Braking System

Braking Systems
With the big brake conversions, GGR offer a switch to disable the ABS, why?
Why do GGR fit a brake bias valve?
What is the difference between 'Hard' and 'Soft' brake pads?
Can my brakes be improved at all without changing to larger components?
What type of maintenance does a braking system need?
Should I use competition brake fluid in my road car?
Brake Parts

BRAKING SYSTEMS
Cosworth braking systems follow a similar pattern to the suspension; it is primarily identical in all models. It consists of disc brakes front and rear, with a power boosted Teves electronic anti lock mechanism (ABS). Two wheel drive cars have ventilated front discs with fixed four piston calipers; the non-vented rear discs have a sliding, single piston caliper with integral handbrake mechanism. Four-wheel drive cars use slightly smaller diameter ventilated front brake discs, with a single piston, sliding brake caliper. At the rear, the discs are now ventilated, but with the same disc diameter & caliper design as the two wheel drive cars.
If maintained correctly, and used sensibly, the standard braking system will be perfectly adequate even with a mildly tuned engine in your road car. When the cars are taken onto the race track however, braking requirements alter dramatically. As a general rule, we recommend that the original brake discs are used with Original Equipment brake pads, we have found in the past that if harder pads are used with the standard discs, disc wear can increase dramatically! (But there is a noticeable improvement in braking power). A big improvement can be made to the feel and effect of the brakes by simply replacing the flexible rubber brake hoses with braided hoses. Surprisingly, the hydraulic pressure in the braking system causes the rubber hoses to balloon slightly, increasing pedal travel & reducing the clamping force between the discs & pads.
As the front brakes do the majority of the braking, this is the first area to concentrate on, when making improvements. To make any significant improvements, the actual size of the brakes must be increased, and this sometimes necessitates the change to larger diameter wheels. (Conversely, many customers who have changed to larger wheels also fit the larger brakes for cosmetic reasons. As the standard items look small inside the bigger wheels!).
Fitting larger diameter wheels does actually reduce the braking effort slightly as the larger wheel has a stronger leverage effect on the brakes, this is relatively small, but must always be considered.
With the big brake conversions, GGR offer a switch to disable the ABS, why?
To attain the maximum stopping power, the brakes should be applied with sufficient force to almost (but not quite) stop the wheels from turning. The ABS system prevents any wheel locking whilst braking, if this happens, you will feel the brake pedal pushing back into your foot. There are times however when the experienced driver may prefer to be in total control of the braking effect. On the road, heavy braking should take place in a straight line, and the ABS will maximise the stopping effort. In competition conditions, it may become necessary to brake whilst turning into a corner. Due to the cornering forces, the weight of the car will be concentrated onto the wheels that are on the outside of the corner, the un weighted wheels on the inside will therefore lock very easily, without destabilising the car. If the ABS is operational in this situation, the complete braking force will be released until all wheels are turning again. In certain conditions, experienced drivers will use wheel locking intentionally to destabilise the car.
Why do GGR fit a brake bias valve?
When the original braking systems are designed, wheel cylinder sizes are selected to give the correct balance of braking force between the front & rear wheels. Fitting different size brakes will affect this, and an adjustable bias valve will allow optimum brake balance to be restored, ensuring maximum stopping power and stability under heavy braking.
What is the difference between 'Hard' and 'Soft' brake pads?
Heat is always produced under braking. (Schoolboy physics again, converting the energy of the moving car into heat.) For normal road use, a 'Soft' brake pad is used. In competition applications, braking is generally heavier, and more regular, producing higher temperatures, so a harder pad material is used. When a 'Soft' brake pad is used it will give excellent braking response when cold, but as pad temperatures rise, braking efficiency will reduce. If the brake pad temperature becomes too high, 'brake fade' will occur. This is where the friction between the brake pad and disc reduces to almost zero, giving no noticeable retardation, from a very hard brake pedal. Conversely, a 'Hard' brake pad will work efficiently at higher temperatures, but when cold, will give noticeably less 'bite'.
Can my brakes be improved at all without changing to larger components?
As explained above, the working temperature of the braking system dictates the type of friction material used. Brake pads are now available that use the latest technology Carbon-Metallic material. This is capable of withstanding far higher temperatures that the traditional organic materials, and also has a far wider working temperature range. The carbon element in the brake pads will also combine with the iron in the surface of the brake disc, to create a harder surface and reduce disc wear. It is important that the bedding in procedure for this type of pad is closely adhered to, and extra care must be taken of the braking system and surrounding components due to the higher temperatures produced.
What type of maintenance does a braking system need?
Simple routines like regular inspections for wear in the discs & pads, leakage of hydraulic fluid from the system, free movement of the brake pads & caliper sliders, and checks of all flexible hoses for cracks or other damage. It is also strongly recommended that the brake fluid is totally replaced every two years, with a good quality Dot 5 (or above) fluid. Hydraulic brake fluid is what is known as hygroscopic, this means that it will absorb moisture from the atmosphere. When the brake fluid becomes diluted with water, its boiling point will reduce. The heat generated by the brakes could then cause the fluid to boil, and this would create air bubbles within the fluid. As the air bubbles can be compressed, this would give a soft feel to the brake pedal, and poor braking efficiency.
Should I use competition brake fluid in my road car?
This is not usually recommended. Most competition brake fluids have a very high level of hygroscopicity, meaning that they will readily absorb water from the atmosphere. With a competition car this is not considered a problem as the brake fluid should be bled through the system prior to each event, but with a road car the improvements of the better fluid would soon be greatly reduced due to the water dilution.
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Correspondence/Requests
Sales Enquiries: sales@grahamgoode.com
Technical Enquiries: tech@grahamgoode.com
Tel: (+44) 0116 244 0080
Fax: (+44) 0116 244 0140

	Braking Systems With the big brake conversions, GGR offer a switch to disable the ABS, why? Why do GGR fit a brake bias valve? What is the difference between 'Hard' and 'Soft' brake pads? Can my brakes be improved at all without changing to larger components? What type of maintenance does a braking system need? Should I use competition brake fluid in my road car? Brake Parts

BRAKING SYSTEMS
	Cosworth braking systems follow a similar pattern to the suspension; it is primarily identical in all models. It consists of disc brakes front and rear, with a power boosted Teves electronic anti lock mechanism (ABS). Two wheel drive cars have ventilated front discs with fixed four piston calipers; the non-vented rear discs have a sliding, single piston caliper with integral handbrake mechanism. Four-wheel drive cars use slightly smaller diameter ventilated front brake discs, with a single piston, sliding brake caliper. At the rear, the discs are now ventilated, but with the same disc diameter & caliper design as the two wheel drive cars. If maintained correctly, and used sensibly, the standard braking system will be perfectly adequate even with a mildly tuned engine in your road car. When the cars are taken onto the race track however, braking requirements alter dramatically. As a general rule, we recommend that the original brake discs are used with Original Equipment brake pads, we have found in the past that if harder pads are used with the standard discs, disc wear can increase dramatically! (But there is a noticeable improvement in braking power). A big improvement can be made to the feel and effect of the brakes by simply replacing the flexible rubber brake hoses with braided hoses. Surprisingly, the hydraulic pressure in the braking system causes the rubber hoses to balloon slightly, increasing pedal travel & reducing the clamping force between the discs & pads. As the front brakes do the majority of the braking, this is the first area to concentrate on, when making improvements. To make any significant improvements, the actual size of the brakes must be increased, and this sometimes necessitates the change to larger diameter wheels. (Conversely, many customers who have changed to larger wheels also fit the larger brakes for cosmetic reasons. As the standard items look small inside the bigger wheels!). Fitting larger diameter wheels does actually reduce the braking effort slightly as the larger wheel has a stronger leverage effect on the brakes, this is relatively small, but must always be considered.

With the big brake conversions, GGR offer a switch to disable the ABS, why?
	To attain the maximum stopping power, the brakes should be applied with sufficient force to almost (but not quite) stop the wheels from turning. The ABS system prevents any wheel locking whilst braking, if this happens, you will feel the brake pedal pushing back into your foot. There are times however when the experienced driver may prefer to be in total control of the braking effect. On the road, heavy braking should take place in a straight line, and the ABS will maximise the stopping effort. In competition conditions, it may become necessary to brake whilst turning into a corner. Due to the cornering forces, the weight of the car will be concentrated onto the wheels that are on the outside of the corner, the un weighted wheels on the inside will therefore lock very easily, without destabilising the car. If the ABS is operational in this situation, the complete braking force will be released until all wheels are turning again. In certain conditions, experienced drivers will use wheel locking intentionally to destabilise the car.

Why do GGR fit a brake bias valve?
	When the original braking systems are designed, wheel cylinder sizes are selected to give the correct balance of braking force between the front & rear wheels. Fitting different size brakes will affect this, and an adjustable bias valve will allow optimum brake balance to be restored, ensuring maximum stopping power and stability under heavy braking.

What is the difference between 'Hard' and 'Soft' brake pads?
	Heat is always produced under braking. (Schoolboy physics again, converting the energy of the moving car into heat.) For normal road use, a 'Soft' brake pad is used. In competition applications, braking is generally heavier, and more regular, producing higher temperatures, so a harder pad material is used. When a 'Soft' brake pad is used it will give excellent braking response when cold, but as pad temperatures rise, braking efficiency will reduce. If the brake pad temperature becomes too high, 'brake fade' will occur. This is where the friction between the brake pad and disc reduces to almost zero, giving no noticeable retardation, from a very hard brake pedal. Conversely, a 'Hard' brake pad will work efficiently at higher temperatures, but when cold, will give noticeably less 'bite'.

Can my brakes be improved at all without changing to larger components?
	As explained above, the working temperature of the braking system dictates the type of friction material used. Brake pads are now available that use the latest technology Carbon-Metallic material. This is capable of withstanding far higher temperatures that the traditional organic materials, and also has a far wider working temperature range. The carbon element in the brake pads will also combine with the iron in the surface of the brake disc, to create a harder surface and reduce disc wear. It is important that the bedding in procedure for this type of pad is closely adhered to, and extra care must be taken of the braking system and surrounding components due to the higher temperatures produced.

What type of maintenance does a braking system need?
	Simple routines like regular inspections for wear in the discs & pads, leakage of hydraulic fluid from the system, free movement of the brake pads & caliper sliders, and checks of all flexible hoses for cracks or other damage. It is also strongly recommended that the brake fluid is totally replaced every two years, with a good quality Dot 5 (or above) fluid. Hydraulic brake fluid is what is known as hygroscopic, this means that it will absorb moisture from the atmosphere. When the brake fluid becomes diluted with water, its boiling point will reduce. The heat generated by the brakes could then cause the fluid to boil, and this would create air bubbles within the fluid. As the air bubbles can be compressed, this would give a soft feel to the brake pedal, and poor braking efficiency.

Should I use competition brake fluid in my road car?
	This is not usually recommended. Most competition brake fluids have a very high level of hygroscopicity, meaning that they will readily absorb water from the atmosphere. With a competition car this is not considered a problem as the brake fluid should be bled through the system prior to each event, but with a road car the improvements of the better fluid would soon be greatly reduced due to the water dilution.

Brake Parts · Back to FAQs & Features · GGR Home
Correspondence/Requests Sales Enquiries: sales@grahamgoode.com Technical Enquiries: tech@grahamgoode.com Tel: (+44) 0116 244 0080 Fax: (+44) 0116 244 0140