Wierd Grove In Brake Disk

Looks like something got caught between the disc and pad - wearing the groove in the disc.

Whatever it was then dropped out, leaving the pad to wear down as the mirror of the groove in the disc.

Well the groove in the pad is actually a wear indicator and once it's disappeared, the pad should be replaced. The groove wouldn't cause that in the disc and if it had anything to do with it, it'd create a ridge.

My bet is that at some time, something has got stuck in the groove. Either way, it looks deep enough to warrant a change of the disc IMO.

He wasn't asking about the wear indicator groove.

He was asking about the raised bit of the pad.

That's cos the rest of its been worn down by the disc. By the time you've taken them off you might as well change them though.

See my other reply.

And, yes, the discs and pads need doing.

Jesus, I sometimes think you lot are preparing the next shuttle for orbit. it's only a van FFS, there's loads of life left in those pads and discs, and there's no particular route to a brake failure...

Julian

Eh? Having driven lots of cars and vans, it's the van brakes you need to worry about. The average car rarely has more than 1 person in it other than the driver, whereas a van can double in gross weight between unladen and loaded.

& they shear. But the real reason you want to change them is that they eat brake pads & they cost more than discs.

So how does that make a half worn pad any less effective that a new one, if you have friction material then you have friction material.... And as for that tiny groove in the disc, if anything that increases surface area :-)

But you assertion that van brakes are somehow more highly stresses than a car's is wrong. Firstly a van's brakes are heavier - take the rear drums on a Combo for example. Secondly weight may double, but an empty (car derived) van is lighter in the first instance when empty.

Julian.

Nah, the disc is sound except for a small circumferential groove - that won't make much odds to pad wear.

Julian.

You can see how it's affecting pad wear in the pics., can't you?

That's good enough evidence for me for swapping them.

Which I recently found out on an ice covered road in my astravan. Stoped on a bit of an incline with h/brake fully on and as soon as I released foot brake the thing starts to slide backwards with both rears locked on!

Anything that can get caught on the pad can cause what you see.

When I got exactly the same as you ... I got a chunk of rust/metal of the edge of the disk (when I had actually cleaned the rust off it) stuck on the pad.

It took a magnifying glass to find the spot of metal on the pad and remove it.

Charles

My guess woulld be that a stone got caught in the pad, grooving the disc. After it dropped out the pad simply wore to match the disc. Not that uncommon, but in most cases not as severe. Mike.

But the metal in that groove will get quite hot compared to the rest of the disc surface as it's thinner and it's not beyond the realms of possibility for the disc to crack.

Considering how piss cheap brake discs are now, it's not worth it.

Add inertia to the list of things Julian doesn't understand.

But there isn't any ''metal'' in that groove - its gone AWOL ROFLAO!

will get quite hot compared to the rest of

Yes whatever, I love it when people come up with all these theories - fatigue, hot spots, hairline cracks etc etc. I've spent about 30 years working on cars and when I was an MOT tester I failed vented discs worn so thin that the working surface of the disc was becoming depressed between the vent ribs. However they still worked fine and didn't explode into a million bits like you would suggest. (probably having watches too many films made in Holywood)

The disc in question has a tinsy winsy ickle groove and a corresponding ridge on the pad, (that doesn't look 25% worn) to suggest that the combination is unfit for further service is just an absolute nonsence.

Two discs + pads £50+VAT? (thereabouts) You sound old enough to know the value of money surely?

Julian

Yes thanks, no abnormal wear whatsoever save for that little ridge

As above...

Julian.

Yup, so that sets worth about a tenner, not worth keeping.