Ideal Brake Kits for 991 GT3
10-03-2014, 05:01 PM
#31
Here are the corner weight figures we pulled from Keith's car While it was here at our shop. Left Front - 589 lbs Right Front - 621 lbs Left Rear - 1018 lbs right Rear - 984 lbs Total 3212 lbs front to rear ratio 37.7%/62.3% I am sure this will help explain the brake bias differences. Mike
10-03-2014, 05:57 PM
#32
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We have not made any adjustments to the suspension as of yet. These were the as delivered numbers that we recorded. Customer will be tracking the car at Daytona this weekend and we wanted to get a good feel for the car before we start making changes. Most cars are not perfectly corner weighted from the factory. Funny enough, his 458 was spot on
Since the car has coilovers, we will get the cross weights dead on for his next event. These are pretty close actually. A little adjustment will bring these numbers to 50/50 cross weight. As you jack the left front, the right rear will go up as well. We also will be looking at tire wear to see about increasing negative camber.
The other thing we are watching is rotor temps with the factory PCCB setup. We have applied thermal paint to each rotor to track how much heat the front and rear rotors are getting up to. Hopefully he keeps the nannies off
Since the car has coilovers, we will get the cross weights dead on for his next event. These are pretty close actually. A little adjustment will bring these numbers to 50/50 cross weight. As you jack the left front, the right rear will go up as well. We also will be looking at tire wear to see about increasing negative camber. The other thing we are watching is rotor temps with the factory PCCB setup. We have applied thermal paint to each rotor to track how much heat the front and rear rotors are getting up to. Hopefully he keeps the nannies off
10-06-2014, 12:20 AM
#33
Nordschleife Master
Not that I am thinking about my brake choice again, lol....can anyone tell me if the stock 991 GT3 red/iron rotor brakes have the closed caliper design not allowing pad changes without removing the caliper like the pccb yellow ones shown at the beginning of this thread ?
10-06-2014, 12:51 AM
#35
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Not that I am thinking about my brake choice again, lol....can anyone tell me if the stock 991 GT3 red/iron rotor brakes have the closed caliper design not allowing pad changes without removing the caliper like the pccb yellow ones shown at the beginning of this thread ?
10-06-2014, 01:15 AM
#36
Banned
There are some hot discussions in various threads about this topic - Center Lock, how hard or not to remove and install correctly may be somewhat debatable, nonetheless I like to illustrate the difference mechanically/physically between the two so that you can evaluate and exercise your own discretion in making such a choice. It's not just a matter of cost & how easy/hard on maintenance, more importantly it's the safety concern.
From above illustration, you can see automotive industry designs a hub follows the rule of physics and strength of material and below 3 criteria are related to the horsepower and weight of the vehicles:
1. The bolt size (M12 or M14)
2. The PCD (pitch circle diameter), from 100 to 150mm
3. The number of bolts (4, 5, 6 or 8)
So a smaller car can use smaller hub, bolt and least number of bolts, but as the vehicles get bigger and heavier, so is the bolt size, hub size (PCD) and number of bolts.
These bolts are used to transmit the torque from the shaft to brake rotor and wheels/tires, and the PCD is the leverage which subject to shearing stress, so you can now compare the leverage of a Center Wheel Lock vs. the conventional 997TT lug bolts
We also learn from the conventional wisdom; Don't put all your eggs in the same basket, if you don't disagree then you shall the risk of one single basket - Center Lock.
I bet you see someone drive his/her car with 1 or 2 broken studs or no wheel nuts, but definitely you will never see any Porsche owner drives a GT3 with a loose or missing Center Lock.
From above illustration, you can see automotive industry designs a hub follows the rule of physics and strength of material and below 3 criteria are related to the horsepower and weight of the vehicles:
1. The bolt size (M12 or M14)
2. The PCD (pitch circle diameter), from 100 to 150mm
3. The number of bolts (4, 5, 6 or 8)
So a smaller car can use smaller hub, bolt and least number of bolts, but as the vehicles get bigger and heavier, so is the bolt size, hub size (PCD) and number of bolts.
These bolts are used to transmit the torque from the shaft to brake rotor and wheels/tires, and the PCD is the leverage which subject to shearing stress, so you can now compare the leverage of a Center Wheel Lock vs. the conventional 997TT lug bolts
We also learn from the conventional wisdom; Don't put all your eggs in the same basket, if you don't disagree then you shall the risk of one single basket - Center Lock.
I bet you see someone drive his/her car with 1 or 2 broken studs or no wheel nuts, but definitely you will never see any Porsche owner drives a GT3 with a loose or missing Center Lock.
Also, having to take the calipers on and off for every pad change is not only more cumbersome, but more importantly, riskier. Frequent messing with the caliper bolts exposes them to stripping, damage, or over/under-torquing.
So between the center-locks and the closed calipers, the risks are doubly increased vs the old GT3 set-up.
10-06-2014, 09:05 AM
#37
Former Vendor
Thread Starter
Not that I am thinking about my brake choice again, lol....can anyone tell me if the stock 991 GT3 red/iron rotor brakes have the closed caliper design not allowing pad changes without removing the caliper like the pccb yellow ones shown at the beginning of this thread ?
Reference from 2014 GT3 Suspension Overview by Elephant Racing
Front:
Rear:
From the pictures the calipers for the standard brakes (iron rotors) appear the same as for PCCB except in color.
RB calipers are offered as an improvement to OE calipers not just for quick pad change but also the performance gain.
The front caliper will be a direct bolt on, while the rear will use an adaptor Both front and rear calipers are to be available shortly.
10-06-2014, 09:19 AM
#38
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Here are the corner weight figures we pulled from Keith's car While it was here at our shop.
Left Front - 589 lbs
Right Front - 621 lbs
Left Rear - 1018 lbs
right Rear - 984 lbs
Total 3212 lbs
front to rear ratio 37.7%/62.3%
I am sure this will help explain the brake bias differences.
Mike
Left Front - 589 lbs
Right Front - 621 lbs
Left Rear - 1018 lbs
right Rear - 984 lbs
Total 3212 lbs
front to rear ratio 37.7%/62.3%
I am sure this will help explain the brake bias differences.
Mike
Last edited by Nizer; 10-06-2014 at 03:13 PM.
10-06-2014, 09:29 AM
#39
Former Vendor
Thread Starter
^this. I'll say it again: 5 > 1
Also, having to take the calipers on and off for every pad change is not only more cumbersome, but more importantly, riskier. Frequent messing with the caliper bolts exposes them to stripping, damage, or over/under-torquing.
So between the center-locks and the closed calipers, the risks are doubly increased vs the old GT3 set-up.
Also, having to take the calipers on and off for every pad change is not only more cumbersome, but more importantly, riskier. Frequent messing with the caliper bolts exposes them to stripping, damage, or over/under-torquing.
So between the center-locks and the closed calipers, the risks are doubly increased vs the old GT3 set-up.
https://rennlist.com/forums/997-turb...rsion-kit.html
We are looking into an alternative solution to converting the Center Lock device back to conventional hub with embedded wheel bolts.
10-06-2014, 04:45 PM
#40
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I am currently waiting for a complete 991 hub and bearing to arrive in order to see if there is a way to convert it using available Porsche parts. If not, I have a machine shop who is going to quote me on what it would cost to fabricate a steel hub that will be a bolt in swap for the existing CL hub. One of the challenges will be to see how easy it is the pull the hub from the bearing without damaging the bearing. Stay tuned.
11-14-2014, 07:35 AM
#42
Status?
I'm done for this year and preparing for next (Winterfest), I'm trying to decide what to do for rotors?
What is the current status w/ R&D on these rotors from Racing Brake/AP? Last I heard, we'd pay more for a new slotted setup, but replacement steel rotors would be less (minus shoe) going forward?
I was really surprised how my OEM drilled rotors started cracking right at the getgo, but Suncoast sells replacements for $1100?
Whole point of this car was to avoid the mistakes I made on my last heavily modified GT-R and to keep this STOCK. Unlike tires, I think brakes are at that gray area but do want to look at options for rotors?
What is the current status w/ R&D on these rotors from Racing Brake/AP? Last I heard, we'd pay more for a new slotted setup, but replacement steel rotors would be less (minus shoe) going forward?
I was really surprised how my OEM drilled rotors started cracking right at the getgo, but Suncoast sells replacements for $1100?
Whole point of this car was to avoid the mistakes I made on my last heavily modified GT-R and to keep this STOCK. Unlike tires, I think brakes are at that gray area but do want to look at options for rotors?
11-18-2014, 09:17 PM
#43
Former Vendor
Thread Starter
Update
It took a while for us to receive OE rotor samples ordered from the dealer. Designs are done and the hats are being made, we expect to officially release the two piece stock iron rotor replacement in 2-4 weeks.
Front P/N: 2421 & Rear P/N: 2422
http://www.racingbrake.com/RB-Iron-R...por-irk-05.htm
We also will be offering optional upgrade to CCM-X rotors using S-T discs and retaining the use of OE (Red) calipers:
Front P/N: 2C26 & Rear P/N: 2C27
Price and availability will be added soon.
Front P/N: 2421 & Rear P/N: 2422
http://www.racingbrake.com/RB-Iron-R...por-irk-05.htm
We also will be offering optional upgrade to CCM-X rotors using S-T discs and retaining the use of OE (Red) calipers:
Front P/N: 2C26 & Rear P/N: 2C27
Price and availability will be added soon.
11-18-2014, 10:19 PM
#44
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It took a while for us to receive OE rotor samples ordered from the dealer. Designs are done and the hats are being made, we expect to officially release the two piece stock iron rotor replacement in 2-4 weeks.
Front P/N: 2421 & Rear P/N: 2422
http://www.racingbrake.com/RB-Iron-R...por-irk-05.htm
We also will be offering optional upgrade to CCM-X rotors using S-T discs and retaining the use of OE (Red) calipers:
Front P/N: 2C26 & Rear P/N: 2C27
Price and availability will be added soon.
Front P/N: 2421 & Rear P/N: 2422
http://www.racingbrake.com/RB-Iron-R...por-irk-05.htm
We also will be offering optional upgrade to CCM-X rotors using S-T discs and retaining the use of OE (Red) calipers:
Front P/N: 2C26 & Rear P/N: 2C27
Price and availability will be added soon.
