StopTech C43 vs StopTech Trophy Front BBK. Pls help me decide

[mrgizmo04]

Clamping force is important. Per given travel in the brake pedal/master cylinder plunger you are moving brake fluid through the lines which then get to the caliper pistons. Having a huge piston requires more fluid to fill the caliper cavity behind the piston, to move it to squeeze the pads vs having multiple smaller pistons like on a bbk. Requiring less fluid to move the smaller pistons on a bbk usually feel "tighter" which is associated with better pedal feel. But the area of several smaller pistons is smaller than single large one, and therefore the clamping force (converting the brake pedal pressure via piston area) is smaller as well. Bbk attempts to spreads and distribute force across a larger pad area for cooling capacity, so it uses several smaller pistons across a wider surface. 1x 60mm piston will have more piston area and force vs a 42 and a 38 together (like I think the st40 uses) because pi*r^2.

Also, potentially contrary to popular belief, size/area of the pad itself does not contribute to clamping force. Think of it as "normal" force (which is independent of the area). The force is dependent on the mu coefficient of friction of the pad and where on the radius of the rotor it gets applied (think leverage via longer breaker bar). So I always have a good laugh whenever I hear someone running a bbk (basically a massive caliper), on stock rotor size with street pads. While the pedal pressure might feel better per first paragraph explanation, there is not more braking power. Maybe the pads will fade a bit later because they are larger in the bigger caliper, but anyway.

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[bigjae46]

1) RIP, TWS

2) TWS CW looks really fun. I only got to run it in CCW

3) Were y’all using the same pads?

4) I def want a rear brake kit as well. The issue right now is, I don’t know what rear kit I can pair with the front C43 kit. Without access to the calculator and no one to help me out, I can’t proceed with purchase.

5) Yeah, C43 offers about a 5 lb reduction per corner. Do you think the ST40 with 355mm rotors would outbrake the C43 with its little 332mm rotors?

He was used Pagid Yellows, I was likely on PF01s. Not a huge difference.

Why the C43 kit? If it’s weight, not sure it’s really worth it compared to the impact of improved braking.

For me, I’d consider throwing on the 4 wheels C43 kit to save some weight but I don’t need a parking brake for the TX state inspection. If it needs to be street legal then the ST40/355 kit is kind of a no brainer. You want a 4 wheel kit.


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[Obioban]

Neither.

After having a stop tech bbk on the m5 and a brembo bbk on the m3, I’ll never buy another stop tech bbk. Rotors last half as long, seals need to be replaced 5x as often, there’s no great street pad option, the caliper finish looks like shit quickly if you put heat into them, and if you get the 6 piston setup there’s dangerous levels of pad knock back.

Brembo makes a vastly superior product.

[bigjae46]

Neither.

After having a stop tech bbk on the m5 and a brembo bbk on the m3, I’ll never buy another stop tech bbk. Rotors last half as long, seals need to be replaced 5x as often, there’s no great street pad option, the caliper finish looks like shit quickly if you put heat into them, and if you get the 6 piston setup there’s dangerous levels of pad knock back.

Brembo makes a vastly superior product.

Brakes on an M5 won’t last nearly as long as they would on an M3.

For the 4 pot calipers, lots of street pads. Just need to look for Porsche 968 pads. Same FMSI shape - pagid, textar, etc.

6 pot calipers, not so much.

Agree that the finish isn’t the most durable. Should powdercoat instead of painting them.

To save money on track...great option. Likely not the best BBK out there but don’t see the need to spend more.

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[r4dr]

ST Trophy calipers are hard anodized aren't they?

If money were no object, the Essex kit with AP Radi-cal calipers would be my choice. The 991 GT3 guys I know have started switching over and swear by them. Essex also sells their 325mm kit which you can pair with either a matching rear AP caliper or stock rears.

[Obioban]

Brakes on an M5 won’t last nearly as long as they would on an M3.

For the 4 pot calipers, lots of street pads. Just need to look for Porsche 968 pads. Same FMSI shape - pagid, textar, etc.

6 pot calipers, not so much.

Agree that the finish isn’t the most durable. Should powdercoat instead of painting them.

To save money on track...great option. Likely not the best BBK out there but don’t see the need to spend more.

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To be clear, my rotors lasting half as long comment was based on running stoptech rotors on the M3 (with the brembo calipers). Once, and only once, due to their short life span compared to the brembo rotors. Penny wise and pound foolish.

I've tried all the street pad options for them stoptechs-- none have felts as good as stock BMW (or brembo) pads.

To save money, there's no beating the 996 retrofit. The parts to buy in are cheaper than a stoptech BBK, and replacements are free forever (FCP). That's why I'm running that setup on my M3 now-- free track pads and rotors from FCP forever.
(I still have the brembos in a box, in case FCP goes out of business)

[mrgizmo04]

For pads, I was just doing some research specific to st40 last night. 968, 944, mid/late 90s 911 with same pad shape, and if you like Ferodo pads, FCP Euro has 1.11 and 2500 (FCP Euro also carries Pagid and Textar street pads). FCP used to also carry DTC60 and 70, but no longer. So great options through a great source with warranty.

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[bigjae46]

To be clear, my rotors lasting half as long comment was based on running stoptech rotors on the M3 (with the brembo calipers). Once, and only once, due to their short life span compared to the brembo rotors. Penny wise and pound foolish.

I've tried all the street pad options for them stoptechs-- none have felts as good as stock BMW (or brembo) pads.

To save money, there's no beating the 996 retrofit. The parts to buy in are cheaper than a stoptech BBK, and replacements are free forever (FCP). That's why I'm running that setup on my M3 now-- free track pads and rotors from FCP forever.
(I still have the brembos in a box, in case FCP goes out of business)

The ST rotors are likely just regular Centric stuff. The 2 pc aero rotors are significantly better.

I feel like the OE pads/OE brakes are too touchy. I prefer a little less initial bite. The ST BBK are going to have less initial bite except with hot track pads.


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[EnzoAtMonza]

To be clear, my rotors lasting half as long comment was based on running stoptech rotors on the M3 (with the brembo calipers). Once, and only once, due to their short life span compared to the brembo rotors. Penny wise and pound foolish.

Do you have a part number for the brembo version of the rotors? I agree the stoptech rotors do wear to quickly if i have to bike the bullet I would rather swap to the brembo rotors.

Thanks

Jeff

[r4dr]

Do you have a part number for the brembo version of the rotors? I agree the stoptech rotors do wear to quickly if i have to bike the bullet I would rather swap to the brembo rotors.

Thanks

Jeff

Try these out: https://www.girodisc.com/Girodisc-35...ng_p_6580.html

Porsche guys run their two-piece rotors on the track and they last a very long time.

[Obioban]

The ST rotors are likely just regular Centric stuff. The 2 pc aero rotors are significantly better.

I feel like the OE pads/OE brakes are too touchy. I prefer a little less initial bite. The ST BBK are going to have less initial bite except with hot track pads.


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it's the stoptech 2 piece aero rotors I was running on the M3.

[Obioban]

Do you have a part number for the brembo version of the rotors? I agree the stoptech rotors do wear to quickly if i have to bike the bullet I would rather swap to the brembo rotors.

Thanks

Jeff

I don't know if it's possible to run brembo rings on stoptech hats (I was running stoptech rings on brembos hats, which is a known thing).

[mrgizmo04]

Knockback, if experienced, has several solutions, but I would say none is really ideal on a street car.
One is the springs of various force that can be installed behind the pistons, downside there is obviously that pads will always be dragging slightly on the rings. I think Zeckhausen sells them from 1lb to 10lbs of force.
The other is in the hardware that mounts the ring to the aluminum hat (the center piece) to make them fully floating. Depending on how the convex washers are oriented they will either act as a spring that "fixes" the hat/ring in place, or it will take the springiness out of it and make them fully floating if installed concave. Flat washers can also be used. Zeckhausen sells different hardware kits. Downside here is that fully floating setup is noisy and they also tend to hammer the hats on the mounting holes, which will require hat replacement at some (?) interval.

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[Sergmann]

To save money, there's no beating the 996 retrofit. The parts to buy in are cheaper than a stoptech BBK, and replacements are free forever (FCP). That's why I'm running that setup on my M3 now-- free track pads and rotors from FCP forever.
(I still have the brembos in a box, in case FCP goes out of business)

Which pads do you run?

[mrgizmo04]

Here is some info from Dave about Brembo rings on Stoptech hats and vice versa. Seems like larger sizes are a direct fit, vs

https://www.zeckhausen.com/catalog/index.php?cPath=82_1516

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