Brake discs warped AGAIN !!!!!!!

SD1s spring to mind.

No, me neither. IIRC the sudden increase in disc wear coincided with the loss of asbestos from the pad friction material. Modern friction material seems very abrasive by comparison, and I guess can't match the overall qualities of asbestos.

Julian.

Dare I point out that drivers are now taught to use brakes in situations where once they would have been taught to use engine braking? Times change, technology changes.

I recall the first time I went off-roading in a landcruiser, and being told, at the top of a 1 in 3 downhill, to just take my feet off the pedals! It works. In fact the landcruiser's engine braking was so effective I had to give it some gas. Now, though, they build 4x4s with electronic hill descent control instead of a low-ratio box (eg Freelander).

Front discs on '80 Bluebird and '84 Celica did 125K miles.

I've suggested SS as a good rotor material on UK car groups before but got shot to pieces as it seems stainless steel warps to hell, far worse than cast iron. Well yes it does if it's thin sheet like they use for catering and you take an oxy acetylene torch or mig welder to it but not a 6-8mm thick rotor at temps that brakes go to.

How the hell do you keep that pivoting caliper working with such little use? Even in 1985 most 550's I saw had 50K on them. 500/4s used to crack rear drums, they couldn't cope with the work needed to compensate as front got progressively worse. 550 drum was usual fix.

Might be 'cos you called 'em "rotors" on a UK group ;)

Oh it doesn't get any use. It's been rusting away in the back yard for 30 years now. Well, everything except the front disk which still appears fine. Last time I rode it would have been 1978/79 when I bought a CB650 (sat rusting alongside the 550) and I only rode that a few months before abandoning bikes for cars.

Yes. Maybe at lights etc but not every time you stop....

ide quoted text -

Sedona is a very heavy vehicle as well.

I'm sorry but even though undoubtedly you should stick the car in neutral and stick the handbtrake on when you stop at lights, I cant see how this is going to (or should) knacker the disks in 1000 miles....

What about when you brake for instance when up to a roundabout and then have to wait like 30 secs for a gap in the traffic to pull onto the roundabout. During this time, you will have your foot on the brake pedal. Dont tell me you'd use the handbrake here. So, by some peoples rational this is causing damage to the brake disk.

I'm sorry but they should not warp just by doing this...

I think the idea is that it may cause a problem if the brakes are very hot.

If you're just driving around town I can't see how leaving your foot on the brake is going to do any harm. After all in many cars the handbrake just clamps the rear disk calipers on anyway.

It's if you've just driven down a mountain on the brakes and then stop and hold them on for a few minutes. They cool unevenly or something.

I think the suggestion that the hubs are running out of true seems to explain the facts best in this case.

Look and see at traffic lights how many (or few!) cars actually seem to have handbrakes these days.

Amazing, isn't it. Has teaching changed, or is it just lazyness? Most of the ones I see aren't autos.

Which raises the question of why cars with handbrakes that work on the disc don't suffer this problem.

Good point. Perhaps because the rear discs don't get as hot as the front ones during braking?

Exactly. I can understand if you're driving like a nutter or something then the brakes are going to get really hot.

I just dont think that disks should warp when you're driving normally and just occasionally leave your foot on the brake pedal....

Yes. I was thinking that as well.

Cars under warranty so I might suggest to the garage that if they can convince the warranty company then feel free to start changing out bits like the hub. After all, it aint going to cost me anything...

Many cars with rear discs use a drum handbrake that operates inside the disc, so would not be a cause of disc warping.

The reason for using this system is that a cooling drum shrinks and applies the braking effort more forcibly; a cooling disc does just the opposite.

The first mainstream production car to be fitted with all-round disc brakes was the MKII Jag; many of them rolled away when parked...

Chris

Chris Whelan (Chris Whelan ) gurgled happily, sounding much like they were saying:

But whilst the DS - four years before the Mk2, in 1955 - may have only had drums on the rear, the handbrake was on the front disks...

That wouldn't explain cars where the handbrake operates on the front discs.