Cracked brake disc

[Snails]

Yesterday I noticed a knocking noise from the n/s rear, upon investigating, I found this:

The discs were fitted less than 1 year ago and have covered just 10000 miles since being fitted. It's not even 10,000 miles of hard driving. Any idea what could have caused this? I've also spoken to the garage who fitted them last year and I'm taking the car in to them this afternoon to investigate.

 

[TheEvilGiraffe]

Sticky caliper meaning too much heat in the system would be my guess ?

 

[02teasda]

This happened to me just before Christmas and it was because the calliper had seized and the disc was heating up and cooling down far too much!

 

[James23]

Sticky caliper meaning too much heat in the system would be my guess ?

Would be my guess too. Must be really bad though cos my scenic had a seized rear caliper for around 15k miles and it never cracked the disc!

 

[Millerin]

blimy. i was expecting a small crack not all the way through

 

[Snails]

I found the crack 30 seconds after driving 20 miles home and the brake disc was not hot like it was when my n/s front caliper seized, I couldn't even feel any warmth from the the disc. When the n/s front seized the disc was hotter than the sun itself!

 

[Lynne172Cup]

This just happened to me too! Same story, roughly 10,000 commuter miles and my pic looks exactly the same.

What kind of discs were they? I had mintex

I also have a sticky brake issue so I'm sure TheEvilGiraffe is right

 

[mitch1503]

also had this although mine was worse than that.. my caliper doesnt seem 2 be sticking but thats usually the cause

 

[Simon@SprayShack]

Ive had this happen multple times, 2bh its crap quality discs imo........my calipers each time were sliding fine, not stuck at all. What most people dont know is that the rear brake discs are 8mm thick to begin with, and are to be replaced at 7mm, theres not much wear in them full stop most people run them for far far to long.

Check the thickness my money they've had it anyway according to renaults specs.

Technical characteristics

Sale unit :	1 pair	Outer diameter :	238 mm
Nominal thickness :	8 mm	Min. thickness :	7 mm

 

[mitch1503]

Ive had this happen multple times, 2bh its crap quality discs imo........my calipers each time were sliding fine, not stuck at all. What most people dont know is that the rear brake discs are 8mm thick to begin with, and are to be replaced at 7mm, theres not much wear in them full stop most people run them for far far to long.

Check the thickness my money they've had it anyway according to renaults specs.

Technical characteristics

Sale unit :	1 pair	Outer diameter :	238 mm
Nominal thickness :	8 mm	Min. thickness :	7 mm

thats good info and yep mine were genuine discs although tom sorted the problem quickly as they were still under warranty

 

[swellybro]

I've had this happen to me with genuine Renault discs (they come with the bearing pressed). It was a sticking rear caliper that cracked the disc on mine.

Whip the rear caliper off (you'll have to clamp the brake pipe), take it to a local motor shop and they'll sort you out with a recon unit for a swap. I paid about £60 all in.

 

[Garyk]

Mine was identical to this. Was a sticky rear caliper. I replace the lot but my wheel bearing was buggered too and the wheel used to get red hot.