What do you do when you have a 734bhp Audi TT-RS but you need to save as much weight as possible, fit your brakes behind 18” used with drag tyres and stop the vehicle quickly from around 150mph?
This was the brief given to us by APR UK earlier this month (April 2019).
The Car: TTRS 8S with TTE700 turbo, APR software and hardware ( Full details can be found at APR UK)
The three primary areas we had to tackle were Weight, Size and Stopping efficiency, not only for that of a TT-RS 8V but that of a TT-RS tuned by APR UK to over 730bhp and driven in anger at Santa Pod Raceway!
The original 370mm AP 8 piston brakes on the TT-RS as standard perform adequately however are known to have their issues and of course are too heavy, so firstly we removed the Brake Calipers, Carriers and Discs and weighed them so we knew what we were up against.
Stock brake discs: 13.23 kg per side
Stock calipers: 6.28 kg per side including brake pads
Caliper Carriers: 1.025 kg per side
A combined weight of 20.54 kg per side
Over the front axle that is over 40kg of braking components.
What could we do to reduce the weight?
We had a number of kits we could choose from in our VAG arsenal and after considering our options we decided on the BK0004 Kit with 343x28mm 2-piece VBT bell and AP rotor combo’ with lightweight Aluminium Brembo 4 Piston Calipers using custom lines built in house. This is a kit we had previously used on KW Suspensions’ S1 Track car with great success.
VBT/AP Racing 343mm brake discs: 7.260kg per side
4 Piston Brembo calipers: 3.305 kg per side Including brake pads
VBT Caliper Carriers: 0.305 kg per side
A combined weight of 10.87 kg per side
We managed to almost half the weight of the front brakes whilst maintaining braking efficiency and of course being able to fit behind the 18” wheels provided.
Having the power, and this car has the power, is all well and good when at the drag strip but having the confidence that when the run is over you will stop safely is another thing! Crossing the line at over 140mph and having to stop as quickly as possible in a safe straight line is as important as the run itself, then of course having the equipment to do it all over again safely on the next runs at sometimes at an increased speed is the requirement on the strip!
On the first run, the car ran a fantastic 9.914 seconds at 135.22 mph
stopping quickly and true at the end of the run. So far so good, but we knew it all had to be done again and we knew the car would be quicker next time.
Following inspection, the car was ready for its 2nd run where it produced an astonishing ¼ distance covered in 9.7 seconds at 144mph.
At Crail on the car’s second outing it managed an amazing 9.5 second run at 149mph!
We thank APR UK for giving us the opportunity to be involved with such an amazing project, done in a staggering 3 days! And look forward to seeing the TT-RS again as APR are promising to be even quicker next time around.
A video of the car can be found here: