Big Brake Kits. Alcon, Stoptech, Brembo?

[waterdamage]

Im having big problems with the brakes on my GEN 5. unfortunately the TA was not even in the works when I purchased mine. I push the car hard on track and clearly the track package stoptechs cant keep up. lots of brake fade! my last track day I used a set of Hawk Racing Pads (HB193 S.670) HT10 Compound.

I have steel braided lines and always use racing brake fluid.

currently Alcon has a big brake kit which upgrades the rotor from 355mm to 370mm and the caliper gets 6 pistons. I spoke with techs from stoptech and AP racing and they both told me that they also have upgrades for me. stoptech increases the rotor size to 380mm which means none of my wheels will fit, I would need custom wheels. I still have not obtained details for the AP racing kit.

I would like input from you guys as to which brand any of you have had experience with and any other suggestions.

here are 2 pictures from my last track day. you can see the aftermath on my stock rotors.

71117112

[XSnake]

Contact Tomball, they developed a BBK

[waterdamage]

do they have a specific department? or do I just call the parts department?

[XSnake]

I'd call Bernie or the parts Dept. You could also just try upgrading to the X rotors

[FLATOUT]

The guy you need to talk to there is Nathan, Bernie can get you to him, or just call the main number and ask for Nathan with Viper Exchange.

[waterdamage]

Do you have that number by chance?

[FLATOUT]

Water damage what braided lines are you using? I want to upgrade mine and switch to SRF fluid prior to COTA in December. I think Parts Rack has something coming out so I might need to talk to Jon B.

[Bruce H.]

I asked Kuno's crew chief about a brake upgrade for my TA's as the stock brakes were appearing borderline, and if I went with slicks and a suspension upgrade they would need to be changed. He recommended that I contact Tom Francis at SRT Motorsports as they apparently have a 15" 6 pot system, and the only wheel they would fit under is the SidewinderII that you have with your Track Pack. It's a Brembo system as I recall. I would definitely recommend that you also check with Jon B at Parts Rack as he is a Brembo dealer, and may be aware of other options as well.

I was definitely much harder on my brakes, from over-braking, but now use them much, much less. If that might apply in your case you could consider that.

Good luck, and be sure to tell us how you make out with your upgrade!

[Shooter]

You could also just try upgrading to the X rotors

Looking at your rotors leads me to agree with MTGTS. You might need the heavier setup like the X comes with. Good luck and good to see more people tracking the Gen V's.

[waterdamage]

Thanks for all your responses. Seems like a have some research to do. I'll keep you guys posted

[V10LEE]

I have the Stoptech 380mm 6 piston kit on my car. If you can get the other kit ( 370mm) that would be perfect since you won't need to get new wheels. I can tell you once you've tried these brakes on the track. You will never look back. The brakes bite HARD consistent lap after lap. I'm also running only a semi aggressive pad ( Carbotech 12's)..

[steve911]

The pads you use aren't the top of the line Hawk's for heavy track use Run the DTC 70's up front and the 60's in the rear.

I guarantee your rotors wont look like that. Stops all of the time without fade. they are about twice as expensive as the intermediate pads you use now. The HT 10's are not a true hard core track pad.

[05Commemorative]

I was going to say something similar. I think too many times people think it is the rotors or the calipers when in actuality is it the pads that make the difference. V10LEE, curious if you ran those carbotech's 12's on your oem rotors/calipers?


The pads you use aren't the top of the line Hawk's for heavy track use Run the DTC 70's up front and the 60's in the rear.

I guarantee your rotors wont look like that. Stops all of the time without fade. they are about twice as expensive as the intermediate pads you use now. The HT 10's are not a true hard core track pad.

[Nine Ball]

I asked Kuno's crew chief about a brake upgrade for my TA's as the stock brakes were appearing borderline, and if I went with slicks and a suspension upgrade they would need to be changed. He recommended that I contact Tom Francis at SRT Motorsports as they apparently have a 15" 6 pot system, and the only wheel they would fit under is the SidewinderII that you have with your Track Pack. It's a Brembo system as I recall. I would definitely recommend that you also check with Jon B at Parts Rack as he is a Brembo dealer, and may be aware of other options as well.

I was definitely much harder on my brakes, from over-braking, but now use them much, much less. If that might apply in your case you could consider that.

Good luck, and be sure to tell us how you make out with your upgrade!

This is the same system Tomball sells. Ben Keating had them on the front of his TA, looked amazing. He said there was a big difference.

[Bruce H.]

This is the same system Tomball sells. Ben Keating had them on the front of his TA, looked amazing. He said there was a big difference.

I had wondered when Ben showed the StopTechs installed on a car at Prefix during Homecoming, but I thought Matt at SRT had said the SRT's were Brembos. Did Ben confirm it is the same, and did he comment on the suitability of him using them just on the front of his TA vs all 4's as seen at Prefix? I assume he's tested his setup aggressively on track.

[FLATOUT]

I had wondered when Ben showed the StopTechs installed on a car at Prefix during Homecoming, but I thought Matt at SRT had said the SRT's were Brembos. Did Ben confirm it is the same, and did he comment on the suitability of him using them just on the front of his TA vs all 4's as seen at Prefix? I assume he's tested his setup aggressively on track.

Bruce he said that adding them on the front only, improved the brake bias issues we deal with in breaking zones. You know how the car likes to "shimmy" in under really heavy brakeing? That's due to the brake bias of having the same calipers front and rear (what Ben told us). He said that adding the 6 pistons up front and leaving the rears with the factory TA setup caused the car to behave much more predictably under heavy breaking.

[VENOM V]

Bruce he said that adding them on the front only, improved the brake bias issues we deal with in breaking zones. You know how the car likes to "shimmy" in under really heavy brakeing? That's due to the brake bias of having the same calipers front and rear (what Ben told us). He said that adding the 6 pistons up front and leaving the rears with the factory TA setup caused the car to behave much more predictably under heavy breaking.

That's encouraging. I'm thinking of going to an in-between set up, not yet feeling the need for 6 pistons. I'm thinking of having two sets of pads and rotors, one for street and the other for track. For the street, stock pads and Stoptech rotors.

For the track:
Front: TA rotors with TA Carbotech pads
Rear: Stoptech rotors with Carbotech pads

This will give the front more bite and may improve the shimmy / brake bias issue. I had been thinking about running TA rotors front and rear, but this may work better.

[FLATOUT]

I know there is a set of Gen V SS lines about to be released as well.

[Simms]

Bruce he said that adding them on the front only, improved the brake bias issues we deal with in breaking zones. You know how the car likes to "shimmy" in under really heavy brakeing? That's due to the brake bias of having the same calipers front and rear (what Ben told us). He said that adding the 6 pistons up front and leaving the rears with the factory TA setup caused the car to behave much more predictably under heavy breaking.

Stoptech or Brembo up front?

[mjorgensen]

Bruce he said that adding them on the front only, improved the brake bias issues we deal with in breaking zones. You know how the car likes to "shimmy" in under really heavy brakeing? That's due to the brake bias of having the same calipers front and rear (what Ben told us). He said that adding the 6 pistons up front and leaving the rears with the factory TA setup caused the car to behave much more predictably under heavy breaking.

The front and rear calipers are not the same, they have different sized pistons that give you the bias balance front to rear already.

The different compounds that Carbotech offer is a great way to change the front to rear bias based on the track and braking requirements.

[JonB ~ PartsRack]

I agree with Steve and others that you are probably over-driving the Hawk HT10s.

And that ACR-X Front Brembo rotors / Pads are most probably all you should need (but they are HEAVY, unlike StopTech)

I think you mis-understood Ben, the caliper blocks are the same, the pads are the same, but the rear pistons are smaller.

PartsRack has FIA-Spec G5 SS lines delivered to Tomball, Cragin, and one other CA race shop for final testing this weekend. We are being overly-cautious even tho we are 100% confident...The custom frame-fittings are very tricky!

A few sets of G5 SS lines should be ready to ship by next week. Advanced orders accepted, to JonB@PartsRack.com

[FLATOUT]

Ok, thanks for correcting my mis statement. Same size stock calipers with different pistons. My car still feels slightly squirly under heavy braking. Not out of control, but it would be nice to improve it with a bigger front setup.




The front and rear calipers are not the same, they have different sized pistons that give you the bias balance front to rear already.

The different compounds that Carbotech offer is a great way to change the front to rear bias based on the track and braking requirements.

[ViperGeorge]

Everyone contemplating a brake system upgrade should check out the following white paper on the Stop Tech site:

http://stoptech.com/technical-support/technical-white-papers/brake-system-and-upgrade-selection

From this white paper:

"1) The brakes don't stop the vehicle - the tires do. The brakes slow the rotation of the wheels and tires. This means that braking distance measured on a single stop from a highway legal speed or higher is almost totally dependent upon the stopping ability of the tires in use - which, in the case of aftermarket advertising, may or may not be the ones originally fitted to the car by the OE manufacturer.

2) The brakes function by converting the kinetic energy of the car into thermal energy during deceleration - producing heat, lots of heat - which must then be transferred into the surroundings and into the air stream.
The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 Mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 Hp. The disc dissipates approximately 80% of this energy. The ratio of heat transfer among the three mechanisms is dependent on the operating temperature of the system. The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with disc used for racecars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1000oF the ratios on a racing 2-piece annular disc design are 10% conductive, 45% convective, 45% radiation. Similarly on a high performance street one-piece design, the ratios are 25% conductive, 25% convective, 50% radiation.

3) Repeated hard stops require both effective heat transfer and adequate thermal storage capacity within the disc. The more disc surface area per unit mass and the greater and more efficient the mass flow of air over and through the disc, the faster the heat will be dissipated and the more efficient the entire system will be. At the same time, the brake discs must have enough thermal storage capacity to prevent distortion and/or cracking from thermal stress until the heat can be dissipated. This is not particularly important in a single stop but it is crucial in the case of repeated stops from high speed - whether racing, touring or towing.

4) Control and balance are at least as important as ultimate stopping power. The objective of the braking system is to utilize the tractive capacity of all of the tires to the maximum practical extent without locking a tire. In order to achieve this, the braking force between the front and rear tires must be nearly optimally proportioned even with ABS equipped vehicles. At the same time, the required pedal pressure, pedal travel and pedal firmness must allow efficient modulation by the driver.

5) Braking performance is about more than just brakes. In order for even the best braking systems to function effectively, tires, suspension and driving techniques must be optimized.
For maximum brake potential, vehicles benefit from proper corner weight balance, a lower CG, a longer wheelbase, more rear weight bias and increased aerodynamic down force at the rear.

To go further it is necessary to understand some of the physics involved, and that requires some definitions.

1) Mechanical pedal ratio: Because no one can push directly on the brake master cylinder(s) hard enough to stop the car, the brake pedal is designed to multiply the driver's effort. The mechanical pedal ratio is the distance from the pedal pivot point to the effective center of the footpad divided by the distance from the pivot point to the master cylinder push rod. Typical ratios range from 4:1 to 9:1. The larger the ratio, the greater the force multiplication (and the longer the pedal travel).

2) Brake line pressure: Brake line pressure is the hydraulic force that actuates the braking system when the pedal is pushed. Measured in English units as pounds per square inch (psi), it is the force applied to the brake pedal in pounds multiplied by the pedal ratio divided by the area of the master cylinder in square inches. For the same amount of force, the smaller the master cylinder, the greater the brake line pressure. Typical brake line pressures during a stop range from less than 800psi under "normal" conditions, to as much as 2000psi in a maximum effort.

3) Clamping force: The clamping force of a caliper is the force exerted on the disc by the caliper pistons. Measured in pounds clamping force, it is the product of brake line pressure, in psi, multiplied by the total piston area of the caliper in square inches. This is true whether the caliper is of fixed or floating design. Increasing the pad area will not increase the clamping force.

4) Braking torque: When we are talking about results in the braking department we are actually talking about braking torque - not line pressure, not clamping force and certainly not fluid displacement or fluid displacement ratio. Braking torque in pounds-feet on a single wheel is the effective disc radius in inches times clamping force times the coefficient of friction of the pad against the disc all divided by 12. The maximum braking torque on a single front wheel normally exceeds the entire torque output of a typical engine.

A few things are now obvious:
1) Line pressure can only be increased by either increasing the mechanical pedal ratio or by decreasing the master cylinder diameter. In either case the pedal travel will be increased.

2) Clamping force can only be increased either by increasing the line pressure or by increasing the diameter of the caliper piston(s). Increasing the size of the pads will not increase clamping force. Any increase in caliper piston area alone will be accompanied by an increase in pedal travel. The effectiveness of a caliper is also affected by the stiffness of the caliper body and its mountings. It is therefore possible to reduce piston size while increasing caliper stiffness and realize a net increase in clamping force applied. This would typically improve pedal feel.

3) Only increasing the effective radius of the disc, the caliper piston area, the line pressure, or the coefficient of friction can increase brake torque. Increasing the pad area will decrease pad wear and improve the fade characteristics of the pads but it will not increase the brake torque."

So, bigger diameter rotors will increase brake torque and braking, so will better tires. Using pads with a higher coefficient of friction will improve braking (I use Raybestos ST44 in front and ST 43 in rear). Using a pad material with a high thermal operating range will also reduce fade. Using the same diameter rotors with more swept area (such as the ACR-X rotors) will not increase braking but will improve heat capacity resulting in less fade.

[JonB ~ PartsRack]

The LAST sentence there: Using the same diameter rotors with more swept area (such as the ACR-X rotors) will not increase braking but will improve heat capacity resulting in less fade... in-re ACR-X rotors is why I talk a lot of owners OUT of buying them! The -X racer was initially designed to use the StopTech rotors, but the 45-90 minute sessions in Viper Cup races exceeded the thermal capacity of the ACR-Rotor. So SRT chose the heavier, larger Brembo. {PartsRack purchased all the take-off ACR-X OE pads, rotors, and A/C equip.}

So if you are a typical HPDE-driver, with 20-30 minute sessions, you probably don't need or want the significant extra rotating unsprung mass. Look first to: Tires, Pads, Fluid, SS lines, Cooling, lighter-slotted rotors, BEFORE you assume that 'bigger-is-better'.

And Remember the tracking rules-of-thumb:

FIRST make it TURN BETTER;
THEN make it STOP Better;
THEN, you can add power.....

[J TNT]

Good advice and thanks for the Stop Tech Rotors Jon ! :)

[XSnake]

And that ACR-X Front Brembo rotors / Pads are most probably all you should need (but they are HEAVY, unlike StopTech)


What does a Stoptech front rotor weigh?

[Bruce H.]

I have had the rear wiggle under heavy braking pretty much disappear at times. I put it down to tire pressures and tread depth because nothing else in my set-up had changed. I'd be curious if others have found the wiggle to be affected when using different pressures, R-compounds with less tread depth, or with slicks. The same wiggle exists on the 911 GT3 RS, and the proven fix is to replace rear suspension rubber bushings to solids. I've also considered if a change in brake bias is needed on my car, but it actually seems perfect for the tracks I drive, and my driving style. If I were to drive much more aggressively I might find a need to change bias, and a change of pads would be my first step. Perhaps changing the brake bias affects the wiggle, but isn't the actual cause of it?

[FLATOUT]

Possibly. I think a small adjustment as you mentioned with the bushings could cure it.


I have had the rear wiggle under heavy braking pretty much disappear at times. I put it down to tire pressures and tread depth because nothing else in my set-up had changed. I'd be curious if others have found the wiggle to be affected when using different pressures, R-compounds with less tread depth, or with slicks. The same wiggle exists on the 911 GT3 RS, and the proven fix is to replace rear suspension rubber bushings to solids. I've also considered if a change in brake bias is needed on my car, but it actually seems perfect for the tracks I drive, and my driving style. If I were to drive much more aggressively I might find a need to change bias, and a change of pads would be my first step. Perhaps changing the brake bias affects the wiggle, but isn't the actual cause of it?

[Shooter]

I know there is a set of Gen V SS lines about to be released as well.

Thanks for taking them for the initial install dude. I planned on getting with Morgan this week, but now having to head back out so quick, I just don't have the time. I'll get the 2nd set :)

[FLATOUT]

Thanks for taking them for the initial install dude. I planned on getting with Morgan this week, but now having to head back out so quick, I just don't have the time. I'll get the 2nd set :)

Always nice swinging by your place, wish I wasn't in such a hurry today. We'll get them on later this week and see how everything seals up.