Front pad replacement

[ChrisH Kerry]

Was going to replace the front pads on my 2002 1150GS (with ABS) yesterday but pistons weren't in a mad hurry to return into callipers - they're all moving free but don't want to push back and I'm wary of forcing them. Had a look at undoing bleed nipple but that didn't want to shift either (are they prone to snapping off?) Any advice gratefully received, thanks

 

[Timolgra]

Don't lever directly against the piston else you'll crack the plastic cover.

Yes the nipples can seize, you need to give it a soaking and try tightening very slightly first if there's a problem.

 

[flatdog]

Also check the brake reservoir level isn't too high -

 

[ELIMINATOR]

Get yourself some brake cleaner in an aerosol can, and a toothbrush. You may have lots of crud on the pistons, if you force them back into the caliper

 

[Cook1e]

Did mine last weekend

Brake cleaner + toothbrush as recommended will remove the crud (brake dust, grit & salt mostly), then make sure piston sides are clear of corrosion.

Push back with old pads & tyre lever or use a dedicated tool. You may find that as one moves back, it pushes the others out - you can use blocks of wood, G-clamps, whatever to manage this.

Ensure there is plenty of space in the M/C reservoir and that the brake lever is fully released. You can loosen a bleed nipple to let fluid out, but you risk admitting air.

HTH, get assistance if any doubt, brakes are critical.

 

[ChrisH Kerry]

All the pistons move freely with no corrosion, and as a pair are pushed in other pair push out (obviously) but if I wedge one pair so they are back in calliper the other pair do not want to go in. Think I'll have to get bleed nipple undone. I removed some fluid from reservoir before starting ... I imagine it's something to do with ABS unit not letting a volume of fluid back so didn't want to force anything - but that's just guessing. Very familiar with ordinary brakes so just being cautious due to ABS unit. Thanks for replies

 

[Cook1e]

If you put the old pads in the caliper and lever them apart, all 4 pistons should push back together. The ABS unit should not interfere (assuming it's ABS2 not servo, about which I know bugger-all)

 

[alfazer]

I thought you weren't supposed to push fluid back up through any system on any vehicle with ABS. Aren't you supposed to let it out through the nipple?
You tighten it just as you are still pushing the fluid back, so the air doesn't get in.

 

[gspod]

As the pads wear out so the calipers should move in and hence the fluid level in the reservoir should drop.

What I do is take the lid off the reservoir to release the pressure, I then rap a cloth/towel round the reservoir in case of spills and the pistons just push out by hand (gently of course).

Not sure this is a recommended technique but I always do my own brakes and never had a problem over the last 15 years with my 1100 abs.

Hope this helps.

 

[ELIMINATOR]

I've cleaned the pistons a few times on my 2004 servo GS, never had a problem pushing the pistons back, or had to release a nipple or remove brake fluid.

 

[ahutcheon]

I removed some fluid from reservoir before starting ...

If it's a servo ABS bike, the fluid in the callipers is in a circuit with it's reservoir in the ABS unit. Removing some fluid from the master cylinder reservoir up on the handlbar (if that's what you've done) might not be enough (or indeed any help - not sure how the lever and wheel circuits interact).

 

[ChrisH Kerry]

Non servo ABS on mine. Got the bleed nipple undone but that's as far as I had time for today... will give it a go over weekend, unless I have to go out riding the bike

 

[ChrisH Kerry]

Well I had another look at the calliper this morning - no way the pistons are going back in. I undid the bleed nipple on left hand calliper but that made no difference, still wouldn't move in. All four of the pistons move freely ie. if you push one in other ones move out, but seems like there is a block against the fluid moving back through pipes, even with bleed nipple open on other calliper. I thought of removing the grub screw and screwing in a bleed nipple on the right calliper, but of course the grub screw doesn't want to shift either. Suppose I'll have to take the callpier off and try to find out what's going on. Might be a good opportunity to replace brake lines, but all I wanted to do was put in new pads

 

[The smudger]

I had exactly this. Brake hoses had collapsed internally. To prove it crack off the flex hose into the calliper and squeeze the lever. I did this and NO fluid came out. I even took the banjo bolt right off and none. I found a small bulge at the bottom of the rubber hose where its clamped. If youre not getting anything out of the nipple remove it fully, you will probably find the nipple blocked with rust, you can clean them out, i used a piece of wire from the wire brush.

 

[ChrisH Kerry]

Thanks for that Smudger - I think there may be an element of that going on. The nipple works fine, I opened it and fluid appeared in the tube I had attached, but no fluid is forced out if I try to press the pads back into the right caliper, in fact nothing happens at all. If I pull the brake lever the pistons do move out - which is why I'm now f**ked as I can't get the pistons back in so can't put the caliper on even with the old pads There must be something stuck in the pipe somewhere that lets fluid down the pipe but not back up - like a one way valve. I thought it must be something to do with the ABS but obviously not. Reckon your theory of pipe breaking down could be spot on. Have to order new pipes and next - see if I can get that stupid grub screw out. Any ideas on that?? I'd say it will round off if I try with a allen key.

 

[The smudger]

Slacken off the banjo bolt, then try to push the pistons back. If they go back it may be your hoses.

Try some heat on the screw.

 

[Chrizm]

Thanks for that Smudger - I think there may be an element of that going on. The nipple works fine, I opened it and fluid appeared in the tube I had attached, but no fluid is forced out if I try to press the pads back into the right caliper, in fact nothing happens at all. If I pull the brake lever the pistons do move out - which is why I'm now f**ked as I can't get the pistons back in so can't put the caliper on even with the old pads There must be something stuck in the pipe somewhere that lets fluid down the pipe but not back up - like a one way valve. I thought it must be something to do with the ABS but obviously not. Reckon your theory of pipe breaking down could be spot on. Have to order new pipes and next - see if I can get that stupid grub screw out. Any ideas on that?? I'd say it will round off if I try with a allen key.

If you do order new pipes I just fitted some from a guy on ebay, full set for 1100gs with abs for less than £90! quite easy to fit and bleeding was far easier than i imagined it would be

Link to lines: http://www.ebay.co.uk/itm/270716544188?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

 

[ChrisH Kerry]

Work out slightly dearer for the 1150, probably get them from one of the dealers as the grub screw has no notion of coming out so going to have to replace that part, unless it's possible to just scrap that bit altogether and replace with a normal bleed nipple? What is the point of that 'filler adapter' anyway?

 

[richierex]

Well I had another look at the calliper this morning - no way the pistons are going back in. I undid the bleed nipple on left hand calliper but that made no difference, still wouldn't move in. All four of the pistons move freely ie. if you push one in other ones move out, but seems like there is a block against the fluid moving back through pipes, even with bleed nipple open on other calliper. I thought of removing the grub screw and screwing in a bleed nipple on the right calliper, but of course the grub screw doesn't want to shift either. Suppose I'll have to take the callpier off and try to find out what's going on. Might be a good opportunity to replace brake lines, but all I wanted to do was put in new pads

If you undid the bleed nipple and tried to push back the pistons, where do the pipes come into this. just make sure the bleed nipple is open, takes a bit more of a turn than you think.

 

[ChrisH Kerry]

My thinking is: the calipers right and left side are directly connected, if I open the only bleed nipple - on left caliper - and try push pistons in of the right caliper, they should displace fluid out of the open bleed nipple. That's not happening, no fluid coming out apart from small amount just from having nipple open. And pistons won't budge, so there must be blockage between caliper on right side and left one. If I pull the brake lever (with bleed nipple closed ) the pistons on right caliper move outward, so the blockage appears to be acting like a one way valve, which is why I can't even get the old pads back in.
I was hoping to avoid having to take the brakes apart but seems like no choice, and was thinking about replacing hoses anyway. Still don't understand why there isn't a bleed nipple on right caliper instead of that other 'filler adapter'...