On Thursday, 19 May 2016 13:18:55 UTC+1, The Natural Philosopher wrote:
On 19/05/16 12:24, Dave Liquorice wrote:
On Thu, 19 May 2016 12:00:34 +0100, The Natural Philosopher wrote:

Nearly happened to me once, but more from worn discs than anything else.
Downhill stretch of te A1, and needed to pull up. Might have been doing
more than 70mph ;-). My beloved old opel manta.

I got it down to about 30mph, and then half the brakes simply didn't
work at all. Rear drums still worked but the front brakes essentially
gone.

Good condition brakes shouldn't fade just stopping a bit quick from
70+ mph, once.

Indeed. That's when I realised they weren't in such good condition.

That car didnt have vented discs, and they were thin,. The car relied
ogn thermal mass to basorbe the energy without overheating the discs and
pads,. with less disc to heat there wasn't enough capacity to absorb a
full stop from the speeds I was doing, down a fairly steep hill.

Brakes that are fine at modest speeds and light loads may not be so fine
at high speeds with full loads - the 'family holiday' scenario.

As I wrote earlier, a production car that can dissipate full braking
heat indefinitely is the exception, not the rule. Most cars will do one
emergency stop from their top speed, once, and that's it. Until the
brakes cool down.

Now think about towing a caravan off a mountain..

Long ago I drove an ancient commercial vehicle with drums all round, split rims, 3 driving gears etc. Brakes were in good condition. Coming down a small mountainside empty I used the handbrake to keep speed to about 20. Due to brake fade the handbrake needed putting on further frequently. Halfway down it was out of handbrake travel and I stopped. And that was empty. People take so much for granted, sometimes too much. Modern cars still can and do fail, just not so often. What worries me is people that drive on the assumption their brakes will always work 100%. It just isn't so. It's wise to have backup plans.


NT