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EVO, EVO, STi: Part 1 brake rebuild

Spring is in the air and the sun is rising on our Japanese performance car customers. The last few weeks we've had a rally of AWD sports sedans come through the shop: a couple of EVOs and a new STi. In part one we describe rebuilding brakes on an EVO 8. Part two goes through a sway bar install on a new EVO X. And part three follows a complete suspension and exhaust upgrade on a new 08 Subaru STi.


A common problem with the red Brembo calipers in Mitsubishi EVOs (and other cars) is that they don't stay red for very long-- especially if they see some hard track use. The heat generated during hard braking at the track quickly turns the bright red into a brownish red and the "brembo" logo yellows.


The only fix is to repaint or powder coat the calipers another, less sensitive color. In this case, the customer wanted to go with a simple black repaint (powder coating, while more durable, is much more expensive and potentially damaging to the caliper if you split the calipers). At the same time, we decided to replace all the dust boots and seals which were also damaged and worn out.

Here you can see the dust boots and seals extracted from the caliper. To get the pistons to come out of their cylinders, we force air through line holes. This should be done carefully as to avoid damaging the pistons should they "pop" out too quickly.


Here's a closer look at a heat damaged dust boot which has dried out and the piston from which it came:


A closer look at the piston, note the grit and particles in the fluid and the marks on the piston:


We polished the piston and replaced the dust boot and inner seal (each piston has a dust boot which can be seen on the assembled caliper, and is designed to keep grit from migrating into the cylinder, and an o-ring style piston ring or seal which is located in a groove in the cylinder and "seals" the piston to the cylinder).

Here's our brake rebuild assembly line, note the cleanliness of the work area. You must keep all brake parts as clean as possible before reassembly!


A picture of a disassembled front caliper before paint:


We did not paint the calipers ourselves; instead we sent them off to the experts. Autometric, a local auto body shop painted the caliper for us, and they really did a nice job.





Since Brembo sold the rights to the caliper parts to Mitsubishi, they do not sell specific rebuild kits. Here is what we used:

Front Calipers
Large piston Small piston
Dust boot Brembo p/n: 20 4872 51 Dust boot Brembo p/n: 20 4872 46
Seal: 46mm ID, 51mm OD, 3mm thick Seal: 40mm ID, 45mm OD, 3mm thick

Rear Calipers
Dust boot Brembo p/m: 20 4872 46
Seal: 40mm ID, 45mm OD, 3mm thick

These p/n and sizes worked for this EVO 8, double check your own calipers.