Thread: Not much Steel holding your Brake rotors together.... I had a scarey experience

Whilst coming back from a fishing trip and towing my boat at 90kph on applying the brakes there was a load bang and my Disco2 swerved to the left. I managed to brake and come to a stop fighting the steering wheel.
Road side inspection couldn't reveal much, looking through the alloy wheel spaces the discs and pads seemed fine all round.
I checked the trailer brakes and all was ok there. I started to move off a short distance and heard a slight scraping noise coming from the front brakes and it pulled to the left. something was not right!.

I pulled the front wheels off this arvo and inspected the brakes, rotors seemed ok except for normal grooving marks, the Brake pads where 90%.
I shook the drivers side front wheel and there was play, at first I thought it was the front hub bearing.
I removed the caliper and was about to remove the brake disc when I saw the brake contact surface was free spinning from the brake disc hub!
It was evident that the disc had cracked and come away from the hub section!
Closer inspection revealed that the disc must have cracked at some time and rust had got into it.
Even more disturbing was the thickness of the casting at that point, a few mils of metal is what your life depends on.
These discs where on the Disco when I purchased it and there were no markings on them . I'm used to seeing stamping of things like wear thickness information. These had nothing.
I've put together some pics of the damaged disc. Discs are often forgotten as they are out of side and out of mind. The sudden loss of brakes and a heavy load behind could have met with disasterous consequences, I was lucky.


The 2 now halves separated, the force of the brake pad gripping the disc and the hub turning on the axle was enough to rip it apart





rust pitted edge, this small thickness of metal is whats left after the disc is machined in manufacture, not a lot really



This pic shows rust and pitting on the rim so a crack must have been there for some time.

I don't know what caused the disc rotor to crack in the first place.

This may or may not be the case with this car, but this worries me a lot when you see brake discs and pads etc for sale cheaply on eBay etc. even stuff which appears to be brand named can easily be cheap copies from China with no quality control and no manufacturing standards etc.

Your life depends on this stuff, it's just not worth messing with. Save the eBay stuff for plastic dash parts and exterior plastic bling etc. anything which your life depends on should come from reputable suppliers.

Also fitting of this stuff, there is no doubt there are lots of people here who really know what they are doing, but for stuff like brakes the have a go guys and amateur mechanics (like me) need to leave this stuff to properly trained professionals.