Mounting Bolt Thread Length: What Fits Your Wheel Base

Why bolt thread length matters

A wheel base is held to a desk, stand, or cockpit by bolts that pass through the mounting surface and thread into inserts in the base. The length of those bolts must be correct: too short and the threads cannot engage fully, too long and the bolt may bottom out inside the base or press against internal components. Either situation can lead to a loose mount or damage to the base. For an overview of wheel bases and mounting options, see the best racing wheel guide.

The thread length is the distance from the underside of the bolt head to the end of the threaded portion. The total bolt length includes the head, but the thread length is what engages with the base. When you choose a bolt, you need to match the thread length to the thickness of the mounting surface plus the depth of the threaded hole in the base.

Common bolt sizes used in wheel bases

Most wheel bases from major makers use metric bolts. The two most common diameters are M6 and M8. M6 bolts have a 6 mm diameter, M8 bolts have an 8 mm diameter. The thread pitch is usually 1.0 mm for M6 and 1.25 mm for M8, though some bases may use a fine pitch. The bolt length required depends on the base design and the mounting surface thickness. Direct drive bases often have different requirements; refer to the best direct drive racing wheels guide for examples.

A few examples: some entry-level bases use M6 bolts with a length of 12 mm to 16 mm when mounted to a thin desk plate. Higher-torque direct drive bases often use M8 bolts with lengths of 16 mm to 20 mm. These are general ranges; the exact length is always specified by the maker in the manual or support page.

How to check clearance

To determine the correct bolt length, you need two measurements: the thickness of the mounting surface (desk, stand plate, or cockpit bracket) and the depth of the threaded hole in the wheel base. The bolt thread length should be equal to the surface thickness plus the hole depth, minus a small margin (about 2 mm) to avoid bottoming out. For more on mounting surfaces, see the wheel base mounting bracket sizes article.

Measure the mounting surface thickness with a caliper or ruler. For a desk, this is the thickness of the wood or metal where the clamp or bolts go. For a stand or cockpit, measure the bracket thickness. Then check the base's threaded hole depth. If the maker does not list the hole depth, you can insert a thin rod (like a paperclip) into the hole and mark the depth, then measure that length.

Add the two numbers and subtract 2 mm. That gives you the maximum thread length that will not bottom out. The bolt you choose should have a thread length close to that value. If you cannot find an exact match, choose a bolt slightly shorter rather than slightly longer.

What to look for in the maker's manual

Every wheel base maker provides mounting instructions. The manual or support page will state the required bolt size, thread pitch, and recommended length. For example, Logitech G, Thrustmaster, and Fanatec all include this information in the product documentation. The manual may also specify the torque value for tightening the bolts, though that is not a thread length concern. For Logitech-specific details, see the best Logitech racing wheels guide.

If you are buying a used base or one without a manual, you can often find the specifications on the maker's support website. Look for the product page under "Downloads" or "Support". The bolt size is usually listed in the technical specifications or the mounting guide. Thrustmaster users can check the best Thrustmaster racing wheels guide for additional context.

Using the right tools

Use a hex key or socket that matches the bolt head size. M6 bolts typically have a 5 mm or 6 mm hex head, M8 bolts have a 6 mm or 8 mm head. Never force a bolt that does not thread smoothly; cross-threading can damage the base's threaded insert. For a broader look at PC-compatible wheel bases, see the best racing wheel for PC guide.

If the bolt is too long, you can add washers between the bolt head and the mounting surface to effectively shorten the thread length. Stacking washers reduces the available thread engagement, so use only enough to prevent bottoming out. Never use a bolt that is too short and rely on washers to fill the gap; the threads must engage fully.

When to use washers or spacers

Washers and spacers are useful when the mounting surface is thinner than the bolt's thread length. Place a washer under the bolt head to take up the extra space. This prevents the bolt from threading too far into the base. Use flat washers that are the same outer diameter as the bolt head.

Spacers (short tubes) can be used if you need to raise the base slightly above the mounting surface, for example to clear a cable or to align with a stand. Ensure the spacer is strong enough to support the base weight and torque. Always check that the bolt still has enough thread engagement after adding spacers. For more on mounting setups, read the desk clamp vs rig mount strength article.

What to pick for your situation

Questions

What happens if I use a bolt that is too long?

A bolt that is too long can bottom out inside the wheel base, pressing against internal parts or the back of the threaded hole. This can damage the base or prevent the bolt from tightening fully, leaving the mount loose.

What happens if I use a bolt that is too short?

A bolt that is too short may not engage enough threads to hold the base securely. Under the force of the wheel's torque, the bolt can strip or the base can come loose. Always use a bolt with at least 6 mm of thread engagement.

Can I use bolts from a hardware store?

Yes, as long as the diameter, thread pitch, and length match the maker's specification. Use grade 8.8 or higher steel bolts for strength. Avoid using bolts that are not fully threaded if the threaded hole is deep.

Do all wheel bases use the same bolt thread?

No. Different makers and models use different diameters and pitches. Always check the manual or support page for the exact size. Using the wrong thread pitch can damage the threaded insert.

How do I measure the thread pitch?

Use a thread pitch gauge or compare the bolt to a known standard. For M6, the pitch is usually 1.0 mm; for M8, it is usually 1.25 mm. If you are unsure, take the original bolt to a hardware store to match.

Should I use thread-locking compound?

Some makers recommend a medium-strength thread locker (e.g., Loctite 242) to prevent bolts from loosening from vibration. Check the manual first. Do not use high-strength locker that may make removal difficult.

Can I mount a wheel base without bolts, using a desk clamp?

Many wheel bases come with a desk clamp that does not require bolts. The clamp uses a threaded screw to press against the desk. Bolt mounting is used for stands and cockpits. The clamp itself has its own thread length considerations for the screw.

Where can I find the bolt specifications for my wheel base?

The maker's manual or support page lists the bolt size, thread pitch, and recommended length. For Logitech G, Thrustmaster, and Fanatec, visit their official support websites and search for your model.