Brembo 345mm rear big brake kits available today

DZeckhausen · 7th March 2003, 01:07

The Brembo rear brake upgrade is now available, effective today. Here are some highlights:

It comes with red, silver, or black calipers. These calipers are not the old Lotus calipers that Brembo used on other rear kits, but are a completely new design with 2x28mm and 2x30mm pistons. They look identical to the front calipers, although they are slightly thinner and use a different pad. On the red calipers, the Brembo logo is white, which may be different than some of the old front kits. All new Brembo kits with red calipers (front and rear) are shipping with white logos.

The rotors are directional, cross-drilled 345mm x 28mm and are floating, just like the Brembo front kit.

The parking brake function is retained by using the rotor hat as a parking brake drum. Installing this kit should be as easy as changing a set of stock rotors, plus installing new brake lines.

I'll have photographs as soon as someone from the NY/NJ area comes here to have one installed! Pricing and part numbers are here: http://www.zeckhausen.com/BMW/E39_M5.htm

Bigtime007 · 7th March 2003, 01:53

Just a quick question. Being that the stock M5 brakes are 13.6 front and 12.9 rear, would adding 14 inch brakes make that much of the difference? I understand that the sole purpose of these BBKs is to reduce brake fade. But would getting cross drilled rotors yield the same effect? I live 10 minutes from stoptech and when I stopped in and spoke to Jeff, he told me that this kit will only stop as good as your tires are. Any truth to this?

DZeckhausen · 7th March 2003, 02:13

Quote:

Originally posted by Bigtime007
Just a quick question. Being that the stock M5 brakes are 13.6 front and 12.9 rear, would adding 14 inch brakes make that much of the difference? I understand that the sole purpose of these BBKs is to reduce brake fade. But would getting cross drilled rotors yield the same effect? I live 10 minutes from stoptech and when I stopped in and spoke to Jeff, he told me that this kit will only stop as good as your tires are. Any truth to this?

The factory M5 rear rotors are 328mm x 20mm and the new Brembo rear rotors are 345mm x 28mm which represents a massive increase in thermal capacity. This would be impressive if the M5 braking was limited by the thermal capacity of the rear brakes. It's not.

The benefit of this rear brake upgrade is that it provides balance to the heavily front-biased Brembo front brake set-up. If I had a front-only Brembo kit, I would get this rear upgrade in a heartbeat, not because of the added thermal capacity, but because of the increased rear brake torque that will return better balance, and thus shorter stopping distance, to the M5. It also looks terrific! :-)

The advice you got at StopTech was valid for StopTech front brakes. If you have a StopTech front brake kit, your brakes are already balanced because that kit is not front biased like the Brembo. A side by side test hasn't happened yet, but I fully expect such a test would show the StopTech front brake kit to yield shorter stopping distances than the Brembo front brake kit. This is based on brake torque calculations done by StopTech using publicly available information on the Brembo caliper piston size, rotor dimensions, and pad swept area.

Who is Jeff? Do you mean Matt Weiss?

I don't agree with your statement that the only reason to get a big brake kit is to reduce fade. Big brake kits also give you a quicker reaction time which does nothing for you on the track but can make a significant difference on the street in a panic stop. They also give you firmer pedal feel and less pedal travel, making heel & toe downshifts easier. It's also easier to modulate these brakes than the stock brakes.

Drilled rotors will not improve your brake system's resistance to fade. Brakes are desinged to convert kinetic energy into heat. For a given stop, the lower the mass of the rotor, the higher the temperature after a stop. The same amount of energy stored in less metal will result in hotter rotors. By removing material (drilling) you are reducing the mass of the rotor and raising the temperature as compared to an identical non-drilled rotor. There is arguably some improvement in cooling with a drilled rotor, but this is a very small difference and convection is not a huge player in rotor cooling for a non ducted system. It's approximately 25 percent. Radiation is 50 percent. Conduction is another 25 percent.

Bigtime007 · 7th March 2003, 02:25

Thanks for the quick reply and the detailed explaination. Jeff is the sales rep at stoptech. He told me that upgrading your brakes will not reduce the length or the time of a stop. I think his exact words were "The chain is only as strong as the weakest link" Meaning if you had stok brakes on slicks, you would stop faster 100% of the time vs. stock brakes with street tires. He told me about the firmer brake feel, but didnt go into detail as to whether stainless steel lines would provide the same. I love the way these brakes look asthetically, but I'm just not sure if the actual functionality difference from stock is worth its price tag. I guess I would have to drive one to truly find out.

Quote:

Originally posted by DZeckhausen
The factory M5 rear rotors are 328mm x 20mm and the new Brembo rear rotors are 345mm x 28mm which represents a massive increase in thermal capacity. This would be impressive if the M5 braking was limited by the thermal capacity of the rear brakes. It's not.

The benefit of this rear brake upgrade is that it provides balance to the heavily front-biased Brembo front brake set-up. If I had a front-only Brembo kit, I would get this rear upgrade in a heartbeat, not because of the added thermal capacity, but because of the increased rear brake torque that will return better balance, and thus shorter stopping distance, to the M5. It also looks terrific! :-)

The advice you got at StopTech was valid for StopTech front brakes. If you have a StopTech front brake kit, your brakes are already balanced because that kit is not front biased like the Brembo. A side by side test hasn't happened yet, but I fully expect such a test would show the StopTech front brake kit to yield shorter stopping distances than the Brembo front brake kit. This is based on brake torque calculations done by StopTech using publicly available information on the Brembo caliper piston size, rotor dimensions, and pad swept area.

Who is Jeff? Do you mean Matt Weiss?

I don't agree with your statement that the only reason to get a big brake kit is to reduce fade. Big brake kits also give you a quicker reaction time which does nothing for you on the track but can make a significant difference on the street in a panic stop. They also give you firmer pedal feel and less pedal travel, making heel & toe downshifts easier. It's also easier to modulate these brakes than the stock brakes.

Drilled rotors will not improve your brake system's resistance to fade. Brakes are desinged to convert kinetic energy into heat. For a given stop, the lower the mass of the rotor, the higher the temperature after a stop. The same amount of energy stored in less metal will result in hotter rotors. By removing material (drilling) you are reducing the mass of the rotor and raising the temperature as compared to an identical non-drilled rotor. There is arguably some improvement in cooling with a drilled rotor, but this is a very small difference and convection is not a huge player in rotor cooling for a non ducted system. It's approximately 25 percent. Radiation is 50 percent. Conduction is another 25 percent.

JamE55 · 7th March 2003, 02:28

Dave

Question on there rear calipers. Are they 1-piece monoblock kind?

DZeckhausen · 7th March 2003, 02:40

Quote:

Originally posted by JamE55
Dave

Question on there rear calipers. Are they 1-piece monoblock kind?

No. They are two-piece with through-bolts, just like the Brembo F50 caliper and the StopTech ST40.

JamE55 · 7th March 2003, 02:41

Ok thanks!

stever · 7th March 2003, 05:06

the initial stopping distance of the M5 is tire-limited, not brake-limited

in terms of feel, i'm not sure that OEM brakes with stainless lines (in front at least -- the fronts do 80% of the work on an M5) will be noticeably different from aftermarket brakes (assuming the same pads)

Brembo or StopTech front brakes will allow a few more stops before braking distance increases with street pads -- this is mostly academic as you won't do enough hard stops on the street to experience it -- and you still can't run street pads on the track

StopTech front brakes can be used with stock front wheels -- the big spacers required by Brembos with stock wheels are not great

The real advantages of StopTech and Brembo are 1) easy pad changes if you track the car, and 2) aesthetics

a) if you're not going to track the car and aren't offended by the appearance of the M5 very effective "farm machinery" brakes leave it alone

b) if you want to track the car for low bucks, put in Superblue, stainless lines in front, and Pagid Oranges in front (and learn to live with some squeal)

c) StopTechs in front preserve brake balance, allow easy pad changes for the track, and work with stock wheels

d) Brembos or StopTechs all-round look great but will not stop the car any shorter or get you around the track any quicker

tfung · 7th March 2003, 09:11

any chance I can send my front brembo calipers in to get them changed to the white script? that's kind of annoying how it will have different color logo if you order the rear brakes now when you already have the front brakes

7th March 2003, 09:57

I want the rear Brembo kit with the red calipers (my fronts have a while Brembo logo). How about a bmwM5.com discount or a group buy discount?

Cheers.