Will 390mm discs fit under OEM 19" B7 alloys using the OEM calipers?

4.2 V8 32v Naturally Aspirated - 414 bhp
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beckford21
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Will 390mm discs fit under OEM 19" B7 alloys using the OEM calipers?

Post by beckford21 » Fri Feb 03, 2023 9:43 am

I've asked this question on the FB groups too so apologies if you've seen it multiple times but no-one seems to know the answer for certain.

Can anyone confirm whether they will fit? I know 380mm will definitely fit. 390mm also seems to fit under the 19" OEM B8 alloys using the standard caliper, but I can't find any info on whether this setup will fit under the B7 Le Mans alloy.

Thanks!

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js47
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Re: Will 390mm discs fit under OEM 19" B7 alloys using the OEM calipers?

Post by js47 » Sun Feb 05, 2023 8:05 pm

I have the 380mm carbon ceramics under the B7 19” alloys. There is definitely >5mm of clearance from the rotor to the wheel.
2007 RS4 Avant in "Cherry Black Pearl" with Carbon Ceramic brakes. MRC Stage 2.

beckford21
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Re: Will 390mm discs fit under OEM 19" B7 alloys using the OEM calipers?

Post by beckford21 » Mon Feb 06, 2023 1:57 pm

js47 wrote:
Sun Feb 05, 2023 8:05 pm
I have the 380mm carbon ceramics under the B7 19” alloys. There is definitely >5mm of clearance from the rotor to the wheel.
Thanks. No-one could give me a definitive answer, so I ended up going for 380mm. Should still be a nice upgrade over the 365mm.
Maybe the OE caliper is more bulky than the carbon ceramic caliper (or are they the same)?!

I heard back from a couple of guys running the 380mm (non carbon ceramic) setup and they said it's super tight with not a lot of clearance - so I didn't want to take the risk in the end of ordering the 390mm and having fitment issues. 390mm seems to fit under the OE 19" B8 alloy, but it's a different wheel so couldn't really compare. Didn't come across anyone running the 390mm setup with the OE B7 alloy.

Gone for 360mm on the back too so hopefully she stops a bit better!

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js47
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Re: Will 390mm discs fit under OEM 19" B7 alloys using the OEM calipers?

Post by js47 » Mon Feb 06, 2023 4:03 pm

I am fairly certain that the ceramic calipers are different from the normal calipers, but I have never actually seen a set of normal calipers. Clearance from the wheel to my caliper is less than 10mm — would need to get the Vernier Calipers out to be more precise than that. Clearance from the wheel to the disc looks to be at least 40mm.

My rear rotors are on their last legs so I will be interested to hear how you like the 360s on the rear. I am very happy with my stopping performance but always thought the 325s looked a bit wimpy (kind of funny since that is bigger than the front rotors on my previous car, which was 50% heavier). From a visual standpoint I always prefer the rotor to fill the wheel as much as possible!
2007 RS4 Avant in "Cherry Black Pearl" with Carbon Ceramic brakes. MRC Stage 2.

coffey555
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Re: Will 390mm discs fit under OEM 19" B7 alloys using the OEM calipers?

Post by coffey555 » Mon Feb 06, 2023 6:55 pm

Standard brakes use an 8 pot caliper, ceramic caliper is a 6 pot so likely to be slightly smaller.

Apparently the rears do much more work on a car with the ceramic front option, as around town, the ceramics never really get up to temperature to do very much! I remember reading a post where the guy was having to replace rear discs and pads very frequently, which offset the fact that the front rotors last much longer.
Misano Red RS4 B7 Avant

beckford21
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Re: Will 390mm discs fit under OEM 19" B7 alloys using the OEM calipers?

Post by beckford21 » Mon Feb 06, 2023 7:19 pm

Yeah that makes sense as there were guys on the FB group for instance with 390mm under the OEM front wheels but using Tarox 12 pots or other aftermarket calipers, and these are much skinnier it seems than the bulky OEM 8 pot - so I think 380mm was the right call. Apparently 16mm is what's needed from the top of the caliper to the wheel and I don't believe the OEM 8 pot has that clearance, or if it does, it would be super tight and probably not worth running something that has like 1 or 2mm of clearance tbh.

Wish I had ceramics, did consider it but probably triple what I paid for these rotor upgrades and can't really justify spending that.

I'll report back both with some pics and with my thoughts from a braking performance perspective once I've got both front and rears fitted.

Thanks for your help both

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