Project VA WRX: Upgrading the Brakes with Stoptech Part 1, Getting a Baseline

Finally the brakes were tested with 6 back to back stops from 100 mph.  It was hard for our car to reach 100 mph and stop in the allotted space.  The brakes faded and caught on fire but still managed to stop the car without terminal failure.  The fire is probably the anti rattle backing on the pads burning.  Once again the temperatures were recorded. Surprisingly the fire burned for a pretty long time but had no effect on the brakes' function.  This concluded the stopping part of our stock brake baseline test.

The next test was the J-Turn.  The J-Turn is a test to make sure that the new upgraded brakes do not contribute to excessive over or understeer and to make sure that they are compatible with ABS, traction control and stability control.  In the J-Turn, the car is accelerated in a straight line then enters a high speed turn of a known radius at a speed when the car is close to the limit if adhesion, slightly drifting.  The brakes are then applied hard.

Having the correct trajectory, speed and line is critical for this test.  In this picture the driver entered too fast and understeered making a wider line than optimal.  The sideways cone is where the driver is supposed to start his hard braking. 

This is the proper line where the driver is right on the cones and the car is cornering at the limit with a very slight tail out attitude.

The car is brought to a controlled stop as hard as possible.  When the car is stopped the distance from the center of the turn to the front wheel is measured and recorded. 

The the distance from the center of the corner to the rear wheel is also measured.  In this way a measurement of the car's oversteer or understeer gradient as influenced by the brakes is able to be quantified. When the number is established for the stock car, the car with upgraded brakes must behave similarly to pass Stoptech's validation testing. This way Stoptech can verify that upgrading the brakes does not cause odd handling when cornering and braking at the same time.  Stoptech wants us to keep the exact speeds and corner radiuses used in the test confidential but were nice enough to allow us to record how the test is run.  To our knowledge no one else in the brake upgrade industry tests this extensively.