Strut Diameter: 50 or 55 mm? The VAG Guide
Strut Diameter: 50 mm or 55 mm?
How to measure and identify the correct diameter before ordering a suspension kit for your Golf
A detail that changes everything during installation
Before ordering a suspension kit — whether coilovers, an air ride kit, or simple shock absorbers — there is one essential measurement on Golf 5, 6, 7, and 8: the diameter of the front strut.
On these models (and many vehicles in the VAG group), two diameters coexist at the shock absorber mounting point on the hub carrier: 50 mm or 55 mm. Ordering without checking risks receiving a kit that cannot be installed.
📋 In this article
- Why two diameters?
- Where and how to measure
- Adapter rings
- Summary before purchase
🏭 Why Two Diameters?
Volkswagen uses two types of front steering knuckles depending on the engine, trim, and vehicle year. As a result, the same Golf can leave the factory with a shock absorber housing of 50 mm or 55 mm — and this difference is found across all brands in the VAG group.
Golf 5 / 6 / 7 / 8
Polo
Passat
Tiguan
T-Roc
A3 (8P / 8V / 8Y)
A1
Q2
TT
Leon (MK2 / 3 / 4)
Ibiza
Arona
Cupra Formentor
Octavia
Fabia
Scala
Kamiq
📐 Where and How to Measure?
The measurement is taken on the lower part of the strut, exactly where the shock absorber is clamped in the steering knuckle — that is, the area held by the pinch bolt.
Lift the vehicle and remove the wheel to freely access the base of the shock absorber.
Locate the clamping area on the steering knuckle — it's the lower part of the strut, held by one or two screws.
Use a caliper to measure the outer diameter of the shock absorber tube at this exact spot.
The measurement will show either 50 mm or 55 mm. This value determines the compatible kit.
🔄 Kits with Adapter Rings
On some kits, no size is specified in the reference. In this case, the kit is usually delivered with adapter rings that allow compatibility with both diameters.
- ⚡ The rings slip between the shock absorber and the steering knuckle to make up the diameter difference
- ⚡ A single kit thus becomes compatible with both 50 mm and 55 mm configurations
- ⚡ The assembly remains perfectly fitted and secure with the rings in place
- ⚡ If in doubt about the presence of rings in your kit, contact the seller before ordering
✅ Summary
The essentials to remember before ordering:
✔ Checklist before ordering
✔ Remove the wheel and measure directly on the vehicle
✔ Note the exact diameter: 50 mm or 55 mm
✔ Check the kit reference or the presence of adapter rings
✔ If in doubt, contact us before confirming your order
At Rasl'Bitume, we always prefer to ask you for this info before shipping rather than seeing you receive an incompatible kit. Feel free to send us your model + engine + year, we will check for you.
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