Project Mitsubishi Lancer EVO X Part 2, Making Great Brakes Even Better!


Stoptech stainless abutments
These stainless steel abutments prevent the steel brake pad backing plates from digging into the softer aluminum caliper body.  This makes for smoother action and a more consistent pedal.  It also protects the caliper body.

We used the Sport Trophy STR calipers which have a few extra features over the race only versions. To keep the STR calipers streetable, they are equipped with piston dust boots to protect the seals from brake dust.  Normally race calipers don’t have dust boots because they usually end up getting oxidized and hardened from heat and race calipers are maintained frequently.  Unfortunately street calipers are usually not maintained as well and corrosive brake dust, dirt and debris often get to where they can abrade the seals and corrode the pistons on a racing caliper causing leaks. The Sport Trophy calipers also have OEM like anti rattle hardware to help reduce pad rattling and brake squeaking.

stoptech brake caliper bridge
The black bolt in part is the bridge which makes the Stoptech caliper very stiff.  The silver clips are the anti rattle clips.  The hollowed out areas are the CNC machined lightening zones that STR calipers receive.

The Trophy kit comes with two piece Stoptech Aerorotors.  These rotors have a proprietary low turbulence vane design which greatly improves airflow throughout the rotor for better cooling. The vanes are staggered at the inner diameter entrance for more air intake and are airfoil shaped in profile. In benchmark testing of the Aerorotor, it had the best airflow of any rotor on the market.  The Aerorotors are also directional so you don’t have reversed vanes on one side of the car like many other rotors. Better rotor cooling leads to longer life, less fade and more resistance to warping.

The stock rotors are pillar vaned where the rotors have a bunch of internal pillars rather than smooth passages.  Pillar vanes are good for dimensional stability on a street car so the rotor won’t develop juddering as easily,  but don’t cool as well as the Stoptech aero vanes.

Stoptech vs Stock EVO X front rotors
The Stoptech rotor is quite a bit lighter than the stock piece due to a larger hat, the annulus of the rotor is narrower so there is less heavy iron and more lightweight aluminum.

We also decided to get the full floating option for our rotors. This allows the rotors to have about 0.012” of free play between the rotor’s hard anodized alloy hat and the rotor itself.  Full floating rotors have a few advantages over rigidly bolting the rotor to the hat. The first advantage is less coning of the rotor due to heat expansion.  This is because the rotor is bolted to the hat only on one edge, as the rotor expands it expands less on the side that is bolted to the flange as the flange acts like a heat sink.  Because of the difference in expansion due to the difference in temperature, the rotor distorts so it is shaped like cone.  This creates odd wear and a softer pedal.  It also increases thermal stress on the rotor and hat which is exaggerated by applying the brakes, due to the caliper’s clamping and straightening action. Floating the rotors also make the rotor less likely to knock the caliper’s pistons back in under cornering loads due to flex in the spindle and hub bearing system.  This piston knockback can suddenly cause a low pedal and is a bad problem for many brake systems under conditions of hard driving.

Stoptech vs stock evo x rotor
The rear rotor is a lot lighter than the stock rear part, mostly because the hard anodized alloy hat also serves as the parking brake drum.  Although this is very light, don’t use the parking brake for drifting if you want it to last very long.  Who drifits an EVO anyway?

Stoptech floats the rotors using a special shoulder bolt which allows the rotors to move on the hats even when fully tight.  A heat resistant inconel cone spring washer allows freeplay but has enough preload to reduce rattling, the fully floating rotors only real disadvantage. Our kit comes with a 355x32mm or 14” front rotor and a 345x28mm rear rotor.

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