SPD Tuning Service

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What is the Subaru Impreza WRX brake conversion for standard Impreza models? rev. 990125

For those wanting to improve the performance of their standard Impreza to WRX level, the chassis responds very well to the following modifications.

Front Brakes:

The pre96 WRX calipers are a good value while supplies last. SPD offers these in the catalog. See Parts, Brakes. These are dual piston calipers and 10.9" vented rotors bolt on. You must use 15x6 Subaru wheels or larger to clear these brakes. Do not forget to order Mintex pads. The other way to obtain these parts in a 10.7" later design is from a late model Forester, Legacy Outback or GT. Ask for the dual piston caliper and disk. Tirerack (www.tirerack.com) has OEM 15" Subaru alloys for $59/69 each to fit these brakes. Best deal going. They are some of the lightest 15" wheels you can buy. AND they fit!

For Subaru RS 2.5 owners  with the RS type 16" wheels required, the latest WRX-RA STi Four Piston Calipers and 298mm rotors are a great improvement. See Parts, Brakes page.

Rear Brakes:

If your car already has disks, you are set unless you insist on vented rear rotors. In that case see the parts list section for WRX Vented rear rotors and the required wide caliper. These calipers are wider than standard to fit the vented rotors. Again, order Mintex pads also.

For those with drum brakes in the rear, the best solution is a trip to
your local Subaru salvage yard. You want a pair of complete Legacy disk
brake rear hubs (some call them knuckles). You want the caliper, the
rotor, the back plate and hub as a complete unit. ANY year will do, but
do not buy rusty junk, sit it out for some good stuff. If your car is a
late model with ABS, make sure that you ask for an ABS set. Also get the
parking brake cables.

You unbolt the brake line, plug it, unbolt your hubs, remove the axles,
install the new corner on your axles and bolt it back together. It is
best to torque the suspension bolts with the car on the ground. Align
the rear wheels by eye from about thirty feet to get them close and the
same on both sides, then use a tape measure to set the toe-in +1/16" max.
The Legacy parking brake cables are a bit too long,  - tie wrap the extra length up at the outer ends of the rear cross member. (or get new Impreza ones at the dealer) It is usually a good idea to make a light pass on the rotors to clean them up and use new pads.

You now have brakes. Next stop: The suspension department.

For those concerned about brake proportioning valves, master cylinders
and upsetting the ABS, a short explanation:

The brake proportioning valve is the same on all cars to 96, even though
there are three different brake boosters. I am running the small
disk/drum brake booster. It provides the hardest pedal of the three and
best modulation feel on turn-in. I suggest you run what ever you have in
the booster/master cylinder department for three reasons. It keeps
things simple, makes this FAQ shorter than to explain the options and
leaves you with money for more important issues.

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Last modified: May 23, 2000