Quote:
Originally posted by Need4Spd
Does replacing the calipers affect the ABS calibration in any way?
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It depends on what you replace them with as well as the size of the new rotors and the coefficient of friction of the pads.
StopTech does track testing of each new brake kit design to make sure the stopping distances are minimized with and without ABS active. They also do a test called a "modified J-turn" which is used to determine if there are any negative interactions between the brakes and the ABS and/or stability control system. This is the same procedure that ABS design engineers use when testing new systems.
Here's how it works:
The turn is a constant radius course which has been carefully measured and marked with paint dots that are calibrated. The car is taken around a skid pad located in the same spot and the maximum speed the car can be driven around that circle is measured. Next, the car makes a run at the skid pad at that speed. Partway through the turn, the driver applies the brakes and the car comes to a stop. A tape measure is then laid out between the calipbrated dots nearest where the car stopped. Then, a measurement is taken from each wheel to that perpendicular tape with the mesurement taken along the line of sight from the wheel to another distant cone that has been placed as a calibrated reference point. The distance from wheel to tape is recorded as is the distances from the dots and this is all entered into a laptop. Car wheelbase and track is also entered. The laptop does some crunching of the numbers and comes up with the "departure angle" of the car from the intended direction. If it is outside of a narrow range, the brake system needs to be rebalanced with either larger or smaller pistons in the front or rear calipers.
As you can see, it's even more complicated than just swapping calipers until you find the set that yields the shortest stopping distances!
I was in California in December helping to test the new Nissan 350Z brake kits (332mm front, 355mm front, and 4-wheel kit) and I took photos of this process. It was pretty cool once I understood what was going on.
Driving the 350Z at 46.5mph on the J-turn course
Getting ready to take measurements for departure angle calculation
The bottom line answer to your question is, the ABS and the dynamic stability control will both work fine after installation of this kit.
These vehicle control systems are designed for a wide range of road conditions. As such, they can adapt to a fairly broad range of caliper choices as well. It's hard to make the systems "freak out" but it is possible, which is why StopTech runs this test. The results of this test sometimes cause the StopTech engineers to go back to the drawing board.
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