The front brake is a dual piston unit made by Nissin. As seems to be a common theme on this bike, it's not been maintained very well. One of the two pistons is seized, so it's due a full rebuild.
I've removed the caliper from the bike. The next step is to get the brake pads removed.
I had to use an impact driver to get the cap out. Think it needs replacing. Even if I cleaned it up with a wire brush, the anti rust coating (zinc plating?) has been worn off, so the steel pin would just rust again.
The pads can be removed now the pin is out. There are two stainless anti-squeal shims that come out not the pads are removed.
The workshop manual is very useful.
The caliper should slide on the two slide bolts. It doesn't.
Won't budge.
I double check the exploded diagram to make sure there's no fasteners I've missed. Nope. It's just stuck.
I gave it a tap with a rubber mallet. Now it's moved.
It's not stuck any more.
Yuck. The other slide bolt on the bracket was much worse. :(
This could really do with a clean too.
One caliper disassembly tool, large.
This is the third caliper in as many weeks I've rebuilt using this cheap master cylinder I got off eBay. Cost £12 delivered and I can rebuild them at a work bench without having to extract the pistons first.
One is quite sticky, the pad is so the working piston can bottom out and then the hydraulics will work on pushing the seized piston out.
One is quite sticky, the pad is so the working piston can bottom out and then the hydraulics will work on pushing the seized piston out.
That's quite a bit of grime that must have been stuck in there.
I try to wedge them with bits of wood and the old brake pads to keep them roughly the same amount of extension.
But ultimately one of them is going to pop out first. The other will pull out by hand.
Quite a lot of crap on both of them.
They cleaned up quite well, considering.
There's a ring worn around both pistons. You can't feel it, but you can see the wear mark.
The seized piston has a lot of sludge in its cylinder.
I use a pick to scrape the dirty (and corrosion) out of the seal groves. New seals installed.
I add a little red rubber grease to the seals to help the pistons slide back in.
Pistons reinstalled.
I should use waterproof grease for the slide pin, but I can't find my tub of it. I'll use copper grease for the moment, and clean and replace it when I change the pads next time.
Caliper slides now.
New pin and cap.
There is a notch cut out of the spring for the brake disk to go through. Make sure you put the spring in the right way round. I didn't and had to take the pads out again to flip the spring over. Not a big deal, but wasted time...
Second anti-squeal spring shim reinstalled.
New pads installed.
New pin and cap installed. The caliper is ready to go back on the bike now.
Now just needs bleeding.
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