Yeah. Those are supposed to be like that.

So one of the calipers has been leaking the past few days which I didn’t notice until one day the brake pedal went halfway to the floor on a steep hill. O . K .

I already knew the problem was a corroded piston because I had made a note of it when replacing the wheel bearing. It wasn’t leaking then, so I figured I could put it off. It was leaking now, so I ordered the rebuild kit with a new piston and set to work today.

Mmmm parts. These calipers were made by Lockheed and used in some old Austins (the landcrabs I think) and also in the SAABs. I have never seen anything like them on any other car ever. The friction material is cut at an angle for some reason - and one end of the caliper rests on a hinge... as the pads wear down the whole caliper pivots until finally the pads are worn flat - no more angle. Why? Because England.

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Popping the piston out. I don’t have any fancy compressed air. So I remove the caliper from the knuckle, remove the pads, set the caliper on a box so it’s not hanging by the brake hose, and pump the pedal until piston pops out. Just make sure the brake resevoir is full before doing this so you don’t suck air into the master cylinder and end up having to bleed that too.

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One of the cool (and I use that term inaccurately) things about these calipers is that the cylinder detaches from the caliper. ??? Shitting fuck if I know why. But it does make the thing easier to take apart. Modern calipers are not built like this. They usually have a dust boot. This one does not have a dust boot. It has a rubber outer seal, and an inner rubber seal. The outer seal is held in by an easily damaged round piece of tin. This is held in by an interference fit. I thought I would be clever and put the new tin piece in the freezer to make it pop into the cylinder. I destroyed the new one trying to get it in. So I reused the old one. Recycling. It’s what’s for dinner.

New rubber and new piston fitted into the cylinder! I used a very light coating of disk brake grease on the piston to help get it into its tight new home. You should be able to push it in by hand. If not, something is wrong. On this type of caliper both seals will fit in either outer or inner position - but they should only be fitted one way around, with the solid “flat” seal going in the inner position. Don’t mess ‘em up.

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Caliper all back together. Success! Put it on the car, bled, and tested. No leaks. Car stops in a straight line.

Here’s the gross old piston:

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No wonder it was leaking.


For reasons: this post is intended for amusement value only. It does not contain complete information and should not be considered instructional advice. Don’t try this at home kids, I am a trained amateur.