I was told by the dealership that had serviced my V8V (before I bought it) that at the time of the last annual service (in September), the rear pads were noted to 'need replacement soon'. The brake pad sensor has not yet been tripped.

Anyway, I'm ordering some Red Stuff pads (front and back) to have on hand when the time comes but the vendor is asking me if I want to buy rotors at the same time. It feels like an up-sell to me.

I have not had a good look at the rotors to gauge wear but am wondering how the rest of you approach this? It would seem odd to me to always replace both together, particularly when the pads are not warn to the point where the rotors are being ground down.

That said, I just got the car so, I don't know 100% what the specific history is but it's only got 12k miles on it and had its 3 annual services done at the dealer where all necessary work was done.

 

There would be no reason to replace the rotors. Unless they are below minimum specs. At a dealer level we dont replace rotors unless they are below the minimum spec. This can be at the 2nd pad change or 3rd pad change. I have heard of parts stores saying that you need to replace the calipers everytime you change pads! The only other reason to change the pads with rotors would be to eliminate any brake squeak.

 

actually it is better to only change one (either pads or rotor) than to have them both new...unless the whole system is shot and you are forced to change both you are better off having used pads with new rotors or used rotors with new pads....as suggested check the rotors for cracks and thickness and if they are within spec just get new pads (and follow recommended bedding procedure)

 

Thanks, that was my conclusion as well so I told them I would just to do the pads for now.

 

huh?? better off having used pads with new rotors or used rotors with new pads... who told you this and what is your theory??

 

it is common knowledge that is is better or easier (however you want to look at it) to break in a new rotor with a used pad (not a used up pad just a used pad) and to bed in new pads with a used rotor (not a used up rotor just a used one)..with a new pad and a new rotor the bedding process is more difficult

 

So if the pads and discs are below spec..you saying to install new discs and bed in the discs with the old pads(still good but at 2mm which should be replaced)..then bed the new pads with the old discs...

I can see your point of bedding in will be eariler, but just because this procedure makes bedding in earier doesn't mean it's the best repair. Which ever way you look at it..I don't see the "common knowledge" ..When installing new discs, you are best to install a new set of pads to bed the pair in together and prevent any uneven wear. This will also get the best grip and correct life expected of the paired unit.

When discs are still in spec but only pads are below spec, you can install new pads and keep the old discs if they are still in spec(thickness and run-out). If the run-out is off but thickness is good, you can machine the discs if you wish providing the thickness does not go below spec(disc wear spec is about 3mm so most of the time machining is useless and new discs are installed when large run-out is detected)

The used disc will still need to be scuffed and then bedded in..weither it was used or new scuffing should be done to bed in correctly. Pads will not wear evenly, that's why on most pad sets the leading edge is chaffed to prevent noise , this is due to the fact the leading section wears more because of the disc rotation(there are other numerious variables that cause wear, this is just one).


None the less.if your mind is setup on your route, by all means continue..just clarifying incase someone reads this

 

No offense, but my friends and I have been working on brakes for many years and have never heard of this "common knowledge" either.

 

nobody is saying you should use nearly used up pads for new rotors but if there is reasonable material left on the pad it is easier to bed in the new rotors and then replace the pads if they are less than 50%...was told to me by long time racing mechanic as if it was common knowledge and I should know better...

 

Thanks for the clarifications.

There are some useful links dealing with some of these issues on the EBC website incl an endorsement of the Pro-cut rotor lathing system (although it does not appear there are any shops in Toronto with this equipment). Additional info on dealing with brake issues here.