Do New Brake Pads Require a New Rotor

On Wed, 6 May 2009 10:22:18 -0400, against all advice, something compelled "eBob.com" , to say:

You should have them evaluated for thickness and runout. If they are within spec, or can be turned true, then go ahead and use them. If not, they need to be replaced.

rotors are normally replaced when they reach a minimum thickness as specified by the manufacturer. If they are worn with uneven surfaces, they can be skimmed flat and parallel again but the costs to do this sometimes outways replacing them with new ones. My A4 has covered 95k miles and its still on the originals.

Front pads and rotors are available at a reasonable price online at places like

If it's not DIY, an independent Audi mechanic will charge about $500 for front pads and rotors - at least that's what I was quoted. I did it myself in about 90 minutes including freeing a stuck-on rotor. Rotors and Mintex pads cost about $160 total.

Thanks iws, and to the several other guys who have responded.

Why do you say that I "should definitely replace both sides". It is a safety issue? Or just that the other side will probably have to be done soon? Or something else?

Thanks, Bob

Both. A new set of brand X pads on one side coupled with a used set of Brand Y pads on the other is almost certainly going to yield uneven - and unsafe - braking. Plus, almost certainly the other side will have to be done soon too. If there was a significant difference in wear between both sides, you probably would have noticed a "pulling" to one side or another - a condition that would have to be investigated and fixed. Also, in my experience, brake pads always come as a complete set for right and left.

Front vs rear is a different story - fronts do more of the braking typically and are sized and designed differently. So it's unlikely that you'd need to do both front and rear brakes at the same time.

It takes a few hours to change the brakes max and that's working slowly, just do it yourself.

The tool for the rear cost me about £12 the only problem you might have is undoing the bolts that hold the disc in place, well it doesn't hold the disc but holds the caliper but needs to be removed to get the disc out.

Set yourself a nice afternoon off :)

Make sure you do all 4 it's worth it in the long run. Cannot believe people are still mentioning turning down discs, it costs approx £120-£140 for 4 x discs and 4 x pads.

Servicing is the same, costs about £60 inc pollen filter and spark plugs.

its probably only tried by those with access to machines (me at one time). An engineer will always try to use the tools if he has them. Anyway I can confirm its a pain in the rump. Cast iron discs that have seen many years of use, surface harden so you have to get under that skin, maybe 2mm or 3mm before you can get a good cut going. This has to be done both sides so then you are most probably going under the min thickness for the disc. Or if you have the machine/adaptor, grinding is another option and only removes a small amount of material.

new pads dont always need new rotors . u need to look at them or have a tech look at them and see how bad they are worn.

I recall reading something about the rotors have to last a certain percentage longer than the pads in TUV (?) tests. Something like 25%. Couldn't find it at the moment.

If that's the case it's best to check the amount of rotor wear during this set of pads. And you need to make sure that within the next set of pads the rotors will remain above the minimum allowed thickness.

But friends tend to be able to change rotors every other set of pads.

Does anyone know if these are ATE or Brembo setup?

i dont think you need a new rotor

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