Binding OSF Caliper
 

Have an intermittent issue with the OSF caliper in that it appears to bind randomly. So far it has only happened twice, once before Christmas and then again at the weekend. Both times, I was on short trips on an A road doing around 50mph. On the first trip (around 12 miles), I started to notice the car vibrate ever so slightly, and just put it down to the road condition and running on winter tyres. I stopped at around 15 miles, and when I got out, I could smell the front brake. It was also hot to the touch. All the other were fine. I left it for about an hour, and the trip home was fine. Something similar happened at the weekend, although this time I stopped earlier, and would like to get it resolved ASAP.

I've done some searching and I've found a couple of options. The first is that the pistons are corroded and I need the caliper refurbished, or a new one. The second is from a comment by Zip in another thread:

"You may well have the classic corrosion problem under the stainless plates at either end of the caliper that the pads track along. The corrosion lifts the plates proud of the caliper body, and can stop the pad fully retracting when you release the brake, causing the pads to drag on the discs and over heating them."

For option 1, would there be any issues with only replacing one caliper (new or refurbed), and for option 2, does anyone have any pictures showing these? I've checked the Service Manual PDF for the braking system, but it doesn't show these plates.

Finally, the PDF shows that there are two different types of HP-2 calipers, steel and aluminium. Short of taking the wheel off, any idea how to identify them?

You can see them clearly on the photos of my refurbished calipers: http://forum.a8parts.co.uk/attachmen...7&d=1379181239

...and you can clearly see where the corrosion has been ground away under the stainless plates, where the new finish is "pitted". Those plates need to be absolutely flush and square in the calliper, or the pads will not retract properly. Indeed, if too much is ground off, the pads will rattle around in there once the plates have been screwed back in. I'm not sure I have photos of mine, but I'll have a look. They were pretty bad pre-refurb.

Z

Cheers for that. Now all I need is some dry weather so I can remove the caliper to check it. Might have to get my bricklayer brother to help :ROFL: