Q. Will my spare wheel fit over an upgrade system?

A. The brake upgrade kits are designed to suit 17" or larger wheels. In the AUII and BA Falcons you can still utilise a smaller spare wheel by fitting the spare wheel to the rear and running the larger wheels on the front. For the VY - VT applications you must have a spare wheel that is 17" or larger.

Q. Are calipers with more pistons really better?
A. A single piston caliper has a limited lining surface area. E.g. If the inner pad on a sliding caliper, overhangs the piston by an excessively large amount, then the pad back plate may bend when high pressure is applied to the brakes. Multi piston calipers allow larger lining surface area without excessive overhanging of the pad. Multi piston calipers can usually be designed to provide greater stiffness, which results in improved pedal feel.

Q. What are the benefits of more pad surface?
A. Larger surface area can have two effects:
1. It will always result in better pad life than a smaller volume pad
(assuming the same lining material and operating conditions).
2. It can reduce operating temperatures if it covers a larger swept area
of the pad. I.e. if the pad covers a larger radial depth of the rotor.

Q. My BA Falcon rear hose seems twisted when I fit it up. Is this right?

A. Yes. This hose has been designed to take this shape so that it doesn't foul on the rim during the extremes of suspension travel.

Q. Are bigger calipers better?
A. That depends on what you are trying to achieve. A brake system needs to be well balanced front to rear to avoid premature wheel locking during braking. Fitment of larger bore calipers to either front or rear alone will upset the brake balance. Premature wheel locking will increase stopping distances and cause vehicle instability when cornering.

Q. Should you upgrade to multi piston calipers if you upgrade discs?
A. As mentioned above, there are potential advantages to multi piston calipers with larger lining surface areas or lining volumes. However brake balance front to rear must be maintained. Brake balance can be affected by a change in effective caliper bore size but also by a change in rotor diameter and by a change in friction level of the pads.

Q. Is there an equation to work out size increase?
A. There is no simple formula for calculating brake sizes. There are numerous factors which influence brake size and brake system balance which makes calculations very complex. However there is one element that is fundamental to braking. I.e. The energy to be absorbed and dissipated during braking is proportional to the mass (weight) of the vehicle and proportional to the velocity squared. So if vehicle speed is doubled then the energy (heat) going into the brakes is increased four times.

Q. What is the best way to take heat out of the brakes?
A. The most basic way to manage increased thermal energy in brakes is to increase the ability of the rotor to absorb and then dissipate heat. To absorb more heat it is necessary to increase the mass (weight) of the rotor in contact with the pads. This can be done with a larger outer rotor diameter, with greater rotor thickness, increasing the cheek thickness of vented rotors, and by increasing the radial depth of the pad lining. To improve heat dissipation it is generally necessary to increase the surface area of the rotor and again that can be done by increasing rotor outer diameter. Another way to improve cooling is to use vented rotors, or wider vents to allow more cooling air through.

Q. Do cross drilled or slotted rotors improve cooling?
A. Cross drilling or slotted surfaces do not improve cooling greatly. They do, however, assist the removal of gasses produced by the disc pads which in turn reduces the incidence of brake fade.

Q. If you put performance brakes on your car, should you upgrade the tyres and suspension?
A. Braking is limited by the contact between the tyre and the road surface. Tyres provide the friction between the car and the road surface. Poor tyres can cause less effective contact with the road which can reduce stopping distance. If the suspension does not keep the tyre in contact with the road then stopping distance is also increased. So suspension, particularly shock absorber control, can influence braking. Another important item to consider is wheel size. The size of a brake system at the wheel is limited by the wheel. When fitting larger brakes it may be necessary to increase wheel size.

Q. Are braided hoses illegal?
A. In Australia, hoses must be certified to Australian Design Rule (ADR)7. Because the steel braiding reduces the flexibility of the hose it may cause a hose to contact other parts of the car (e.g. wheel, tyre, suspension or body) during the range of suspension and steering movements. Contact will eventually lead to hose failure. PBR uses braided hoses in their Performance brake upgrades which comply to ADR7.

Q. Do braided hoses add much to braking performance?
A. Because braided hoses are stiffer they reduce the amount of brake fluid being displaced when the brake is applied which improves the overall pedal feel.

Q. How often should you bleed your brakes?
A. Bleeding is done to remove air from the brake fluid. It only needs to be done when there is air in the system, which is usually very obvious by deterioration of the brake pedal feel. Bleeding should not need to be done unless there is a problem which causes air to enter the system in service. However brake fluid absorbs water over time which lowers the boiling point. Most car service manuals suggest changing fluid every two years to maintain a high boiling point. This should be the minimum recommendation for high performance cars. When changing fluid it is necessary to bleed the system.

Q. How long do performance disc pads last?
A. There is no simple answer to this question. Disc pad life depends on the type of driving and the characteristics of the pad material formulation.

Q. Do performance disc pads wear rotors prematurely?
A. Race pads and high performance pads will generally wear rotors faster than O.E. pads for normal cars or trucks. It would be usual to replace rotors at every pad change with the pads wearing faster than is normal for every day passenger car driving.

Q. Bedding in: what is involved?
A. Bedding in, or burnishing, is usually done by conducting a number of medium level stops with sufficient distance between them so that the brake temperature at the start of the stop does not become too high (e.g. 100-120oC lining temperature at the start of the stop). When testing at PBR we conduct 200 stops from 65km/h at 0.4g with an initial brake temperature of 120oC. That equates to about one stop every kilometre. The purpose of burnishing is to have the lining wear to match with the rotor and to deposit a film of the lining material onto the rotor to stabilise performance.