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Bilstein

Bilstein B4 Front Strut Damper Cartridge 45mm Strut Tube – BMW 3 Series E21 1975–1984 – Shock Absorber Insert Gas-Charged Twin-Tube OE/OEM Replacement – Front Axle L/R – Part 21-030420 (BILSTEIN-21-030420) – Fits 315 316 318 318i 320 320i 320/6

Bilstein B4 Front Strut Damper Cartridge 45mm Strut Tube – BMW 3 Series E21 1975–1984 – Shock Absorber Insert Gas-Charged Twin-Tube OE/OEM Replacement – Front Axle L/R – Part 21-030420 (BILSTEIN-21-030420) – Fits 315 316 318 318i 320 320i 320/6

£70.66
£124.80 £70.66
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Heads-up on cancellations & returns: if you cancel an order or return an item, you won't get back 100% of what you paid. We apply a 10% restocking fee, the outbound shipping is non-refundable, and we have to pass on Shopify / PayPal payment processing fees; these aren't returned to us when we refund you. International orders also lose on exchange-rate spread in both directions. If the original packaging is damaged or missing, a reboxing charge applies. For international orders specifically, if you refuse to pay our shipping invoice or supply a prepaid label after placing the order, the same deductions apply. We're upfront about this — please be sure of your purchase before ordering.

Bilstein 21-030420 Front Strut Damper Cartridge for BMW 3 Series E21

Give your E21’s front end the tight, confident feel it deserves with the Bilstein part 21-030420 strut insert. This gas‑charged, twin‑tube cartridge slots straight into the 45 mm front strut housing and restores crisp steering response, stable braking and a smooth, composed ride on British roads. It is the ideal factory‑spec replacement for everyday driving, restorations and MOT prep on classic 3 Series models.

We run these on our own cars and customer feedback is consistently positive: quieter over bumps, better body control, and that reassuring Bilstein consistency mile after mile. If your E21 feels floaty, skittish or underdamped, this bolt‑in front damper insert is the clean, no‑hassle fix.

Highlights

  • Direct replacement front strut cartridge for E21 3 Series with 45 mm strut tube
  • Gas‑charged twin‑tube design maintains consistent damping under load and heat
  • Brings back as‑new ride comfort, grip and road holding without harshness
  • Engineered to match original chassis characteristics and alignment geometry
  • Trusted Bilstein quality for reliability, longevity and safety

Technical details

  • Position: Front axle, left or right
  • Type: Strut insert, gas‑charged, twin‑tube
  • Mounting: Bottom plate with top pin
  • Strut housing size: 45 mm outside diameter
  • Quantity: Sold individually

Vehicle applications

BMW 3 Series E21 (1975–1984), including:

  • 315
  • 316
  • 318 / 318i
  • 320 / 320i / 320/6

Common search terms: E21 front damper insert 45 mm, BMW 3 Series E21 shock cartridge, BMW 320i front strut cartridge, classic BMW suspension parts UK, Bilstein 21‑030420 front insert, BMW E21 shock replacement, front shock cartridge BMW 315 316 318 320, gas‑charged front damper E21, direct replacement strut insert.

Fitment support

We will confirm compatibility before dispatch. Add your UK reg or the last 7 of your VIN at checkout so we can verify this front insert suits your specific E21.

Professional installation

For expert fitting, book with MJ Modifications in Warwickshire. Request a quote: info@mjmodifications.co.uk.

Tip: Replace dampers in axle pairs to maintain balanced handling and even tyre wear.

Part numbers

  • Main reference: 21-030420
  • Alt reference: BILSTEIN-21-030420
  • EAN: 4025258430771
  • UPC: 651860430775

What’s included

1 x Bilstein B4 front strut damper insert for BMW E21 3 Series, designed for straightforward, stock‑spec installation and dependable everyday performance.

Why buy from us

MJ Modifications supply and fit quality suspension components for classic and modern BMWs. Our customers choose this Bilstein insert for its predictable road manners, durability and value when refreshing ageing E21 front suspension.

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