When to replace brake rotors

[yrebrac]

Hi All,
New here but looking for some advice.
My mechanic just advised me I need to replace front and rear pads and rotors since the rotors are now too worn to be machined. Since I now have the space I am planning to do the job myself.
Firstly I am wondering how can I confirm I need to replace the rotors. I had a quick look and there are some slight and smooth grooves on the surface of the disc, and there is an overhang at the rim.
Secondly can anyone recommend where to buy the spares. I would normally use a wreckers but not sure if that is great idea for rotors where they may have been sitting in the elements for a long time.
cheers,
Ben

[Brett_jjj]

Mate dont use second hand or machined discs.Brand new discs are so cheap these days theres no need to go second hand.Have a look on ebay for some new cheap discs to suit your car.Ive seen them on there before for $30 each brand new..
Discs slowly wear down to a minimum thickness which for the VR/VS front discs is 20mm,and for the VR/VS rear discs is 8.5mm.
Just had a quick look at ebay.Heres a couple that I found for an example,that are pretty cheap,but its definitely worth having a look through them all on ebay..

---http://www.ebay.com.au/itm/DISC-BRAK...item2eb0d91760---

---http://www.ebay.com.au/itm/DISC-BRAK...item2eb0d92f1b---

You can also pick up cheap new discs up at places like supercheap auto etc..

[yrebrac]

Thanks for that, couldn't find the thicknesses. I'll go measure..
Yeah, not too bad new, $66 for fronts from super cheap.

[Brett_jjj]

Just be sure to measure the disc where the pads run, and not just from the edge of the disc.You will need a suitable micrmeter to measure them properly..

[Not_An_Abba_Fan]

You could upgrade to slotted rotors and performance pads. I do a special curve slot and dimpled rotor for $180 plus $45 for pads.