I need to sovle a brake riddle - SCCA STL

[CSG Mike]

You basically have to use stock brakes. However, with the weight of the cars being low in STL, you'll be totally fine with just good pads and fluid.

C12 front C1 rear is a super popular combo for classes with this type of restriction; you won't run out of ceiling with this pad combo unless you're just blatently sitting on ABS at every braking zone.

[Autoxer62]

In the NC Miata world there's a "little big brake kit" which is Wilwood calipers on stock rotors. Thinking about it, you only need caliper brackets and custom lines for such a setup. Perhaps there's a fabricator out there that could do the brackets? I realize these are brakes and the fabricator has to be skilled, but maybe some company that does brackets for other cars would be willing to make some for this platform? I'd expect getting custom lines wouldn't be too difficult, I know there are suppliers for those.

[Stonehorsw]

Confused here, if the only restriction is rotor size, AP sprint would work.

If more, then I would suggest the wrx Sumitomo calipers. Those are good and pads may be limited here, and would require to use japanese sourced ones.
Save 4lbs per corner

[Luns]

Originally Posted by rice_classic

So I am looking for non-floating monoblock calipers that work on the OEM rotors. Must also clear 17" wheels.

*06-07 WRX calipers look like the easy button
PROS: bolt on, cheap, symmetrical piston size so orientation doesn't matter, no issues with bias
CONS: heavier than aluminum, limited race pad options, especially where SCCA contingency exists.

Note that while the WRX caliper is non-floating (fixed), it is not a monoblock caliper. The caliper consists of two halves that are bolted together. A monoblock caliper is machined out of a single piece.

Originally Posted by Stonehorsw

If more, then I would suggest the wrx Sumitomo calipers. Those are good and pads may be limited here, and would require to use japanese sourced ones.
Save 4lbs per corner

Do you have a definitive source for that 4lb/corner delta? I've seen people quoting each other back and forth on the weight savings, but the actual measured weights I've seen suggest it's much much less of a difference than that.


https://www.ft86club.com/forums/showthread.php?t=44669
gives the weight of the stock front caliper+bracket+pads at 7.8+3.8+1.8 = 13.4lbs per wheel


https://forums.nasioc.com/forums/sho...5&postcount=12

gives the Sumitomo front calipers+pads at 24.5 lbs, or 12.25lbs per wheel.

These put the weight savings around 1.2lbs per front corner. Other measured values I've seen vary a little bit, but not enough to get to 3-4lbs/corner.

I haven't looked into the rear weights but it may be closer to the 3-4 lbs there given the rear calipers are aluminum. But between the need for an adapter bracket and the shift in brake balance, I haven't considered this option.

[Stonehorsw]

Originally Posted by Luns

Note that while the WRX caliper is non-floating (fixed), it is not a monoblock caliper. The caliper consists of two halves that are bolted together. A monoblock caliper is machined out of a single piece.




Do you have a definitive source for that 4lb/corner delta? I've seen people quoting each other back and forth on the weight savings, but the actual measured weights I've seen suggest it's much much less of a difference than that.


https://www.ft86club.com/forums/showthread.php?t=44669
gives the weight of the stock front caliper+bracket+pads at 7.8+3.8+1.8 = 13.4lbs per wheel


https://forums.nasioc.com/forums/sho...5&postcount=12

gives the Sumitomo front calipers+pads at 24.5 lbs, or 12.25lbs per wheel.

These put the weight savings around 1.2lbs per front corner. Other measured values I've seen vary a little bit, but not enough to get to 3-4lbs/corner.

I haven't looked into the rear weights but it may be closer to the 3-4 lbs there given the rear calipers are aluminum. But between the need for an adapter bracket and the shift in brake balance, I haven't considered this option.

That is a good question, I saw in different discussions numbers thrown. Best way would be to get a GC8 caliper and weight, let me ask around and confirm.

[rice_classic]

Originally Posted by Luns

Note that while the WRX caliper is non-floating (fixed), it is not a monoblock caliper. The caliper consists of two halves that are bolted together. A monoblock caliper is machined out of a single piece.

I bet you're fun at parties.

[Stonehorsw]

Originally Posted by Luns

Note that while the WRX caliper is non-floating (fixed), it is not a monoblock caliper. The caliper consists of two halves that are bolted together. A monoblock caliper is machined out of a single piece.




Do you have a definitive source for that 4lb/corner delta? I've seen people quoting each other back and forth on the weight savings, but the actual measured weights I've seen suggest it's much much less of a difference than that.


https://www.ft86club.com/forums/showthread.php?t=44669
gives the weight of the stock front caliper+bracket+pads at 7.8+3.8+1.8 = 13.4lbs per wheel


https://forums.nasioc.com/forums/sho...5&postcount=12

gives the Sumitomo front calipers+pads at 24.5 lbs, or 12.25lbs per wheel.

These put the weight savings around 1.2lbs per front corner. Other measured values I've seen vary a little bit, but not enough to get to 3-4lbs/corner.

I haven't looked into the rear weights but it may be closer to the 3-4 lbs there given the rear calipers are aluminum. But between the need for an adapter bracket and the shift in brake balance, I haven't considered this option.

Thanks to a GR forum piening2150 member, who had a GD Wrx caliper and pads at hand, now I have a confirmed weight.
GD Wrx Sumitomo Opposite piston Iron casting: 4.575 kg
Pads: 740g
Loaded caliper: 5.315 kg

Compared to OEM, which have the measured weight (loaded) of 6.342kg, we have about 1kg reduction (2.2 lbs) per corner, or 2kg (4.4lbs) per axle.


Hope this data helps folks here.

[rice_classic]

Just updating this thread for the outcome...

I have installed the ESSEX AP Racing kit with 299mm rotors. The supplied hat/rotor combo is great, however they are a bit too wide for STL rules. I will run these in other classes but when I run STL I will use a Wilwood rotor. I was able to source a Wilwood 8bolt Hat with a rotor that is a legal width. Because the wilwood rotor is narrower, I needed to utilized spacers behind the pads to take up that space.

On the rear of the car I installed the FHI WRX calipers with the KNS adapter - I did not weight these but they do feel lighter than the floating caliper that came off the car.

AP kit:
https://www.essexparts.com/essex-des...0299brzfrsgt86

Wilwood Hat: https://www.wilwood.com/Hats/HatProd?itemno=170-9206

Wilwood Rotor: https://www.wilwood.com/Rotors/Rotor...emno=160-15877

Spacer: https://allstarperformance.com/calip...hick-all42042/

Weights: (according to my bathroom scale!).
Oem rotor: 17.2 lbs
Oem caliper: 12lbs
AP rotor: 12.6 lbs
AP caliper: 4.8
Wilwood rotor: 8.2 lbs

OEM caliper+rotor = 29.2
AP Caliper + Wilwood hat/rotor = 13
Weight saving per corner: 16.2 or 32.4lbs total off the front end


Edit: My ESSEX rotors may be for sale. Just the rotor, not the hat. https://www.essexparts.com/ap-racing...nd-60-vane6603

These retail for $299/ea, meanwhile the Wilwood equivalent is $75/rotor so it makes sense for me to sell these to someone who wants them and swap to the Wilwood rings. If you have the AP kit and need to replace your rotors/rings - ping me, I'll make you a deal.