O-ring calipers and excessive run-out

[Dan Pepper]

I recently read a thread on another site that included a comment that o-ring type calipers are less prone to pumping air into the system should rotors be on the verge of excessive run-out. I just measured runout on my rear rotors and they are right at the limit - maybe even .001 or .002 over. Can installing o-ring calipers inhibit air-pumping into the system so I can stave-off rebuilding my trailing arms a bit longer?

[Joe L.]

Re: O-ring calipers and excessive run-out

Dan-----

O-ring type piston calipers are, for all practical purposes, immune to the "air pumping" phenomenon. There may or may not be other problems associated with this type of piston, but air pumping is not one of them. Many folks report excellent performance with these calipers.

[Dennis D.]

Re: O-ring calipers and excessive run-out

Bought them from the guy that developed the O ring, about 10 years ago. Just honed out my caliper bores,(no need to sleeve), and no more air pumping. I understand they are now sold by many venders.

BTW, I did set all my bearing clearances.

[Ed Jennings]

Re: O-ring calipers and excessive run-out

Then again, you can just take the springs out of the calipers. The o-rings apparently work, but you are treating the symptom rather than the cause.

[Bernard S.]

Re: O-ring calipers and excessive run-out

Two years ago replace all four caliper pistons with the o-ring type setup. Been great! In the past, every summer I had to clean brake fluid from the rotors and shoes, refill master cylinder and bleed the system before driving the car for the summer. Geart improvement.