I've reached the limit of my expertise for a layman regarding a Disc/Disc Brake Layout for our Project Car. Whereas the Front & Rear Brakes are installed with the Brake Lines run. I am now at the point to purchase the Firewall-Mounted Master Cylinder, Booster, & Combination Valve as well as the Firewall-Mounted Pedal. Before I commit, I'd value Feedback and Advise on the Disc/Disc Brake Layout (ensure connections are correct) as well as to ensure the Parts Selected will meet the requirement. Thanks in advance for your help! Doug
If I was in your position I'd be purchasing matched components to suit the application from a vendor that can be spoken to for assistance / advice. The illustrated 1 1/8" master with a 9" booster and an appropriate pedal ratio ( I'll punt 4:1) should stop all but the largest vehicles rather well. Very broad questions are somewhat impossible to answer without huge effort. Specific concerns, along with all the relevant details should garner responses. Chris
Thanks Chris. Greatly Appreciate the Feedback. I didn't even know if the brake line layout was correct. Saw a conflicting diagram on mpbrakes.com. And, was uncertain of the "universal" master & pedal ration and sizes. Thus, my quest to turn to the experts. Will definitely look to source from a vendor that is responsive as well as matching the master & pedals. Thanks Again. Doug
I don’t think anyone will be able to tell you if that master will meet your requirements until you let them know exactly what brake units you have on each axle.
Also, in the diagram for your brake line/hose routing, I have never seen the front brakes (if disc are used) use a tee fitting from one line. That style distribution block is a GM style introduced in 1970/71... There is one port for the rear brakes, and two ports for the front brakes to have their own independent lines. The block in the ad also states that it is for disc/drum application. You have to use one for disc/disc application. The block for a disc/drum has an internal proportion valve so the rear drums don't lock up when you use the brakes. Disc/disc blocks do not need the proportion valve. I'm not saying that it won't work the way the diagram shows... I'm just saying I've never seen or ran them that way. You would have to plug one of the ports on the block for the front brakes to do it that way.
Alchemy, As a novice, I don't understand what is meant by "brake units on each axel?" If you would help me understand the question, I'll do my best at answering.
Travlr, Great Catch! I based the Brake Layout Diagram directly from this article which was using a APV. https://www.hotrodders.com/threads/brake-line-diagram.174814/ Will ensure I get the appropriate Master Cylinder & Booster. Further, I can see where I would either need to plug one of the front brake ports on the Combination Valve or remove the Front Tee.
Doug, Using a new combination valve, while popular with the brake suppliers and those that like the looks, is great on a vehicle it was designed for, but not so much on a custom brake system, especially if you don't intend to use a dash warning light. An adjustable proportioning valve is all that may be needed, as many 4-wheel disc systems used proportioning. The use of a "T" for the fronts is proper plumbing without using the combo valve's two front ports. Now, 4-wheel disc brakes with power assist on a gross weight vehicle of 1650lbs! Seriously??? Bob
There’s no way anyone can tell you that the size of the master cylinder (bore) is correct until they know the size of the wheel cylinder. Tell them what calipers you have. Exact ones, not just “Chevy” or “metric” type of answers.
With a gross weight of 1650 lbs, this must be a T bucket or stripped down roadster. A 1650 lbs car is very light. That kind of makes me wonder if there is enough firewall structure to support a firewall mounted master cylinder, unless there is a roll cage involved. With that light of a car, the need for power brakes is questionable. A manual brake with the correct pedal ratio would solve a lot of problems. Generally, a light car with a firewall mounted power brake booster does not produce a good visual impact in a mostly open engine compartment. Maybe a picture of your project would be helpful. It sounds to me like someone may be trying to take advantage of you being new to the hobby. If the project is not of the 64 or older traditional nature, there is an off topic section for this board where your project can be covered. Click on the H.A.M.B. tab at the top of the page and open the menu, scroll down to the "Off Topic" section and open it up there. You can then post in that section, but the only way to get back there is to reopen on the H.A.M.B button.
I wouldn’t ugly up a nice firewall on a 1700 pound car for a booster. In my pro days we hardly ever put boosters on cars. Even the crazy HP full size cars
You need to remember the aftermarket suppliers are in the business of selling product. They never suggest what to use for any project. Those Brass valves are nothing more than a manifold with a switch for the Idiot light. I haven't installed one in a new build in over 30 years, but they will tell you you "should" have one. Once you purchase everything you can from them and then have issues, they will be very clear that the issue is not from their products. And I agree with a car that light I would not be using a Booster at all.
Squirrel, I chalk this up simply to my novice status as a Hot Rod guy. So, I understand with such a light vehicle, a Booster nor Combination Valve is required. Rather, a simple disc/disc Master Cylinder and Adjustable Proportion Valve will suffice.
As I’m sure you have figured out from the responses, your car is very lite. It won’t take massive brakes to stop it. And we all tend to learn from our’s and anyone else’s mistakes that we learn of. For future reference other than the fact that discs look cool, a drum disc combo would probably have been a better option. Drum brakes generally have more stopping power than disc brakes. Disk brakes are less susceptible to fade. Generally cars have more brake bias to the front brakes as the weight shifts forward while stopping. Thus with the same disks or drums on all 4 corners you would normally use a valve to put a little more pressure to the front brakes. Too much front bias could make the car hard to handle if the surface is at all slippery. For what you already have I personally would probably use a single reservoir master to an adjustable proportioning valve and from there to the front and rear. One line to the rear differential and a T to the calipers. The fronts could T at the crossmember. The only reason to run a dual resubmit master would be to prevent brake failure if a line brakes. Some proportioning valves will also provide that protection. Simple is clean and clean is eye catching in the hot rod world.
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