Front disc brake Re&Re from a 78 Westy

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With Russ' hard work and experience the Westy is now got some "go power". So my attention has turned to getting some decent "stop power" in the Bus. The front RHS caliper had seized up so I had taken off some time ago. Being totally honest, this is not the RHS one, but the work is the same. The big difference is that when the system is left open on the other side, getting the pistons out cannot be done hydraulically, as with the first piston in the first caliper.

First you take the caliper off the vehicle(some curse words will probably be necessary here because those bolts are on tight!) and set it up on a bench. Next step is to take off the dust seal(boot). This one's seals were on there really well, so to start them coming off I used a beater chisel with a sharper edge than a screw driver.



Remove the seal with a screw driver once it starts to come free. Put it in the "to be cleaned" pile. Now if the piston is frozen it might be necessary to put some penetrating fluid in there or physically scrape any rust out that you can see between the piston and the cast bore that it sits in. But even if the rust isn't too bad, as this one wasn't, the next step might take you by surprise….it did me and chickenwing on the first caliper! You see, once in the vice, compressed air becomes your go to tool. At this point you will want to have your safety glasses on and possibly shield your dog's ears. You have to somehow clamp the other piston in place and put a piece of hardwood, or thicker softwood as I have used here in between the two to "catch" the piston. Go gently at first with the air and you might see results quickly enough!




Then POP !! out it comes….Tada! 






more to come….

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Yes, it is pretty yucky, but even yuckier is the bore



The wire wheel cleans up the piston nicely in this case



The bore first needs the square-cut O-ring taken out



And then it can be cleaned up with some sandpaper. No need to go crazy here, but get it clean after the sandpaper treatment. The piston rides in the bore, but only touches the O-ring, it is not like the cylinder of an engine that requires honing, instead it just needs to be rust free



Once all cleaned, the O ring gets a thin smear of brake grease and is installed. The top of the bore gets a little brake grease to keep the rust at bay. Now put a thin smear of brake grease on the piston and seat it against the O-ring in the bore. If it is a new O-ring it might very well need a clamp to press it in. You will need a way to press it in from the centre to keep it from going cock-eyed. I used a small cube of wood for the clamp to bear on, but something like a nut or even a plastic throwing die might work. Press it in far enough to get the bottom past the O-ring but do not press it in all the way. If you accidentally do push it all the way in, don't fret and move towards the compressed air gun (like I did)…instead use Russ' trick of using 2 flat screw drivers, one each side in the piston's groove and gently pry the piston back out. The cleaned dust seal has to get some brake grease on the inside and it needs to be fitted around the groove in the top of the piston.



Inside of boot in groove, but piston not pushed in far enough to seat outside here



Now you can go ahead and press the piston pretty much all the way in. Don't squish the outside of the boot though. With both the new and the old seals I used(I got a kit for the other side because the boots were ripped), I was able to press the outer seal into place sufficiently with my fingers. Bentley says it can't be done, but I don't see how much more it can go on, and Russ agreed with me. Luckily, because I don't have the Bentley recommended special tool





When I get some pics, I will cover what you do if you get the "teeth" in the piston, that mate to the shim that goes in first before the pad, in the wrong place

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Well, looks like I never got pics of turning the piston in it's bore. Don't know how I did it now, but I think it was done with a flat screwdriver. From what I can remember they turned pretty easily at this time so I could line up the notches in the piston with the shim "punch-outs".