Yes, yes - there's been a whole number of threads on this topic, but I wanted to condense my experience and possible solutions into one place.
PS - before reading on, I apologise but I cannot seem to post links today, I can't paste anything and I can't use the link tool as it never closes, I'll try and update with links later...
The problem scenario
Over the last couple of days, I've been touring around the Alpine roads of Italy, Slovenia and Austria, culminating yesterday in driving the Großglockner high mountain pass. Some parts of these roads are fairly demanding, twisty technical sections followed by some great straights and hill climbs - similarish to some track work. (If you ever get the chance to drive these roads by the way, I highly recommend it).
Anyhoo - these roads are the perfect place to really put a car like the RS3 through it's paces right?
Sorta...
I found a pattern emerging as I used these roads -
- the brakes would start to chirp (just a little) at lighter/low speed braking, could be cured temporarily by a hard application of the brakes
- you'd start to smell the brakes pretty obviously at a stop
- there would also start to be a rather obvious turbine noise/pitch from the front discs when slowing down, again, could be cured temporarily by a hard brake
- eventually, there would also be some juddering when applying the brakes
As you might imagine, this didn't instill a great deal of confidence.
But deepspacemillar, you were probably hammering the car/using those brakes hard etc
Well, no... No more than anyone else. Especially yesterday, after a two hour stop at the summit the entire descent was stuck behind a fully loaded people carrier in a line of slowish traffic. My car was the only one making any brake noises.
So what's going wrong?
Well, in my opinion it's a combination of three factors;
- Pads
The OEM pads seem to be aimed at lighter road use - this influences the temperatures they work best with etc. The OEM pads work best at lower brake temps and noticeably fade when the heat levels get high, which is kinda silly given the discs issue mentioned below.
See the RS3 brakepads topic for more detail on this - Discs
The OEM discs certainly look the part, but they are not particularly well designed in several regards, the most prominent one here is that the right hand disc is the same as the left hand disc, but they have directional cooling vanes.
What this means is that the right side disc is actually spinning the wrong way to efficiently expel hot air, the left one is working as expected. I personally think this is incredibly stupid on Audi's part, as what it means is that the ride side disc gets considerably hotter than the left, resulting in a myriad of potential issues, not least that the life of the disc is significantly reduced because of heat deformation and cycling.
My observation yesterday and previous was that the squeaking noises and other errata were only really coming from the right side of the car (the problem disc).
There is a good discussion on this in the Tarox Replacement Front Discs Now Fitted topic - Ventilation
Good discs can only do so much if the airflow to them is poor. The older 8P RS3 received some tweaks over time to increase airflow into the wheel wells to improve the airflow to the brakes. These tweaks lower the operating temperatures and improve the performance and lifespan of the brake parts. My impression is that the OEM airflow isn't particularly impressive, and improvements here would be noticeably better in heavier use.
See the Brake Ventilation topic for more info
Solutions
I think the solutions depend on how you use the car and how often you are likely to encounter the issues mentioned above. They pretty much follow the order above;
- For the daily driver - Pads
I have already replaced my pads with EBC redstuff, and I truly believe they are an improvement over OEM - they are quieter, have better brake feel, and I haven't noticed any fade to speak of, despite the heat issues mentioned above. I think these are top notch and I would recommend them over OEM to anyone. They're also half the price of the OEM pads...
I will be sending my old OEM pads to EBC when I return and hopefully they can make an RS3 specific set, which will make things a complete drop in replacement in future. In the meantime, the correct EBC set is 'DP31513C'
- For when your OEM discs need normal replacement, or for a more spirited driver - Discs
In normal road use at home, I very rarely think the right disc is getting into the heat range where it shouldn't be, but I don't usually drive hard enough or long enough to really see it - I have been looking at a whole host of different options here however - there is much discussion to be had about whether you should have drilled, slotted, plain discs etc and exactly what brand is best etc. I may start a separate topic on this at some point, but upgrading the discs to ones that are properly 'sided' and vented will probably solve the issue for 99% of people to be honest.
So far I have my eyes on a particular set of ECS Tuning discs that are wavy like the OEM ones, but drilled and slotted - search for 'ECS-ES2785596'. They're available from UK retailers for cheaper than OEM...
I personally like the OEM+ look, and you can also get discs that match at the rear, in either wavy or 'normal'
- For a serious driver/track demon - ventilation mods or removal of brake shield/hardware mods
See the linked thread for more information, but what I would like to see at some point in a new undertray design for the RS3 that adds some ducting to the wheel arches. From comments in the thread, this can reduce temps by 25%, which to me sounds perfect. At the moment these mods seem a bit too DIY for me, but at least there's some progress here. This alone could significantly reduce temperatures and be relatively cheap, I hope a company picks this up.
Bonus mods
A feature of the MQB cars that arguably can exacerbate the problem is Torque Vectoring By Braking. This of course brakes the inside wheel as you turn a corner in order to keep the car flat through the corners.
I've heard this in action on the mountain passes, causing minor noise when my foot isn't on the brakes.
This of course doesn't help your overheated brakes down a mountain pass if your brakes are still being applied just going round a corner, although the general effect normally is positive.
How can you make this better? Well - the Torque vectoring is being used in lieu of a proper limited slip differential at the front axle. The RS3 uses an open diff at the front which means power will get wasted if a wheel spins or loses traction. The torque vectoring function essentially replicates a LSD, except it removes power rather than distributes it.
A potentially very positive solution (and one I wish had been offered from factory) is to replace the open diff with a LSD, and turn off the torque vectoring via VCDS.
Problem so far... I talked to Quaife and Wavetrac a number of months ago and asked if they had any products available yet - neither did. Also, installation is not exactly trivial - the entire gearbox needs to be lowered out and opened to fit the diff. However, for the ultimate grip in what is essentially a FWD biased car, this is the shiz, and means you wouldn't lose out by simply disabling torque vectoring.
Thus concludes today's diatribe - I would love to hear if anybody has further thoughts on this or any experience they can add.
Cheers.
Edited by deepspacemillar, 14 September 2016 - 10:57 AM.