Do I need to get my rotors machined/resurfaced?

[Burnt]

Hi all, just doing my second brake pad change and would like to know if I need to get my rotors machined/resurfaced.

Got the car when it had 32,000 miles, did a front pad change at around 40,000, it is now 63,000 miles and the light has gone off. Last dealership trip (about 6 months ago) they measured all my pads at 5mm left on each. I decided to replace all of them now wondering if the rotors need some love.

My next pad change, I may decide to replace all rotors and pads.

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[MSq5]

Hi all, just doing my second brake pad change and would like to know if I need to get my rotors machined/resurfaced.

Got the car when it had 32,000 miles, did a front pad change at around 40,000, it is now 63,000 miles and the light has gone off. Last dealership trip (about 6 months ago) they measured all my pads at 5mm left on each. I decided to replace all of them now wondering if the rotors need some love.

My next pad change, I may decide to replace all rotors and pads.

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“Looks like light has gone off”. Do you mean it is on or off? Which light?

Are you handy with basic tools? Do you have a set of dial calipers, or can borrow some? Unless they are scored deeply or otherwise damaged, measure their thickness with calipers. If out of spec, replace them. If not, continue to use them, I don’t have the thickness spec for your front or rear, but someone will come along with that information. Will probably need know what 6/7 model you have to find it.

Visibly, I don’t see any reason to replace them. Looks like normal wear. Thickness is the key.

[Nachos Libres]

EDIT:

So you replaced the pads 6 months ago but the sensor has tripped? What error are you getting? And seriously, if you do replace brakes buy the parts yourself and have a competent shop do it, if replacing rotors you will save thousands.

[Vinng86]

Grab some calipers, and measure about 10mm inside, away from the outside radius of the rotor.

Judging by your post history, you have an A7 TDI, which means you have 345mm steel front brakes and 330mm steel rear brakes.

From the manual:

345mm
New = 30mm
Wear Limit = 28mm


330mm
New = 22m
Wear Limit = 20mm


So if you measure less than the wear limit, replace the rotors. Also, measure in increments all the way around the rotor and if it varies by more than 0.06mm then you should replace the rotors also. Obviously clean everything up super well so rust doesn't affect your measurement

[Burnt]

Thanks for all your replies. I had the pads check out 6 months ago and the pads measured 5mm. Replaced front pads about 20k miles ago and the "BRAKE" light is on now, not sure if fronts or rears tripped it, but replacing all pads.

Now about the wear limit. If I measure the rotor from the inside, it has a lip on the outer edges like this \_________/ if I were to do a cross section. Do I count the lip or do I have to get it machined off and I'm assuming I have to pull the rotor off to measure it correctly?

[Incandescent]

You measure from inside your "valley" so to speak, the lip is normal. You want to find out how thin the rotors are. If they're too thin, you need new rotors.
Generally you'd only machine them if they're really badly scored.

I also thought German rotors can't be machined since they're already as thin as possible to save weight?

Can you measure the rotor thickness or is there a dust shield behind?

[MSq5]

Grab some calipers, and measure about 10mm inside, away from the outside radius of the rotor.

Judging by your post history, you have an A7 TDI, which means you have 345mm steel front brakes and 330mm steel rear brakes.

From the manual:

345mm
New = 30mm
Wear Limit = 28mm


330mm
New = 22m
Wear Limit = 20mm


So if you measure less than the wear limit, replace the rotors. Also, measure in increments all the way around the rotor and if it varies by more than 0.06mm then you should replace the rotors also. Obviously clean everything up super well so rust doesn't affect your measurement

^ ^ ^. This.

If there is a dust shield behind the rotor, you may not be able to get calipers in without removing the rotors. But, try to see if you can find a place around the circumference to place the calipers.

If the “brake” light is on, you might just be low on brake fluid. Check that. If not and the pads are that worn again, they will have to be replaced. Once a sensor is scraped with a pad, it will have to be replaced also, if it is separate from the pad.

[FourRingThing]

Do yourself a favor and get all new rotors and use Akibono Ceramic pads you will be set for along time. I did this like 50K miles ago and everything looks like new zero rotor wear not even the slightest lip I had a huge lip before I changed them. And no brake dust

[Valpo A7]

You only got 23,000 miles from a set of front pads? You must be hell on brakes as they should not go out that fast unless you are on them all the time.

It looks like you have a ridge on the rotor outside edge which is common. Based on the amount of ridge you have I would say you are probably at or below minimum thickness on the rotor. You will need a set of calipers to measure that though.

If you are smooth when braking (no warped rotor feeling) and the rotor meets minimum thickness then you should be okay to reuse the existing rotor.

All city stop and go I can see the brakes going in about 30,000 miles. A mix of city and highway should last closer to 60,000. Mostly highway will go even longer. My last car I did the fronts at 125,000 miles and the backs were original when I traded it in at 190,000 miles. Yeah I am almost all highway.

[Burnt]

Changed my rear pads, the wear sensor wire looked like it was protruding out, and prematurely cut. I had about half of my pads in the rear and about 7mm left in the front.

Ended up changing the rears while I was at it, probably could of lasted 90k miles
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[bozack]

rule has always been you don't turn German car rotors like you do Hondas, Nissans etc.

replace every other brake pad change on average also