Hi,
[To join the fashion of posting pictures of disks]
I have what looks like lots of mini cracks across the surface of both front disks (which hopefully shows a bit in the pic).
So, is that down to hard use or a sign of something? They’re not new but as you can see there’s still a reasonable groove left in them.
Cheers, Ian 
Ian, as I understand it these will be micro surface cracks - just meaning that area has got pretty hot and cooled rapid - as its where the piston acts I guess thats right …
The crack are thus just superficial and a sign they have had some hard use.
You have to worry when the cracks get longer and deeper then its time to change …
Hopefully someone can confirm … |I have the same on mine
this is the surface crack as what AndyD just said, but just keep an eye on those as it may develop to bigger cracks later…
Whose discs are they and what setup do you have fitted?
They are Alcon Rotors 295mm with bells supplied by me !
I have have same set up on my Black Exige and they are showing the same signs - I think the set up is 5 years old now so really the life of them considering the abuse they get is not bad …
What he said, on the standard Exige set-up just with spacers on the front calipers. Ran RS14s initially and switched last year to PF pads.
I am potentially going to switch the 295 fronts to the rear with the calipers and put 4-pots on the front with slightly bigger disks. As they’re get less abuse at the back I was hoping they’d still be up to the job.
Hey, Andy! Abuse?! ABUSE?!! Oh ok, abuse. 
Ian
I have some barely used AP 295 discs and bells for sale 
Noted, cheers
Ian et Al
I had similar surface cracks on my previous AP 295 discs - nowt to worry about.
Abuse
295 to the back is my plan as well - but you need new bells for the fronts as the existing rear ones are special for the smaller rotor. I just ordered some 308 Alcons from Seriously for the front … and have BG Dev making me another set of Bells.
However … I understand from JDS that the Elise trophy guys may be interested in them as they have to run standard sizes … someone may like a set of 4 ??
Same on my last set of front grooved AP’s and rear Lotus drilled using PF pads. Maybe 15+ TD’s over 18 months.
Just a little warning…Keep an eye on the inside surface of the disc…it gets hotter than the outside. The outside of my std rotors started looking like that but eventualy spotted HUGE cracks on the inside…cant see them without removing the disc…Just my 1/2 pence worth.
Ta, top tip MrBean.
or possibly take a digital photo? Remembering the recent photo someone took by pushing their i phone up their airbox 
If I may add my two-penneth. This rapid cooling that can cause cracking (and warping) is often caused by heat transfer from the disc to the pad and is a result of holding a car on the brakes, instead of using the handbrake. You’ll know that the front brakes deal with something like 70-80% of the braking effort of your car (due to weight transfer) and therefore have a heck of a lot of heat in them, especially after a track session. The rear brakes will be relatively cool, and therefore using the handbrake when stationary will minimise localised heat transfer, saving your front discs from such damage, and as there will be less heat in the rears, any transfer will be negligable.
Of course it’s very fashionable to never use the handbrake in traffic (witness the amount of blinding brake lights at traffic light junctions),but the consequences of using the brake pedal as opposed to the handbrake in a rear end collision will rock your foot of the brake pedal and send you careering into WHATEVER is in your path. My one man crusade ends here. Happy braking.
Kurt
Leave the car in gear (no handbrake) when stationary after a track session. Use the “cool down lap” to cool the brakes, & the rest of the car, with minimal braking until safely parked up. This also prevents the fluid from boiling!
Agree about using the handbrake in normal traffic
Yeah . .I doubt very much that Ians cracks are created by holding the car on the brakes
Kurt - agree with your comments here; however, my g/fs Smart car has “eco” stop/start technology and that only works by keeping your foot on the foot brake. Not sure if that is a common feature across other makes but if it is then expect to see more brake lights on at the traffic lights.
What he said
most cars these days are auto’s i suppose, so they just sit with foot on brake.