Setting the Piston 20º Angle, I get this question a lot... Options

[Eric_Shea]

I get this question a lot so I thought it might help to have it posted in a thread that can be searched etc.

The best way to set a piston angle without using the gauge is to draw an imaginary “Center Line” down the center of the pad cavity. This is illustrated by the “Red” line in this picture.

Set the angle facing the side that has the bleeder. This is illustrated by the yellow arrow in this picture. This denotes the “Top” of the caliper.

By setting the bottom notch of the piston on the center line it will automatically give you the 20º angle as illustrated by the “Green” line in this picture.

[Eric_Shea]

Good question Phil.

The answer is "probably not". Hopefully, your pistons had been set at the correct angle when they were rebuilt. Always good to check when you're changing pads. A lot of the mass-rebuilders often miss this step or have it backward.

This brings up another good point. "Do not try to change this piston angle while the piston is fully seated in the bore." To do this properly requires special tools and chances are "great" that you don't have them. I simply cannot count the number of pistons I've removed with "Vise-Grip" marks on them. If you're rebuiling your calipers and you goofed... best to blow the pistons back out and start over. It takes a few minutes to get it right vs. a lifetime of chewed up pistons.

Regarding the rears... 914 rears all have flat pistons so, this is not an issue here. It brings up another interesting fact though; ever wonder why 914's have a fat pin and a skinny pin on the rears? The rear pads were actually tappered back in the day to accomplish this. 914 rear caliper are about the only caliper out there that doesn't incorporate this feature.

If we can rope Jeff back in here, I believe he has a picture of an old tappered pad set.