i'm putting on new rotors this weekend, and i checked to see if i needed to change the pads, but i still have half the pad life there. does anyone know if i have to change out the pads when putting in new rotors? i don't want to change pads when i still have a lot of life left on them.
i remember reading somewhere that the pad material that's actually on the rotor helps in braking or something? so if i have a new rotor, then the used pad will be coming into contact with a brand new surface...just wondering if anyone had any insight on this...

 

what's the reason for changing rotors? short of severe brake pedal pulsing, i would leave it as is until your pads are worn down. then install new pads and rotors as a set.

 

No need to change the pads if they have some miles remaining on them.

 

no harm in changing both out.

 

If the pads still have life there is no reason to change. Just perform an extra bed-in procedure when bedding the brakes if you come across any NVH issues.

Refer here for bed-in procedure:
http://www.zeckhausen.com/bedding_in_brakes.htm

That said, I would probably switch if they had any less than 1/3 pad left just for convenience sake.

 

^^^ good call. To the OP, you're right. For best results, some pad material embeds itself on the surface of the rotor to provide best braking characteristics. If you replace pads or rotors, you need to go through the bed-in procedure. If you do it right, you'll see the difference between before and after.

Generally, I've found that shops and most people are all too eager to replace rotors and pads when only usually pads are just required. A lot of times uneven pad deposits are misdiagnosed for warped rotors. Heck, I am still on my original rotors and I have an 03. I did change out the pads all around since I already used up one set in front and rear. Last time at the dealership, the service guys wanted to replace my rotors. No thanks. Current combo works just fine

 

Is there (or was there) some sort of law that said all shops have to also turn the rotors when doing a brake job? I kind of remember something like this in CA about 5 years ago, but not sure if it was a federal law or what. Foggy memory...

However, if this is the case, I could see a shop saying that the rotors are too thin to be turned and new rotors should be purchased -- even though the original rotors were probably fine in the first place!

 

I don't recall any such law. Maybe an informal law of milking customers for money

The truth is that you if you, as a shop, turn the rotors, you can charge for it, and assuming you're already doing the brakes, it reduces the likelihood that the customer will come back complaining because they didn't break the pads in correctly. It's a lot easier to just turn them and have people drive away with clean surface, assuming the rotor has enough thickness where you can do it. I don't recall what that thickness is exactly.

 

No need. My rotors laster 61k and 2 pad changes.