Gas Strut Ball Studs Explained: UK Guide to Sizes, Threads & Installation (2026)

By SpringFix UK Team | Reading time: 9 minutes

You've bought your gas struts. They're the right length. They're the right force rating. But there's still one thing you need to think about: the ball studs.

Ball studs are the small metal balls that gas struts connect to at each end. Get them right, and your strut clips on smoothly and holds fast for years. Get them wrong, and the strut either won't fit at all, or worse — pops off unexpectedly under load.

This guide covers everything you need to know: what ball studs are, why the two measurements matter, how to size them correctly, what materials to choose, and how to fit them properly. If you've ever been confused about "10mm ball M8 thread" — this article clears it up in five minutes.

What Is a Gas Strut Ball Stud?

A ball stud is a small hardened steel component with two parts:

  1. A threaded shank (the screw part) — bolts into a bracket, panel, or vehicle body
  2. A precision ball head (the round part) — the gas strut socket clips onto this

The ball allows the strut to pivot as the panel opens and closes. Without a ball joint, the strut would bind and snap on any angular movement.

Ball studs are one of the most common failure points in gas strut installations — but only because people buy the wrong size. Get the sizing right, and they last decades.

The Two Measurements That Matter

Every gas strut ball stud has two independent measurements. Confusion here is the #1 reason people buy wrong parts.

1. Ball Diameter (The Round Part)

This is the diameter of the ball head — measured across the widest part. The gas strut's end socket must match this exact size.

The three common ball sizes in the UK:

  • 10mm ball — 90% of UK gas struts (ottoman beds, kitchen cabinets, most car boot struts)
  • 13mm ball — Larger or older commercial applications
  • 16mm ball — Industrial, truck cab tilts, heavy machinery

2. Thread Size (The Screw Part)

This is the metric thread size of the shank that bolts into your mounting surface.

Common thread sizes:

  • M6 — Small/light applications, small ball studs
  • M8 — Standard applications, most ball studs
  • M10 — Heavy-duty, industrial
  • M12 — Very heavy-duty, rare

They Are Independent

You can have any combination of ball size + thread size, though some are more common:

  • 10mm ball / M6 thread — Small cabinet doors, light lids
  • 10mm ball / M8 thread — Ottoman beds, kitchen cabinets, standard cars
  • 13mm ball / M8 thread — Some older cabinet fittings
  • 13mm ball / M10 thread — Larger commercial hardware
  • 16mm ball / M10 thread — Heavy industrial

Critical point: The gas strut's socket matches the ball diameter (10mm, 13mm, 16mm), NOT the thread. The thread only affects how the ball stud bolts to your surface.

How to Identify Your Existing Ball Stud

Replacing a gas strut? Before ordering, check your existing setup:

Step 1: Measure the Ball

Use a caliper or ruler to measure across the widest part of the ball. Round to the nearest whole millimetre — you'll get 10mm, 13mm, or 16mm.

Step 2: Measure the Thread

Look at the base of the ball stud where it meets your bracket or panel. The thread should be visible if the stud is removed. If it's still installed, unscrew it and measure the thread diameter.

Quick trick: Take a common bolt to compare:

  • If the ball stud thread looks like an M6 bolt, it's M6
  • Same for M8, M10

Step 3: Note the Thread Length

The ball stud will also have a specific shank length. Standard lengths are:

  • 8mm — For thin panels
  • 12mm — Medium (most common)
  • 16-20mm — Thicker panels or bulkheads

Match the length to how thick your mounting surface is.

Materials Explained

Ball studs come in three main material grades.

Zinc-Plated Steel

Standard grade. Steel body with a zinc coating for corrosion resistance. Suitable for:

  • Indoor use
  • Furniture (ottoman beds, cabinets)
  • Automotive interior applications
  • Anywhere protected from water/salt

Lifespan: 5-10 years in indoor conditions.

Stainless Steel A2 (304)

Corrosion-resistant. Best for:

  • Marine (above waterline)
  • Outdoor use
  • Coastal areas
  • Gate hardware
  • Wet environments

Lifespan: 15-25+ years in outdoor UK conditions.

Stainless Steel A4 (316)

Marine grade with added molybdenum. Best for:

  • Below-waterline marine
  • Direct saltwater contact
  • Chemical exposure
  • Swimming pools

Lifespan: Decades in extreme conditions.

For most projects: Zinc-plated is fine. Upgrade to A2 for outdoor use, A4 for direct marine.

Common Applications by Ball Size

10mm Ball Applications

The most common by far. If you're replacing:

  • Ottoman bed struts → 10mm ball, M8 thread
  • Kitchen cabinet lifts → 10mm ball, M6 or M8 thread
  • Vehicle bonnet/boot struts → 10mm ball, M8 thread
  • Toolbox lids → 10mm ball, M6 thread
  • Office chair mechanisms → 10mm ball, M8 thread

13mm Ball Applications

Less common but still important:

  • Older commercial furniture
  • Some vintage vehicles
  • Industrial machinery covers
  • Heavy-duty cabinet doors

16mm Ball Applications

Rare in domestic use:

  • Truck cab tilts
  • Heavy industrial hatches
  • Agricultural equipment
  • Large marine hatches

How to Fit a Ball Stud

Fitting is straightforward but attention to detail matters.

Tools You Need

  • Spanner or socket to match the thread size (10mm for M6, 13mm for M8, 17mm for M10)
  • Drill and correct bit (if drilling a new hole)
  • Thread-locker (optional but recommended for vibration environments)

Step-by-Step Installation

Step 1: Determine position
If replacing, use the existing hole. If it's a new install, mark the position carefully — errors mean the strut angle will be wrong and the whole assembly won't open smoothly.

Step 2: Prepare the hole

  • If it's a through-hole with nut on the back: check thread condition, tap if needed
  • If it's a captive thread in metal: verify thread integrity
  • If it's a new install in wood: drill pilot hole (M6 = 5mm pilot; M8 = 6.8mm pilot; M10 = 8.5mm pilot)

Step 3: Apply thread-locker (optional)
For vibration environments (vehicles, industrial), apply a drop of medium-strength thread-locker (Loctite 243 blue or equivalent) to the thread. Don't use on cabinet/furniture applications — they need to be removable.

Step 4: Thread the stud in
Insert the ball stud by hand, then tighten with a spanner. The stud should tighten firmly but not require excessive force. Over-tightening can strip threads or crack panels.

Step 5: Verify orientation
The ball should sit in the correct plane for the strut to swing freely. If your strut will operate horizontally, the ball must be vertical. Rotate the ball stud in the last quarter turn to align.

Step 6: Test-fit the strut socket
Snap the gas strut's socket onto the ball. It should click firmly onto the ball with a positive engagement. If it feels loose, the ball is too small for the socket. If it won't clip on, the ball is too large.

Step 7: Test operation
Open and close the panel a few times before regular use. Check for:

  • Smooth operation without binding
  • No unusual noises
  • Strut socket stays firmly on the ball
  • Full range of motion works

Common Installation Mistakes

1. Ball Size Mismatch

Buying a 10mm ball with a 13mm socket (or vice versa) is the #1 error. Always match sizes exactly. A 10mm ball in a 13mm socket will pop off within days.

2. Wrong Thread Size

M8 stud in M6 hole (or vice versa) won't work. Measure carefully before ordering.

3. Over-Tightening

Ball studs need to be firm but not aggressively torqued. Cranking hard can strip threads, crack the mounting panel, or break the ball off the stud.

4. No Thread-Locker in Vibration Environments

Automotive and industrial applications experience constant vibration. Without thread-locker, ball studs can loosen over time. Small drop of medium-strength thread-locker prevents this.

FAQs

Can I convert a 10mm ball socket strut to fit a 13mm ball?
No — the socket sizes are non-interchangeable. Either replace the ball stud with a 10mm version, or replace the strut with one that has a 13mm socket.

How do I know if my ball stud is worn out?
Signs of wear: visible flat spots on the ball, socket clicking or feeling loose, difficulty opening/closing smoothly. Ball studs are cheap — when worn, replace them.

Can I use two different length struts on the same lid?
Only if they're the same force rating and the difference is small (<5mm). Larger mismatches cause uneven lifting and premature failure of one strut.

Do I need to grease the ball?
A small amount of lithium grease can help in outdoor/marine applications, but standard indoor use doesn't need any lubrication.

Why does my strut pop off the ball randomly?
Two common causes: (1) ball is worn undersize; (2) socket retention clip is damaged. Both mean replacement — usually of the strut, since the socket is not user-replaceable.

Can I use a bolt with a rounded top instead of a proper ball stud?
No. Ball studs are precision-ground with hardened chrome plating. A regular bolt won't allow the socket to swivel freely and will wear the socket immediately.

How long should a ball stud last?
Indefinitely in indoor use. 15-25 years in stainless. Zinc-plated in outdoor use starts corroding in 3-5 years.

Shop Ball Studs at SpringFix UK

We stock ball studs in all the common UK sizes:

  • Gas Strut End Fittings Collection →
  • 10mm ball, M6/M8/M10 threads — the most common
  • 13mm ball, M8/M10 threads — heavy-duty
  • Zinc-plated steel — indoor and general use
  • A2 304 Stainless Steel — marine and outdoor
  • Same-day dispatch on orders placed before 4pm

Not sure which ball stud you need? Send us a photo of your existing setup — we'll confirm the exact match before you buy.

Related Guides

Article by SpringFix UK Team — Gas struts, ball studs, brackets, and precision engineering hardware. Over 1,700 positive eBay feedbacks. UK stock, UK dispatched.

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