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KTL KTL is offline
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Join Date: Sep 2000
Location: Frankfort IL USA
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Fantastic work by Shaun once again! Both sets of calipers look fantabulous!!!!

Do the pistons typically need much tumbling or polishing? Their anodized surface is usually very resistant to attack, as long as nobody has mangled them like this

The rule of thumb for the piston steps is they are oriented to be perpendicular to the rotor. If you were to draw an arrow in the direction of forward travel around the rotor, the arrow should hit the step perpendicular. On the Ate calipers it's 20 that gets the piston in the right position

However, on the 930 calipers the steps can be aligned parallel with the edge of the pad box. Just make sure you point the steps to face the direction of travel. That means on the front calipers the steps point up (calipers are mounted in front of the axle) and the rear caliper has the steps facing down because 930s have the calipers mounted behind the axle.

The purpose of the step is to reduce tapered pad wear. Apparently the step allows pad outgassing without the pad coming off the face of the rotor. Without the step the pad tilts away from the rotor face and you get tapered pad wear. It's not insignificant pad wear either. It's actually very substantial if the brakes are used hard like on the track. Later calipers on other cars like the 944 Turbo, 928 S4, 944S2, 964, etc. that have calipers with different sized pistons accomplish the same thing without the need for stepped pistons. The differing piston diameters take the place of the stepped pistons.

Keep up the great work Shaun. Very impressive level of detail and beautiful results.
Kevin L
Present: '86 Carrera, '79 911SC widebody conversion rolling racecar shell
Past: '87 Carrera
Old 01-24-2019, 07:25 AM
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