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Old 04-01-2017, 12:23 AM   #21 (permalink)
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, I mean there is a spec for the rotors so the fact that they don't care or bother to check still irks me a lil.
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Old 04-01-2017, 01:38 AM   #22 (permalink)
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It's been that way, starting with European cars for almost 30 years. If you want to turn rotors pick up a brake lathe on the cheap because nobody uses them. Even more pedestrian cars have followed suite. In my 20 years of driving I have never had any shop or dealership offer the service of turning rotors. And all the brake jobs I've done myself I've just replaced pads and rotors. My Cobra was the worst, it used to consistently eat pads and rotors at 20k miles, to the point that you could run your finger over the rotors and know they were trashed.

Just grab some aftermarket pads and rotors and do it yourself. Same or better performance then factory for way less money. I'll pay to have the pros do oil changes, tire stuff, seals, etc. but brake jobs and air filters are one of the few car things I still find myself doing myself because it's such a scam at the dealers.

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Originally Posted by C5TEK View Post
With most performance cars you'll find that when your brake pads are worn the rotors are just about at the machine to limit. So by trying to machine them you'll go below that limit. But you won't be at the wear limit yet. Now why is this important? For average driving you wouldn't know the difference. However in an extreme instance such as panic braking you can run the risk of overheating the rotor and introducing brake fade or warping the rotor.
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German brake pads seem to be incredibly abrasive for some reason... Mercedes-Benz rotors develop 1/16-1/8" ridges pretty quickly, long before the pad wears out.

Most performance cars have ceramic or metallic break pads. Much better performance, but physics dictates that higher friction=better stopping=higher wear on the rotor.

In this day and age most 4 door family sedans will run 1/4 mile times in the 13's, so daily drivers now use performance brake compounds. Average highway driving will have a lot of those family sedans hitting 100+ and braking back down to 60. It's always common on the autobahn, but it's not uncommon now to see it on American Highways. With 80 mph speed limits being more common it's not even that big of a ticket to break 100.

We were turning rotors in the era of mandated 55mph speed limits everywhere. Zee Germans haven't turned rotors for a while because average driving on German highways would leave rotors beyond the wear limit.

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Old 04-01-2017, 01:45 AM   #23 (permalink)
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Dude. A grand is atrocious.

I didn't turn my rotors last time I messed with them because I found them for something like $20 a piece on rockauto.com.

I had brakes and pads for all four wheels for under $100.

You said you could do it parts for $600? Still sounds high. I don't think it cost that much when I did them in my infiniti.
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Old 04-01-2017, 01:48 AM   #24 (permalink)
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I guessed on the year, but rockauto shows rotors for 2015 Audi s4 cost between $20 and $100 a piece. A rotor and brake job should take you an afternoon and under $200.
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Old 04-01-2017, 01:57 AM   #25 (permalink)
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Just to chime in a bit: One other factor that applies is the simple fact the manufacturers don't make the rotors as thick as they used to.

Yes, I know that rotors come in different thicknesses for different cars, etc. Not what I mean. What I mean is that, back in the "old days" (probably through the 80s and into the 90s) rotors generally had a significant amount of extra "meat" to them.

This both provided additional thermal mass (over whatever the calculated minimum was) additional strength (resistance to warping) and, for the purposes of this topic, more life thanks to them being able to be turned/refreshed several times.

However, as mileage requirements rose, every additional ounce has become a nontrivial problem. And as drivers' demand for improved performance and handling also rose, unsprung weight has also become more and more important.

So one of the things the engineers have taken to do, is to thin the rotors. Instead of an extra eighth of an inch or more, as many older cars had, now you're talking only an extra fifty thou- nominally the 1mm per side as noted. I've heard of one car that came with brand-new rotors just 0.030" total over minimum spec.

With such minimum specs, technically the rotors can be turned, but it's recommended (that is, by the manufacturer) to simply replace them.

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Old 04-01-2017, 02:47 AM   #26 (permalink)
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We turn rotors in my shop, and I've seen a small handful of newer audis and bmws come through for brakes. Given our typical brake job is pads and turning rotors I've definitely seen why they say to replace rotors. They are dead *** thin anymore, honestly the front rotors on some of them are thinner than the rear rotors on mid-90s fords.

That all said, over a grand for a brake job? That is an immense level of cocaine fueled BS. Then again, it's European, and they like expensive fixes/difficult to maintain.
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Old 04-01-2017, 10:59 AM   #27 (permalink)
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Quote:
Originally Posted by apamburn View Post
I guessed on the year, but rockauto shows rotors for 2015 Audi s4 cost between $20 and $100 a piece. A rotor and brake job should take you an afternoon and under $200.
you guessed right, and yes, over a grand is insane, which is why its going somewhere else

and i know there's a ton of options for cheaper aftermarket rotors, hell even a nice pair of cryo treated stop techs is only $300 for the front pair (still 100 less than oem)

im just trying to actually get a useable lifespan out of my rotors. before i have to replace them
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Old 04-01-2017, 11:07 AM   #28 (permalink)
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Old 04-01-2017, 01:19 PM   #29 (permalink)
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Quote:
Originally Posted by DocsMachine View Post
Just to chime in a bit: One other factor that applies is the simple fact the manufacturers don't make the rotors as thick as they used to.

Yes, I know that rotors come in different thicknesses for different cars, etc. Not what I mean. What I mean is that, back in the "old days" (probably through the 80s and into the 90s) rotors generally had a significant amount of extra "meat" to them.

This both provided additional thermal mass (over whatever the calculated minimum was) additional strength (resistance to warping) and, for the purposes of this topic, more life thanks to them being able to be turned/refreshed several times.

However, as mileage requirements rose, every additional ounce has become a nontrivial problem. And as drivers' demand for improved performance and handling also rose, unsprung weight has also become more and more important.

So one of the things the engineers have taken to do, is to thin the rotors. Instead of an extra eighth of an inch or more, as many older cars had, now you're talking only an extra fifty thou- nominally the 1mm per side as noted. I've heard of one car that came with brand-new rotors just 0.030" total over minimum spec.

With such minimum specs, technically the rotors can be turned, but it's recommended (that is, by the manufacturer) to simply replace them.

Doc.
I'd like to point out the fact that until FWD became the norm, brake rotors also housed the wheel bearings/supported the wheel assembly. Today's two piece setup - rotor separate from hub/bearing assembly - makes for a significant reduction in mass and weight.

Cars/trucks also have much larger wheels and tires on them - Hyundai's, for example, come with 18" rims - compared to yesteryear, where a 15" or 16" tire/wheel was considered large, and 13" wheels normal on a compact. More rotating mass = greater stopping effort on brakes, something to consider for the enthusiast who puts big wheels on their ride.

One other point of interest - ceramic brake pads work by depositing a layer of braking material into or onto the brake rotor surface... that's what the pad uses as a friction surface. In this case, "warped" rotors are often simply an uneven coat of material on the brake rotor... a light skim on the rotor can clean it up nearly as good as new, we're not talking taking .050 off a rotor.

Brake lathes were considered a mandatory dealer tool at Nissan when I worked there, I'd be surprised if Audi doesn't have that mandate as well. That being said, you don't want someone who doesn't know what they're doing machining those rotors.
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Old 04-01-2017, 01:43 PM   #30 (permalink)
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First mistake is taking your Audi to Audi. Dealers over charge like crazy! Any decent mechanic can change brakes. Tho I did need to electronically release the calipers on my A6 rear breaks.

It's not all that hard to do why not do them yourself. You can rent most of the tools you need from autozone or the likes. There are step by step instructions and How To vids all over the place you could do it cheap.

It's really very simple. Rear breaks on some require a computer to release the rear brake calipers. But the rears rareley go bad because the fronts most of the work. A simple search would tell you what you need for your year and model.
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