Jessa

I was reading about Porsche's composit breaks and wondering what it would take to get them on a 928. Is it doable? Parts cost?

Jim bailey - 928 International

Probably more than you paid for either of your cars and possibly both !! and certainly not needed . If you have sufficient brakes to skid , lock your tires at anytime and a 928 any 928 should , you have exceeded the traction of the tires MORE brake will NOT stop any quicker just make it easier to overpower the traction of the tires . Add bigger stickier tires and you might benefit from bigger better brakes but the primary benefit is for repeated high speed stops and a slight increase in feel the ability to approach lockup but not skid because a rolling tire has more traction than one skidding . The vast majority of brake "upgrades" are for LOOKS not function ; not that there is anything wrong with that . Now the ceramic clutch on the Carrera GT v-10 that is another story 6.8 inch diameter muti-disc .

epbrown01

Read a current Porsche magazine. Several owners are reporting premature wear but Porsche is claiming it's normal and charging the full $10,000 for a brake service. But relax, that's discs, pads, and fluid - pads alone are only $3200! I doubt we want to know what it would cost to upgrade to them, calipers, brake lines and all.

Emanuel

Jim bailey - 928 International

Yes indeed "bragging rights" do not come cheap !! $10,000 brake service .

Jessa

eek!
Well, that sure satisfied my curiosity. Thanks

perrys4

Greg at precision was telling me about a GT2 that a magazine had ( not the one I work with I hope) that when it was returned to Porsche, they had to do all 4 brakes at a cost of $26,000.00 Was a dealer that did the work and Greg happened to be talking with the guy that did it. That is just insane...some people have waaayyy too much money!!

slate blue

There major advantage comes in the form of unsprung weight and less inertia. Less mass to accelerate and brake. This is one of the reasons an F1 car car easily outbrake a champ car. Yes I do know that F1 cars use carbon brakes, same principle. These things will get cheaper as time goes on.

hacker-pschorr

Mr. Bailey,
Correct me if I'm wrong, doesn't Mark run off the shelf Brembo's on his white race car? I know his car is quite a bit lighter than any of our cars, but I doubt many of us hit 180+ at Road America either.

So if he can get away with upgraded stock components, a street car is fine.

I don't have pictures, but my mechanic has 6-piston calipers on his 928, cannot remember the brand, I think it starts with an "A". That might be the hot setup for a 928 vs the composite stuff. Problem is you have to run huge wheels to make these fit.

hacker-pschorr

Here is a shot of Mark A's front brakes:

Mark Anderson

My front brakes consist of Ferrari F50 calipers which are just like S4 front but have a radius to work with 14" rotors. The rotors are standard 355mm racing rotors and I have used both Brembo and Performance Friction. You can buy the kit from Race Technologies for about $2,500. I still use stock rears as I have not seen a need more more rear brake. I have tried 3 different front brake set ups and this is by far the best and the reason it is so much better than S4 or GTS is the rotor diameter give you the best leverage. Even the new MB and Jaguars are using 14" front rotors now. For those of you thinking about 6 piston calipers keep in mind the necessary master cylinder size.

fst951

Hey Jim,

I think that you missed one of the biggest issues of all in large brakes. Inertia is very important, but the ability to shed heat and keep the coefficient of friction needed at high braking temperatures in probably the most important issue in choosing larger brakes. The caliper can hold more heat and disperse it better as well. Certainly so can the brake rotors. The new pick up trucks have smallish calipers still, but very large meaty rotors. This has nothing to do with being able to lock the wheels, for a caliper and rotor combo half the size will do that just fine. It is really about brake loading when pulling a trailer down a steep grade. They won't warp as easily and when you hit the brakes they will still be functional.

Also the Carrera GT clutch is nothing special. This technology has been around for years, decades maybe. Have a few on the shelf from Champ Cars. Nothing new to see here, keep on moving along...


Thanks

Jim bailey - 928 International

My old very brown 1980 which my son in law Jeff and I have been thrashing at the Streets of Willow 1.1 mile 12 turns the last couple years we tag teamed it so it often runs 30 minute sessions with only a brief driver change a couple hours per day total . Using good race pads we have never had a problem with brake fade and were able to brake late and hard . I did upgrade to S brakes primarily to see if the pads would last a bit longer but not for better braking . I do believe we drive it pretty hard and it weighs 3000 lbs plus . I took Andy Keel for a ride so total weight was more like 3500 lbs that session brakes were fine . My point was and is the stock 928 brakes are pretty good and far better than the vast majority of people will ever NEED . As far as trucks with trailers being PUSHED down a big hill anyone silly enough to ride the brakes and not use the engine to slow down probably deserves to have warped rotors and brake fade Where is that runaway truck ramp ??

goliver

The 911 guys on the pelican board that race the GT2 or 3 (whichever they come on) are changing to steel brakes because they have had issues with rapid wear and other problems that aren't supposed to happen with this system but do in competition. If you hang out there you can get the general view in a hurry. The consensus is they are junk. Sound good on paper but in the heat of battle don't justify the huge expense.

I was watching open practice this am on Speed for the Silverstone F1 race this weekend and David Hobbs and Steve Matchett both commented that steel brakes with todays technology are almost equal to carbon except for the weight penalty. With Hobbs who knows, but I think Matchett knows wherof he speaks as he was the head mechanic for Benetton back when Schumacher was becoming the guy to watch in F1.

Regards,

dr bob

In the late '80s we experimented with carbon brakes on our little 400lb Yamaha-powerd sports racer. Biggest advantage was pad and rotor life. We needed a special dispensation from SCCA to use the graphite rotors, BTW. They are WORTHLESS until they are racing hot, but would work fade-free once they got there. The warm-up lap was spent with a foot on the middle pedal to get the brakes up to temp before the green flag.

Most if not all of the carbon or graphite pads sold over the counter today are blends with a little graphite in them. They would be WORTHLESS or worse on a street car if they were the same ones the airplanes use, as we found out at the time.

One of the "who you know's" in our program was a principal at Hitco, which at the time was in the business of making composite seats for airliners and such. That gateway into the aircraft industry netted titanium suspension parts from the prototype shop at MM. along with the Ti roll hoops and footwell reinforcment. Hitco pulled the two-layer "monocoque" tubs, and we filled the cavity with foam to make a very rigid platform to hang the rest of the bits on. Lots of fun, working with what was then cutting-edge technology. Now every little stoplight gran-prix car has corbon-fiber this or that attached to it. To save weight I'm sure....

epbrown01

I just picked up the latest GT Purely Porsche today - they've got an entire article about the issues with ceramic rotors. An excerpt:

"Announced at the beginning of 2001 and launched with the 996 GT2 later the same year, Porsche billed its ceramic composite technology as a revolutionary leap forward in brake performance. Some 50% lighter than conventional steel rotors, PCCB was to offer a more consistent frictional co-efficient which rendered the high-tech system all but impervious to overheating and brake fade under the most extreme circumstances.

"At the same time, Porsche's literature claimed that, with a less abrasive surface than their conventional equivalents, ceramic rotors could be expected to last up to 300,000 kilometres (186,000 miles), while their composite construction meant that they could be 'absolutely immune to sale' duringthat life time."

"However, since the controversy sprung up some months ago, Porsche seems to have withdrawn the 300,000-kilometre service life claim and is instead now saying that 'the actual wear rate on sll brake components...is entirely dependent on individual driving styles.'

"But while Porsche's original lifetime longevity claims may have thus far proved true for the majority of customers, the enthusiast online forums and media alike have been abuzz with reports that a handful of track day drivers have found their PCCB kit to wear at alarming rates and, in worst case scenarios, experienced partial failure of their composite brakes in as little as 2000 miles."

The article goes on the state that a single rotor is $9250USD, while a complete set of brakes and pads are $49950!

Emanuel