Big Brake Kits
So what is the best Big Brake Kit ?
We list kits from AP, Stoptech & Brembo and can also supply bespoke kits from smaller manufacturers but the most important aspect of performance braking is to ensure that you are not getting brake fade on any axle. The primary reason for upgrading to a Bigger Brake Kit is to eliminate the weaknesses of the factory system. Generally speaking the weakness comes not on the first or second stop, but under consistent heavy braking. Sliding piston calipers work brilliantly for a long life on the road car, but their inconsistent application of pressure to the pad, poor release characteristics combined with high weight and weak heat capability make them a poor choice for high-performance use.
We've recently seen a manufacturer of brakes launch a range of Big Brake Kits which they market as a Balanced Brake Kit. Stoptech brakes have a trademark registered for Balanced Big Brake Kits®. What does that mean though? Depending on the driver and the application (e.g Race, Sprint, Road etc) brake balance is generally best when it's either adjustable or fully automated. A modern car with an ABS system will continuously monitor the braking performance based on telemetry from various sensors, in conjunction with the ABS system in heavy braking situations. A race car will tend to have a pedal box with a brake bias valve. Either way brake balance is achieved by the electronics or the driver. Granted it certainly makes sense if on a budget, that when you upgrade the front brakes you do something to the rear. This is where Stoptech brake kits score as they will size the pistons accordingly to ensure the car has the correct balance. So although they only offer a handful of calipers there are many piston sizes.
If you want a big brake kit on the front axle (where the majority of upgrades occur due to static and dynamic weight transfer) then we'd generally recommend using the same pad compound in the rear, however sometimes this may vary. For example in a Saloon you could find Ferodo DS2500 in the rear works well with Ferodo DS3000 in the front. .
The reality is for a truly balanced brake upgrade you need to consider the overall set up of the car and the operating environment. You may need larger brakes front and rear, you may need a different brake compound in the front and rear, you may need to monitor temperatures and add more cooling. You may even need to remove the ABS system on a race vehicle, add a different master cylinder and a bias valve.
FOR A TRULY BALANCED BRAKE SYSTEM CONTACT BALANCE MOTORSPORT - it's in the name !
As well as the larger discs which increase braking performanceincrease the heat capacity of the system.
Technical information on pedal effort
If you fit a Big Brake Kit, the larger discs will increase the braking mechanical advantage. This will reduce pedal effort. If you find this results in brakes that are too sensitive for track use you can increase pedal effort by changing the master cylinder or removing the brake servo. A larger master cylinder bore size will increase pedal effort but reduce pedal travel. Master cylinders are usually available in inch sizes, pedal effort in lbs per sq inch and piston sizes in mm (great!).
Some formulas will demonstrate what you might end up with:
If you increase disc size from 284mm to 300mm you would end up with a 5% decrease in the pedal force required to get the same braking force (assuming the piston area in the caliper remains the same). Therefore a 100lb force required before would become 95lb
New pedal force = Pedal force x (Old brake disc radius/New brake disc radius)
The rolling radius of the tyre has the opposite effect - increase the diameter of the tyre/wheel combination and you increase the pedal force required.
New pedal force = Pedal force x (Old tyre radius/New tyre radius)
In this case if you went from a 14” Wheel with 195/60 up to a 16” wheel with 205/55 you would increase the pedal effort required by 10% (bear in mind though legally for road use rolling radius must be no more than +/- 3% from Original specification. So when people say they will fit bigger wheels to fill the arches you know they aren't aware of this!)
When looking at master cylinders the formula is as follows:
New pedal force = Pedal force x (new master cylinder bore diameter²/ old master cylinder bore diameter)²
Because of the square in the above formula the effect of a change is more pronounced. E.g a move from a 1” master cylinder to a 1.25” master cylinder will change the pedal force required from 100lbs to 156lbs.
Next thing to remember is bigger pistons in the calipers mean more force and, therefore, less pedal effort. Bigger pistons in the calipers mean more pedal movement. For comparing one brake to another on the same car, you can simply multiply the total caliper piston area times the effective radius. If you have a sliding calliper although it has piston(s) on one side only the area should be doubled. A single piston sliding calliper with the same piston size as a twin fixed calliper will have the same clamping force, this is due to the fact that the pressure from piston operates on both sides via the sliding mechanism.
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- AP Factory Big Brake Kit - AUDI A4 Front 1994- 6 pot 330 mm disc 8x17 inch wheel£2,723.15 £2,269.29AP Factory Big Brake Kit - AUDI A4 Front 1994- 6 pot 330 mm disc 8x17 inch wheel Learn More
- AP Factory Big Brake Kit - AUDI A6/ A6S Front 1994/97 6 pot 343 mm disc 8x17 inch wheel£3,618.95 £3,015.79AP Factory Big Brake Kit - AUDI A6/ A6S Front 1994/97 6 pot 343 mm disc 8x17 inch wheel Learn More
- AP Factory Big Brake Kit - AUDI A8 Front 1994- 6 pot 325 mm disc 7x17 inch wheel£3,235.64 £2,696.37AP Factory Big Brake Kit - AUDI A8 Front 1994- 6 pot 325 mm disc 7x17 inch wheel Learn More
- AP Factory Big Brake Kit - AUDI A8 Front 1994- 6 pot 356 mm disc 8x18 inch wheel£3,304.84 £2,754.03AP Factory Big Brake Kit - AUDI A8 Front 1994- 6 pot 356 mm disc 8x18 inch wheel Learn More
- AP Factory Big Brake Kit - AUDI S3 1999- 6 pot 330 mm disc 7.5x17 inch wheel£2,723.15 £2,269.29AP Factory Big Brake Kit - AUDI S3 1999- 6 pot 330 mm disc 7.5x17 inch wheel Learn More
- AP Factory Big Brake Kit - AUDI TT 1997- 6 pot 330 mm disc 7.5x17 inch wheel£2,723.15 £2,269.29AP Factory Big Brake Kit - AUDI TT 1997- 6 pot 330 mm disc 7.5x17 inch wheel Learn More