As you might have noticed, the past few upgrades I've made to my B9 A4 Allroad have been in the performance department. Horsepower has now increased from roughly 252 HP (crank) and 273 FT-LBS to 334 HP and 370 FT-LBS of torque with the 034Motorsport Stage 1 ECU tuning. Now that the car accelerates much faster and is capable of significantly higher speeds, it's time to improve braking performance. As the saying goes, you can only drive your car as fast as you can stop it.
Room For Improvement
While I've found the factory equipped brake calipers to be sufficient to provide good all around braking performance, the stock pads definitely leave a lot to be desired. There is essentially almost no initial bite whatsoever. Also, while they do stop the car adequately at normal speeds, if I'm driving a "more spirited" speed, it does take a bit longer than I would like to safely slow the car down.
Brake fade is also a bit of an issue with the factory pads as well. When taking the Allroad through some of my favorite twisty backroads, the braking performance very quickly falls off after only a few passes. Many of the roads I'm driving on have several technical turns that require significant slowing to nail the apex. With the factory pads, you quickly lose confidence in your stopping capability once you've got some serious heat in them.
Better Pads - EBC Yellowstuff
Having performed this song and dance before with many of my previous vehicles, I already knew what pads I wanted: EBC Yellowstuff. While my go-to street pad used to be EBC Redstuff due to it's quiet nature and low dust production, I've switched to using Yellowstuff for a few reasons.
For one, I like the high initial bite you get when Yellowstuff pads are still cold. There's nothing like needing to make an emergency stop on the highway after the brakes cool off only to realize the brakes have no heat in them. Even if they're cold, Yellowstuff pads have a fantastic initial bite that stops you quickly.
Another plus is that Yellowstuff pads do not easily fade under performance driving situations, such as the aforementioned backroad driving. You can drive literally all afternoon on your favorite twisty roads without ever overworking the pads.
As if they weren't good enough already, Yellowstuff are also long wearing. The lifespan of these is typically as good as if not slightly better than a factory equipped semi-metallic pad.
There are only two minor drawbacks with the Yellowstuff pads: dust and noise. I'm not going to try and sugarcoat it, Yellowstuff pads produce a lot of dust, and you will really notice this if you are making the switch from Redstuff or other ceramic based pads. Also, Yellowstuff pads do make a little squealing from time to time. However, I've found that it mostly only occurs when the pads are very cold and goes away after the first handful of stops.
High Quality Rotors
Since it's Project Practical Performance, I opted to go with standard brake rotors. While I do love a good drilled or slotted brake rotor, I just couldn't justify the increased cost since I gain no benefit from them on the street. I ended up choosing Textar brake rotors since they are a long lasting high-carbon steel brake rotor for a relatively low cost. Textar is also an OEM producer of brake rotors, so the production quality of these is high. Because of their high quality and great price, Textar is often the most used brake rotor brand at both of our professional service centers.
Down the road I may end up switching to a light-weight two piece rotor, such as those produced by 034Motorsport. If I do, I'll be sure to make a post about it.
Don't Forget the Wear Sensors
The brake wear sensors on your car let you know when it's time to replace the pads. This information is incredibly important. Unfortunately, I've seen far too many vehicles come into the shop that have had DIY brake pad/rotor changes where the owner skipped replacing the pad wear sensor and simply looped the connection so the warning wouldn't trigger. Please do not do this. Even if you plan on keeping an eye on your pads, all it takes is a little forgetfulness before you end up in a bad braking situation.
Fortunately we stock most common Audi and VW brake wear sensors at our shops. Due to their high quality at a low cost, our go-to brand for these is once again Textar. Most models, such as my A4 Allroad, simply use one front sensor and one rear sensor, but there are a few that have a sensor on each corner.
- Textar Front Brake Pad Sensor - Audi B9/B9.5 A4, A5, A4 Allroad, Q5, C8 A6
- Textar Rear Brake Pad Sensor - Audi B9/B9.5, C8, D5, 4M
Upgraded Brake Lines
Normally, I would be installing a set of new stainless brake lines when installing new calipers. However, I wanted to test the ability to swap the new calipers onto the car without having to change the brake lines.
The plan was (and still is) to install a set of 034Motorsport stainless brake lines. These provide a nice, firm, top of the pedal feel to each stop. Even though I don't plan on tracking this car, these are a great addition to any Audi. I will be installing these to the car when my schedule permits and I'll be sure to update this review then as well.
Caliper "Side-grade"
In the introduction to this post, I mentioned that I found the factory braking system to be fairly adequate for the Allroad. The 4 piston ATE front calipers paired with 338mm front brake rotors provide excellent braking performance to stop the Allroad in most situations. However, during my research of different possible bolt-on caliper upgrades, I did find an interesting side-grade in the form of Brembo 4 piston brake calipers from the same generation B9/B9.5 Audi Q5.
These Brembo calipers utilize the same exact 338x30mm front brake rotors and are a direct replacement for the ATE calipers I already have on the car. Because I'm not increasing the brake rotor size, I'm not adding any extra rotational weight, which means acceleration isn't affected. The weight of the Brembo calipers are also basically identical to the ATE calipers that they're replacing, so no increase in un-sprung weight.
Now some of you are probably scratching their heads at this point because there is already an established easy OEM+ brake upgrade available from the B9/B9.5 S4/S5 models. These feature six piston Akebono calipers paired with 350mm brake rotors. On paper, this sounds like an all around great upgrade. For track enthusiasts, it really is a good upgrade. However, for a daily driven vehicle, there are no real improvements and they actually degrade the performance slightly. That's because at the speeds I'm going on the street, the braking distance improvement is only about 4 feet or less. The 350mm rotors also weigh a good bit more, which means slower acceleration and decreases in fuel economy.
I also feel good knowing that I have a high quality set of Brembo calipers stopping the car. I've always been a big fan of Brembo calipers and these certainly do not disappoint. After all, Brembo is the best in the business for a reason.
I also took the opportunity to fully paint these calipers in a high gloss black to match the "Stormtrooper" look that I'm going for. Since they're real Brembo calipers, I also added some high temp decals to let the world know that they're the real deal. I think that they came out looking great and add a nice little bit of flare to the Allroad.
