AP Brakes seized?

[Nick]

So I popped my shiny new EBC brake discs on today and think that the nearside caliper inner pistons are seized! That explains my errant handling under braking.

Does anyone know if theres an overhaul kit or if there's a common issue with these AP 4 pot calipers.

I also think the nearside spring retainer is in upside down which probably explains the seizing. But also know that getting the pins out to swap it all over is a nightmare so I'm kinda putting it off.

Any advice / thoughts appreciated oh and if anyone has a drift I can borrow to punch out the retaining pad pins I'd appreciate it.

See you all on a wobbly convoy at the weekend.

[Matt Parker]

Overhaul kits are available from Mike Satur in parts depending on what exactly you require http://www.mikesatur.com/acatalog/Front_AP.html

The pad retainer pins can be tight in the callipers but it is very easy to remove them with a small punch or screw driver and hammer and tap them out from the front face. The spring plates have a directional arrow cut in them to indicate the direction of rotation of the discs for which way the plates need to be fitted.

The common faults with the AP's are the dust seals failing/ripping which then allows water to get in around the pistons leading to corrosion build up on the side walls of the pistons which makes the pistons seize in the housing. The other fault is corrosion again but around and under the shims where the pads sit. Corrosion builds up pushing the shims up and out of shape which then locks the pads in the callipers that causes un-even wear on the pads or lock the pads out so you only get half of the caliper working or some times no caliper action at all.