AST 03/2014-07/2021 BMW 4 Lowering Springs – 40mm/40mm

This AST Suspension 03/2014-07/2021 BMW 4 Lowering Springs – 40mm/40mm is a vehicle-specific lowering spring set selected by exact part number, chassis, drivetrain, body style, suspension configuration, and stated front and rear drop. Confirm every application note before ordering.

Key Features

• 40mm Front/Rear Drop: Lowers ride height evenly for aggressive stance and better aerodynamics without sacrificing daily drivability.
• Direct OEM Bolt-On: Vehicle-specific engineering allows drop-in installation with no modifications to suspension geometry.
• Progressive Spring Design: Varies rates for smooth compliance over bumps and firm control in corners, preserving OEM comfort levels.
• High-strength chrome-silicon steel coiled on Wafios CNC machines for superior fatigue resistance and longevity.
• Advanced manufacturing delivers exact tolerances for BMW chassis dynamics.
• Yes, ASTLS-21-041 fits 2015-2016 BMW 428i Gran Coupe Base models precisely as a direct OEM spring replacement.

Fitment

Specifications

What’s Included

One new AST Suspension product in the exact part number, dimensions, rate, adjustment specification, and quantity identified on this page. Springs, dampers, top mounts, reservoirs, adjusters, links, tools, lines, fittings, and hardware are included only when expressly stated for this exact configuration.

About AST Suspension

AST Suspension develops performance springs, dampers, coilovers, top mounts, and motorsport suspension components. Vehicle fitment, dimensions, rates, adjustment functions, and included components remain exact-part specific.

Related Parts

• Shop the complete AST Suspension collection
• Shop suspension components
• AST 03/2014-07/2021 BMW 4 Lowering Springs – 30mm/30mm
• AST 03/2014-07/2021 BMW 4 XDRIVE Lowering Springs – 40mm/35mm
• AST 07/2013-10/2020 BMW 4 XDRIVE Lowering Springs – 30mm/25mm

Frequently Asked Questions

How do I confirm these springs fit my vehicle?
Match the exact year, make, model, chassis, drivetrain, body style, engine, factory suspension, axle-load notes, and AST part number.

Will I need an alignment after installing lowering springs?
Yes. Measure ride height after the springs settle, then perform a complete alignment and verify tire, wheel, brake-line, and suspension clearance.

Can these springs be used with factory dampers?
Only when the exact AST application permits it. Check damper condition, available travel, bump-stop requirements, and every product-specific suspension note.

Is the advertised drop exact on every vehicle?
The stated drop is a target for the listed configuration. Actual ride height can vary with equipment, vehicle weight, spring isolators, damper condition, and prior suspension changes.

Installation Instructions

1. Confirm the exact AST part number, complete application or dimensional specification, included components, and current instructions before disassembly.
2. Support the vehicle at approved points and record the original ride height, alignment, suspension orientation, and adjustment settings.
3. Install components in the specified position and sequence using correct spring-compression, torque, preload, ride-height, and damper setup procedures.
4. Verify full suspension and steering travel, tire and wheel clearance, brake-line routing, fastener torque, and damper operation.
5. Settle the suspension, measure final ride height, complete a professional alignment, and recheck the installation after the initial driving cycles.