Anybody running manual disc brakes? Pics

[Gregski]

Originally Posted by HO455

I think they're called Quadrazaps.

that's the one! lOl

[MARKDTN]

Late I know, but square bodies did manual discs. Here is a picture of a '73 with a '74 Master. Seems real '73 masters are hard to find and this one had already been replaced. I put it back the way it came off but doing some research I found that the front and rear was reversed. I swapped the lines and got rid of the adapters show in the photo. If you look the small compartment is in the front for drums and the big one is for discs. Compare to the one in post 1 and they are opposite.

[Gregski]

Originally Posted by MARKDTN

Late I know, but square bodies did manual discs. Here is a picture of a '73 with a '74 Master. Seems real '73 masters are hard to find and this one had already been replaced. I put it back the way it came off but doing some research I found that the front and rear was reversed. I swapped the lines and got rid of the adapters show in the photo. If you look the small compartment is in the front for drums and the big one is for discs. Compare to the one in post 1 and they are opposite.

thanks so much I had a '74 with power brakes if I recall correctly but I remember arguing or discussing with someone that the front chamber is not always for the front brakes and they must have thunk I was crazy, and yet here you are

I just made a YouTube video where I ask this very question, I hope I link correctly right to the point in time here: Electric C10 - Give Me A Brake

[americanmusc1e]

Originally Posted by Gregski

and a few hours and a bucket of sweat later she's on

Wait!? You are building an electric truck with manual brakes!?

[Gregski]

Originally Posted by americanmusc1e

Wait!? You are building an electric truck with manual brakes!?

yes, lol, please watch the video

[Gregski]

So I just stole some great brake info from here Master Cylinders FAQ

here are some highlights

Do disc brakes require more pressure than drum brakes?
Yes.


Can I run disc brakes with a manual brake master?
Yes. The bore size of the master can not be larger than 1" and your leverage at the pedal has to be greater than power brakes.


If I add disc brakes will I need a proportioning valve?
Yes. The addition of a proportioning valve is a must. Without it your braking system will not operate properly.


How does a disc brake master differ from a drum brake master?
A drum brake master will differ from a disc brake master in two ways. The amount of fluid that a drum brake master has to move is less than disc brake. Drum brake masters have 10 lb residual valves at the outlet to keep a residual pressure on the drums. If you use a drum brake master for disc brakes you would move an insufficient volume of fluid and the disc brakes would drag because of the residual valves.


Can I use my manual master on a booster?
Yes.


Why is one fluid chamber larger than the other in a disc/drum master?
As disc brake pads wear the caliper pistons will move outward. The fluid level in the master will drop more rapidly than the drum portion so you need more reserve.

[RichardJ]

Before you take all that info as fact, there are things you should think about.

>>The amount of fluid that a drum brake master has to move is less than disc brake<<
Think of that from the perspective that the drum master and the disc master are in the same unit as opposed to a drum/drum or disc/disc MC.

The volume of a cylinder = πr²h (That's supposed to be PI).
On ALL dual master cylinders, the forward piston is called the Secondary Piston and the rear piston is the Primary Piston. The fluid in the Primary Chamber, pushes the Secondary Piston forward until the Secondary Chamber compresses and begins to develop pressure. The primary chamber begins to develop pressure at the same time.
Both the Primary and Secondary pistons move forward the same distance at the same time.

The Diameter (and Radius) is the same for both the Primary and Secondary pistons, so the same volume exits both the front and rear ports and it is under the same pressure.

>>Drum brake masters have 10 lb residual valves at the outlet<<
I think you will find that very few new and rebuilt master cylinders have a residual valve because the cup spreaders have been improved and do a better job of keeping the air from entering.

>>Can I use my manual master on a booster? - Yes<<

There is something they are not considering. If your foot moves the manual master pistons forward a 1/2 inch, the pistons move a specific volume and produce some specific pressure.
If you place a vacuum booster between your foot and the MC pistons and your foot moves that same 1/2 inch, the booster will only move the pistons about 7/16 inch. The action of the booster looses distance.
This is why a MC used with a booster usually has a larger bore. The piston in the larger bore doesn't have to move as far to move the same volume and then produce the same brake line pressure.
The same braking with less foot pressure.

In your video, you are holding a old MC which you describe as being a power MC. It looks like it has a rubber dust boot on it. Rubber boots are used on manual master cylinder to keep dirt away from the exposed piston. The boots don't fit between the MC and the booster.
You should have a boot on your new manual MC.
Your questions about large and small reservoir sizes should be answered by looking at the single reservoir on the MC mounted on your truck. It doesn't matter the reservoir size as long as you don't run out of fluid when the disc pads wear down.
Drum brakes with self adjusters never have an issue with small reservoirs.

[dmjlambert]

That is a bunch of very good technical info here, I like reading it.

When I had the original 4-wheel manual drum brakes on my 1969 truck, the braking worked very well except my self-adjusters were not the best and needed work. One side would differ from the other after a few hundred miles and the truck would swerve in an emergency stop or slow down. Instead of working more on the drum brakes to fix that, I had the opportunity to change all 4 wheels to a great condition stock 1971 setup due to a posting in the parts section.

With disc brakes I noticed some things changed. 1) the swerving problem went away. 2) the pedal braking effort reduced. 3) the total pedal travel reduced such that with full application of the brake the pedal no longer went down as far, a difference of about 1 inch. 4) the brakes have a better feel and are very smooth.

When I drive my truck with manual front disc brakes, it makes me wonder why there appears to be a great amount of interest in power brakes for a C10. I can't imagine having the desire to add power to mine.

But who knows, I could change my mind in the future. I wonder if the majority of posts dealing with brake problems are related to booster failure and vacuum or hydroboost problems, and we just don't hear from the manual brake crowd very much because the systems are simpler and less prone to problems and therefore superior. Or maybe there's only a dozen people left with manual brakes and we're just missing out.

So, anyway, it appears I'm long-winded, my point is I'm not just running manual disc brakes, I'm liking them a lot and would recommend them. Specifically I recommend manual front disc rear drum brakes for a half ton truck.

[Steeveedee]

Personally, I'd like manual disc, even on my 3/4T truck (don't have that- it's power). If the engine quits and the vacuum disappears, it isn't yet a problem for me. I can stand on the pedal. My frail wife, though...different story. Though she did manage to get our Astrovan off the freeway and stopped when the fuel pump failed. No Hydroboost brakes or power steering. Luckily she drives like a snail and was on an offramp that had a "Yield" sign at the bottom when it happened. Could have been way worse.

[Gregski]

Originally Posted by RichardJ

In your video, you are holding a old MC which you describe as being a power MC. It looks like it has a rubber dust boot on it. Rubber boots are used on manual master cylinder to keep dirt away from the exposed piston. The boots don't fit between the MC and the booster.
You should have a boot on your new manual MC.

super info thank you and I picked out the quote above because we thought the same thing after making the video and taking some measurement of the recess of the piston in the old rusty "power" drum/drum master cylinder to only find out it was also just as deep as the new manual disc drum one so about 1 1/2"

in my defense I bought that "power" one maybe 5 years ago and I specifically asked for a power drum/drum master cylinder, I am not sure i bought it as a kit with the vacuum booster but maybe, not pointing the finger but I wanted a power MC and I ranned it with a booster for like 5 years, hence me posting that FAQ about can you use a manual MC with the booster

anywho thanks for the tip on the rubber boot, that was the first thing I asked the counter guy at Oh Really's when he took it out of the box for us to stare at it, I said shouldn't it come with a rubber boot? he shrugged his shoulders

as a heads up, I didn't see any of the computer screens at AutoZone, Oh'Reilly's or NAPA say manual or power for any of the MCs we looked at they just specify drum/drum or disc/drum so I wonder if they are saying they are interchangeable, I don't know

once again I really appreciate you taking the time to write all that info up, I love learning this stuff, thank you very much

the pic below is from like 6 years ago when I first got the truck and put a new drum/drum brake MC on it

[RichardJ]

Most manual MC have the deep hole and most power MC applications use a shallow hole.
CPP, supplies MC's with an adapter plug to use as a manual or with a booster. You still have to decide what bore size you need.

[Gregski]

Originally Posted by RichardJ

Most manual MC have the deep hole and most power MC applications use a shallow hole.
CPP, supplies MC's with an adapter plug to use as a manual or with a booster. You still have to decide what bore size you need.

Yeah, having three trucks I forget which one this happened on, but I installed the booster and the MC and then found that little pinky finger in the box and thought oh shoot, where does this go... and I had to remove the MC and shove it in there LoL

[Tomchev]

My 71 c10 had manual disc brakes very hard to stop. Found a booster and brackets off a c20 what a difference in pedal pressure

[dmjlambert]

Hearing things like that makes me wonder what's up, since mine is easy pedal effort with manual disc brakes from a 71.

[Gregski]

happy to report brakes are done and all working, son helped me bleed 'em! thank you Michael you won't hear me talk about them ever again, sheesh enuff of that, we have an electric truck to build!

just wanted to say THANK YOU so much to everyone on this thread who offered help, this had me in a funk for 6 months, I really appreciate the exchange of know how on this forum, thanks again