by the federal government in 1967.

I have my own opinions on why the USDOT ruled a dual reservoir was needed.
*) There was no national speed limit until 1965 when the speed limit was set to 70 mph. Speeds were increasing.
*) Sometimes a lack of manufacturer's required periodic braking system maintenance (originates with DOT3 (hydroscopic fluid), moisture, rust and leaking seals).
*) More panic braking (braking system stress).
*) Vehicle speeds were too fast for our brains to react and downshift and/or use parking/emergency brake (instinctive reaction).

It makes no sense to pick out just one classic/antique part and worry about it's effectiveness (safety wise) and overlook the plethora of other parts. If you really want to get serious about it, our old trucks need modern brakes, a modern suspension, modern steering, crumple zones, driving assistance tech, video cams and airbags just to be safe in modern world of driving.

When I'm in my 55, I like to pick roads less traveled and slow down.

I like to pick crowded roads and slow down- - - - -everybody else is so friendly- - - - -they honk as they pass, and tell me "You're number one!" I just wish they would use the proper finger!
Jerry

1963, my bride-to-be was driving our 55 BelAire on a steep downhill toward a stop sign at a busy 4-lane. NO BRAKES. Fortunately she was able to thread into and through the 4-lane traffic without incident. Somehow one tailpipe had shifted and was rubbing on the brake line and had actually worn it through so there was no pressure. Granted, this was on 17 year old me for a poor installation of the tailpipes. But stuff happens. It made me a believer of the dual brake systems when they became generally available. I have upgraded both of my toys to dual systems even though they came stock with single master cylinder systems. I don't see how they are less safe than with the original systems. My 2 cents.

Mark

War Eagle, I agree with Mr. Lincoln. I have single reservoir systems on 6 of the 9 vehicles I own and have never had a problem. It doesn't even cross my mind as being "unsafe". The '56 Cadillac has been a daily driver for 20 years - rebuilt at the time of purchase. They're the best brakes on any vehicle I own - 12" drums with 3" shoes all around.

I'm not aware of any state that requires antique vehicles to be retro-fitted with seat belts. If they weren't required when the vehicle was built they can't force you to put them in.

One of the best reasons to install lap belts in a vehicle is to keep you behind the wheel at all times. It's pretty easy to slide around on a vinyl bench seat when going around curves or in a skid.

Mark you made a good point and provided an excellent example.

Please explain the steps you took to select the correct dual reservoir for your cars/trucks.
Sorry to put you on the spot.

My two toys, a 56 VW beetle and a 59 Fleetside long wheel base. On the VW it is fairly common practice to use the system from a later Beetle. Its been several decades but as I recall I used a 67 beetle master cylinder. I also changed the drums to larger size as the early Beetle brakes were not great.

The 59 is a mixed bag of parts with larger drums in the rear from a 69 GMC and front discs from a late 70's full size Oldsmobile. The Master cylinder and proportioning valve match a late 70's full size GM car, but using an 8" dual diaphragm booster because of space limitations. .

In both cases I just used combinations of parts that were similar or identical to those in later vehicles that originally had the dual system. The bug does not stop as well as i like and may eventually receive a front disc system, but the truck stops and tracks very well. I don't think it is rocket science, and the proportioning valve needs to either be adjustable or one that is from a similar weight vehicle with a similar brake system. Proportioning valve may not be needed for a drum/drum system.

This worked for me and both vehicles stop better than when they were born and with less pedal effort. Your mileage may vary, I am not advocating as an expert, just sharing my experience.

Mark

My main concern when one of these discussions comes up is that someone will buy a bunch of mismatched parts and end up with a system that's actually dangerous, instead of being "safer" than what was there originally. A minor miscalculation where the diameter or pedal stroke is concerned could result in brakes that either require too long a pedal stroke to get all the brakes applied, or a very short stroke that requires a massive amount of pedal effort to get the vehicle stopped. Either situation could get exciting, or worse, particularly if there's a failure of half the system. I seriously doubt that many, if any people on this site actually understand how the system becomes redundant in case of the failure they're so afraid of. Do they realize that the brake pedal will go to within a couple of inches of the floor before they get any one-axle braking at all, and pumping the pedal won't help?
Jerry

I plan to do one of the following with purchases from a supplier such as "LMC Truck":

1) Install an OEM-style single reservoir system with the appropriate stainless steel brake lines with existing original wheel cylinders

Or

2) install a dual reservoir with booster system with the appropriate stainless steel brake lines with existing original wheel cyllnders

Wouldn't either approach be sound?

Thanks

If you go with the boosted dual piston MC, be sure that it has the same diameter bore and volume displacement as the original part. Most vendors will have no clue about either one of those questions, so you'll probably need to do your own research on the subject.
Jerry

Mark's response brings out some good points.

"In both cases I just used combinations of parts that were similar or identical to those in later vehicles that originally had the dual system."
"The proportioning valve needs to either be adjustable or one that is from a similar weight vehicle with a similar brake system."

https://lugnutz65chevystepside.weeb...aster-cylinder-brakes-1963-1966-c10.html

I have known several people who still have single master cylinders on there classic cars with front disc brakes and all have said they have never had any problems stopping there cars.

Don’t think so………disc brakes run on about twice the pressure as drums. So single master on disc/drum vehicle is not going to work.
Stock OE master with disc brakes is NOT an upgrade.


Power brake dual master cylinder disc kits are not mystery or new concept. Q

I'd love to see some pressure gauge readings to support that claim. Getting different fluid pressures to the front and rear of a brake system would require a master cylinder with different diameter pistons operating the front and rear brakes. Getting different line pressures from a master cylinder with a single bore diameter would require repealing several laws of physics, with or without a power booster.
Jerry

Maybe he meant volume.

Had a pressure gauges permanently connected to a training car……just for the non believers. Will see if I can find a the photos and videos will post them
Full lock up on power disc often exceed 1000psi


In the mean time maybe duckduckgo will work:

For starters, the two brake systems work under different fluid pressures utilizing different master cylinder bore sizes (learn about master cylinder bore size and its effect on braking in this guide. Drum brakes use approximately 400 psi to apply, whereas disc brakes use 900 psi and higher to apply.

The proportioning valve or combination valve will limit the rear brake pressure and allow the front disc pressure to increase as needed. Thats the way to get the different pressures from one master cylinder.

Mark

Proportioning valves limit the rate of application, not the pressures. The rear brakes apply slightly ahead of the front to avoid swapping ends in slippery conditions. Does that training car have pressure gauges on both brake circuits? Somebody please measure those MC pistons and post the diameter differences.
Jerry

The 'combination valve' I used in my system has a proportioner function that reduces the pressure to the rear brakes during maximum braking. The metering function delays the front pressure for a bit to allow the rear shoes to make contact before allowing pressure to the front discs. The proportioner function only reduces the pressure to the rear during a panic stop, otherwise both front and rear get the same pressure. Photo is a paragraph from the GM shop manual for the vehicle that my combination valve came from.

Mark