MP4.2+6.0

So, if you looked at my winter wheel post carefully, it happened to use a picture of the back wheel as mounted. https://www.audiworld.com/forums/sho...php?p=24518480. If you looked extra carefully, the full body shot might have raised questions about the front rotor sizing and a curious hole in the rotor hat. Below you will find the actual front wheel and brake. That leads to the brakes explanation.

So, basically for the heck of it (just being honest) I did the RS5 brake mod up front. As explained below, the Q5 brakes in 345 front/330 rear are actually functionally plenty good enough, so I won't bother w/ a big "really needed it" pitch there. The mod is unusual to start with, though it's been posted on once or twice that I've seen. I have previously done performance type Brembo upgrades on our Mini S (up to the JCW Brembo's) and on my A8 W12 (mostly cosmetic since that vehicle already has 385/335mm brakes and enough stopping power to send you through the instrument panel).

BBK's cost big bucks, so that wasn't happening. I thought about just running off the stock brake life first too, but in getting to the winter wheels started to get the mod itch. I did the first 5K service, so kind of figure I'm on my own for most brake wear stuff anyway.

By chance with some surfing and watching over the months, I eventually found a full set of used RS5 brake calipers buried on eBay UK. I won those and squirreled them away. By buying just the calipers and not rotors and the rest abroad, shipping was rational too. Same thing I did with the Mini to cut out the big mark ups by either dealers or commercial mod suppliers. I got the rotors as OES. Not OE from a dealer, but rather OES with the made in Germany markings; they are actually nominally for an R8, but R8 and RS5 rotors in 365's are the same and Audi uses the same part number. I've actually seen rotors with the same construction as these before, having done a recent generation M6 (same as M5) brake job where they use a floating pin rotor set up with an integrated alloy hat. I thought about the wild wavy rotor design now found with RS5's, but that was too over the top for me on this level of Q5. Thus, I stuck with the regular/prior R8/RS5 conventional round rotor.

Since I started this parts gathering, the SQ came out here and I can see they have very similar rotors (in 380mm). I thought about going SQ, but am always a fan of a zillion piston non-floating/fixed caliper design like the recent RS's. SQ's also can't be found in used parts AFAIK, so this was my cheaper route too. A disappointment in the factory RS5 set up (and R8 for that matter) is the rotors are not vaned on a directional basis, nor is the drilling side specific. Thus, the same part number rotor is used on both sides. But, the drilling is very careful and aligned to the internal vanes correctly (including some "holes" that are just dimples); your typical aftermarket drilled rotors are just done on a press with a template that doesn't pay good attention to the internal structure. Factory Q5 rotor BTW wasn't bad--it has relatively open air venting done by point type connections between the sides that cut out a bunch of hidden weight, open up the air flow a lot compared to older designs, and make them much more omnidirectional for both sides. DBA (Disk Brakes Australia) has performance rotors of a design a bit like these for air flow and weight, but now it's Q5 factory/stock.

This project involved fronts only. I have been pursuing the rears, but that is virtually all just cosmetic. The calipers are the same as regular Q5's. Like with the SQ's for that matter it's just a black paint job. But on the RS5 they also use the semi floating rotor set up, which lightens the rotor. The SQ just uses the standard larger Q5 rotor, just like the Hybrid. But, the RS5 also moves the offset of the rotor swept area approx. 5mm. Makes it very difficult as a retrofit, since the 5mm is buried in the hub which is unique to the RS5. Lots of bad info is out there about this, including erroneous posts, bad/obsolete vendor info and you name it, but I have confirmed both that there is an offset shift in the RS5 rear, and it's in the hub. What that means is if you don't do a hub change, absent a hokey spacer approach under the rotor, you can't just use RS5 rotors on a Q5, B8 A/S4 or A5/S5. You can get rear two piece rotors (only from JH Motorsport, not ECS or another place), but can't use factory RS5's. The hub change necessitates a new bearing pretty much, and the rear rotors actually cost about 40% more than the fronts. So the rears are on ice for now, though I have a nice set of factory painted black rear calipers, brake motor and all, that I may use. Pads actually are identical to the rear Q5's too, so I might swap out when I get to needing to replace pads.

Clearances. Some of you may recall I have consistently replied to the SQ wheel posts that they don't "need" 20's with the SQ factory brakes. It can be done with factory 19's and apparently even 18's. Here I actually figured I would run my factory 19's until right before the first snow country trip near the holiday season. The rotor diameter would allow it. But I went to bolt them up--factory 19 x 8, ET39--and they hard jammed the caliper. First I thought it was at just one or two points, but then I realized it was really along most of the inner caliper edge. I have the OE wheel scrape on the inside of one single spoke of the OE 19's to prove it... So, out came the winter 20" wheels. Again, see my other post today also linked above: https://www.audiworld.com/forums/sho...php?p=24518480 Those clear, but not by a lot. Per the picture below, only by a bit over 3 mm. Still tight, but fine even if wheel bearing ever started to wobble some, which I haven't seen in like forever on any modern design Audi. All goes back to it's really the many piston Brembo set ups with the very fat sides that tend to lead to OE fitment challenges. Same issue existed with the old factory HP2's used on D2 A8's, C5 A6 2.7Ts and 4.2's, and early B5 S4's; part of why Audi moved away from those in the early millenium too.

Feel: just in the early phase so far so taking it easy. Honestly, having driven the stock brakes on the Autobahn with 3 on board and a couple hundred pounds of luggage and gear, they worked fine. And that includes at way super legal speeds here, to where the hood would literally shake some from the aero disturbances. I haven't seen that in a long, long time and in much younger (wilder) years. One question I was curious about is if pedal travel would actually deteriorate given I was pumping fluid into now 8 pistons on each side up front instead of only 1. The net is no, so the stock master cylinder can handle just fine. S5 owners who did similar prior conversions said the same in posts I found, so I figured it would be fine already. I noticed as I pulled off the stock brakes that they had a very large single piston--larger than I have seen before compared to pad size--so it actually probably has a lot of total fluid fill volume too. As an unusual Hybrid, I wondered a bit if it would affect regenerative braking at all. Again, no change or problem; makes sense since the starting point was also stock 3.0T or TDI widely used already, and the regenerative stuff is up in the drivetrain, not at the brakes themselves. As far as transparency, RS5 pads also have one wear sensor, and you just plug it into the same plug as the Q5 sensor. Unlike the Q5 set up, the sensor is built into the pad instead of separate, so there is no additional sacrificial part.

Weight type stats: Little info is around about this either (and some in vendor questionable on things like rotor weights), but a dark side of BBK's can be adding a boatload of unsprung weight. The 385's on my W12 (shared with S8's) are proverbial boat anchors, but it also has the HP and torque to just power through it. So the numbers are...factory 345mm set up used by Hybrids, 3.0T's and TDI's all in--rotors, calipers, dust shields, pads, and brake line: 44.8 pounds. Per the digital bath scale, weighed three times to validate. RS5 set up even with bigger rotors and huge calipers: 42 pounds even. Subcomponents: rotors actually up slightly at 25.2 lbs each, vs. 24.8 at factory 345. But small delta and a large swept area step up. The caliper weight was where the big step DOWN was--all in with dust shield, pads, caliper, hose and caliper clips and pins (for RS) I went from 19.6 pounds to 16.8. The RS5 caliper is only 11.6 pounds (I forgot to weigh stock bare). Pads are in total meaningfully larger in length (twin pads per side; four per caliper; 3.4 pounds), and the steel dust shield weighs over a pound, while the std. Q5 aluminum one is only a handful of ounces. If I did it again, I would just use the stock Q5 shield and pull out another pound and some cost. The air venting of the RS one probably only really plays out on sustained Autobahn use or a track; the Q5 one is about the same diameter as the RS rotors and somewhat oversize on the regular Q fitment.

In some self replies I will post with more time, I will get in some pics of the regular Q5 brakes as I pulled them off, and a side by side pad comparison.

Oh, BTW, since it's actually the "wife's ride," we'll see how long it takes her to notice the little mod I did quietly. I expect the kids will be the tip off point!

Some pics follow. Various shots of the brakes and also the caliper, both without pads where you can see the workings, and then with.

D_Frost

Good info as I forgot to get the specs when I did my mod. Though I went with the RS4 Avant setup, which will have the proper offset. There may also be a slight weight difference with the updated "wave" rotors.

Though, did you notice that the pedal travel is now slightly different compared to stock? Where the brake engagement is more progressive and less abrupt.

MP4.2+6.0

On the rotors, yes I understand the B8 RS4 Avant rear rotors would work offset wise to the stock Q5/A5/S5 and the rest of the B8 chassis (A4/S4). I almost threw that into my original post as a to-do. But from some inquiries, I could not find any non-wave ones for the Avant thus far. The part numbers also aren't available since the vehicle isn't sold in the U.S., and I can't find them on Euro EKTA on line. Meanwhile, do you have non wave RS Avant rotors, and if so how did you source them? And yes from your reply, my understanding is there is a further (modest) weight reduction to the wave style, but absent something like an SQ starting point that was a bit too far for me visually.

On pedal travel, it seems no greater in any obvious way first of all. And yes, probably somewhat more progressive/less abrupt. Definitely not any grabby type feel either. My starting point are the '13 factory brakes, which from the posts the past year sound like a somewhat more positively viewed compound/set up. My same favorable description is also how I would describe my 4 piston fixed caliper Brembo set up after I upgraded to it on the R56 Mini S. I didn't say it in the original post, but I am using the factory RS5 pads, though I considered EBC reds. On the Mini I am using a Carbotech street compound, and those are definitely thought of as progressive feel pads too. It's a bit harder to be sure about the pure hydraulic feel with the Hybrid because of the regenerative feature, though relative to most others (Toyota's, etc.) it is much less obvious and pretty transparent. Once you are at moderate braking at any speed above about 25 its beyond any obvious regen. and definitely into friction braking. So using that as a benchmark for friction braking, it's progressive and easy to modulate. Once the tires are broken in and with a few more miles on the brakes I will also do some harder stops from speed on the deserted road scenarios, which I expect to be favorable.

MP4.2+6.0

Earlier today, I actually did a reply to another post with a bunch of qualitative description about the stock brake set up. That reply is here: https://www.audiworld.com/forums/sho...php?p=24518379 About the first half or two thirds is background before I got to the OP's situation of uneven pad wear.

Below are several shots I took of the stock Q5 set up. These brakes have about 5800 miles of use over about four months of driving (net of the Euro delivery shipment time). Thus, still pretty new looking.

You can see the reasonably substantial Q5 caliper w/out the wheel in the way. Then you see the edge view of the caliper and rotor. Notice the more open vaning in the casting that I discussed in the original post above. The final shot is of the Q5 caliper from the inside, and then with the RS5 pads simply placed along side. It gives you an easy visual reference for the greater pad area of the RS set up. There is actually somewhat more space between the two pads (per caliper side) in the RS5 caliper, but the picture gives you a sense of the running length. Also notice that even with what looks like a fairly broad caliper in the Q5 design, the pad material really only falls inside of those two knurled nut looking bumps on the side of the caliper you see looking in from outside the wheel spokes. You also see in the last shot the big single piston on the inside; I discuss this some in the linked earlier post in the preceding paragraph above. Radically different than the RS non floating eight piston set up, but very common mass production calipers in general, and here with good sized OE rotors.

D_Frost

I have the wave rotors for the RS4 Avant sourced from Europrice. I'm not sure if the current generation RS4 Avant was ever released with the non-wave rotors. And coming from the 2012 setup with the floating caliper design (facelift version has the monoblock setup), the brake feel was pretty much as you described: less grabby but very progressive.

PreciseD

I am about to install the RS5 calipers on my Q5 and I am a bit confused to which rotors you went with and what else was needed to do the install. I know that you did this mod a while ago, so if you can recall what you used that would be great!

I see there are kits for these from ECS, but their quality lately is lacking.. I would rather use OE/OEM rotors, stoptec lines and a good set of pads.


-Chris

MP4.2+6.0

Rotors: You use the 365mm rotors from RS5, R8 or RS6. Offsets in front are straight bolt up. Rear true RS5 is where it gets tricky, but not front.

You can sometimes find the R8 front ones via an independent supply chain (as in, not Audi marked) that seem to trace back to the same exclusive supplier these quasi two piece factory ones come from. Those are what I used and per my original install pics. IIRC there may be a wave option from Audi, but I have just used the conventional cirnular edge one. All of them are (modest) drilled style.

I used OE RS5 brake lines, which were direct bolt up to Q5. Originally I used RS5 dealer (Audi) pads, but on next two pad cycles went to EBC reds. Easy to get in the RS5/R8 fitment, and they have the factory sensor which is also direct plug and play to Q5 connector. For pad change bit hardware (clips and such) you can either get it for more $ from Audi, or for cheaper if you search the R8 and RS5 applications for the Brembo parts on EBay, which is where Audi gets them to begin with. Make sure search includes Europe, where sometimes even w/ shipping it is cost effective.

hashimedic

Chris,

What did you end up doing on this?? I want to do the same for my 16 Q5. After reading this thread, I see why people lose their s*** when you post a question without first searching for the answer. Sometimes you just may find the exact post with the exact mod for your exact vehicle that you want! Thank you MP4.2+6.0 for the write-up!!

Hashim

hashimedic

MP4.2+6.0,

I just want to confirm that the 2013 - 2015 RS5 front calipers (assuming this is what you used) and rotors are a direct bolt on to the 2012 - 2016 (‘17 SQ5) B8 Q5, correct?

Hashim