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2015 S8 purchased in the spring with 34k miles and has 41k now. When I bought it CPO it had seemingly new pads and rotors and I think that's a requirement to be a CPO but could be wrong. Rotors were smooth and pads looked new.
Now I am getting screech, squeal, whatever it's called when slow speed stopping with constant brake pressure when coming to a stop. I am noticing the rotors getting noticeable grooves in them more so closest to the outside. I am wondering how much is normal and I'm worrying too much, or if the dealer put on some sub-standard pads that are causing the groves or something. Would like to replace the pads with some that make less brake dust anyway, this might be the time before the rotors get too bad unless that's too late too. Any thoughts? Couple photos try to show it.
My take is, probably normal. But if dissatisfied with either feel or dust, have an independent (or DIY) change brake pads as the likely path of least resistance without big bucks. As explained below, noise may be a sign pads are nearing end of life. Dealer will use Audi pads of course. Mine still have them. Performance is good and as expected, but they do dust up, much more so in front. Rotors do have typical wear ridges and grooves as the miles add up.
Unless you also looked at rotors when you bought it, a guess is the rotors were already grooved. Unless they were turned. That could have happened if pads (only) were changed pre-sale. As mentioned, a further guess is your pads may be reaching end of life. To check, get a bright flashlight and inspect visually, through the wheel. If you look carefully, you should be able to see parts of both the metal backplate and the pad material. I can on mine. At about 3mm of material left (1/8"), the worn pad sensor will turn on the warning light. If you see only ¼" of pad material or less, it confirms my suspicions.
The CPO provisions have changed on this over the years. Given your purchase only this year apparently, in plain English and skipping Audi marketing hype, they are watered down compared to what they once were. Read your CPO paperwork for the inspection to be sure. If you are internet surfing for the info, unless it has a clear time stamp on it and was based on first person reading of paperwork, you are likely just picking up old echo chamber information from what it was some yeas ago. Thus yes, it used to be a condition pads were at least 50%, and I think it may have been rotors too. True when I got mine in 2016, but then CPO also went out to 6 years instead of current 5. Now I think the fine print gives them more leeway on brakes specifically, especially on rotors. As in, they figured out belatedly it was pricy and so quietly watered down the CPO qualification rules. Nothing you can do about that really. But don't believe all you read on the web without verifying it via the Audi sale paperwork directly.
Technically, why I suspect your pads may be fairly worn is the squeal. As pads wear, the caliper pistons stay pushed out more. They can then twist over very slightly or vibrate, or just not hold pad quite as square on. Probably at the thousandths of an inch level tolerance wise for recent calipers, so you may never see it with a basic visual inspection. Another possibility is they did actually change the pads but perhaps cheaped out and did not replace the anti vibration stick on pads that fit between the caliper pistons and the brake pads. Those are more expensive than the pad set themselves, so the incentive is there to cheat. They are unique to S8 conventional rotor set up with the six piston Brembos, as far as D4's. Any of this prep cost is on dealer, hence their incentives to skirt if possible. Not stuff they put in the CPO brochure happy talk...
Only the old pre-sale repair records for your car would really clue you in. As in, they black out the prices if warranty or probably if shop (internal) repair, but the parts are still shown on the paperwork. If you play nice, your service advisor may be willing to pull those. Dealer work is in the Audi overall computer system by VIN, and for any work done at that dealer, of course they should have it anyway. I got them by asking quietly at time of purchase of both my D3 W12 and my D4 S8--where I have more leverage and they want the sale. Both bought CPO when about a year old.
"2015 S8 purchased in the spring with 34k miles and has 41k now. When I bought it CPO it had seemingly new pads and rotors... Rotors were smooth and pads looked new."
Doesn't sound normal to me... heavily worn rotors after 7K miles??? What am I missing?
Not enough info to arm chair speculate accurately, either way. Could have been cosmetically resurfaced. Quick and dirty pad change might have been done w/out replacing the anti vibration shims specific to S8 as stated in prior reply. Or as also stated, the wear may have been overlooked. Being realistic, no one normally brings a flashlight to inspect pads close up, and in bright light it is also hard to see them. Can't see them in the pics either.
As usual with brake stuff, really need more CURRENT info to judge well. What is CURRENT pad thickness? What are CURRENT rotor wear measurements? I provided the way to eyeball pads at least. The service records would help too; eliminates arm chair guessing and last year's casual memories. FWIW, I thought the possible come on too strong w/ dealer was, well too strong with info available so far. It starts with not being clear on what CPO terms really were. As in, like all things that are really contracts, read the actual document, don't rely on internet fifth hand stuff. Said more directly, I think OP's sense of CPO terms at the time he actually purchased his is mistaken (which he noted he was unsure of). The terms shifted. I have read them first person along the way. Going in with a head of steam and erroneous coverage info often does not prove out. On the other hand if old paperwork shows some brake work and the S8 specific shims are missing, tampered with or clearly reinstalled, things get more interesting...
I need to replace my pads, and my rotors look new compared to those above. When I see something like that, I wonder if the car has been four-wheeling in the sand!
I need to replace my pads, and my rotors look new compared to those above. When I see something like that, I wonder if the car has been four-wheeling in the sand!
Look carefully at the tire size you see in a pic... Not stock. Apparently winters? Camera angle is tricky, but I was not entirely sure those were front's either.
FWIW, I recall a post on Gen 1 Q5 board where some road crap from extensive unpaved roads (like Alaska) got into pads and trashed everything. I have found grooves in that zone on older ones, but more commonly like on a 15 year old D3 and lots of miles and general component wear. Once I saw the tire size I started to think there may be more extenuating factors here.
Thanks for the responses. I have some more info to share for those interested. I took out the CPO checklist that was done on the car at 35,451 miles. I haver attached photos of it for those interested. The main reason is that is lists pad thickness and rotor thickness (if actually measured who knows) 9mm pad thickness both sides and 38.22 mm and 38.4mm thick rotors. What would the original thickness be for pads and rotors? I'll do some searching but if anyone knows off hand...
The other photo I post is of a brake rotor only a couple weeks after purchase. Happened to have a photo of one for some reason, I think for the tire size. Shows a smooth rotor. I double checked the mileage its its actually right at 6,000 miles I put on.
Look carefully at the tire size you see in a pic... Not stock. Apparently winters? Camera angle is tricky, but I was not entirely sure those were front's either.
FWIW, I recall a post on Gen 1 Q5 board where some road crap from extensive unpaved roads (like Alaska) got into pads and trashed everything. I have found grooves in that zone on older ones, but more commonly like on a 15 year old D3 and lots of miles and general component wear. Once I saw the tire size I started to think there may be more extenuating factors here.
Correct, winter wheels & tires. Not driven in really bad conditions, mainly when roads are clear just cold temps. Certainly get more than junk from the road still though. I do get a car wash a few times a week and make sure the wheels and by proxy brakes are cleaned regularly.
No unpaved Alaska roads or four-wheeling in the dunes... Grooved, squealing brakes with only 6K miles on rotors that photographed good at purchase? Sometimes pads don't seat properly (possibly due to improper break-in) and wear poorly. Whatever the problem, Something is wrong. Get a couple of hands-on opinions from local indys, then get that car back to the dealer.
02-01-2021, 05:38 PM
Grooves in brake rotors and low speed squeal
