I'm ordering Wilwood's reverse swing pedal assembly for my FC race car, and was looking for some feedback on what some of you fellow racers are using.

By some rough calculations I'm leaning towards the 5.1:1 pedal ratio, 3/4" front master and 1" rear master cylinder bore sizing. This is for the stock TII brakes, and an approx. 2600lb race weight. This gives me line pressures of 350psi front and 260psi rear.

Pedal feel is driver preference, however I'd like to compare what I think will work for me, to what some of you are running.

Thanks,
Andrew.

 

Sounds about right for your car....

My first gen has t2 calipers with the same size front m/c, but I have t2 calipers in the rear aswell.....

If I recall my pedal ratio is 6:1.....

 

Is that enough to stop the car?

 

I am using 3/4" front and 7/8" for the rears. I have also tried it reversed. smaller diameter gives longer stroke and softer(less input power) pedal. larger diameter gives shorter stroke and firmer(more input pressure required) pedal. I have seen people use the 5/8" diameter for the fronts as well.

 

Thanks for the input guys.

Yeah, the bigger the bore the shorter the stroke, the more muscle that's needed to obtain the same line pressure as a smaller bore.

What pedal ratio are you running tims?

Thanks,
Andrew.

 

And what calipers?

 

I am using 5/8" front and 3/4" rear with the 5.1:1.

Have to play with the balance bar adjuster a little to get it right, but in general no problems.

 

Eggie,
It really doesn't matter. I have used that setup on the stock FC calipers and my Wilwood bilet supelite 6 calipers

Andoru,
I am using the wilwood reverse mount pedal assembly.

 

The name on the caliper may not matter, but the piston sizes make one heck of a difference.

I've been a bit too cryptic in this thread.

After doing some calculations, I highly doubt that Mazda calipers will provide enough braking at ~300psi. The FD's proportioning valve doesn't even kick in until 570psi (per FSM P-19).

Is my math way off?

 

Your math is probably fine, I must have been drunk when I typed 350psi. Its 461psi front with a 3/4" master and 260psi rear with a 1" master. This is with a 5.1:1 pedal ratio and 80 pounds of force on the pedal by the driver. I calculated 400psi as the required line pressure according to all the required variables for my car (piston diameter, dynamic weight etc.).

If you want the exact math layed out, stop techs website has a very well written article laying out the calculation of master cylinder sizing.

My biggest dilemma is should I get the 5.1:1 or 6.25:1 pedal ratio offered by Wilwood. Because when it comes down to it, I can calculate all I like. Real world application out weights my calculations. I may find it too hard for me to press the pedal with the 5.1:1 ratio. 461psi may also not be enough, requiring me to press harder to achieve a higher pressure.

Anyway, good eye on catching me in my bluff

Thanks,
Andrew.

 

I agree.

That's where we differ. My spreadsheet is set up for FDs, but I figure the 4-piston FC setup should be close. Continuing from 460/260psi, I get about .5g braking with .5u pads.

PM me your email address, and I'll send a copy of the sheet.

 

i have a dual master swing pedal fs, let me know, pm me



didnt mean to thread jack

 

For some reason, the board will not allow me to send pm's because of my post count. Send me a pm with your email address and I'll email you my address. Don't want to post it here in fear of spam.

I appreciate the input you've given.

Andrew.

 

everybody's math seems correct, but in the real world it doesn't matter. the larger the piston size of the caliper does require more volume of brake fluid. This will then give you a longer stroke on the M/C, and if you used a larger diameter M/C it would give you a shorter stroke. In the real world I have used all types of combinations with the same results. If you want a softer(less pressure needed) pedal use the smaller diameter M/C. Most people will find that there is very little pressure needed for the rear brakes so the larger M/C will give you more adjustment on the balance bar. I started by calculating what I "should" use and found the best combo for my particular style by trial and error. I do have a collection of used M/C's though. I personally would start with (2) 3/4" M/C's.