I did some searching last night on this, but the things I read basically just said how to calculate the ratio of the master to the caliper pistons to the pedal ratio. None of them got into it more than that and kind of left it at "driver preference" for feel.

I remember someone had a post that got into brake torque, and at the time it was way over my head. I would think that would help me a little in this situation now if I understood all the parts of the equation.

The long and short is that I am interested in putting in BIG brakes on my "new" Formula and I am thinking of going to a Tilton pedal setup with a balance bar. Looking at the application of from the car the calipers come from I am thinking to start there, but it was a vacuum assist car, so that may not be the best place to start.

I am wondering if anyone has any advice where to start, short of just buying one and trying and replacing if I don't like the pedal effort? I'd rather not buy 2, 3, 4+ masters, or more since there is one for front and one for the rear.

One front caliper has a 4.26 square inch combined piston area and from what I see the master is a 1" bore for a .785 square inch surface area. I am not sure on the pedal ratio of the car, but the Tilton setup is variable from 5 to 6.2:1, depending where you set the brake pedal pad. I haven't calculated the rear caliper yet, nor do I know whether the application has a stepped bore master. I figure the rear brakes are doing a lot less, and setting them up with the balance bar isn't too hard.

Should I start with something slightly smaller so I get more pressure? Or start with what the application car has first? Or if there are other questions that can/should be asked before I even start thinking about which size to choose?

 

Hi, Scooter. I think you were thinking of my thread,

https://www.thirdgen.org/forums/brak...ng-torque.html

 

That's the one, thanks

But if you have any input on where to start with master bore size I would appreciate it

 

You don't need to worry about all that jazz about calculating how the stock prop valve works. You'll just use an adjustable prop valve and set it to whatever it needs to be to create the front-rear torque ratio that you want.

Maybe aim for a braking system that's capable of achieving 70/30 front/rear braking torque ratio, and then use an adjustable prop valve to dial in the ratio that works best.

And then the big question is how much total braking torque can you actually use? There are some rules of thumb based off how you're going to use the car. If the brakes become ultra powerful then they might work with really sticky tires on the track at full stomp, but then be overly sensitive on the street and just plain shitty to drive with.

And remember, those BIG brakes weigh a lot. That hurts you accelerating and stopping. There are two ways to go big: diameter and thickness. It doesn't look as cool, but going with thick rotors is better than going big diameter. It keeps the rotating inertia down but still has the mass to control the heat.

 

Heh, no they won't The tires will probably move out my inertia though, but with the wheels I will be forced to get it should keep my total mass down.

I have to do a lot of math and talking to the wheel manufacturer before I buy anything. I need to make sure I don't have to go larger than a 19" wheel. Tires for the 19s can be had and still be in the 26" diameter. Once I step into 20s the tires get a bit too tall, and I don't want to rub any more than I already do with the 275/40-17s on the R15's. I am hoping MAYBE an 18" wheel will work since tire selection is better, but I can settle for a 19 if I have to.

 

I sent you the spreadsheet. Hopefully it helps.

Please help keep my other thread up to date if you have additional technical data for other brake packages. Much of what I got came from Lukeskaff's website, most of which were real measurements and not general specs from a catalog. But there are plenty of holes in the tables that need to filled in, and other brake packages out there!

 

That seems high, only one side of a caliper is used for the volume calculation. If the 8.52 sq/in is correct, will require a lot of M/C to prevent a low pedal.

RBob.

 

I didn't know that you only use one side of the caliper. Between QwkTrip and the internet I have now learned that info, thanks

 

Going through QwkTrip brake torque thread, it looks like the 1" bore will net me a VERY low amount of brake pressure. Looking at the available Tilton master cylinders I will need to go to their smallest MC for the front circuit to have any decent amount of brake torque. I have more math to do though, I want to compare the math on different systems before I make any decisions. I am still a long way from buying anything.

 

Oh, you're definitely going to be smaller than 1 inch with manual brakes. I think Detroit Speed did dual Tiltons with balance bar. Maybe see what they have.

 

I want to keep this relatively low key for the moment, but I had to share