The following is a message originally posted on 2/14/09 on RX8club.com
There are different types of calipers:
1. Floating type single piston CI caliper - Typically for stock OE calipers such as RX8 (Grand AM allows only stock calipers but can use two piece rotors).
2. Fixed type multiple piston aluminum/CI calipers - Axial (leg) mount like some stock caliper: RX7, Sti, EVO 8 (Al) or heavy trucks (CI)
3. Fixed type multiple piston aluminum calipers - Radial (top) mount like RB4000 caliper BBK for RX8
4. Fixed type multiple piston aluminum calipers - Radial (top) mount but with differential bores like RB400 caliper BBK for RX7
Caliper deflection is unavoidable due to cantilever stress; however several factors can affect the degree of flex or deflection:
1. The axial distance
(disc center to spindle mounting surface) - The shorter the span the less of the deflection - RBís center mount two piece rotor design requires less span
than traditional surface mount two piece rotors.
2. Caliper design
including how itís mounted - Leg (part of aluminum body) mount will flex more than radial or top mount with high strength alloy steel blots.
3. The radial distance
(diameter of the rotor), the smaller the rotor the less of the deflection.
4. The caliper material
- A more rigid aluminum material means less flex.
Type of uneven pad wear:
1. Between inboard and outboard
- Typically seen in stock floating caliper due to the sequence of applied pressure, inboard side is engaged with caliper piston before the outboard side is engaged by retracted claws.
2. Between outer and inner edge
- This can cause due to caliper flex and uneven temperature, usually outer edge wears more than inner edge.
3. Between leading and trailing edge
- Leading edge engaged with rotor before trailing edge, this can be alleviated by piston size differentials - smaller piston for leading and larger piston for trailing.
A better designed and well built brake system not only can provide a more responsive and powerful braking performance but also extend the life of pad and rotors.
We certainly appreciate all the supports and trust you put on RB brakes
Warren - RB