Porsche Brembo 996 BBK conversion

[Tbonem3]

Rotors have changed. Few m3s are zcp.

[Arith2]

Rotors have changed. Few m3s are zcp.

This applies to me.

The 996 Brembo setup discussed here is using OE BMW rotors- there is no improvement in heat capacity, as the rotors have not changed. There is a difference between the base rotors and the ZCP rotors, but if you already have the ZCP rotors, there is no difference.

Rotors are definitely not the only factor in heat dissipation. It is objectively false that ZCP brakes have the same heat capacity. When losing pad material, you lose heat. When losing rotor material, you lose heat. Pads matched with certain rotors will affect this. That's literally how rocket engine stop from melting. There are four pistons with a lot more brake fluid as well as more caliper surface area to dissipate heat. There is more fluid in the calipers for heat capacity. The pads will also be applied more evenly rather than more on one side which will utilize the rotor cooling much more effectively. There is also the fact that there less force is applied with the same pedal force allowing for more fine tuned braking. You have a wider range of tolerance. Don't skip leg day and the performance is there.

[t44tq]

If there was a big difference in how much fluid was moved, you'd have to change the master cylinder.
If there was a big difference in swept area, the 996 setup wouldn't work over ZCP rotors.
Brake pistons do not dissipate heat- they're actually ideally thermally insulated so that it's harder for heat to get into the fluid.
Losing pad material actually generates the friction needed for braking and creates heat, not the other way around.

You're not fully versed in how brakes work based on your post above. Rotor mass is the biggest factor- the rotor is a big heat sink, which is why you need to ventilate the rotor and bring cool air to the rotor to help the rotor dissipate heat from braking.

Those thin 28mm rotors can't absorb that much heat- there's a good reason why motorsports brake setups generally have a lot more mass- the Essex/AP kit runs 32mm thick rotors, for example.

[t44tq]

Rotors have changed. Few m3s are zcp.

Base are 325x28mm, ZCP are 345x28mm. Bigger diameter, same thickness- you'll marginally increase heat capacity this way. You need to go thicker for great heat capacity. Thermal mass is the key.

[Obioban]

If there was a big difference in how much fluid was moved, you'd have to change the master cylinder.
If there was a big difference in swept area, the 996 setup wouldn't work over ZCP rotors.
Brake pistons do not dissipate heat- they're actually ideally thermally insulated so that it's harder for heat to get into the fluid.
Losing pad material actually generates the friction needed for braking and creates heat, not the other way around.

You're not fully versed in how brakes work based on your post above. Rotor mass is the biggest factor- the rotor is a big heat sink, which is why you need to ventilate the rotor and bring cool air to the rotor to help the rotor dissipate heat from braking.

Those thin 28mm rotors can't absorb that much heat- there's a good reason why motorsports brake setups generally have a lot more mass- the Essex/AP kit runs 32mm thick rotors, for example.

I'm actually surprised how well my ZCP (with 996 calipers) rotors are holding up. They've already outlasted the stoptech 335/32s I ran once (though they're not yet anywhere near the life I got out of the Brembo 355/32s, yet). That said, I also don't care-- being free (FCP) means service life basically isn't a consideration. But, I've already gotten a full year of events out of them.

[Tbonem3]

t44tq, show us where the evil 996 kit touched you

Or better yet, f/o to some other thread. No one claimed the 996 kit is the best. This is a diy thread.

[repoman89]

There is a pretty big difference in how much fluid is moved, the pedal has noticeably more travel than my stock ZCP setup did and some simple math will confirm. Some might choose to swap in a larger master cylinder if there was a plug and play one available for firmer brakes. I find it acceptable, makes it easier to heel and toe actually being a little deeper in the brakes.

[t44tq]

t44tq, show us where the evil 996 kit touched you

Or better yet, f/o to some other thread. No one claimed the 996 kit is the best. This is a diy thread.

A lot of people are under the misconception that this will improve your heat capacity, which is not correct. Since you have no manners I’m not going to continue engaging with you, but as an information sharing exercise, I posted my thoughts.

[Arith2]

A lot of people are under the misconception that this will improve your heat capacity, which is not correct. Since you have no manners I’m not going to continue engaging with you, but as an information sharing exercise, I posted my thoughts.

Your thoughts are not scientific and you are literally trying to tell us more contact area doesn't matter because the piston is somehow insolated by some imaginary barrier. The backing a brake pad is metal, which is highly conductive. Losing material does not create friction, it's because of friction. Stop giving feedback about things you don't understand. A 30 minutes bit of research to understand the basics of thermodynamics will show you what I said is true. If you don't want to look it up, that's perfectly fine but please stop giving out objectively false information.

It's ok you don't think the 996 kit is worth it. That doesn't negate that it has better performance in regards to heat.

[COVID-19]

This brings back m3forum memories

[Obioban]

A lot of people are under the misconception that this will improve your heat capacity, which is not correct. Since you have no manners I’m not going to continue engaging with you, but as an information sharing exercise, I posted my thoughts.

The ZCP rotors are 345x28mm, drilled, and floating. The stock rotors are 325x28mm, solid, and non floating. The ZCP rotors have more heat capacity, expel heat faster, and deal with heat better than stock. Not as much better as a good BBK rotor, but absolutely better than stock.

[t44tq]

Your thoughts are not scientific and you are literally trying to tell us more contact area doesn't matter because the piston is somehow insolated by some imaginary barrier. The backing a brake pad is metal, which is highly conductive. Losing material does not create friction, it's because of friction. Stop giving feedback about things you don't understand. A 30 minutes bit of research to understand the basics of thermodynamics will show you what I said is true. If you don't want to look it up, that's perfectly fine but please stop giving out objectively false information.

It's ok you don't think the 996 kit is worth it. That doesn't negate that it has better performance in regards to heat.

First point- if you're using the same ZCP rotor, you are limited by the dimensions of the friction surface. You can't really increase swept area, unless you get a long, curved caliper with a matching pad. 996 pads are rectangular and somewhat tall, so not the correct shape to increase swept area over the stock caliper. My point is, you're not effectively increasing swept area with the 996 setup- measure the swept area of the 996 pad versus the stock pad. I don't know the exact dimensions and don't care to look it up, but swept area is your limiting factor here.

Second- it's not an "imaginary barrier" that insulates a piston. If you look at a proper motorsports caliper's pistons, they are designed to prevent heat transfer from the pad to the caliper and fluid inside. Stainless steel (poor conductor) and vented.


Compare the image above to this one:


See the differences in the piston? The Porsche Brembo uses an aluminum piston, not vented, and the caliper has no venting either, compare to above.

My point is not that the ZCP rotor and the stock 325mm rotor have the same heat capacity- it's that if you compare the stock brake on the same ZCP rotor to the 996 setup, you're not gaining any heat capacity.

Brake pad backing plates are steel and are not designed to conduct heat- steel is a poor conductor. If they were supposed to conduct heat, they would not be painted, and would be made of aluminum, which is a far better heat conductor.

You can make personal attacks all you want, but it is clearly you who does not understand how good brakes work. Furthermore, if this setup requires more pedal travel, then you really need to change out master cylinders or you're actually _losing_ braking power. You're spreading around bad information, which people are taking as gospel. If you don't want to listen, sorry that you aren't willing to learn.

[Obioban]

First point- if you're using the same ZCP rotor, you are limited by the dimensions of the friction surface. You can't really increase swept area, unless you get a long, curved caliper with a matching pad. 996 pads are rectangular and somewhat tall, so not the correct shape to increase swept area over the stock caliper. My point is, you're not effectively increasing swept area with the 996 setup- measure the swept area of the 996 pad versus the stock pad. I don't know the exact dimensions and don't care to look it up, but swept area is your limiting factor here.

Second- it's not an "imaginary barrier" that insulates a piston. If you look at a proper motorsports caliper's pistons, they are designed to prevent heat transfer from the pad to the caliper and fluid inside. Stainless steel (poor conductor) and vented.


Compare the image above to this one:


See the differences in the piston? The Porsche Brembo uses an aluminum piston, not vented, and the caliper has no venting either, compare to above.

My point is not that the ZCP rotor and the stock 325mm rotor have the same heat capacity- it's that if you compare the stock brake on the same ZCP rotor to the 996 setup, you're not gaining any heat capacity.

Brake pad backing plates are steel and are not designed to conduct heat- steel is a poor conductor. If they were supposed to conduct heat, they would not be painted, and would be made of aluminum, which is a far better heat conductor.

You can make personal attacks all you want, but it is clearly you who does not understand how good brakes work. Furthermore, if this setup requires more pedal travel, then you really need to change out master cylinders or you're actually _losing_ braking power. You're spreading around bad information, which people are taking as gospel. If you don't want to listen, sorry that you aren't willing to learn.

Heat capacity isn't really an issue with the stock brakes, much less the ZCP brakes, assuming track pads/fluids. The main benefits of a BBK on this chassis are faster pad swaps (996 retains), rigidly mounted caliper for better feel (996 maintains), longer pad life through bigger pads (996 retains), and longer rotor life (996 does not retain, but makes free, so it doesn't matter).

[t44tq]

I was more responding to Arith2's allegations that I didn't know what I was talking about when it comes to heat management of braking systems. What he was talking about was wrong, about where and how heat transfers in braking systems. Also, the 996 brake caliper change does not improve heat capacity, which is what he claims.

[Arith2]

I was more responding to Arith2's allegations that I didn't know what I was talking about when it comes to heat management of braking systems. What he was talking about was wrong, about where and how heat transfers in braking systems. Also, the 996 brake caliper change does not improve heat capacity, which is what he claims.

Science is science and if you disagree, fine. The facts don't change. Don't take things so personally. I pointed out where you are wrong and you pointed out where you think I'm wrong. I don't know how that's personal.