The steel monocoque of the B7 RS4 comes in saloon, Avant estate and Cabriolet forms and all share the same suspension layout. At the front, there are upper and lower magnesium control arms with hollow anti-roll bar, coil springs and gas shock absorbers. At the back, a multi-link set up uses coils springs, shock absorbers and anti-roll bar. This set-up lowered the RS4 by 30mm compared to a standard B7 A4, while the optional Sport suspension further lowered the RS4 by another 10mm. Not all owners are keen on the Sport suspension as they feel it makes the ride too harsh.
Wider tracks give the RS4 a great stance
The RS4 suspension design gave a 37mm wider track at the front than the S4 and 47mm of extra width at the back. Filling the wheelarches are 18-inch five-spoke wheels as standard, though it's more likely you will find an RS4 with the optional 19-inch double seven-spoke alloys.
Behind the wheels are floating ventilated and cross-drilled discs of 365mm diameter up front and 324mm at the rear. Audi incorporated extra brake cooling for the RS4 with NACA ducts underneath the front bumper. ABS anti-lock brakes are standard, as is a two-stage ESP system where the ASR anti-skid regulation could be switched off but with stability still active or the whole ESP system could be disabled.
Steering is by a servotronic set-up with hydraulic assistance and fewer turns from lock to lock for the RS4 than other A4 models to give a more direct feel and quicker responses.
Audi fitted its Dynamic Ride Control (DRC) system to the RS4 and this has been known to cause problems. The individual DRC shock absorbers are linked diagonally to each other to reduce roll and pitch in corners without compromising the ride quality.
Many RS4s come with the 19-inch wheels
It works very well but the shock absorbers can fail when their seals wear out. This allows the shocks to lose their pressure, which means either new seals or a complete new unit. Specialist tools are needed to replace the DRC shocks and to repressurise the system.
The DRC system can fail without any warning, but listen out for a knocking noise from the suspension that indicates the DRC's main valve has failed. To replace each shock absorber will cost around £300 per corner. Some owners have reverted to a standard coil spring and damper set-up to do away with the DRC system, but most owners prefer the car with DRC due to its impressive handling ability.
Any other knocks or clonks from the suspension will most likely be a worn front control arm, which will be audible when the steering is on full lock. This fault usually manifests itself at around 40,000-mile intervals.
The RS4 came with Pirelli P-Zero tyres from the factory and many owners have stuck with them as replacements, though others report good things about Bridgestones and Vredesteins. For winter use, Vredestein Wintrac tyres are highly rated by owners who use their cars year round.
The tyre pressure monitoring system can fail and it means replacing the battery in the tyre valve. They tend to stop working after around five years.
EBC or Pagid brake tweaks are common
Brakes are one of the RS4's key strengths and the car will stop hard and fast repeatedly on standard discs and pads. However, they are expensive to replace, with Audi dealers charging as much as £2,000 for a full set fitted. This is why many owners are now using EBC or Pagid pads for even better brake feel and lower costs.
LOBA Motorsport offers an uprated front disc brake conversion for around £1,100 that saves 3.36kg from each front wheel assembly. The discs are 3mm smaller than the standard 365mm discs but owners report improved stopping power and less fade during track day use.
Audi offered its own carbon ceramic brake upgrade as an option for the RS4, but it's rare to find a car fitted with this. More likely is to find an RS4 with brake judder caused by a build-up of brake dust on the disc. It's straightforward to have the discs skimmed to cure this problem.
PHer's view:
To be honest its one of the best car's I've ever owned. Everything from the power, handling to the phenomenal brakes! The RS4 brakes put my current 997 C2S to shame! It never missed a beat. Never needed any work done. The only warning light I ever saw was for washer fluids. Solid on the road. No rattles. Hits the top speed limiter with relative ease.
Rishi Sharma