Pedals

I am starting on the pedal assembly and have a few questions:
1. I have two Wildwood master cylinder kits that are 3/4 bore and one that is
7/8. Do the brakes get the two 3/4 and the clutch get the 7/8. On the last
car I built, the rear brake master cylinder was larger than the front.

2. What are the part numbers for the rods ends and rod required for the
accelerator?

3. Do all master cylinders rods need to be cut 3/4 of an inch?

Thanks
 
I am starting on the pedal assembly and have a few questions:
1. I have two Wildwood master cylinder kits that are 3/4 bore and one that is
7/8. Do the brakes get the two 3/4 and the clutch get the 7/8. On the last
car I built, the rear brake master cylinder was larger than the front.

2. What are the part numbers for the rods ends and rod required for the
accelerator?

3. Do all master cylinders rods need to be cut 3/4 of an inch?

Thanks

The 3/4 goes to the front brakes, 7/8 to the rear brakes and 3/4 to the clutch.

I tap left hand and right hand threads into the same hollow rod that supports the splitter and use 1/4-28 rod ends with a 1/4" hole.

All the rods get cut, I put the masters in place and mark the rods with the pedals in the position I want them in.
 
I used the 3/4 for te brakes and 7/8 for the clutch. Works fine for me

The larger bore for the rear brakes is meant to balance the braking. 7/8th is way to big for the clutch making the pedal hard to push and can cause over extending of the clutch fork or hydraulic throw out bearing. Not something that you want to happen.
 
I brake fine and clutch is light as a feather. If you properly set your clutch stop you're not going to overextend it.
 
Quick calculation on brake bias. Assuming both had 3/4" it would be 54% front and 46% rear. With 3/4 front and 7/8 rear it would be 61% front and 39% rear and better. Just for giggles with 3/4 front and 1" rear it is 67% front and 33% rear. I currently run 59% front and 41% rear on my mid engine race car and it is a bit rear biased still and we use more aggressive pads up front than the rear. When the rear wing is working well (100mph+) and the tires are good and hot it is not a big deal and we are used to it, yet I would like a few % more to balance it out a bit. We are not allowed a balance bar. With this I would think the 3/4 front, 7/8 rear and 3/4 clutch would be a better setup.

Front rotor size? 355 14"
Front caliper piston size? 44mm
Front caliper quantity? 4

Rear rotor size? 365 14.4
Rear caliper pistons size? 40mm
Rear caliper piston quantity? 4
 

Howard Jones

Supporter
Troy what is the piston area of the calipers on your car. Front and rear. I have done my car with different rear calipers and the combination of the original front wildwood 6 pots and the new rear 4 pots result in about 60%/40% F to R of the total piston area. I am also using the same size master for front and rear. So I have done the balance a different way.

With all four rotors being the same size on my car, brake effort will end up at about 58% F and 42% rear. The calculator I used came up with these numbers using about 1000 pounds of down force and 9 inch F and 12 inch wide tires R on the car with 60% of the total down force on the rear axle.

You seam to be in the same ballpark and I appreciate the information. Thanks
 
On my race car, single master cyl so pressure is the same.
Front 43% weight and rear 57% weight for 2650 with driver and fuel.

Front 12.72"
Caliper dual piston 1.43" diameter each
XP24 pads

Rear 10"
Caliper single 2" diameter
XP10 pads (I tried XP12, but was a bit too grippy for more rear bias and did not work well)

59% front and 41% rear brake bias.

At 100mph front downforce about 200-250lbs and rear around 500lbs, give or take. The spring rates are 650 front and 850 rear and car weights 2650 with driver and fuel. There is not much weight transfer with the stiff springs and rear engine.

If I could adjust it to like 65% front or even 68-70% front and use some more aggressive pads in the rear I would, but you have to live with what you have at times. You better be in a straight line if you want to fully threshold break the car and just something you learn. What I would do for a break balance bar. As you can tell I have gotten a bit anal about the breaks as I have had not a few times on track for different reasons and never fun. Turn 5 at 120mph+ at Road American, OMG, scariest moment of my life in a car.
 
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