Mounting-hole spacing is the distance between the centres of your seat's mounting holes. It helps determine whether the seat fits your brackets or sliders directly, or needs a compatible adapter. Check it before ordering, alongside the mounting type and fastener requirements.
A seat can fit your body perfectly and still be incompatible with the hardware on your cockpit. A few measurements and a look at the mounting drawings can prevent that problem before assembly starts.
The Core Recline also has an additional 193 × 193 mm (approximately 7.60 × 7.60 in) under-seat mounting pattern for compatible office-base conversion hardware. This is an additional pattern, not a universal cockpit or office-chair standard: confirm the intended interface, threads, clearances and approved conversion kit. For comparison, the Core Bucket uses a 360 × 385 mm (approximately 14.17 × 15.16 in) bottom-mount pattern; it is not a side-mounted shell.
Side mounts and bottom mounts work differently
A side-mounted seat attaches through mounting points on the sides of the shell, using brackets secured to the cockpit. This arrangement is common on fixed bucket seats. Depending on the bracket design, different holes or slots allow adjustment of seat height and inclination.
A bottom-mounted seat attaches underneath the seat base, often through a slider assembly. This is common on reclining seats. Compatibility still depends on the exact mounting pattern, rail spacing, bracket design and hardware; the description “bottom mount” does not guarantee a direct fit.
Is there a universal mounting pattern?
No single hole pattern covers every sim racing seat, slider and office-chair mechanism. Some mounting arrangements are widely used, but even apparently similar parts can differ in hole spacing, thread size, rail height or clearance.
For a Core Recline Seat installation, compare the current seat drawing with your chosen brackets, slider or approved office-chair conversion hardware. A similar-looking square pattern under the seat is not enough to establish compatibility with an office-chair mechanism.
Check the complete combination, including the supporting structure and the required fasteners. If you want one seat to serve both a cockpit and a desk setup, ask for confirmation of the intended mounting hardware before ordering.
How to measure your mounting-hole spacing
Use a rigid ruler or tape and measure from the centre of one hole to the centre of the next. For bottom mounts, record the front-to-rear and left-to-right distances. For side mounts, record the spacing along each side and the distance between the mounting faces.
Then check the hole or thread size, bracket thickness, required thread engagement and available clearance. A bolt must clamp the assembly without bottoming out in a threaded insert or contacting another component. Choose its length from the actual assembly and the manufacturer's instructions, rather than from the profile's outside dimensions.
Why aluminium-profile cockpits give you more adjustment
On an aluminium-profile cockpit, compatible brackets can be positioned along the profile slots. This makes it easier to line up seat supports without relying on a fixed set of holes in the frame. You still need suitable T-nuts, brackets, profile spacing and enough room around the seat.
The SIMGASM Club uses 40 × 80 mm main profiles and measures 500 × 1350 × 620 mm, or approximately 19.7 × 53.1 × 24.4 in (W × L × H). The Pro uses 40 × 160 mm main profiles and measures 580 × 1320 × 750 mm, or approximately 22.8 × 52.0 × 29.5 in. These outside dimensions do not replace the seat mounting measurements.
Avoid unnecessary layers of adapters
Every bracket, adapter and slider adds connections that need to be aligned and secured. Extra components do not automatically create play, but an unnecessary stack can increase seat height, complicate access and make movement harder to diagnose.
Use the simplest compatible mounting arrangement. If an adapter is required, choose one designed for the seat and loading involved; thickness alone does not establish stiffness or compatibility. Our article on why you slide around in your sim racing seat explains how seat support and movement affect your driving position.
Leave access for future adjustments
A good installation lets you reach the fasteners you need for adjustment. Some combinations hide the bracket bolts behind the seat shell or place a slider handle too close to a crossmember. Check tool access and the full intended adjustment range before final assembly.
Plan the assembly order, position the brackets, and check clearances before securing the seat. Verify the driving position only when the seat is adequately supported and fastened, then complete final tightening to specification. Body fit matters too; our guide to measuring the right sim racing seat size covers the key checks.
With your mounting measurements confirmed, compare our sim racing seats. Explore aluminium sim racing cockpits if your current frame limits adjustment, and find suitable mounting components among our sim racing accessories.
Frequently asked questions
What mounting pattern does an office-chair mechanism use?
Patterns vary between mechanisms. Measure both directions, check thread sizes and confirm that the seat and conversion hardware are approved to work together. Do not assume compatibility from a similar spacing alone.
Are side mounts stronger than bottom mounts?
Either arrangement can provide a secure installation when the seat, brackets and fasteners are suitable. Side mounts often offer height and inclination adjustment, while bottom mounts are commonly paired with sliders. The complete assembly matters more than the mounting category.
Which bolts should I use?
Use the diameter, thread pitch, strength grade, length and washers specified for the seat and mounting hardware. Follow the stated tightening torque and do not substitute a generic bolt recommendation for the manufacturer's requirements.
Does an adapter reduce rigidity?
A correctly designed and installed adapter can provide a stable connection. An unsuitable adapter, excessive unsupported span or poorly assembled stack can introduce flex or movement.
How can I check the installation?
Confirm that the fasteners are tightened as specified, both slider locks engage and there is adequate clearance. Apply controlled pressure while observing the connections for unexpected movement. A quiet hand check is useful, but it does not replace the manufacturer's assembly checks.
Unsure about your mounting pattern? Send your measurements and photographs to SIMGASM so we can help identify the appropriate seat and mounting hardware.
