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If I'm using a Fox mustang as a platform for mostly street and some autocross, which of the following brakes would be better:

  1. 11" rotors and 4 piston calipers; or
  2. 12.2" rotors and 2 piston calipers.
Both setups use Baer brakes of roughly equal cost. This ultimately comes down to a tradeoff between 1.2" of extra rotor diameter or 2 extra pistons. Any advice would be appreciated. The coolness factor has mean leaning in favor of the 12.2" setup.
 

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  1. 11" rotors and 4 piston calipers; or
  2. 12.2" rotors and 2 piston calipers.
Both setups use Baer brakes of roughly equal cost.
What kits are you looking at? I didn't think Baer sold anything that small these days.
 

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More pistons don't make the brakes stop the car faster.

Brake rotor diameter is the single biggest factor.
Ok, so why do they have 6 piston Baer brakes now that used to be 4 piston for the 13 inch rotors? I am not doubting anything you said, just educating myself.
 

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If it is just money, then why are the GT Lemans and GT Daytona guys running them? I just watched the race at Lime Rock and they had close ups and those guys were running them. If 4 piston is just as good, I would think they would just run that? No? Not trying to argue with anyone at all, just asking questions that I would love to know the answer to. Thanks.
 

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Besides ultimate stopping power and lack of fade, brake pedal feel and modulation should be at the top of the list of criteria.

Opposed piston calipers theoretically have more consistent pad actuation than a single sided sliding setup will. Presumably the Baer kits consist of the PBR 2 piston sliding and their own T4 opposed 4 piston designs.

When I switched from the Cobra PBRs to 4 piston Brembos the brake performance was improved, especially at the road course. BUT....By far the bigger benefits were the amazing increase in modulation and the lack of pad taper from hard use; meaning longer life for pads and rotors.

If they are the same money, the bigger dia rotors with 4 piston is without question the better mod overall; assuming your wheels can clear them.


Total piston area determines potential pad pressure and brake torque.......larger dia disc = more torque potential. When using large discs and in need of lots of piston area, multiple pistons allow for a narrower caliper to fit within the smallest possible wheels. Some newer Vette's have 8 piston calipers, and use multiple, separate pads in order to mitigate pad taper across a longer pad area. This is why multi piston calipers typically have mulitple piston diameters.
 

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Yes, as Paul pointed out, opposed piston calipers can be made stiffer.

Beyond that, as the rotor diameter gets larger, the radial width of the pad stays more or less constant. This means that the length to width ratio increases. To provide constant pressure between the pad and brake rotor, more pistons are needed rather than one large piston. This ensures less pad taper and keeps the backing plate from bending. OEM calipers tend to have nearly square shapes, which already therefore don't benefit from multiple pistons on each pad. In endurance racing applications, brake pads with a large volume of friction material are needed. Once they have made the pad thicker, the next best way to increase the volume is to make it longer. This drives the requirement for 6 and 8 piston calipers.

http://www.miataturbo.net/attachments/race-prep-75/39862d1334083329-track-brakes-dscn1356.jpg
 

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edit: Now I see that Tulowd addressed this already, but anyway...

Another advantage of higher piston-count calipers is they provide the same clamping force as lower-count calipers by using more pistons of smaller diameter. What do smaller pistons allow you to do? Make for a far shallower caliper than would otherwise be possible. What's the benefit of that? You can run far bigger rotors without increasing wheel size. And then, it's that increase in rotor size that makes for better braking, not the piston count itself.
 

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Id say pull some 03/04 cobra brakes for the front and enjoy a entirely new car! Plus you can get them 500 bucks or less.
 

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I added Hawk HP+ on stock 11" rotors and added cooling ducts for my before test. I was quite surprised how well they worked, 20-25 minutes on a road course with no fade.

Next I went to a full 04 cobra setup with the same pads. Much better feel and my confidence went up at the end of the straights. Also added weight. If I were building a fox for AX and street I would probably get the MM upgrade kit with SS lines pads and shoes. Cheap, light, just not as cool as big rotors.

I assume you already have 17" or larger wheels that are needed for 13" rotors.

My $.02 Good day.
 
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