back brake pads destroyed!!

[budd]

After my incident running into the Gixer 1000 I noticed my rear brake wasn’t working, now the RSV rear brake isn’t the greatest to start with but would at least hold in on an incline, but not anymore it was totally u/s, a quick visual inspection revealed the braided hose had parted company from the union at the caliper end so a new hose was duly ordered. While I was waiting for the hose to turn up I thought I’d use the down time to strip and rebuild the caliper and it’s just as well I did, I’ve never seen pads in this condition…




The pads they are just destroyed,the backing plate has been bent out of shape by the piston they and are supposed to be flat not concave!!



and the seals have MELTED!! the first pic below shows one side of the caliper which is Ok the second shows the otherside where you can see where the rubber seal is melted..

Quite how hot it must have got I don’t know but it must have been f***ing hot to soften the pad backing plates enough for the pistons to bend them, as to the cause I really don’t know it’s obviously stuck on but why? The caliper seems in good condition and the pads had plenty of meat on them so it’s a bit of a mystery, new pads / seals / pistons are now ordered along with the hose so all I can do is put it back together and go from there, I’ll wait and see if it’s warped the disc is warped and may end up replacing that too.

[Wicky]

Something very wrong there! that'll be fun to clean out the melted seal material in the cylinder - What's the disk looking like?

[budd]

Yes something very wrong indeed, possible culprits,are the push rod is incorrectly adjusted or the res is over filled I think there should be a small air gap
The seals came out without much trouble a bit of 00 wire wool and the calipers will be good as new, rear dics looks straight it's just covered in SBS pad meterial I've got some share pads that I'll use for a few miles to clean up the disc before fitting new ones,

[sirch345]

I don't know, first the front brake lever is not where it should have been (scary I'm sure) then the rear brake is in this state
A good job it's getting serviced

Chris.

[budd]

I don't know, first the front brake lever is not where it should have been (scary I'm sure) then the rear brake is in this state
A good job it's getting serviced

Chris.

I'm not having a great year, 2 puntures so far, dropping the bike in the garage, my promptu stoppie, hitting the gixer and now like you say the rear brake is in this state although it's possible that there is a connection between the last two events,it had new tryes 2 weeks ago and the rear brakes were tip top, I had the caliper off and gave them a brief check no issues, no binding nothing to suggest any potencial problems. So whatever as happened to cause this as happened since then and the only thing out of the ordinary is my little collision quite how it could have caused the issue I'm not sure, although the Aprilia's rear brake m/c is mounted under the engine so it's possible it took an impact through the belly pan, once it's all back together with new bits I'll know the caliper/pads and hose are OK so any further issues can only be the M/C..

[sirch345]

I don't know, first the front brake lever is not where it should have been (scary I'm sure) then the rear brake is in this state
A good job it's getting serviced

Chris.

I'm not having a great year, 2 puntures so far, dropping the bike in the garage, my promptu stoppie, hitting the gixer and now like you say the rear brake is in this state although it's possible that there is a connection between the last two events,it had new tryes 2 weeks ago and the rear brakes were tip top, I had the caliper off and gave them a brief check no issues, no binding nothing to suggest any potencial problems. So whatever as happened to cause this as happened since then and the only thing out of the ordinary is my little collision quite how it could have caused the issue I'm not sure, although the Aprilia's rear brake m/c is mounted under the engine so it's possible it took an impact through the belly pan, once it's all back together with new bits I'll know the caliper/pads and hose are OK so any further issues can only be the M/C..

You could be onto something there, or at least it could be something to do with the master cylinder/operating lever I agree. At least you are now aware of a problem and you're going through the possibilities, good luck with it,

Chris.

[AMCQ46]

have you checked that there is not a bit of Suzuki debris trapped under then pedal?

[VTRDark]

Wow those pads are messed up. Are you sure they are not Chinese copies. Even if neglected and worn to extremes the metal should't go like that.

[bigbadjonno]

Seen something sort of similar with my Dad's old Renault Scenic where he'd had a caliper off it to change the pads and had twisted the caliper/hose before refitting (and didn't notice). Eventually when the hose kinked, it jammed the caliper on and ran the pads down to the metal in a couple of miles.
Christ knows how he didn't notice!

[budd]

Wow those pads are messed up. Are you sure they are not Chinese copies. Even if neglected and worn to extremes the metal should't go like that.

SBS pads so not cheap'n nasty,

[cheekykev]

It looks to me like your pads jamned on, what colour is your disc, and how much scouring is on it ?
I've had rear pads jamn on me years ago, the heat they produced was unbelievable, if that proves to the case you will definitely need a new disc.

[E.Marquez]

The only time I have seen a bent pad like that was when the pad was seized in place on pins and caliper body...so the piston was just a nice hydraulic press ram and put pressure and force on the pad center while the edges stayed put.
That bike had been rear ended and the caliper was bent... Not sure just dirty slider pins would hold the pad ridged enough

I dont think I would be reusing that caliper, at least not without a complete rebuild and then a lot of testing after

[KermitLeFrog]

A surprisingly common problem. Brakes are binding for whatever reason, no clearance on the pushrod for instance or the brake lever. The caliper heats the fluid up which expands; positive feedback and after a little while the brakes lock up. When it happens on the front on a powerful setup the results can be painful.

[budd]

all rebuilt, bled and back in use, got some cheapo kyoto pads to see it the disc will clean up, it's not warped and as minimal scoreing so it may be OK, but it defo needs to be checked and re-checked to ensure it is Ok, I'll probably change the disc anyway along with the pads just to be on the safe side.
as for cause I think mr marquez is on to something, if you look at the pic below you can see the little notches worn into the caliper, I think this as caused it to lock the pad, so I've ground it smooth so this it now moves freely, the pad indexes at the sides to this shouldn't effect the function.

So what as caused this? well I'm afraid to say it probably my fault, when I got the bike one of my jobs was stripping and rebuilding the brakes, I think when I've bebuilt the rear I haven't paid enough attention to lining the 2 sides of the caliper up, there's a small amount of movement due to the tolerences around the bolt holes, if the 2 sides aren't perfectly alinged then the retaining pin won't go through quite square and in this case as held the pad up against the caliper under pressure and eventually worn the little notches, and led to the pads sticking and ultimately overheating and destroying the pads ( and possibly the disc too), the good news is it all seems to be working as it should at the moment, but the rear brakes is one of the Aprilia's weak points ( just about good enough to pass the test but that's about it) it's so poor it's virtually a waste of time to use it while riding, so it's something i'll be looking at improving either on the winter service or sooner if I have further issues. Improving the Ape rear brake involves moving the M/C from it's current location, it's not ideally positionplace bolted to the underside of the engine right next to the exhaust (quite what they were thinking I've no idea) so the solution is to re-locate to the more traditional position behind heal plate the foot rest, I already have a Ducati brembo M/C so just need a suitable rearset to mount it on, I think it will involve some fabrication and I'd rather not have it off the road while we are having such good weather, a job for the winter me thinks.

[sirch345]

Very interesting to hear what you have found. Not a brilliant idea though if you can reassemble the caliper out of alignment IMHO.

As you say though, keep an eye on it,

Chris.