Bilstein B12 12-15 BMW 328i Front and Rear Suspension Kit

Complete Monotube Suspension Upgrade for the 2012-2015 BMW 328i (F30 Sedan, RWD)

The Bilstein B12 is a precision-engineered front and rear suspension kit designed specifically for the 2012-2015 BMW 328i RWD sedan (F30 chassis) without electronic damping control. Part number BIL46-223661 pairs four Bilstein monotube gas-pressure B8 Performance Plus dampers with a matched set of Eibach Pro-Kit progressive-rate lowering springs for a complete bolt-in solution. The kit lowers the vehicle approximately 25 to 30mm (roughly 1.0 to 1.2 inches) in the front and approximately 25mm (roughly 1.0 inch) in the rear, reducing body roll and improving cornering precision while retaining near-stock ride comfort for daily driving. This same kit also fits the 2013-2018 BMW 320i RWD, 2014-2018 BMW 328d RWD, and select 330i, 330e, 428i, and 430i models on the same F30/F32 platform.

Key Features

• Bilstein B8 Performance Plus monotube gas-pressure dampers for fade-free, consistent damping response
• Eibach Pro-Kit progressive-rate lowering springs matched and tuned to the B8 dampers
• Front lowering of 25 to 30mm and rear lowering of approximately 25mm on the BMW 328i RWD
• Bilstein digressive valving technology: damping force increases progressively with piston velocity for enhanced stability
• Monotube upside-down design keeps the working chamber away from road heat for consistent performance
• Corrosion-resistant yellow powder-coat finish on dampers; dark grey spring coating for long-term durability
• German TUV-certified; meets strict German ABE homologation requirements
• Designed for RWD (non-xDrive) BMW F30 and F32 chassis without electronic adaptive suspension (EDC)
• Compatible with OEM shock mounting hardware; no drilling, cutting, or modifications required
• Made in Germany by Bilstein; covered by the Bilstein lifetime warranty on dampers

Fitment Guide

Product Specifications

What's Included

• 1x Front left Bilstein B8 monotube strut assembly
• 1x Front right Bilstein B8 monotube strut assembly
• 1x Rear left Bilstein B8 monotube shock absorber
• 1x Rear right Bilstein B8 monotube shock absorber
• 1x Front left Eibach Pro-Kit progressive lowering spring
• 1x Front right Eibach Pro-Kit progressive lowering spring
• 1x Rear left Eibach Pro-Kit progressive lowering spring
• 1x Rear right Eibach Pro-Kit progressive lowering spring
• All necessary washers, bump stops, and mounting hardware

Frequently Asked Questions

Does the BIL46-223661 work with the xDrive all-wheel-drive 328i?

No. This kit is engineered for rear-wheel-drive (RWD) F30 chassis BMW models only. The xDrive all-wheel-drive 328i uses a different rear suspension geometry and subframe configuration that is not compatible with this kit. xDrive owners should look for a kit specifically validated for the 328i xDrive application.

What is the lowering drop of the Bilstein B12 46-223661 on the BMW 328i?

On the 2012-2015 BMW 328i RWD, this kit lowers the front suspension approximately 25 to 30mm (roughly 1.0 to 1.2 inches) and the rear approximately 25mm (roughly 1.0 inch). The exact drop can vary slightly depending on your vehicle's current ride height, options package (sport vs. standard suspension), and current spring fatigue. Bilstein rates the front axle load capacity at up to 965 kg and the rear at up to 1170 kg for this application.

Do the Bilstein B12 46-223661 dampers require any modification for installation?

No cutting, drilling, or custom fabrication is required. The dampers and springs use the factory mounting points and are designed to be a direct bolt-in replacement using the vehicle's existing hardware. The one important requirement is that the vehicle must not be equipped with BMW's Electronic Damping Control (EDC) adaptive suspension system. If your 328i has EDC, the system must be properly disabled or coded out before installation, which typically requires a BMW-compatible coding tool and an additional retaining bracket.

Will installing this kit void my BMW factory warranty?

Under the federal Magnuson-Moss Warranty Act, a dealer cannot void your entire vehicle warranty solely because you installed an aftermarket part. The dealer must demonstrate that the aftermarket part directly caused the specific failure before denying warranty coverage on that component. Routine wear items like tires, brakes, and wheel bearings may receive additional scrutiny after a suspension change. Bilstein provides a lifetime warranty on all dampers in this kit, covering any defect in materials or workmanship for as long as you own the vehicle.

Can I pair the BIL46-223661 with aftermarket sway bars or other suspension upgrades?

Yes. This kit is fully compatible with aftermarket front and rear sway bars, upgraded end links, strut tower braces, and camber adjustment kits. Many F30 owners install this kit alongside a front strut brace and upgraded rear sway bar for additional chassis stiffness. Because the Bilstein B8 dampers are tuned with Eibach Pro-Kit spring rates in mind, coilover conversions or alternate spring rates would require a different product.

What spring rate does the B12 46-223661 use front and rear?

The kit uses Eibach Pro-Kit progressive-rate springs, meaning the spring rate is not a fixed single number but increases as the spring compresses further. This progressive characteristic provides a supple initial response for normal driving and increasingly firmer support under hard cornering or braking loads. The specific rates are calibrated by Eibach for the F30 328i RWD application to complement the B8 damper valving. For precise spring rate data, contact Eibach or Bilstein directly with your vehicle's chassis and options codes.

How do the Bilstein B12 dampers compare to the Bilstein B8 for street driving?

The B12 Pro-Kit bundles Bilstein B8 Performance Plus dampers with Eibach Pro-Kit springs as a pre-matched system. If you purchased standalone Bilstein B8 dampers, you would need to source compatible lowering springs separately. The B12 system advantage is that the dampers and springs are tested and tuned together as a unit, ensuring optimal compression and rebound characteristics for the specific spring rates used. For daily street driving, the B12 Pro-Kit delivers a well-balanced compromise between sport performance and ride comfort.

Do I need an alignment after installing this Bilstein B12 kit?

Yes, a four-wheel alignment is strongly recommended after installation. Any change in ride height affects camber, caster, and toe settings, which directly impact tire wear and handling balance. Skipping the alignment will result in accelerated and uneven tire wear. Most shops that perform BMW alignments can accommodate the lowered ride height. Bilstein and Eibach recommend a professional alignment as part of any suspension installation.

Installation Instructions

1. Park the vehicle on a flat, level surface and allow the exhaust and brakes to cool completely before beginning work.
2. Gather all required tools: floor jack, jack stands, spring compressor, torque wrench, breaker bar, impact driver, and a BMW-compatible alignment gauge if checking toe at home.
3. Loosen the front wheel lug bolts slightly while the vehicle is still on the ground, then raise and support the front of the vehicle on jack stands placed under the factory jack points.
4. Remove the front wheels and set aside. Disconnect the front sway bar end links from the strut assembly.
5. Unbolt the brake line bracket from the strut, then remove the two lower strut-to-knuckle pinch bolts. Unclip the ABS sensor connector from the strut to allow freedom of movement.
6. From inside the engine bay, remove the strut tower nuts (typically three nuts under the plastic cover). Support the strut from below, then slide the assembly down and out of the strut tower.
7. Use a spring compressor to safely compress the OEM spring until the spring seat is free, then remove the strut nut, top mount, spring seat, bump stop, and spring. Transfer the OEM top mount and bump stop to the new Bilstein B12 strut assembly with the Eibach spring in place. Torque the strut nut to factory specification.
8. Install the new front strut assembly into the strut tower. Start the three tower nuts by hand before tightening. Reinstall the lower pinch bolts, sway bar end links, and brake line bracket. Torque all fasteners to BMW factory specification.
9. Repeat steps 3 through 8 for the opposite front corner.
10. Move to the rear of the vehicle. Raise and support the rear on jack stands under the factory jack points. Remove the rear wheels.
11. Support the rear trailing arm or control arm with a floor jack to relieve tension. Disconnect the rear sway bar end links if applicable, then remove the lower shock bolt at the trailing arm.
12. From inside the trunk or beneath the rear seat panel, remove the upper shock tower nut. Slide the old shock down and out.
13. Install the rear Eibach spring into the lower spring perch on the trailing arm. Place the new Bilstein B8 rear shock absorber through the upper mount hole, start the top nut by hand, then lower the jack and guide the lower shock mount onto the trailing arm bracket. Install and torque the lower bolt to the factory specification listed in the Bilstein B12 installation sheet.
14. Repeat steps 11 through 13 for the opposite rear corner. Reinstall the rear wheels.
15. Lower the vehicle to the ground and torque the wheel lug bolts to factory specification in a star pattern. Bounce each corner several times to settle the suspension before driving.
16. Drive the vehicle to a professional alignment shop for a four-wheel alignment as soon as possible after installation. Inspect all fasteners for proper torque after the first 500 miles.

WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.