Bernb6
Go Kart Champion
- Location
- Palo Alto, CA
- Car(s)
- 2017 GTI Autobahn
BBK's generally have a number of potential advantages over GTI's PP brakes - IF you're currently taking your brakes to their heat limits.
1. Much better heat dissipation leading to
2. Much longer rotor life
3. Better pad life
4. Longer fluid life
5. Better brake feel
6. Easier pad changes*
7. Unsprung weight
8. Front to rear pad taper
Before I get flamed, let me say that I'm not advising people to go BBK. It's not needed in most cases. But the question has been asked about the (potential) benefits and these are the ones I have experience with. And I'm talking about my experience with Stoptech - other systems may be comparable or better in some aspects. I'm also not talking about value - how anyone spends their money is up to them.
Improved heat dissipation is a function of larger surface area and improved air flow through the center of the rotors. Internal vanes are curved to provide more centrifugal effect pulling air through the rotor and the open center allows more air in. If your calipers are discoloring or you see small cracks in your rotors, then they are getting pretty hot.
Two piece rotor material is different from single piece rotors and provide more thermal stability and much longer life. In extreme heat, single piece rotors are constrained in their thermal expansion and warp in the shape of a sombrero. Floating rotors simply expand as a flat ring. It's unlikely that many of us would be getting our stock rotors up to these temps but if you see your pads tapered such the the outer edges are thicker or thinner than the inner, this is the cause. Overheating rotors may need to be replaced because of large thermal cracks rather than wearing too thin. And the metal composition leads to much longer wear - in my personal experience, up to 4-6 times longer.
Pad life is affected by two factors: temperature and proper bedding. Overheated pads crumble, crack or glaze. Properly bedded brakes result in a thin layer of pad being laid on top of the rotor - you can see the color change when this is done and as it wears off. Proper bedding reduced the possibility of glazing and reduces both pad and rotor wear. Of course, street pads won't survive heat as well as track pads. If the rotors are 200 degrees cooler, pads last longer.
You've probably all seen night time photos of rotors glowing on race cars. Glowing happens at 900 degrees and higher. We are unlikely to be doing that but certainly can get to 600 and higher depending on our equipment and how we drive. A friend and I compared caliper temps coming into the paddock at Sonoma. My BBK temps were more than 100 degrees lower than his Macan calipers with PP rotors. But for most of us, using quality 600 or 660 fluid is enough to prevent fluid boiling.
*Stoptech calipers are not mono block. Once the wheels are off, pad changes take only a few minutes because the pads are quickly accessible from the top of the calipers. This also makes it easy to flip the pads to even out wear between inside and outside.
Stoptech BBK reduces weight at each wheel by 12 pounds over PP brakes Comparative weights (note, prices have gone up substantially since the price noted in the link)
Most multi piston calipers have a smaller piston at the caliper's leading edge since the the leading edge of the pad gets hotter. Macan calipers share this feature. But the GTI location of the caliper is reversed, so that the larger Macan piston is at the leading edge. In extreme use, this will exacerbate pad taper.
Bern
1. Much better heat dissipation leading to
2. Much longer rotor life
3. Better pad life
4. Longer fluid life
5. Better brake feel
6. Easier pad changes*
7. Unsprung weight
8. Front to rear pad taper
Before I get flamed, let me say that I'm not advising people to go BBK. It's not needed in most cases. But the question has been asked about the (potential) benefits and these are the ones I have experience with. And I'm talking about my experience with Stoptech - other systems may be comparable or better in some aspects. I'm also not talking about value - how anyone spends their money is up to them.
Improved heat dissipation is a function of larger surface area and improved air flow through the center of the rotors. Internal vanes are curved to provide more centrifugal effect pulling air through the rotor and the open center allows more air in. If your calipers are discoloring or you see small cracks in your rotors, then they are getting pretty hot.
Two piece rotor material is different from single piece rotors and provide more thermal stability and much longer life. In extreme heat, single piece rotors are constrained in their thermal expansion and warp in the shape of a sombrero. Floating rotors simply expand as a flat ring. It's unlikely that many of us would be getting our stock rotors up to these temps but if you see your pads tapered such the the outer edges are thicker or thinner than the inner, this is the cause. Overheating rotors may need to be replaced because of large thermal cracks rather than wearing too thin. And the metal composition leads to much longer wear - in my personal experience, up to 4-6 times longer.
Pad life is affected by two factors: temperature and proper bedding. Overheated pads crumble, crack or glaze. Properly bedded brakes result in a thin layer of pad being laid on top of the rotor - you can see the color change when this is done and as it wears off. Proper bedding reduced the possibility of glazing and reduces both pad and rotor wear. Of course, street pads won't survive heat as well as track pads. If the rotors are 200 degrees cooler, pads last longer.
You've probably all seen night time photos of rotors glowing on race cars. Glowing happens at 900 degrees and higher. We are unlikely to be doing that but certainly can get to 600 and higher depending on our equipment and how we drive. A friend and I compared caliper temps coming into the paddock at Sonoma. My BBK temps were more than 100 degrees lower than his Macan calipers with PP rotors. But for most of us, using quality 600 or 660 fluid is enough to prevent fluid boiling.
*Stoptech calipers are not mono block. Once the wheels are off, pad changes take only a few minutes because the pads are quickly accessible from the top of the calipers. This also makes it easy to flip the pads to even out wear between inside and outside.
Stoptech BBK reduces weight at each wheel by 12 pounds over PP brakes Comparative weights (note, prices have gone up substantially since the price noted in the link)
Most multi piston calipers have a smaller piston at the caliper's leading edge since the the leading edge of the pad gets hotter. Macan calipers share this feature. But the GTI location of the caliper is reversed, so that the larger Macan piston is at the leading edge. In extreme use, this will exacerbate pad taper.
Bern