The following is a message originally posted on 9/8/08 at SubaruForester.org
We recently received an inquiry about what makes our calipers different from Brembo or Subaru WRX 4-pot calipers. Below is the question as well as our response.
Originally Posted by ewong_kaizen
Why should I get a RB caliper versus say a WRX 4pot or Brembo?
Yes - I read the stuff about the move out kits etc. What I wanted to know is what (if anything) makes your CALIPERS better than say Brembo?
Here are key features of RB calipers:
1. Caliper material and overall construction:
RB Caliper bodies are made from forged aluminum and precisely machined to every detail; while those stock calipers - Aluminum (Brembo) or Cast Iron (Newer WRX) calipers are in mass production and are usually made through a casting or extrusion process which is not as dense and strong in structure as forging. Also if you compare to WRX’s 4-pot caliper there is a substantial weight saving in aluminum calipers.
2. Caliper mount:
RB calipers are mounted to the adaptor (with two high strength alloy steel bolts) in a radial direction (top mount) - from the caliper down to the adaptor, whereas stock Brembo and CI fixed piston calipers are mounted in an axial direction (side mount), from the spindle to caliper. A top mount caliper is more rigid than those side mount calipers which typically used in stock calipers.
3. Piston material:
RB calipers use stainless steel pistons (RB4000, RB400 and RB600 models) vs. Brembo and other manufacturers' aluminum pistons. Stainless steel transfers about 1/10 the heat of aluminum, resulting in significantly less heat transfer from the pads to the brake fluid. Stainless steel is also more rigid and higher in strength than aluminum. Being that stainless steel has comparable melting temperature (2700 def. F) as brake pad steel backing plates, the pistons will never melt to the pad backing plates. Aluminum pistons (1220 deg. F) can melt to brake pad backing plates under extreme high speed braking.
4. Piston seals:
RB calipers have double seals – Inner one for brake fluid and outer one for fluid and dust, while those stock calipers typically use dust boot (instead of seal) which can easily be torn out.
If you compare the performance, durability and maintenance cost all together, clearly RB calipers are the right choice.