About to do a rear caliper overhaul and I was looking at how to get the pistons out.
My plan was to hold the outer piston in place with a clamp and pump the inner piston out completely using the brake pedal.
Then I was thinking it might be possible to knock the outer piston out with a punch/hammer once the banjo bolt is off as you will have access to the back of the piston.
Is that right?
Also I will need to split the calper into two halves so can I slacken the two bolts holding the two halves together before I start pumping out the piston while the caliper is attached to the bike or is the pressure gone if those bolts are loosened at all?
Get some grips, use a thick rag over the jaws so it doesn't mark the Pistons and wiggle them out, try not to squeeze really hard though, you don't want to mark Pistons.
don't care too much about the pistons really as I have some new ones though it would be nice to have an extra set if they are ok. The front ones were not when I replaced them so I bought some rear ones too.
I was going to attempt what delboy does here at 7:59:
His inner piston came out while the outer one was stuck fast due to grit.
So once the banjo bolt was off he just drifted the other piston out.
You think the gs500 rear caliper is the same? You have access to the back of the piston once the banjo bolt is off?
https://youtu.be/SbP0Iqky7eU?t=7m59s
Clamp the one that's free in position and try to blow the other out with compressed air.
The caliper is still connected to the master cylinder. I can pump one piston out with the brake pedal while the other is clamped in place. Don't have any compressed air anyway.
I'm just wondering if it is possible to access the back of the outer piston once the banjo bolt is off. If you can see the back of it once the banjo bolt is off, then I could punch it with a hammer and punch. Delboy does it in the video I linked above with another Suzuki caliper at the 8 minute mark.
I don't see why it wouldn't work, give it a try. I'd probably use something softer, like a wooden dowel, but it probably doesn't matter if the back of the piston gets a little dinged.
The bleed nipple is at 90deg to the piston.
How are you going it drift it out?
Or am I missing something?
I think he's doing it from the banjo bolt opening, not the bleed valve.
oh ok, guess it will either work or it wont :dunno_black:
yeah, going to do it from the banjo bolt opening. When you take the banjo bolt off, I should be able to see the back of the piston through the hole and be able to punch it out. I think I'll try tomorrow. It's getting dark now.
Currently looking for the easiest way to torque down the banjo bolt connected to the master cylinder when I need to do it tomorrow as I am putting on a steel braided hose. If I can't get to it by taking the seat and right panel off, I might have to take the wheel and mudguard off. Unless I can get some suitable extenders for my wrench.
Well, Toner, you just NEED compressed air, from there, everything is easy!
(And the compressed air will continue to be VERY useful for many other jobs, for years).
Compressed air does look useful but I'm going to do this job without it today.
However I do have a vacuum gun and some a new speed bleeder type nipple to make bleeding the brakes easy! I highly recommend them.
The ones the GS500 take are the Stahlbus bleeder valve size M7x1.0x16mm if anyone is thinking of getting them. I mentioned them here before:
(edit: damn, turns out the guys actually sent me the m8x1.25-16 size, I have to send it back and get it exchanged)
http://gstwins.com/gsboard/index.php?topic=68508.msg827325#msg827325
Learned my lesson from doing the front brakes last winter which you all helped me with.
It worked. You can access the back of the outer piston when you take the banjo bolt off.
I first tried to knock it out with a punch and toffee hammer. It came some of the way but then didn't really move much.
If I kept tapping it probably would have come out eventually.
I would have preferred to use a small brass drift though.
However, then I just used some quick grips again with a brace and a bolt. I had used the quick grips and the brace to hold piston in place while I pumped out the other one.
I put the smaller diameter bolt into where the banjo bolt and been attached and rested a flat brace on top of it. Then squeeze down on the bolt using the quick grips attached to the brace and the caliper. The other piston just popped out smoothly.
Very nice.
Now I have to put on a new hose and put the caliper back together with new seals and pistons after cleaning it up.
Well I finished changing the hose to a steel braided one, probably the first time in its 10 years and 80,000 km and put in new pistons too.
Unfortunately, I could not change the bleed nipple to a speed bleeder type valve because I got the wrong size. I'll have to look into what went wrong there.
Learned a good lesson however, those dust caps on the bleed nipples are vital and not just for dust.
My bike didn't come with one and I think the damage was already done even if I had stuck something on it.
There was rust at the bottom of the threads on the nipple and inside the caliper where these threaded in.
Water must have got in through the hole and rusted this area over time.
Might actually need a whole new caliper though it still seems air-tight.
All my work didn't have the desired affect however. There is still way too much travel in the rear pedal.
I'm curious about your rear brakes. Do all gs500s have a lot of travel in the pedal?
I pretty much have to depress mine all the way before it brakes hard.
Now it could be I did not bleed it properly and I might get a professional to do it so I know whether this is the issue or not.
I might wait until I get the right speed bleeder and try with that first.
Otherwise, it could be the master cylinder needs an overhaul....
You know what gave me the most trouble today? Taking the split pin out of the pin at the bottom of the master cylinder which attaches it to the pedal. That thing was stiff in there.
I wanted to see if I could turn the MC to get at the banjo bolt that way. In the end I just attached two extenders and got it from the other side with the chain guard off.
Anyway, I have some R-clips on the way after that :D