The Porsche brake caliper 'conspiracy'
12-06-2013, 08:10 PM
#1
Nordschleife Master
Thread Starter
The Porsche brake caliper 'conspiracy'
So, a bunch of us that track cars have been bitching about how the entire brake caliper has to be removed now on all new Porsche cars, including the GT3, in order to change brake pads.
I helped a buddy of mine with his 991S the other day, and it's a total pain in the ***. Not only does it take a lot more time, but you have to worry about hanging the caliper, replacing the caliper bolts or risk cross threading, and stressing the hard brake lines. This basically makes swapping street/track pads not feasible. I'll probably run track pads 100% of the time and forget the OEM street pads. Swapping to a caliper stud kit and getting flexible braided lines to replace the hard lines will help, but it still won't be as easy as the traditional 'pop out the pins/bolt, then swap pads' that we all used to enjoy.
Why was this done? According to brembo and Porsche, they did it to make the caliper more rigid, and this was the 'sacrifice'. I noticed that some (not all) of brembo's aftermarket kits had the same 'bar' running across, and basically surrendered that they had a good reason to do it.
Fast forward to today, where I had a chance to drive the cadillac CTS-V around Sonoma raceway. Doing my best to forget the horrible experience of having a female instructor constantly yell at you to slow down, brake, and let off the throttle, while going at a blistering 3/10ths pace, I did some exploring and asked some questions while at the exhibits. This is what I found:
Notice something? These are 6 piston brembo calipers used on a 560+hp CTS-V that look pretty damn similar to the Porsche 6pot calipers. NO BAR!. Easy, 'old school' in/out of the brake pads. I asked the brembo rep that was at the event why some calipers have the bar and others don't. His answer to me was that they put the bar there if the 'customer' (ie porsche) requests it. The funny thing is, the rep had a presentation about the brake calipers and highlighted 'serviceability ease' for pad changes in his presentation. While this doesn't change my love for the new GT3, I find it strange for Porsche to do this. Is it really a 'conspiracy' to stop people from changing pads and jacking up service hours for the dealers? What the hell am I supposed to do with my girodisc pad spreader now?? LOL.
Take a look at the C7 calipers. Brembo. Easy in/out:
I helped a buddy of mine with his 991S the other day, and it's a total pain in the ***. Not only does it take a lot more time, but you have to worry about hanging the caliper, replacing the caliper bolts or risk cross threading, and stressing the hard brake lines. This basically makes swapping street/track pads not feasible. I'll probably run track pads 100% of the time and forget the OEM street pads. Swapping to a caliper stud kit and getting flexible braided lines to replace the hard lines will help, but it still won't be as easy as the traditional 'pop out the pins/bolt, then swap pads' that we all used to enjoy.
Why was this done? According to brembo and Porsche, they did it to make the caliper more rigid, and this was the 'sacrifice'. I noticed that some (not all) of brembo's aftermarket kits had the same 'bar' running across, and basically surrendered that they had a good reason to do it.
Fast forward to today, where I had a chance to drive the cadillac CTS-V around Sonoma raceway. Doing my best to forget the horrible experience of having a female instructor constantly yell at you to slow down, brake, and let off the throttle, while going at a blistering 3/10ths pace, I did some exploring and asked some questions while at the exhibits. This is what I found:
Notice something? These are 6 piston brembo calipers used on a 560+hp CTS-V that look pretty damn similar to the Porsche 6pot calipers. NO BAR!. Easy, 'old school' in/out of the brake pads. I asked the brembo rep that was at the event why some calipers have the bar and others don't. His answer to me was that they put the bar there if the 'customer' (ie porsche) requests it. The funny thing is, the rep had a presentation about the brake calipers and highlighted 'serviceability ease' for pad changes in his presentation. While this doesn't change my love for the new GT3, I find it strange for Porsche to do this. Is it really a 'conspiracy' to stop people from changing pads and jacking up service hours for the dealers? What the hell am I supposed to do with my girodisc pad spreader now?? LOL.
Take a look at the C7 calipers. Brembo. Easy in/out:
12-06-2013, 08:20 PM
#2
Rennlist Member
Well isn't that interesting, makes you wonder if they're trying to drum up more business for the dealer network.
On the other hand we know Porsche has better engineering than GM (better for the price), perhaps this is one of those little things that makes a significant difference when you add all the little things up???
On the other hand we know Porsche has better engineering than GM (better for the price), perhaps this is one of those little things that makes a significant difference when you add all the little things up???
12-06-2013, 08:23 PM
#3
Race Director
Maybe the GM corporate customer's engineers have lower standards for the performance of their braking systems than do Porsche's. 
I get the PITA factor, just sayin' it's an alternative explanation to the conspiracy theory. Interesting either way......
I get the PITA factor, just sayin' it's an alternative explanation to the conspiracy theory. Interesting either way......
12-06-2013, 08:32 PM
#4
Nordschleife Master
Thread Starter
Well isn't that interesting, makes you wonder if they're trying to drum up more business for the dealer network.
On the other hand we know Porsche has better engineering than GM (better for the price), perhaps this is one of those little things that makes a significant difference when you add all the little things up???
On the other hand we know Porsche has better engineering than GM (better for the price), perhaps this is one of those little things that makes a significant difference when you add all the little things up???
Also, has anyone had any problems with the old design on their Porsches? I haven't...
12-06-2013, 08:38 PM
#5
Race Director
OK, but Brembo apparently builds the brakes to the spec of the car manufacturer. It's not who builds the caliper in this case, it's the specific design that they build it to. Maybe Porsche's requirements for their Brembo brakes are more rigid. (pun intended)
12-06-2013, 08:43 PM
#6
Nordschleife Master
Thread Starter
12-06-2013, 08:46 PM
#7
Nordschleife Master
Thread Starter
It's kind of funny that nobody complained about the old brake design, but they changed it.
People bitch constantly about the center locks..... And they're still there. Hopefully they are better than the old design, though.
People bitch constantly about the center locks..... And they're still there. Hopefully they are better than the old design, though.
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12-06-2013, 08:56 PM
#9
Rennlist Member
Don't have my car yet but are the new ones forged one piece calipers? Or still two pieces mated on a seam line with the bar? Typically they'll claim they're stiffer but like you said I've never had a problem with the two piecers. My one piece forged Alcons we're amazing but I don't know if I could objectively say they were that much better because of the single piece with no bridge.
12-06-2013, 09:01 PM
#10
Nordschleife Master
Thread Starter
Don't have my car yet but are the new ones forged one piece calipers? Or still two pieces mated on a seam line with the bar? Typically they'll claim they're stiffer but like you said I've never had a problem with the two piecers. My one piece forged Alcons we're amazing but I don't know if I could objectively say they were that much better because of the single piece with no bridge.
12-06-2013, 09:06 PM
#11
Three Wheelin'
Having owned a 2009 Corvette Z06 and a 2010 Corvette ZR1 I can attest that GM often doesn't put the engineering thought behind the design decisions made for even their highest performance vehicles.
The C5 Z06 was known for very uneven pad wear with pads getting a wedge shape in the radial direction caused by caliper spreading kind of equally.
C6 Z06 is known for pads getting a wedge shape in the opposite direction (if one piece pads are used) so one end of the caliper is spreading more than the other or the pressure on the pad is uneven. This is the reason PBR used the "padlets"
On the ZR1 I'm not aware of a caliper spreading and uneven pad wear issues, but GM did a poor job of the requirements flowed to Brembo for the acceptable balance of the carbon ceramic rotors. The ZR1 steering is very sensitive to poor rotor balance and a poorly balanced rotor or pair of poorly balanced rotors causes the wheel to shake pretty violently - I personally went round and round until GM sent out a field engineer and authorized new rotors. The new rotors were still not perfect and required 1/2 to 1 oz of additional wheel weight to be really smooth with no steering vibration.
I'm an engineer by day and I cannot fathom Porsche engineers selecting that additional stiffener in such a critical system if there was not good engineering justification. Also keep in mind small portions of structure can have a number of purposes including strength, stiffness, vibration dampening, thermal mass, thermal conductivity, etc.
I wouldn't take the word of a Brembo factory rep (not a Brembo design engineer) that the bar is merely provided on a customer whim.
Ryan
The C5 Z06 was known for very uneven pad wear with pads getting a wedge shape in the radial direction caused by caliper spreading kind of equally.
C6 Z06 is known for pads getting a wedge shape in the opposite direction (if one piece pads are used) so one end of the caliper is spreading more than the other or the pressure on the pad is uneven. This is the reason PBR used the "padlets"
On the ZR1 I'm not aware of a caliper spreading and uneven pad wear issues, but GM did a poor job of the requirements flowed to Brembo for the acceptable balance of the carbon ceramic rotors. The ZR1 steering is very sensitive to poor rotor balance and a poorly balanced rotor or pair of poorly balanced rotors causes the wheel to shake pretty violently - I personally went round and round until GM sent out a field engineer and authorized new rotors. The new rotors were still not perfect and required 1/2 to 1 oz of additional wheel weight to be really smooth with no steering vibration.
I'm an engineer by day and I cannot fathom Porsche engineers selecting that additional stiffener in such a critical system if there was not good engineering justification. Also keep in mind small portions of structure can have a number of purposes including strength, stiffness, vibration dampening, thermal mass, thermal conductivity, etc.
I wouldn't take the word of a Brembo factory rep (not a Brembo design engineer) that the bar is merely provided on a customer whim.
Ryan
Last edited by reidry; 12-06-2013 at 09:47 PM.
12-06-2013, 09:45 PM
#13
Rennlist Member
12-06-2013, 09:49 PM
#14
Three Wheelin'
12-06-2013, 09:53 PM
#15
Nordschleife Master
Thread Starter