We were brought this Unitronic Stage 3 RS3 to solve some braking issues.
Issue #1: overheating brakes and cracking rotors after only one track weekend
Issue #2: balance under braking, car was standing on the nose and making the back tires light
This car had upgraded front calipers and rotors from AP Racing. I thought they were very nice, but so powerful that the rear needed to catch up. Although it has upgraded Girodisc rear rotors, we found it was the caliper that was lacking as the owner reported changing front pads 8-10 times before even seeing any wear on the rears. We're used to controlling brake bias in racecars using independent master cylinders for front and rear, where the Audi only has a single master cylinder. So how can we get some brake force off the front and fix the brake balance? By installing a more efficient caliper on the rear that will move more brake pressure and fluid to the rear!
We used the same rear calipers that we use on the NASCAR trucks for ovals (the roadcourse ones were going to be overkill). Usually when you bleed the brakes on these cars, the front gushes out fluid when you hold the pedal down, while the back on lets out about a drop of fluid. With this new caliper we could see right away when we were bleeding the system that it was moving way more fluid to the rear.
Next, we installed a duct system that directs air at the front calipers, rotors, and hubs. Usually on a NASCAR Cup car, where we borrowed the tech from, the hose will connect all the way to the dust cover but we ran it shorter so the owner doesn't have to worry about any tire rubs and can street-drive the car if he so pleases.
THE RESULTS! Rotor temperatures taken after a cool-down lap were 300 degrees cooler. The car made it through the weekend without damaging the rotors this time. The driver reported that the handling of the car under braking was improved immensely and that the car was stopping sooner than he expected.
Important note: these rear calipers are from a racecar so they delete the electronic parking brake. We came up with a solution to trick the car's system into thinking it still has a park brake so you don't have to see those annoying warning lights.
Also: Some folks have said the balance under braking could be fixed by adding compression to the front shocks and/or rebound to the rear shocks. While I would agree, this problem with the balance under braking only showed up after installing the new AP Racing front brake kit.
I'm going to try to attempt to attach a few photos of the different parts in this post, but bear with me as this is my first forum post. :-)
You can see more of our work and keep up with the team in these places:
facebook.com/LiraMotorsportsFL
instagram.com/1michaellira
liramotorsports.com
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