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Did you dress and lube the caliper and mount?
Wrrap a bastard file in crocus cloth and dress both mating slides. A thin coat of grease helps as well. But on second glance it looks like that pad ain't seated right..
I was thinking the same thing, but the previous pads wore unevenly as well. I'm wondering if something fundamental is bent / out of whack. Hub, or caliper? I will strip it down again and see what I might be able to find.
I did lube the guide pins, the pads and use disc brake quiet on the contact points to the pads.
If you did the work, I would suggest getting back in there and seeing if anything looks out. If a shop did the work, I would be taking it back and having them make sure it was all put together correctly. From the picture, something isn’t right. But also from the picture, can’t tell what’s wrong….
Hi - I'm in the middle of replacing rear calipers on a 2007 R55 that was wearing the outside pad on the RH side of the car unevenly (that pad 3mm, inner pad 9mm). Normally the inner pad wears more than the outer. The caliper piston on the RH one is sticking such that once the handbrake (ebrake for you guys?) is released there's still contact on the rotor. My initial thought was sliders were sticking but they are fine and the piston cannot be retracted. In this situation you may see one wheel gets a good covering of black brake dust (and/or one rotor/hub heats up quickly on a short drive from cold).
This may account for the original problem but not the lack of wear in your picture?
One other thought - check that the 'legs' or 'ears' on the new pads are not carrying an excessive amount of black paint/plastic/whatever - sometimes that can cause them to stick in the stainless steel carriers, a quick file/sand can help if they are.
Hi - I'm in the middle of replacing rear calipers on a 2007 R55 that was wearing the outside pad on the RH side of the car unevenly (that pad 3mm, inner pad 9mm). Normally the inner pad wears more than the outer. The caliper piston on the RH one is sticking such that once the handbrake (ebrake for you guys?) is released there's still contact on the rotor. My initial thought was sliders were sticking but they are fine and the piston cannot be retracted. In this situation you may see one wheel gets a good covering of black brake dust (and/or one rotor/hub heats up quickly on a short drive from cold).
This may account for the original problem but not the lack of wear in your picture?
One other thought - check that the 'legs' or 'ears' on the new pads are not carrying an excessive amount of black paint/plastic/whatever - sometimes that can cause them to stick in the stainless steel carriers, a quick file/sand can help if they are.
A piston that will not retract is usually caused by an old seal and/or boot. You need to either get a rebuilt/new caliper or pull the piston out of yours and replace the boot and piston seal. Scrape the grooves for the boot and piston seal until they are completely free of corrosion. Make sure both boot and seal are lubed with brake lube (SIL-Glyde for example).
Piston R&R is not that hard - use the brake lever on the caliper back to jack the piston out.
Piston can be screwed in with special tool. I think Pelican has a "how to" that shows this.
A piston that will not retract is usually caused by an old seal and/or boot. You need to either get a rebuilt/new caliper or pull the piston out of yours and replace the boot and piston seal. Scrape the grooves for the boot and piston seal until they are completely free of corrosion. Make sure both boot and seal are lubed with brake lube (SIL-Glyde for example).
Piston R&R is not that hard - use the brake lever on the caliper back to jack the piston out.
Piston can be screwed in with special tool. I think Pelican has a "how to" that shows this.
The piston on this one is showing a fair bit of corrosion under the seal lip (138,000 miles and I think the calipers are original). Over here (UK) a refurbed caliper including handbrake mechanism/lever is not much more than the refurb kit itself so I tend to just go for a replacement caliper and save myself time and mess. Sitting around unloved outdoors during lockdowns has not done the car any favours.
I have two 'specialist' caliper retraction kits one is for van/light trucks - but to be honest I've usually managed cars with just a pair of needle nosed pliers and if the heavy duty 'winder inner' is needed then it is usually an indicator that the piston or handbrake mechanism is in need of some TLC - you can bet your bottom dollar that if a hard 'wind' is needed to get the piston rewound then the next pad change will involve a refurb.
Pretty severe uneven wear. Did you make sure the pins slid easily in their holes? Did the pads fit easily in their seats? Does the parking brake mechanism on caliper retract properly after released? Does it look like the pad is sitting flat on the rotor?
When we serviced the brakes on my son's MINI after noticing uneven wear (and too much heat) we found the parking brake wasn't releasing, the internal parking brake mechanism in the caliper had seized up from corrosion. Another time we found some white corrosion caked up between the hole in the carrier and the rubber bushing. We had to file that stuff out before the guide pin would move freely.
08-09-2021, 04:13 PM
