Brake discs

The discs do wear more than they did 15 + years ago. I remember when a disc would last years and years and even then usually only needed changing because the pads had been left until they were metal to metal. The pads and discs today are made of different compounds and while discs do wear out quicker, the braking efficiency is far superior.

Dunno whether it's related (I think it is) but since asbestos has been banned from being used as a friction material, disk-life has been reduced dramatically. On average I'd say every other pad change is a pad+disk change...

In message , John writes

28k? I've just had to replace the front and rear disks on my 2002 Civic at 48000, and was feeling slightly resentful about it.

a friends Micra 2003 needs new discs 36,000 scandalous I know - what must they be made of?

Fluke

MDF I think.

Years ago I read an article by LJK Setright about brake discs, and for yonks afterwards I waited for someone to ask me something along the lines of "Do you need a special kind of steel to make brake discs?", then I could reply "No, any austenitic type steel with a Brinell hardness in excess of 150 will suffice" No-one ever did of course. Bastards.

Steve

Same stuff as before. Its just that the Eurocrats decided asbestos in brake pads wasn't clever so banned it. End result is pads are harder on discs than they used to be in order to get the same stopping power.

Can I just say all large garages will tell you to have your brakes and discs replaced as they know 80% of people won't even bother checking themselves, and its a big earner for them. All you have to do is take the wheel off and look, does it look safe to you? Is there a ridge to your brake disc? If so its worn but not dangerous and will allow you to brake succesfully, until the ridge is over a millimetre say or the disc is warped/cracked then it needs replacing. Pads generally need replacing when you have less than a centimeter left on them. I've done 80k on my discs and 60k on the original pads, although yes the pads no longer existed.

It is not just the mileage, but disks can rust over time. I was told to replace the rear disks on my old Saab as they were pitted. The front disks were OK even though they had more wear. It looked like only a small are of the rear disks were active when braking. Disks can also be poorly aligned as special measuring equipment is required to fit them correctly.

Unless you're doing something very strange you don't need any special measuring gear to change brake discs.

Johannes ( snipped-for-privacy@stop-spam-sizefitter.com) gurgled happily, sounding much like they were saying :

Don't be daft.

Just get the mounting face on the hub clean, and plonk 'em on.

they saw you coming then.

They should always be checked by a Dial Test Indicator (DTI).

Oops. Never done that. Haynes doesn't say do it either.

Are you sure you're not being a tad paranoid?

clive

[...]

Indeed. Just like they always do at Kwik-Fit, ATS, National Autocentre, and all main dealers.... :-)

Chris

Johannes ( snipped-for-privacy@stop-spam-sizefitter.com) gurgled happily, sounding much like they were saying :

Don't be silly.

What the hell?

If you're suspicious they're faulty then it's worth doing , but anything made in the last 30years should have hubs & discs manufactured to a better tolernce than you'll see on a dti.