A4 (B9 Platform) Discussion Discussion forum for the B9 Audi A4 2017-

Brake pad thickness/specs?

 
Old 04-17-2019, 07:35 AM
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Default Brake pad thickness/specs?

Mechanic is telling me front breaks are at 7 mm and rear brakes are at 6 mm.

How do I know when it's time to replace them?

Anyone know the new pad thickness and what does Audi recommend for replacement? Is there an official document that lists these kinds of things?

Thanks


Last edited by xreycon; 04-17-2019 at 07:43 AM.
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Old 04-17-2019, 08:56 AM
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Do you know how that was measured - was it an Audi dealer or independent? Brake pad limits are typically in the 2-3mm range. But I've seen a lot of Audi specs/service manuals that give measurements including the backing plate, and the minimum is typically about 7mm, which equates to about 2mm in actual pad.

New pads are typically 10-12mm, so 15-17mm including the backing plate

If he told you 6mm and 7mm and didn't tell you it was time to replace them, I'd assume these were measurements of just the pads. So you're a bit more than 1/2 way through the thickness (though pads sometimes wear faster as they get thinner).

I haven't found the actual manual/specs for our car - this is just my Audi experience.

Last edited by PghRich; 04-17-2019 at 08:58 AM.
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Old 04-17-2019, 09:05 AM
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Yes, new pads are typically around 10mm, and it's recommended to replace them once they are worn down to 3mm. Depends on your driving, but once they are down to 3mm they don't deal with heat all that well anymore. You also have a brake wear sensor in the front, so the simplest answer to your question is replace them once the car tells you, but the dealership will start telling you to replace them at about 3mm. Typically the front pads wear faster than the rear pads, but in your case it's the opposite. Are you the first owner and is this the original set of pads? You definitely wanna keep an eye on the rear pads. Some Audis have sensors in the rear as well. My B8 RS5 does for example, but I'm not sure about the B9 A4.
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Old 04-17-2019, 09:06 AM
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Originally Posted by PghRich View Post
Do you know how that was measured - was it an Audi dealer or independent? Brake pad limits are typically in the 2-3mm range. But I've seen a lot of Audi specs/service manuals that give measurements including the backing plate, and the minimum is typically about 7mm, which equates to about 2mm in actual pad.

New pads are typically 10-12mm, so 15-17mm including the backing plate

If he told you 6mm and 7mm and didn't tell you it was time to replace them, I'd assume these were measurements of just the pads. So you're a bit more than 1/2 way through the thickness (though pads sometimes wear faster as they get thinner).

I haven't found the actual manual/specs for our car - this is just my Audi experience.
Thanks PghRich.

It was at the dealership.

I had just asked to let me know what they find, and that's what he emailed me, I haven't talked to him so I don't know if he's going to recommend replacement, but I wanted to have some information before I talked to him...

Sounds like I need to find out exactly what was measured...

Any ideas what the diagram showing the the 3 4s and 3 for the back right could be indicating?
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Old 04-17-2019, 09:11 AM
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Originally Posted by superswiss View Post
Yes, new pads are typically around 10mm, and it's recommended to replace them once they are worn down to 3mm. Depends on your driving, but once they are down to 3mm they don't deal with heat all that well anymore. You also have a brake wear sensor in the front, so the simplest answer to your question is replace them once the car tells you, but the dealership will start telling you to replace them at about 3mm. Typically the front pads wear faster than the rear pads, but in your case it's the opposite. Are you the first owner and is this the original set of pads? You definitely wanna keep an eye on the rear pads. Some Audis have sensors in the rear as well. My B8 RS5 does for example, but I'm not sure about the B9 A4.
Thanks superswiss.

I am not the first owner, and I am not sure if these are the original pads...but in the maintenance records I have for the car I don't see anywhere that they were ever changed. But I'll go back and double check in case I missed it.

So if new pads are typically 10mm I am still OK (unless like PghRich points out they measured 6mm and 7mm including the backing plate).
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Old 04-17-2019, 09:29 AM
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I was flushing the brake fluid last weekend and noticed that B9 A4 also has a rear pad sensor. It's only one sensor on the Passenger side rear though.
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Old 04-17-2019, 09:59 AM
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Thanks minmet. How do those sensors work? Can the car show you a history of when the sensors went off or once they're cleared or reset, that's it you can't see them again.

Any ideas what the technician's diagram above the 6mm and 7mm could be indicating?
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Old 04-17-2019, 10:14 AM
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Sorry! Don't know much else. For me, I would change them before the sensors tell me. As mentioned above, 3 mm would be the general guideline. If you are going to have dealer or other mechanics work on your cars, just bring it to them when the sensor gives the signal. I saw you need change your tires right away as the sheet indicated they are down to 4/32" and one already at 3/32". That's legal limit in our state.
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Old 04-17-2019, 10:22 AM
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Originally Posted by minmet View Post
Sorry! Don't know much else. For me, I would change them before the sensors tell me. As mentioned above, 3 mm would be the general guideline. If you are going to have dealer or other mechanics work on your cars, just bring it to them when the sensor gives the signal. I saw you need change your tires right away as the sheet indicated they are down to 4/32" and one already at 3/32". That's legal limit in our state.
Thanks minmet.

Yes, definitely getting the tires done.

How can you tell about the 4/32" and 3/32"? (I'm thinking that's the diagram I was asking about? where it says 4 4 4 3, right? I didn't realize that was about the tires.).
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Old 04-17-2019, 10:54 AM
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Originally Posted by xreycon View Post
Thanks minmet.

Yes, definitely getting the tires done.

How can you tell about the 4/32" and 3/32"? (I'm thinking that's the diagram I was asking about? where it says 4 4 4 3, right? I didn't realize that was about the tires.).
Yes. That's the info. Unless the tech was talking about something else. The diagram definitely looks like for Tires.
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