Q5 BBK upgrade for our S4s

[coloradom3]

Have any of you tried it? How noticeable are the 4 piston calipers vs stock? I'm actually pretty satisfied with my stock brakes. Just want something in there more for aesthetics/appearance Please post pics of you got em. I searched but didn't find but a couple pics. Any and all help is appreciated. I'm sure there are others out there who would also like to see them on other S4s. Thank you!

[Nixon_S4]

Are you talking about ECS's kit? I find the calipers everything but aesthetically better - unless you paint the calipers yourself and add some kind of a badge.

[coloradom3]

Yes. Exactly my plans, they would look much better than stock.

Are you talking about ECS's kit? I find the calipers everything but aesthetically better - unless you paint the calipers yourself and add some kind of a badge.

[Mat@1975]

Just received them.
Will make them instal at the beginning of september. I have allready zimmermann drilled rotors, ebc yellowstuff pads , lines and good fluid.
Will tell you.

[Frinkferta]

I might pick some up when my front pads and rotors are toast...should be another 35k miles or so.

[coloradom3]

Awesome! Thank you!

How much larger than stock?
You mind putting them close to your oem calipers and taking a pic?

Just received them.
Will make them instal at the beginning of september. I have allready zimmermann drilled rotors, ebc yellowstuff pads , lines and good fluid.
Will tell you.

[drob23]

The biggest drawback IMO is gonna be pad options. And now I see stoptech selling 6 pot bbk's for ~$2200 on carid.com I just don't see the appeal of this Q5 kit in terms of performance/price.

[derek.kritz]

Just got the kit as well. Gonna be installing next week and yes, there are limited pad options. Just gonna run the pads that come preloaded with the kit. Which are OEM pads. Figured the calipers with lines and pads are like 1k. Can't get a aftermarket bbk for less than $2100. 🏼🏼


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[derek.kritz]

Painted black. High temp brembo decal with high temp clearcoat over all of it. Came out great!!!


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[flixman_420]

they look really nice

[ChobeG]

hey all...

funny that i found this thread today... as i have been running this Q5 set up for a few months now and put 7,200 kilometres in the car since I installed these callipers.

I have only just managed to put them through a proper test this weekend whilst having a bit of fun on a Hill Climb track. Unfortunately after a couple of laps of hard braking and during a hard stop from 120km/h to slow down for a corner, I experienced massive brake fade as the pads overheated and caused me to overshoot the corner and go straight into the grass.... no damage or scratches whatsoever thankfully, i just run into grass!.. it was still scary!

so i'm interested in other people's thoughts on these brakes.

I'm using the ECS two piece rotors with the Q5 callipers (as pictured below) and posi quite ceramic pads at the front ( only choice of pads i found), OEM or standard S4 rear brake callipers and pads at the rear along with ECS braided stainless lines front and rear. Unfortunately there wasn't much of a pad selection when i bought these and couldn't find any performance pads for these Q5 calipers. So that was a bit disappointing!... on the plus side.. yes these are lighter and changing pads is extremely easy!

One thing i have noticed, however and i'm a bit concerned about, is that the rear rotors are showing more wear than the front rotors on the surface. The front rotors are still showing the machining fine lines that these had on the surface when new whereas the rear rotors show more wear and no longer show any of the machining lines these once had when new. It almost seems to indicate that the rear brakes are doing more of the stopping than the front on the car...unless these posi quite ceramic pads are very gentle on the rotors?.... interested to hear recommendation or opinion on these.

Here's a pic of my set up





Interested to hear other people's thoughts... I'm considering going back to the S4 OEM, until i can afford a set of Alcon 6 piston callipers and 365mm rotors for the front. At least with the OEM i will have more of a pad selection which may improve the braking for the time being!

[drob23]

First off, what fluid were you running? My new opinion is the only fluid you should run with this car is Castrol SRF. It's quite expensive at ~$60/L, but the wet boiling point is 520F!!!! That is insane compared to other choices. Is the extra $20/L vs motul really going to break the bank (motul rbf660 is $20 for .5 L)? The RBF wet boiling point is more like 410F. Fluid is probably number 1 factor towards ending up in the grass. Pad fade can definitely happen, but much less likely.

Regarding the pads though, you (or someone in the states) might consider mailing a used backing plate to carbotech. There's a good chance those guys would make some carbotech pads for your car. There are a couple choices for high quality track pads, but carbotech are certainly in the conversation for best track pad setup. Something like xp20/xp24.

Regarding your rear pads, I would be surprised if the bias has shifted rearward. But if you are running a different compound in the front vs rear, it's possible. My rear pads tend to drag worse on the rotors (floating calipers will always kind of drag the pads on the rotor surface, removes a dead zone in pedal travel). I'm not sure how much you can gather by looking at the rotor surface. The pad surface area in the front might be the reason for better looking rotors...dunno.

[Mat@1975]

hey all...

funny that i found this thread today... as i have been running this Q5 set up for a few months now and put 7,200 kilometres in the car since I installed these callipers.

I have only just managed to put them through a proper test this weekend whilst having a bit of fun on a Hill Climb track. Unfortunately after a couple of laps of hard braking and during a hard stop from 120km/h to slow down for a corner, I experienced massive brake fade as the pads overheated and caused me to overshoot the corner and go straight into the grass.... no damage or scratches whatsoever thankfully, i just run into grass!.. it was still scary!

so i'm interested in other people's thoughts on these brakes.

I'm using the ECS two piece rotors with the Q5 callipers (as pictured below) and posi quite ceramic pads at the front ( only choice of pads i found), OEM or standard S4 rear brake callipers and pads at the rear along with ECS braided stainless lines front and rear. Unfortunately there wasn't much of a pad selection when i bought these and couldn't find any performance pads for these Q5 calipers. So that was a bit disappointing!... on the plus side.. yes these are lighter and changing pads is extremely easy!

One thing i have noticed, however and i'm a bit concerned about, is that the rear rotors are showing more wear than the front rotors on the surface. The front rotors are still showing the machining fine lines that these had on the surface when new whereas the rear rotors show more wear and no longer show any of the machining lines these once had when new. It almost seems to indicate that the rear brakes are doing more of the stopping than the front on the car...unless these posi quite ceramic pads are very gentle on the rotors?.... interested to hear recommendation or opinion on these.

Here's a pic of my set up





Interested to hear other people's thoughts... I'm considering going back to the S4 OEM, until i can afford a set of Alcon 6 piston callipers and 365mm rotors for the front. At least with the OEM i will have more of a pad selection which may improve the braking for the time being!

Hello,

EBC Yellowstuff avaible for these calipers.

BR

Mat

[drob23]

Hello,

EBC Yellowstuff avaible for these calipers.

BR

Mat

If someone was pushing enough to go off track due to brake fade, EBC yellowstuff is not going to be the solution. I personally went off track with yellowstuff and dot 5.1 fluid with the stock calipers. The track worker ran over because he thought my brakes were on fire from all the smoke. The pads cracked and crumbled in places when we took them off.

[Mat@1975]

If someone was pushing enough to go off track due to brake fade, EBC yellowstuff is not going to be the solution. I personally went off track with yellowstuff and dot 5.1 fluid with the stock calipers. The track worker ran over because he thought my brakes were on fire from all the smoke. The pads cracked and crumbled in places when we took them off.

oops... impressive ! :o)

but if ChobeG was running stock fluid with ceramic / no dust pads, i am pretty sure that EBC Yellow / Decent fluid like RBF 600 will be better, isn't it ?

Please keep us informed is someone find other / better avaible pads for these calipers .

Best regards,

Mathieu

[Li ls4]

Same question here as the op. Also do the pads the kit comes with give off a lot of break dust like our oem pads do? Im about to change my pads and rotors so im toying with the idea of upgrading the front brakes to these.

With the pad selection though. Which pads do you guys run on the rear when you have the q5 kit up front? The original plan was getting either the hawk or akebono pads which people have said does not give off a lot of break dust. So with looking at the pad selection of the q5 calipers we have either stoptech or textar pads (just looking on ecs). Ideally you would want to have the same pads all around correct? Or is it really not that big of a deal having either stoptech or textar up front and hawk or akebono in the rear.

[drob23]

oops... impressive ! :o)

but if ChobeG was running stock fluid with ceramic / no dust pads, i am pretty sure that EBC Yellow / Decent fluid like RBF 600 will be better, isn't it ?

Please keep us informed is someone find other / better avaible pads for these calipers .

Best regards,

Mathieu

I certainly can't disprove your conjecture. But can't say if that would have saved him. My point is once you are running faster than the green/beginner group, or possibly running at a bad track for brake cooling, or possibly running stickier rubber...it makes sense to run actual track pads. Not dual use pads like EBC yellow stuff. This is my opinion because I've personally gone off track before and will never chance it. The amount of people I've seen with brake issues at HPDE's is actually kind of scary. So why not run the best equipment you can? I personally would not take this car on track without *at least* carbotech xp10 pads and fresh high performance fluid like SRF.

So if it was me with this q5 caliper, I would ship a backing plate to carbotech and see if they can make a pad for me. Then just swap whatever track compound with 1521's for the street. The 1521 has been an awesome street pad for me. No brake noise, no dust, good performance in cold, and no issues with lock-up (like some have reported). If you are going to the track enough to change brakes, then you should learn/know how to change pads.

[LINDW4LL]

I can't help but think that this "upgrade" is a waste of money.

The slight aesthetic improvement and a bit better pedal feel is not worth the cost and effort.

[Mat@1975]

Hello,

If it can help ChobeG when he'll ask carbotech is the "universal" pad shape for aftermarket pads: FMSI D1663 for Q5 calipers
Please keep us informed !

Drob 23 must be right, EBC Yellow are decent dual use pads. they are OK for street (although a slight poor bite when cold....) and can survive to a "cool/gentle" trakday.

But, for me, the choice of Q5 calipers is somewhow pertinent:
- The main reason is that i NEVER got a proper bed in whith the stock calipers. I explain: i never managed to obtain a whole rotor surface "grey/bluish" deposit as expected. THere is still remaining a 1/4" zone on the outer radius and a 1/8" on the inner radius of the rotor that does not see pad deposit, as a consequence, IMO, of a bad clampping capability of the stock caliper. The lost surface is a pitty and i think that using all the surface could reduce heat, fading and wrappage issues (in a certain extend of course...). Q5 calipers (fixed 4 pots) will do better than stock !

- These calipers allow a very quick change of pads: i think i will consider now the drob23 way, i.e having distinct pads for street/track.

- The better pedal feel is for me a great thing too. we'll see.....

see you !

BR

Mathieu

[ChobeG]

Drob23... interesting you mentioned that as i am using the RBF600!!...I might have to change to the Castrol, although the RBF here in Australia is only $45 dollars for a 500ml bottle as opposed to $120 dollars for the Castrol bottle of the same size... big difference in price man!... but it may be worth giving it a try for sure!.

I viewed your video too and it definitely gave me some flashbacks!..haha.. that's pretty much how i went off.. with lots of white smoke coming off my front brakes!. I was, however pushing the brakes a bit through my laps as i wanted to see how they would stand coping a fair bit of braking.. not abuse as such, just accelerating hard and then getting on the brakes late before a corner and oh boy!.. that feeling when you're trying to stop and the car just isn't responding... :-O..... haha..

Mat, I didn't know these callipers had Yellow stuff pads available. That means there might be a chance that red pads may also be available for road use, so i could potentially have both sets, however it sounds like drob23's suggestion of the carbontech 1521s might be answer for the road instead of the red stuff. I will contact carbontech and ask them if they could manufacture an specific track pad and get my hands on the 1521 as well for both front and rear.

Definitely these q5 callipers do make it so easy to swap when you want to do a track day and that's the big plus for me. The only problem is that changing the rears would be the issue if i wanted to keep all four pads the same!....if the difference in pads between front and rear is affecting the dynamics then this problem will still be present.

The wheels i'm using are the OEM 19" V-spoke wheels wrapped with the OEM continental tyres so nothing special in that department, but that aside, i have the H&R Sport Springs and Eurocode swaybars and endlinks. I'm pretty happy with the handling!.. just the brakes have disappointed me a bit as i was expecting more out of these Q5 calliper upgrade...

maybe you're right drob23, i might be the one that hasn't done the set up correctly by using the different pads at the front and rear AND then using the RBF600 fluid instead of a better one... but I've also had pedal issues when i first installed them if you recall from another post..which took me three bleeds to get right, so I'm not over the moon with this upgrade and i guess i was expecting more out of it. ...Anyway.. i have them on now, so I'll follow both suggestions and report on back once done and hopefully i will see an improvement. Thanks for your input too Mat@1975, very much appreciated!

Li ls4 i'm not sure which pads ECS includes on their Q5 kit as i didn't get mine from ECS and the pads i'm using I bought from yet another reseller. I'm using the posi quite ceramic and later noticed that ECS carries the stoptech and textar as well as the OEM, but quite frankly i don't care if a pad is dusty as long as it brings me to a complete halt quick and without fade after a few runs!...i rather focus on pad performance than keeping my wheels clean and i think that's the trade off with good performance pads.. but correct me if i'm wrong.

thanks all

Rob

[drob23]

Rbf600 is pretty damn good fluid...I'm assuming it's fresh because I remember your other thread.

SRF only comes in 1L bottles, which are larger than the 500ml motul. So the cost isn't as bad as you think...but still bad.

I would say don't worry about changing the rear pads until you get some more experience tracking your setup. I swap rears, but it takes a lot longer cause you need vcds.

I think you'll enjoy your setup a lot more once you get some proper track pads. Pagid, carbotech, some race compound stoptech,... Having brakes that you can trust is really worth itself in gold out there.

But I'd say that until you are running 390mm alcons, radical ap racing, brembo gt or 380mm st60's...there is always a cause for concern.

There is also the holy grail of brake duct cooling. But unfortunately no bolt on solution for that...

[derek.kritz]

The Q5 calipers come with OEM pads preloaded.


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[Mat@1975]

Hello. Should be time to start a new thread. "Avaible pads for Q5 4 pots brembo calipers upgrade".
May i?

Br

Mat.

[ChobeG]

Please...do start it Matt!..:)

Derek, when i bought these callipers i didn't get any pads whatsoever...i was just sent the callipers on their own.

Drob23.. definitely fresh i would say... only been on the car for 7,500kms approx. again.. thanks for all your input man! very much appreciate your advice!..

[Mat@1975]

Hello,

I just have an answer from PAGID. It seems that they have a pad for those Q5 calipers: Ref E2487. The best compound for trak days adviced by Pagid is RS29.

I will start a dedicated thread for the pads choices soon.

Best reagards,

Mathieu

[drob23]

Hello,

I just have an answer from PAGID. It seems that they have a pad for those Q5 calipers: Ref E2487. The best compound for trak days adviced by Pagid is RS29.

I will start a dedicated thread for the pads choices soon.

Best reagards,

Mathieu

Hard to find a better pad than Pagid RS29. Even endorsed by westwest himself lol

[derek.kritz]

Please...do start it Matt!..:)

Derek, when i bought these callipers i didn't get any pads whatsoever...i was just sent the callipers on their own.

Drob23.. definitely fresh i would say... only been on the car for 7,500kms approx. again.. thanks for all your input man! very much appreciate your advice!..

I bought mine from ecs. They came preloaded with the OEM pads. I even tried to get them to swap them for the stoptech ceramics. But they wouldn't do it. So, I'm just running the OEM ones. Just got them installed yesterday. I got to say, very happy with them. Went on a VERY spirited run last night. With a lot of real hard braking. Bite was great and I got zero fade. Multiple hard brakes were done. Can't speak for a true track application but for me they are great. As for pads, there are only 3 options I know of. OEM, textar, and stoptech ceramic.


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[ChobeG]

Just thought i should share an update on this since the changes i did recently made a substantial difference to my set up. The new changes have now put a smile on my face and i'm now happy I purchased these callipers.

After contacting several local distributors to see if they had anything or if something could be made (sorry i didn't contact carbotech as the logistics of it all and also the exchange rates atm for the Aussie dollar isn't that great so I tried to source something local instead) i got no where trying to find something. So i contacted the local Audi dealership service people and shared details of the upgrade and my slight disappointment with the whole exercise. They were very keen to help and see the set up since i also mentioned it was a q5 calliper on an S4. Further to this i spoke to the mechanic that initially assisted me with the install and he couldn't remember what type of fluid was used and if the rbf600 had in fact gone in or not. He had a feeling that just plain vanilla fluid had been used.

Back at the dealership the mechanic mentioned that the design of the pads in place (Centric posi quite ceramics) were showing visible signs of allowing dirt, tiny stones or road sand in between the contact area and the rotor since the corners of the pads are cut out rather than left squared. Here in Melbourne it rains a lot so dirt gets washed onto the wheels and callipers as you drive along. The evidence was in the pads having deep grooves or deep scratches across the contact section of the pad with some chucks missing and little stones still encrusted on the pad. He also felt that the for some reason the pads and rotors where not showing signs of making a strong contact considering i had also done a track day. So we organised a day to have the system flashed.

In the mean time we looked through the spare parts bin and found a set of brembo pads that were recommend for the Q5. The part number of the pads is: 8R0-698-151K - The pad compound is very rough, the material is all black showing pieces of metal in it and the pads also have both; a brembo and the audi logo stamped at the back of it. The set was $285AU Dollars..Ouch! apparently that was with a $100 dollars discount too!

The following week i had the fluid replaced with Motul RBF660 and the new brembo pads installed. Oh boy the results have been substantial!... The difference is VERY noticeable and the braking is now how it should be. In contrast with the ceramic pads these pads feel aggressive on the initial bite but i love them and the stopping distances have definitely decreased. These pads are also very quite even when braking hard!!. I took the usual bed-in steps and after that i took the car for a spirited run through the mountains.. Wow...the braking is awesome!.. even after aggressive braking i did not experience any fade whatsoever.....so i can only say... bravo!, magnifico.. fantastico!...Lol

I can now recommend this set up as a worthy upgrade!.. and i can only imagine how strong the braking from a set up like an Alcon or Stoptech 6 pistons calliper would be like, or even the original RS calliper in comparison to this Q5 set up... these set ups surely would be car ejecting aids if not used with care.. hehe...... But nevertheless I'm very happy with the Q5 upgrade and glad this is now all sorted!...

Next... to sort out my alignment issues since my rear and front tyres are showing substantial inner wear even after only having done 8900kilometres on the car and having fitted H&R Sport springs only...:/.... otherwise i will be going through tyres like the cookie monster goes through his cookies!... :(... but i'll leave this for another post!

Thanks
Rob

[IC3MAN SQ5]

I have a set of 2015 Audi SQ5 front brake calipers in black, with brake lines, brake pads & front rotors for sale. They came off my SQ5 and only have 300miles on them, about 2/3weeks old from when I bought my SQ5. Pm me for details and pics are in my signature to my build.

[wwhan]

Q5 calipers with Audi OEM Q5 pads work fine for street legal speeds, low dust and linear feel, Akibono pads are a nice choice for the rear stock calipers and match well for front OEM Q5 pads. It is nice low dust solution.

[eurotic]

First off, what fluid were you running? My new opinion is the only fluid you should run with this car is Castrol SRF. It's quite expensive at ~$60/L, but the wet boiling point is 520F!!!! That is insane compared to other choices. Is the extra $20/L vs motul really going to break the bank (motul rbf660 is $20 for .5 L)? The RBF wet boiling point is more like 410F.

A question about the boiling points, if you were bleeding the brake system before or after a track event wouldn't the fluid be closer to it's dry boiling point in which case the Castrol SRF is about the same dry boiling as the cheaper RBF600? How long does it typically take for brake fluid in a car's brake system to become wet?

I'm asking because some guys I autocross with that also track their cars simply swear by using a good fluid but bleeding very frequently. Their argument is that regardless if they went with something like SRF or some basic DOT 4 from a parts store, they would bleed the brakes at the same interval/schedule. They suggest that they can go with a high quality fluid like RBF600 and save a few bucks since they don't feel the fluid is ever near being wet when they race since it is fresh.

However if you are only changing your fluid once or twice a year then maybe the fluid with higher wet boiling point is a better choice because the fluid might be close to or in the wet zone.

Thoughts?

[chaos2984]

Hey Chobe so what did you guys exactly do to fix the issue. Just change the pads. It looks like you had the same pads on there before correct? Was it just the bad contact patch bad seat in with the original pads or did you go to a different pad all together?

Also the sides of the pads are chamfered to reduce pad noise is all.

[ChobeG]

Hey Chobe so what did you guys exactly do to fix the issue. Just change the pads. It looks like you had the same pads on there before correct? Was it just the bad contact patch bad seat in with the original pads or did you go to a different pad all together?

Also the sides of the pads are chamfered to reduce pad noise is all.

We changed the fluid as we suspected the guy that did the initial install just used plain and simple fluid instead of a good high boiling point fluid... The audi mechanic also suspected that there might still be air in the lines somewhere as he didn't see evidence of enough clamping force being applied to the front rotors... and we also changed the pads to a set of OEM brembo non chamfered and non ceramic pads. I had a set of centric posi quiet ceramic pads before.

He also noticed that the pads didn't have any brake grease behind them so the whole install wasn't done right. ..

The brembo pads and new fluid definitely made a hell of a difference...now the rotors are showing evidence of clamping force and you definitely can feel the brakes working now..

So probably a combination of things was the cause of my set up not working correctly.

[chaos2984]

Gotcha. Sounds good. Sounds like the pads were the main factor for the issue. If you had air in the system you would know it with pedal feel. unless the pedal feel changed with the new calipers and you "thought" the new feel was normal. But fluid is fluid for normal driving. But i can see the fluid making a difference on the track. Did you notice a difference with normal street driving as well?

[rlfletch]

I have a set of 2015 Audi SQ5 front brake calipers in black, with brake lines, brake pads & front rotors for sale. They came off my SQ5 and only have 300miles on them, about 2/3weeks old from when I bought my SQ5. Pm me for details and pics are in my signature to my build.

Lazy question: What are the differences between the Q5 and the SQ5 calipers?

[derek.kritz]

Lazy question: What are the differences between the Q5 and the SQ5 calipers?

I think just the paint. The Q5 calipers come grey. Sq5 come painted either black or red.


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[acsgp]

Lazy question: What are the differences between the Q5 and the SQ5 calipers?

The Q5 family has 3 different calipers, best I know - the 2.0T/3.2 version, the 3.0T version, and the SQ5 version. The discussion here on the 4 pot Brembos are the 3.0T version. The SQ5 version has 380 mm disks.

I have the 4 pot Brembos on, and I will never track the car. It's an upgrade for the street as it's both lighter and has a large swept area than the stock S4 caliper. If I tracked the car, I would go for at least a 355 mm floating disk with 6 pot AP, Brembo or StopTech calipers.

I had the 355 StopTech 6 pot on my A6, and they are far superior to the current 4 pot Brembos. I wanted a cost effective brake upgrade, and am very concious about unsprung weight. The stock S4 calipers weigh a ton.

[ChobeG]

Gotcha. Sounds good. Sounds like the pads were the main factor for the issue. If you had air in the system you would know it with pedal feel. unless the pedal feel changed with the new calipers and you "thought" the new feel was normal. But fluid is fluid for normal driving. But i can see the fluid making a difference on the track. Did you notice a difference with normal street driving as well?

I would say so... the pads were definitely not doing this set up any favours.... You're right, the fluid wouldn't make a difference on normal street driving, but i did do a fairly spirited run and with the old pads and the old fluid and experienced brake fade. I also ended up on the grass with the old pads and fluid, so which ever was the cause it has now been rectified :). Pedal feel is still the same as factory, nice and firm and short travel, but the mechanic suspected air since the rotors were showing sings of very little clamping force. Anyway changing the fluid would have also rectified this if there ever was any air left in there.

Definitely this set up is great for the occasional track day but if you I agree with ACSGP, if you're going to track the car regularly, best to go with a 6 piston set up :)

[drob23]

A question about the boiling points, if you were bleeding the brake system before or after a track event wouldn't the fluid be closer to it's dry boiling point in which case the Castrol SRF is about the same dry boiling as the cheaper RBF600? How long does it typically take for brake fluid in a car's brake system to become wet?

I'm asking because some guys I autocross with that also track their cars simply swear by using a good fluid but bleeding very frequently. Their argument is that regardless if they went with something like SRF or some basic DOT 4 from a parts store, they would bleed the brakes at the same interval/schedule. They suggest that they can go with a high quality fluid like RBF600 and save a few bucks since they don't feel the fluid is ever near being wet when they race since it is fresh.

However if you are only changing your fluid once or twice a year then maybe the fluid with higher wet boiling point is a better choice because the fluid might be close to or in the wet zone.

Thoughts?

This is a great question. I honestly don't know enough about the science of brake fluid to say one way or the other. I've heard people say the wet boiling point is the only one that matters, since there is water in the air that immediately contaminates the fluid when you open the cap. But flushing your fluid after each event or at least the caliper seems like a pretty good risk mitigation strategy.

My current rationale is to buy 2L of SRF before the track season starts...takes around 1-1.5L to flush...then flush the calipers with the left over fluid after every other event. I haven't decided if I will flush some ATE super blue in there after the season to get me through the winter. I've heard bad things about leaving racing fluid in there, but also heard it's no big deal.

But going with Motul fluid and frequently bleeding it seems like a very sound strategy.

[acsgp]

I have a strange issue since I swapped front calipers. While the stock S4 calipers had a slightly spongy feel, they were consistently (and slightly) soft.

But now, I can press the pedal almost to the floorboard. Then the 2nd time I pump the pedal, it's hard and high. The race shop first thought it was air in the system, and I had it bled a 2nd time with proper equipment. But same issue. Then they thought it was the slave pump, until the race shop checked it and said the unusual behaviour pointed to the master pump. The S4 is now with the distributor, and I'm having the master pump changed at my cost (with no labour charge), unless there is evidence that the master pump was damaged by the agent when bleeding the brake system originally.

I'm running the OE brake pads, decent bite, but dusty as hell.