Contour Enthusiasts Group Archives Forums Modifications Brakes Why replace pads w/ machined rotors?

I know that conventional wisdom states that when you get your rotors machined, that you should replace your brake pads.

I've wondered why this is?

My thinking is, wouldn't the softer compounds of the pads even out in just a couple uses when mated with the newly machined surface of the rotor?

The reason I'm questioning is that I have warped front rotors (mild) but I know the pads Mintex have tons of life left in them and it just seems like a waste to replace them.

Rotors warp ever so slightly that you can't really see any difference but when you brake you can feel a good shake. Machining the rotors takes the warp out of the rotor. If you saw it done one time you would understand how it works. The only thing that can go wrong is if the warpage is so bad that you machine the rotor down below specs. But rotors can be had pretty cheap and it's probably worth getting new ones anyway!

-Andy

The rotors were new in December, that why I feel confident that they'll be machineable.

But why replace the pads?

Good question, why replace perfectly good pads? Perhaps you're thinking of the reverse; I know when you replace your pads, you should machine your rotors. This prevents the new pads from making noises, and it beds the pads properly.

Perhaps when people think of typical brake work it's time for the pads to be replaced anyway, so they lump pad replacement with machining rotors.

My pads and rotors are relatively new though, so when I get my rotors machined, there shouldn't be any adverse effect by keeping the same pads right?

I'm just trying to get the warp out. :rolleyes:

Very often the pads will be somewhat torn up from the old rotor surface, especially if the rotors are scored or dished. It that case, the old pads will tend to score the fresh surface on the rotors all over again. Also sometimes the pads will be a bit glazed or may even have some metal transfer from the rotor onto the pad.

I have often reused old pads if everything looks fine and they are nearly new. If they are even half worn it is wise to install new pads so that you do not have to do it again very soon. The rule of thumb is in there is any doubt, change the pads.

Either your rotors are poor quality or your wheels were not torqued properly (I'm assuming < 10k miles and new pads installed with new rotors).
If it is a mild warp you could try re-torquing wheels.

Yeah, I re-torqued the wheels and that has cut the vibration down a lot. It's just annoying. Why can't we have big fat rotors that don't warp?
:rolleyes: