What's technique to rotate brake piston?
 

Need help on rotating brake pistons to correct angle. What's best technique. ('79 930)

EDIT: Just realized single piston caliper drawing below is not appropriate to 930 as that caliper is dual piston.

EDIT: Have posted 930 piston orientation drawing below... post #6.

http://forums.pelicanparts.com/uploa...1463687815.jpg

Pliers.



No, really, put some padding in there so you don't scratch them, and grab them with some big pliers. They don't take much effort to turn.

Just replaced mine, even with new ones I had to push them out almost entirely and than rotate or rotate while pushing them in again. A piece of straight steel or angle iron will help getting some grip over the slotted part. (unless you're willing to grip them using some pliers)

http://forums.pelicanparts.com/uploa...1463688739.jpg

If you do a bunch of them, and typically all the same size, a dedicated piston wrench is the hot setup. Here's one for the 38mm pistons in the 930 front calipers

38.0mm Piston Removal Wrench - Brembo

But only doing it occasionally, you can get away with some expanding pliers. Circlip pliers work good when you use them in the expanding manner and cover the plier legs with some rubber hose


http://forums.pelicanparts.com/uploa...1463689814.jpg

I stuck a box wrench in there at an angle almost same OD and ID of the piston and turn as needed

Here's orientation for 930 from factory manual. Credit to Dan for image.

http://forums.pelicanparts.com/uploa...1463692346.jpg

Thanks for input guys! I'm on it.

(Just put Textar pads in and car is now pulling to right under braking. Porsche friend suggested checking piston orientation. Braked straight with old pads so am already doubting orientation being issue but will check.)

Here's tool from Kevin's link (TY Kev). Not a hard one to make.

http://forums.pelicanparts.com/uploa...1463692948.jpg

Also good for nudging out stubborn pucks...
 

^^^^^^ I would really like to see this method in action. Tried numerous times and I just didn't get it. Maybe on Newly rebuilt calipers.

Well I would always advise the correct tool for the job, so that would be best. In a pinch, I grabbed a box end that, when inserted straight in, then tilted, gives you inside grip at two internal points. It is not possible to deform the puck and is really quite effective.

If you have rebuilt enough of these you know that one moment that sucker is not moving, then with a rock and twist, it is out easy as you please (think oyster?). I found that this method gives me tremendous mechanical advantage and combined with a very subtle nuanced motion can help coax a puck in, or out, or rotate.

But again, using the right tool means you can't blame it for failure!

Pistons were not precisely on spec orientation. Did fine tune them using circlip remover. All turned quite easily. Can't imagine pistons being slightly off accurate orientation would cause pull to right under braking but good to check and adjust anyway. Next... visually checked flexi hoses for deformation that might cause one side (left in particular) to be spongy. Hoses are not dry and look/feel good entire lengths. Next... I had bedded pads but thought perhaps not enough. Bedded more... problem solved.

Thanks for all the input guys!

I use a set of heavy duty lock ring pliers to grap the inside bore of the piston and spin it. Similar to what KTL is showing.

best to put them in at the correct angle in the fist place :rolleyes: