Building a split personality CS - a luxury cruiser on a date, an insane monster on the track...
Tires, wheels, brakes, suspension
Posted 02-06-2008 at 10:41 PM by facelvega
Though I may jump around a bit depending on lead times for different items, I would really like to start the project by addressing tires, wheels, brakes, and suspension. For both performance and luxury, reducing unsprung weight and reducing rotational mass is important. This is an area where both of the objectives can be in sync. Lower weight means the tire and wheel can stay more firmly planted on the pavement, or return to it more quickly after being bounced loose. Lower rotational mass allows for faster acceleration, braking, and turning. There is no downside in any way to reducing unsprung weight as long as strength is not sacrificed.
I will be looking at lightweight wheels, lightweight brake rotors and calipers, and lighter and more adjustable suspension.
For the suspension I am currently leaning towards PSS9, or PSS10 if available. The adjustable feature of the suspension will hopefully make it better at supporting a dual purpose car.
Stop Tech has some interesting lighter weight brake kits. They also have some carbon ceramic brakes in development. Of course, there is also Porsche PCCB as a possibility.
Wheels are wide open. The current group buy looks really good. I also want to check on a few other possibilities.
Tires will be a difficult and critical decision. One of the reasons the Cayman is so much quieter than the Cayman S is the narrower front tires. The front tires are perhaps the largest source of noise in the cabin. By using a quieter tire and by using a narrower tire, we can reduce the source of noise without having to add any soundproofing. The tradeoff between handling, noise and comfort push in opposite directions. I expect to use narrower tires for comfort, swap to wider for performance days.
From work I did starting out on this forum ("Comfort Tires"), I have shown that you can reduce noise and improve ride substantially with a tire change. The limit of the tire's ability to kill bumps is about 1/2" objects, however. This covers tar strips, expansion joints, etc. This is not insignificant, but will not help on potholes and rippled tar surfaces. This is where lighter unsprung mass and suspension adjustments come in. When your tire is bumped by a pothole, all it has to push against is the car. Force=Mass*Velocity^2, so the jolt you feel is directly proportional to the mass of the unsprung tire/wheel/brake/suspension. If we can cut the unsprung weight by 20%, the car will ride 20% smoother.
The Continental Sport Contact2 and Michelin PS2 are both lighter than the equivalent Bridgestone tires. A 225/40 x 18” PS2 weighs 21 pounds. A nice light wheel, such as the one in the RAC Monolite group buy which is currently going on weighs in at 18 pounds. This means we can bring in the front wheel at 39 pounds. My stock front wheel with a 19 inch CS wheel and Bridgestone tire weighs 47 pounds.
I will be scouring the boards, working on making final decisions. I currently have some Bridgestone, Pirelli, and Michelin tires on hand. I will be doing tire swaps to get a sense of how they ride and how they sound. From a weight standpoint, I am leaning towards Continental or Michelin tires, but still need to learn a bit more.
Suggestions and thoughts are always welcome!
I will be looking at lightweight wheels, lightweight brake rotors and calipers, and lighter and more adjustable suspension.
For the suspension I am currently leaning towards PSS9, or PSS10 if available. The adjustable feature of the suspension will hopefully make it better at supporting a dual purpose car.
Stop Tech has some interesting lighter weight brake kits. They also have some carbon ceramic brakes in development. Of course, there is also Porsche PCCB as a possibility.
Wheels are wide open. The current group buy looks really good. I also want to check on a few other possibilities.
Tires will be a difficult and critical decision. One of the reasons the Cayman is so much quieter than the Cayman S is the narrower front tires. The front tires are perhaps the largest source of noise in the cabin. By using a quieter tire and by using a narrower tire, we can reduce the source of noise without having to add any soundproofing. The tradeoff between handling, noise and comfort push in opposite directions. I expect to use narrower tires for comfort, swap to wider for performance days.
From work I did starting out on this forum ("Comfort Tires"), I have shown that you can reduce noise and improve ride substantially with a tire change. The limit of the tire's ability to kill bumps is about 1/2" objects, however. This covers tar strips, expansion joints, etc. This is not insignificant, but will not help on potholes and rippled tar surfaces. This is where lighter unsprung mass and suspension adjustments come in. When your tire is bumped by a pothole, all it has to push against is the car. Force=Mass*Velocity^2, so the jolt you feel is directly proportional to the mass of the unsprung tire/wheel/brake/suspension. If we can cut the unsprung weight by 20%, the car will ride 20% smoother.
The Continental Sport Contact2 and Michelin PS2 are both lighter than the equivalent Bridgestone tires. A 225/40 x 18” PS2 weighs 21 pounds. A nice light wheel, such as the one in the RAC Monolite group buy which is currently going on weighs in at 18 pounds. This means we can bring in the front wheel at 39 pounds. My stock front wheel with a 19 inch CS wheel and Bridgestone tire weighs 47 pounds.
I will be scouring the boards, working on making final decisions. I currently have some Bridgestone, Pirelli, and Michelin tires on hand. I will be doing tire swaps to get a sense of how they ride and how they sound. From a weight standpoint, I am leaning towards Continental or Michelin tires, but still need to learn a bit more.
Suggestions and thoughts are always welcome!
Total Comments 1
Comments
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Good info, but I have a question not any answers.
I weighed my Profile 10s (Fikse) wheels with the PS2s mounted. I also weighed the stock Carrera Classics with the stock PS2s mounted. They weighed about the same! I know these wheels are supposed to be lighter than stock but im not seeing it. Where is the weight loss? Stock: Carrera classic 19 8.5/9.0 New: Fikse Profil 10 18 8.5/10 |
 
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