The Bilstein B4 22-145550 is a front strut assembly from the B4 OE Replacement line, a gas-pressure twintube design built to bring a worn Mk1 Audi TT's ride back toward factory behavior. It is meant to pair with the car's original coil springs, so the stock spring rate and ride height carry over. If you are searching for a Mk1 TT front strut replacement, a 22-145550 strut, or a Bilstein B4 OE-style upgrade, this is the part those searches point to.
Choose this over stock or a cheap no-name strut when the original dampers have faded and the car is floating, nosing into corners, or hopping over bumps. The B4 is tuned to stay close to OE damping rather than chasing firmness, so it restores control without the harshness of a coilover. Owners on user forums typically describe the result as a return to the car's original composed feel, not a track-focused change, so it suits daily driving and spirited weekend use alike.
Published fitment data is not uniform across sources, so confirm your model year, drivetrain, and engine against the manufacturer's application data before ordering. Most listings cite 2000 to 2006 Audi TT and TT Quattro models. Plan on replacing both fronts together for even damping. Installation involves the top strut nut, the lower clamp bolt, and the drop link, and a wheel alignment is needed afterward.
Published fitment data is not uniform. Most sources list 2000 to 2006 Audi TT and TT Quattro models, but the engine and trim coverage varies between references. Confirm your exact application with the manufacturer before ordering.
Owners on user forums report that the strut can often be removed with the spring still in place by releasing the top nut and the lower clamp bolt. Moving the original coil spring onto the new strut requires a spring compressor.
Difficulty is moderate and best suited to someone comfortable with suspension work. Raise and securely support the car, remove the front wheel, and clean corroded fasteners with a wire brush and penetrating spray before breaking them loose. Owners on user forums advise disconnecting the drop link and using a spreader or wedge to free the lower clamp. Keep the spring compressor on hand if you are reusing the original springs, and have the car aligned once the job is complete.
