BBK Crisis-996 or Anything Else

[eacmen]

As I see it, the issue with stock brakes is heat, not clamping force.

Heat capacity is a primary issue. However another main issue with the stock brakes is caliper flex. Which is mitigated but not solved by brass guide pins. Flex yields really bad pad radial taper.

You get longitudinal pad taper on some BBKs but well designed ones it will be very minimal. Generally attributed to mismatched piston sizes on the leading vs trailing part of a 4pot or higher caliper design.

You’d be surprised how much pad material and taper can translate into pedal feel and travel.

Pad taper can be mitigated by swapping pads inboard/outboard but that can affect pedal feel.

[Fresh1179]

As I see it, the issue with stock brakes is heat, not clamping force.

Bingo. If you put a DTC 70/60 combo on the stock brakes the initial torque and subsequent secondary bite will have the car dancing around.


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[mrgizmo04]

Porsche setup requires more leg force because the pi*r^2 (mainly due to r^2) portion of the piston areas from multiple pistons is less than the single stock one. Look up Pascal's law and think through how a hydrolic jack works - small piston with handle is "easy" to pump with your hand to lift up a 3000 lb car via a huge piston.

This is somewhat equivalent to mc vs caliper pistons (former to jack handle, latter to piston that raises the car).

The clamping force is proportional to pressure from your foot/mc and the area of caliper piston bores. The larger the difference in the areas, the more pressure is generated in the lines which then gets applied to pad via the caliper piston bore. So camping force would go up for same leg pressure if mc is smaller than stock, since Porsche bore areas are smaller.

The question about larger mc is not on bore but on depth/length of the piston/plunger - can it pump enough fluid to fill the depth/length of the caliper pistons. But the force exerted is proportional to the bore, not the depth/length.

On the hydrolic jack example, the small size piston that you pump by hand via a handle only holds a little fluid volume, that is why you have to pump the handle 5-10 times to raise the car. The fact that the piston bore is much smaller than the one operating the arm that raises the car gives you the superman power to raise the car. If the small piston depth/length was much larger (not the bore), you would have enough fluid volume to pump the handle once to raise the car. You want the difference or ratio of bores to be as large as possible, from a point of view of the bore you are operating (jack handle, or brake pedal/mc) to be much smaller vs the bore of what you are trying to get work out of (end of jack raising the car, or caliper pistons clamping on pads/discs).

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[bigjae46]

Bingo. If you put a DTC 70/60 combo on the stock brakes the initial torque and subsequent secondary bite will have the car dancing around.


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The other issue with stock brakes is control. You can trail brake much deeper with a BBK because the feel is much better. I know my stoptechs don't have the initial ramp up of brake pressure like stock does. I love this because the brakes feel far more linear and it is easier to modulate off the brake when you're turned in. Meaning, you can get on the brakes that much later and brake that much deeper into the apex which maximizes traction and grip. Makes you faster.

[Cronenberged]

Not to derail this thread, but what is the consensus, on best cooling back plate or kit? Any experience or if anyone has used multiple set ups would be appreciated.

[Actuary]

I’m using burkhart carbon backing plates. I ended up installing them at the same time as the 996 and ecs rotor. The setup was great a Watkins Glen. I was running caliper temps way lower than my brothers (one had stoptech trophy and the other ap racing). I never had brake fade on track. But I also manage my driving to try to keep them cool.

I really need to create a build thread. Just remembered a cool brake ducting setup that I got to work with my csl bumper. Added some pics on that😊

[mrgizmo04]

I reused the original dust shield and enlarged the hole that already exists right in front of the bearing. Trimmed off pieces of the dust shield that sit super close to the inner rotor surface so it didn't trap heat. I also reused the stock inlet and didn't bring the hose inlet to the front of the bumper (because eventuri). I went the cheaper diy route. Pics of pass side below.

I know the stock shied doesn't seal perfectly, but I did some testing with a leaf blower and on track. Without cooling I lost 3mm of pad after an hpde day, with cooling a new set of pads wore only 1mm.

I posted a video: https://youtu.be/EwsULYBOrVU


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[Obioban]

I'm running the Hard backing plates, low profile transfer tubes, and ducts. I like that I can get full steering lock without rubbing and that it looks unexceptional/stockish from outside.

[bigjae46]

I have a steel backing plate, BW or Turner. $40 NACA duct and $40 rubber ducting from eBay.

I used rivet nuts and some l-brackets from Home Depot to secure the ducts on the back of the rebar.

Now I can remove the bumper in 10 seconds. Takes about 30 seconds to install.






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[Cronenberged]

Sweet. Thanks guys

[Fresh1179]

Does anyone know who a good contact at Stoptech would be to inquire about the C43 kit. Specifically, Bimmerworld indicates on their website that the C43 calipers are transitioning from their "mil-spec" coat to nickel plating. It appears the nickel plated versions are available for the S2000 and some other vehicles. I frankly don't care how the actual calipers look, but is sounds like the nickel plating would make the finish less prone to cracking, flaking. I don't know the history of the mil spec coat, although I think it "looks cooler" instead of blingy.

[Cronenberged]

Follow up question cause I'm a huge noob, but brembo makes a 345x28mm rotor for the rear of our cars, why isn't there a front option? Would it just take having a hat made?