I’ve been researching brakes and think I have calipers picked out that will work with my C5 suspension on my AP build: Wilwood 6 pistons up front and 4 pistons in the rear with their Spec 37 rotors. I have a similar setup on my 69 Firebird street/track car that works very well at the track with a much heavier car that has 120 more horsepower. Wondering how the rear engine layout in the GT40 affects choosing the size of the calipers and rotors, with much of the car’s writ over the rear tires. Thoughts?
Thought on brakes size?
- Thread starter jlwdvm
- Start date
Chris Kouba
Supporter
Have you run through a calculator?
brakepower.com
That said, as long as you're not re-inventing the wheel, using something similar to others should get you in the ballpark. I am traveling now but am sure someone could post their components.
Brake Bias Calculator | Master Cylinder Calculator
Calculator for Automotive and Racing Brake Systems, Master Cylinders, Brake Bias, Piston Area, CG Height, Weight Transfer, Pedal Stroke and Maximum Deceleration
That said, as long as you're not re-inventing the wheel, using something similar to others should get you in the ballpark. I am traveling now but am sure someone could post their components.
Howard Jones
Supporter
wheel size?
Howard Jones
Supporter
Ok you have plenty of room for rotors. Here is what I have on my cars.
GT40:
front 12.19 X 1.25 wilwood ultralight 32 rotors 1.75 X 4 willwood superlight calipers. R 12.19 X 1.25 rotors 1.38 X 4 superlight calipers. Master: stock GTD tandem pistons vacuum assisted with GTD standard drop down peddles. This master/peddle system is aproximately the equlivant of two 5/8 masters F&R with a 6 to 1 peddle ratio. I use a variable proporting valve in the rear circuit, I would estimate that it reduces the presure by about 10-15%.
SLC:
front 13.6 X1.25 GT48 rotors Wilwood superlight 4 pistion 1.88 X 2 1.75 X 2 rear 12.88 X1.25 rotors calipers 1.25 X4 pistion superlight wilwood. Front and rear masters are 1.75 X 2 on a tilton twin ballance bar peddel box. Note: this setup is near perfece ballance f to r with the ballance bar centered.
Interesting info: In my case the main thing is the total piston area ratio between front and rear brakes. The front pistion area on my SLC is 5.18 and the rear is 2.46. When I had 6 pistion caliper on the front (1.62, 1.12, 1.12 pistion area 4.04 the car never felt right. I had the ballance bar all the way to the front and it still was not right. The difference between the current 5.18 f pistion area and the other 4.04 is night and day.
If you do the math on the GT40 it comes out very similar.
My best guess would be 12.19 X1.25 front rotors with 1.75X4 calipers and rear 1.25X4 calipers on 11.75X1.25 rotors. Start with two .75 masters F&R on a ballance bar twin master peddle box. I think this would be very close. Just don't under size front caliper pistion area.
Last note: the 6 pistion calipers with the small pistions in them are ment for honda civics upgrades. The 6 piston thing on street cars on street tires is a bling thing IMHO
This is my story and I'm stickin to it.
Really last note: If you intend to track the car on slicks then spend the money on the Thermlock pistons in wilwood calipers at least on the front of the car.
GT40:
front 12.19 X 1.25 wilwood ultralight 32 rotors 1.75 X 4 willwood superlight calipers. R 12.19 X 1.25 rotors 1.38 X 4 superlight calipers. Master: stock GTD tandem pistons vacuum assisted with GTD standard drop down peddles. This master/peddle system is aproximately the equlivant of two 5/8 masters F&R with a 6 to 1 peddle ratio. I use a variable proporting valve in the rear circuit, I would estimate that it reduces the presure by about 10-15%.
SLC:
front 13.6 X1.25 GT48 rotors Wilwood superlight 4 pistion 1.88 X 2 1.75 X 2 rear 12.88 X1.25 rotors calipers 1.25 X4 pistion superlight wilwood. Front and rear masters are 1.75 X 2 on a tilton twin ballance bar peddel box. Note: this setup is near perfece ballance f to r with the ballance bar centered.
Interesting info: In my case the main thing is the total piston area ratio between front and rear brakes. The front pistion area on my SLC is 5.18 and the rear is 2.46. When I had 6 pistion caliper on the front (1.62, 1.12, 1.12 pistion area 4.04 the car never felt right. I had the ballance bar all the way to the front and it still was not right. The difference between the current 5.18 f pistion area and the other 4.04 is night and day.
If you do the math on the GT40 it comes out very similar.
My best guess would be 12.19 X1.25 front rotors with 1.75X4 calipers and rear 1.25X4 calipers on 11.75X1.25 rotors. Start with two .75 masters F&R on a ballance bar twin master peddle box. I think this would be very close. Just don't under size front caliper pistion area.
Last note: the 6 pistion calipers with the small pistions in them are ment for honda civics upgrades. The 6 piston thing on street cars on street tires is a bling thing IMHO
This is my story and I'm stickin to it.
Really last note: If you intend to track the car on slicks then spend the money on the Thermlock pistons in wilwood calipers at least on the front of the car.
Last edited:
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