Audi B9 S4 & S5 Suspension Guide: Springs to Coilovers

The B9 S4 and S5 are quick, comfortable cars from the factory, but the suspension is set up for a wide range of buyers. They sit high, roll more than they need to, and lean on understeer when you push. The good news is that the platform responds well to small changes, and you don't have to replace everything at once to feel a difference.

How the B9 suspension works

The B9 uses a five-link front suspension: two upper arms and two lower arms on each side, plus the tie rod. The rear is a multi-link setup on a rubber-mounted subframe. A few things matter when you shop:

1. Passive or adaptive dampers. Some cars came with standard shocks, others with adaptive (electronically controlled) dampers. Some parts are made for one or the other, so check which your car has before you order.
2. Springs and sway bars set how low the car sits and how much it rolls.
3. Control arms and bushings set alignment and how much the chassis flexes and moves under load.
4. Mounts and inserts (subframe, differential, engine) control how much the drivetrain and rear subframe move around.

Lower the car and you'll usually want camber adjustment up front, so plan arms and an alignment together with springs.

Lowering springs: the easy first step

Springs drop the car, cut the wheel gap and reduce roll. They work with your factory dampers, so it's the simplest change you can make.

• 034Motorsport Dynamic+ springs for S4/S5: developed on 034's B9 S4. A balanced drop for a car you drive every day.
• iE lowering springs: platform-specific springs for the B9 and B9.5, listed for the A4, S4 and A5.
• Eibach Sportline: Eibach's more aggressive drop, listed for the B9 S5.
• Racingline sports springs: made for the S4 sedan.
• KW H.A.S. height-adjustable springs: for the S5 coupe with electronic dampers. You set the ride height instead of living with a fixed drop.

Coilovers: for the driver who wants control

Coilovers replace the shock and spring together. You get adjustable ride height and damping, and a car that's built around how you actually drive. They make the most sense if you track the car or want a specific stance.

• Öhlins Road & Track: Öhlins' Dual Flow Valve dampers for the B9 A4/A5/S4/S5/RS4/RS5. One of the best street-and-track coilovers you can buy for this car.
• RS5 owners: the KW V3 for the B9 RS5 coupe with Dynamic Ride Control is made for that car only.

Coilovers need an alignment after install, and on a lowered car camber arms help you get it right.

Sway bars: less roll, better balance

A stiffer sway bar (anti-roll bar) cuts body roll without making the ride harsher over bumps. On the B9, a stiffer rear bar is the main tool for dialing out understeer.

• 034Motorsport Dynamic+ sway bar kit: front and rear bars together, if you want to do both at once.
• 034 Dynamic+ adjustable rear bar: rear only. The single best handling change per dollar on this car.
• iE adjustable rear and front bars: adjustable, sold separately so you can mix and match.
• CTS Turbo rear sway bar: another adjustable rear option for the B9 and B9.5.

End links connect the bar to the suspension. Adjustable links let you preload the bar correctly on a lowered car: 034 Dynamic+ billet rear links, 034 front links, or the iE front and rear cast aluminum links, which replace the plastic stock ones.

Control arms and alignment

Lowering the B9 adds negative camber up front and there's very little factory adjustment. Adjustable upper arms fix that, and fresh arms or bushings tighten up a high-mileage car.

• 034 Density Line adjustable upper arms, camber correcting: for lowered street cars. A Track Spec version is there for more aggressive alignment.
• 034 complete Density Line control arm kit: upper and lower arms at once, the best choice when the factory arms are worn.
• SPC adjustable upper arm pair (camber and caster adjustment) or the four-arm SPC kit for full adjustment.
• CTS Turbo front upper arm kit: another adjustable option.

While you're in there: 034 heavy-duty tie rod ends and front ball joints.

Bushings, inserts and braces

The B9's rubber mounts let the rear subframe, differential and engine move under load. Inserts fill those voids, so the car responds more directly when you get on and off the throttle. Expect a little more vibration in the cabin.

• Rear subframe inserts: 034Motorsport billet or CTS Turbo.
• 034 rear differential mount inserts: less diff movement on launches and shifts.
• 034 Street Density motor mount: made for the S4/S5 3.0 TFSI. Firms up engine movement for sharper throttle response.
• 034 Street Density rear shock mounts: for cars with non-adaptive suspension only.
• Front strut braces: 034 billet, CTS Turbo or APR. They replace the stamped factory brace and stiffen the front of the car.
• 034 X-Clear tunnel brace: makes room for an aftermarket exhaust.

Want it all in one order?

034Motorsport's handling packages bundle their parts for the B9 S4/S5 3.0T in stages: Stage 1, Stage 2 and Stage 3. RS5 owners have their own RS4/RS5 2.9TT packages and RS5 springs.

What we'd do

• Daily driver: lowering springs, a stiffer rear sway bar with adjustable end links, and camber-correcting upper arms so the alignment stays in spec. That covers most of what the car needs.
• Weekend canyon car: add front and rear bars together, subframe and differential inserts, and a strut brace.
• Track car: Öhlins coilovers, a full adjustable control arm kit, and a track alignment. Add the motor mount and the rest of the inserts if the car feels loose under hard braking and turn-in.

Always get an alignment after changing springs, coilovers or arms. We can install all of it at our shop in Dallas.

See every suspension part for your car on the B9 S4 / S5 / RS5 suspension page, or browse everything for the B9 S4 / S5.