Changing Brake Pads

**Slingshot** · 9th September 2004, 12:22

Hi all, need some advise.

The rear pads on my wife's bike need to be replaced (CBR 250R hurricane).

The problem is I can't get the piston to retract so that I can get the pad out. Do I need to do something like bleeding the brakes? Anyone know if there's a guide to this anywhere??

Thanks in advance.

**Blakamin** · 9th September 2004, 12:24

Originally Posted by Slingshot

Hi all, need some advise.

The rear pads on my wife's bike need to be replaced (CBR 250R hurricane).

The problem is I can't get the piston to retract so that I can get the pad out. Do I need to do something like bleeding the brakes? Anyone know if there's a guide to this anywhere??

Thanks in advance.

Could send you a copy of the cbr250 manual on CD-rom if you like?

pm me if you want it!

**riffer** · 9th September 2004, 12:37

Originally Posted by Slingshot

Hi all, need some advise.

The rear pads on my wife's bike need to be replaced (CBR 250R hurricane).

The problem is I can't get the piston to retract so that I can get the pad out. Do I need to do something like bleeding the brakes? Anyone know if there's a guide to this anywhere??

Thanks in advance.

Here's what I do. I know this sounds dodgy (and probably is) but it works for me and I've never had a problem.

Use some mole grips. Then (and this is the important bit) Set them so that they will JUST close over the caliper if you pushed them all the way in.

Gently put them over the caliper and the piston. And then just squeeeeze slowly and they will pop back inside the caliper.

Don't try and do this fast and brutal as you will wreck the piston. Nice and gentle and they will just pop back in.

**Mr Skid** · 9th September 2004, 12:38

Had a quick squiz through the service manual, it doesn't outline any particular procedure for removal..

Have you got the assembly removed from the disc yet? Or are the pads biting too hard for you to remove it? I usually use a large screwdriver across the caliper to lever the piston back in when reassembling the whole affair. Not sure if that'd work for taking it apart.

If you want I'll go disassemble my rear brake and see if there is a trick to it.

**Paul in NZ** · 9th September 2004, 12:39

The piston?

Probably has 2? One each side.. Sometimes brake dust and shit jams them but a good squirt with a can (not the whole can fer gawds sake) of brake cleaner will help. I use a wooden wedge thing to ease the pad back a little, pull em out, repeat (clean and push back) before dropping the new pads in.

Watch the fluid level in the master cylinder does not spill over and you will have NO brakes until the pistons pump back out to the disk.

If this makes no sense...

Read the manual!!!!!

Paul N

**riffer** · 9th September 2004, 12:41

Actually, having read your original post again, you seem to have trouble just getting the pads out full stop.

You could try bleeding the fluid out but that won't push the pads back in.

What you will possibly have to do is:

Put a small host over the bleed valve on the brake, and undo the valve.
Try to push the pad backways slowly with a screwdriver or suchlike wedged between pad and disk.

I don't really like giving this advice cause its so easy to get it wrong. But if you have the pressure off the pad should go back easily enough that you can then take it out.

After you've done this you might as well drain the brakes completely and replace the fluid.

Of course, my advice could be completely wrong and someone else could have a better idea....

**Blackbird** · 9th September 2004, 12:42

I don't know how the setup of the Slingshot is, but if you can get a fine screwdriver between the disc itself and the backing plade of the disc pad, then give it a gentle turn, that should drive the cylinder back. I'm a bit surprised that you can't extract the pad though even if the clearances are small. Sometimes the spring retainer clip means that the backing pad needs a firm tap. Dumb question, but has to be asked.... Is there a pin through the caliper which holds your pad in place, and if so, has it been removed? (sorry to ask, but covering all eventualities!)

Geoff

**Slingshot** · 9th September 2004, 13:08

Firstly thanks for the replies (what a great site this is)!!!

Now, my first post wasn't quite clear (and I actually did this a couple of weeks ago and it's all coming back now).

I'm able to move the caliper up, it pivots on the bolt at the front of the caliper. I can get both pads out but when I put the new ones in the gap between the pads is out of alignment. If I only replace the new outer pad and left the old inner pad in then it's no problem.

So I guess my real question is...should I be able to lever the pistons without having to undo bleed screws etc.

**Mr Skid** · 9th September 2004, 13:31

Originally Posted by Slingshot

Firstly thanks for the replies (what a great site this is)!!!

Now, my first post wasn't quite clear (and I actually did this a couple of weeks ago and it's all coming back now).

I'm able to move the caliper up, it pivots on the bolt at the front of the caliper. I can get both pads out but when I put the new ones in the gap between the pads is out of alignment. If I only replace the new outer pad and left the old inner pad in then it's no problem.

So I guess my real question is...should I be able to lever the pistons without having to undo bleed screws etc.

So the problem is fitting the caliper back on with new pads?

Sounds like an easy one, there will be more meat on the new pads than the old ones, and the piston(s) will be extended far enough to make the old thin pads contact the disc.

I'd grab a piece of wood (bit nicer and more uniform pressure than my dodgy screwdriver method) and stick it in on the piston without the pads in place, then apply pressure to it to force the piston back far enough to accomidate the new pads.

Maybe have a quick look at the resevoir, to check that it's not topped up to MAX before you do this though, and be careful not to push it too far and squish the seals on the piston.

**F5 Dave** · 9th September 2004, 13:31

Don’t have much time but will add. Don’t use brake clean anywhere near the seals. It is fine on the disk, or to clean the calliper when you have stripped the seals out, but will damage/swell the seals.

If you pump the pistons out a smidge you can clean around them with thin bits of rag. I push the pistons back with a small sashclamp (for holding wood together ($4 from guess where). Check level in MC, you may need to take some out if some extra has been added at some stage, but easier to open the bleed on the calliper (with a hose).

Don’t use the disc to lever against anything, use may well bend it.

**riffer** · 9th September 2004, 13:39

Originally Posted by paparazzi

So the problem is fitting the caliper back on with new pads?

Sounds like an easy one, there will be more meat on the new pads than the old ones, and the piston(s) will be extended far enough to make the old thin pads contact the disc.

I'd grab a piece of wood (bit nicer and more uniform pressure than my dodgy screwdriver method) and stick it in on the piston without the pads in place, then apply pressure to it to force the piston back far enough to accomidate the new pads.

Trust me Slingshot. My method works better.

**vifferman** · 9th September 2004, 13:42

Originally Posted by Slingshot

I'm able to move the caliper up, it pivots on the bolt at the front of the caliper. I can get both pads out but when I put the new ones in the gap between the pads is out of alignment. If I only replace the new outer pad and left the old inner pad in then it's no problem.

So I guess my real question is...should I be able to lever the pistons without having to undo bleed screws etc.

I have a feeling that the caliper may have only one piston. Regardless of that, you should be able to lever the piston(s) in, but clean them first as Paul said, otherise any crud that's present will stuff your seals. You can lever them in however you want: mole grips, vice grips, your thumbs, or a small G-clamp. Just do it slowly, and watch the level of the brake reservoir to make sure it doesn't get too high.
When my front pads were replaced a couple of weeks ago, they were VERY worn, and despite the reservoir being at the full mark, and there being a total of 8 pistons, the reservoir didn't overflow.
If everything is clean, and anything that's supposed to be lubed is lubed (like the caliper pin) with high-temp grease or copperslip, then everything should end up straight when you're finished.