What's wrong with this caliper/pad?

[samdale]

Found an abnormal amount of brake dust on one of my wheels and noticed it was a bit worn when I got to work this morning.

Just taken the caliper off and found this

Outside edge of disc



Seems fine, a little worn, but not too much of a lip.

However the inside edge looked like this



And the inside pad looks like this



The rusty edge of the disc is thicker on one side than the other and thus has put a step into this pad.
Can't really see how to make this pad start "biting" and clean the disc. Just a case of getting new front discs?
And what's the cause?

[Checkmate]

New discs and pads I'd say. Can probably get that skimmed out but they aren't that expensive, so best just to go new.
Assuming 2 piston calipers, is the inside pot free, and working properly. Had a similar problem where one of the pistons was sticking. Refurbed caliper sorted that.

[clarkson22]

from a mr2? seized sliders, or one piston is seized

[NotReallyBored]

I'd go with new discs and pads and clean/lube the caliper slides, as I'd assume they are single piston calipers sometimes sticky slides cause uneven wear. If a piston each side of disc, could be a sticky piston or even pads grabbing at caliper surfaces. Easy enough job to do.

Edited by NotReallyBored on Monday 4th March 18:14

[samdale]

To clarify, yes, front caliper from MK2 MR2.

Sliding pins have both been removed cleaned and regreased but they seemed free and were greased anyway.



Both pistons are on the same side and the pad seems to be wearing evenly (at least as far as stuck pistons are concerned)

[NotReallyBored]

All seems well then. I've seen this on cars a thousand times personally. Either a combination of low miles and lack of extreme heavy braking, or I have a theory that condensation builds on the inboard side due to the back plate after the discs get hot, hence the corrosion build up on the swept area. Make any sense?

[samdale]

Can't really understand why they got hot though. It wasn't the big cloud of smoke and too hot to touch like last time I had a caliper seized (after a very short distance). The alloy was warm after a 7.5 mile gentle journey (others were stone cold) and no noticeable hot brakes smell. Will check again tomorrow and get some discs/pads ordered anyway.

Hmm interesting theory, makes some kind of sense. Just looked on eBay and can get discs next day delivery for £45.

[clarkson22]

disc could be warped, but you would probably feel it through braking

[clarkson22]

also on my mr2, when ive had a sticky piston , they looked even on inspection, i just couldnt push them both in at the same time, changed caliper and tons of brake dust, hot caliper are no more

[LukeSi]

I believe MR2s have a tendency to eat calipers and warp discs.

[samdale]

clarkson22 said:

also on my mr2, when ive had a sticky piston , they looked even on inspection, i just couldnt push them both in at the same time, changed caliper and tons of brake dust, hot caliper are no more

Guess I better exercise the caliper a bit then before I go and buy new discs and pads and wreck them both in a week

ETA:

LukeSi said:

I believe MR2s have a tendency to eat calipers and warp discs.

Only problems I've had so far have been brake related.

1) seized caliper left me stranded.
2) Scratching noise from rear brakes suggested pads were worn out. Outside one had plenty of meat left, inside one looked like this:

3) Whatever this turns out to be.

So far I've been lucky and not replaced any discs so far, as I've stopped short of damaging them. Like I said, best I resolve all other brake issues before fitting them and warping them on the first outing

Edited by samdale on Monday 4th March 20:05