Customer Car - Spire GTR with Sparco Sprint L Bucket Seats
The Spire GTR is a track-focused kit car known for its lightweight construction, motorcycle engine powertrains, and uncompromising performance. The Spire GTR is a rare, open-top kit car built by Spire Sports Cars (Derbyshire), powered by bike engines like the Kawasaki ZX‑12R and Ford Sierra running gear. It’s designed for the driver who wants raw racing feedback and razor-sharp handling, whether on a competitive circuit or a weekend track day. With its low-slung chassis, compact cockpit, and open-wheel design, it’s not the kind of car you’d typically expect to accommodate an XL-sized seat. Fitting XL-sized bucket seats in such a compact cockpit was no small feat. We were thrilled to match this punchy, sub‑600 kg track day weapon with our Sparco Sprint L seats that perfectly cater to broader drivers (38–42″ waist sizes), and they surprisingly fit snugly inside the tight Spire cockpit. That’s why this customer project really stood out to us.
We supplied a pair of Sparco Sprint L bucket seats, and they fit inside the tight Spire GTR cabin surprisingly well. These seats are designed specifically for broader drivers, offering exceptional comfort and lateral support for those with wider hips and shoulders. The result? A track car that’s not only built for speed but also perfectly tailored to the driver. The combination of supportive bolsters, a strong steel frame, and FIA approval makes the Sparco Sprint L a brilliant choice for larger drivers who want to feel secure and connected in a high-performance car like the Spire GTR. A great track car made even better!
Seat Spotlight – Sparco Sprint L
The Sparco Sprint L is one of the most popular XL-sized fixed-back bucket seats in the motorsport world. Designed for drivers seeking a wider fit without compromising on safety or support, this seat combines FIA-approved performance with practical comfort for broader builds. With generous shoulder and hip room, the Sprint L is a go-to choice for drivers with a waist size between 38 to 42 inches, offering support where it’s needed most. This seat is built with a strong tubular steel frame and features enhanced bolstering across the thighs and shoulders to keep the driver securely planted through high-speed corners and heavy braking zones.
It supports both base mount and side mount configurations, making it adaptable to a wide range of setups, from dedicated track builds to highly customised kit cars like the Spire GTR. With 5 harness slots that accommodate a full 6-point harness setup, anti-wear fabric reinforcements on contact areas, and sleek black styling, the Sprint L doesn’t just perform, it looks the part too. Whether you’re upgrading for a more supportive driving position or need a seat to match your body type, the Sprint L delivers reliability and value from one of the most trusted names in motorsport.
Key Features:
- FIA 8855-1999 approved for motorsport use
- XL size – ideal for drivers with broader hips and larger waist sizes
- Steel tubular frame for strength and durability
- Dual mounting options: base and side mounted
- 5 harness slots – compatible with 4, 5, and 6-point harnesses
- Anti-wear patches in high-friction areas for longer-lasting trim
- Available in Sparco’s signature black fabric finish
- Compatible with 345mm bolt pattern for universal base mount fitment
- Strong side bolster support for track-day and fast-road use
Dimensions That Matter
When selecting the right bucket seat for your build, especially one as compact as the Spire GTR, understanding the dimensions of your seat is crucial. The Sparco Sprint L is categorised as an XL-sized bucket seat, meaning it’s significantly wider than standard fixed-back options. This makes it an excellent choice for broader drivers, offering comfort and secure support, but it also means installation into smaller cockpits can be challenging.
Incredibly, our customer managed to install two Sparco Sprint L seats into the narrow chassis of the Spire GTR, proving that with the right planning and fabrication, even wider seats can fit in tight spaces. For anyone considering this seat, taking accurate interior measurements before purchase is essential to ensure a proper fit, not just for width, but also for height, bolstering, and leg clearance with the pedals.
Main Seat Measurements (Approximate):
- External width at shoulders: 570mm
- External width at base (front): 470mm
- External width at base (rear): 470mm
- Mounting bolt width (base mount): 345mm
- Mounting bolt width (side mount): 405mm
- Seat height: 915mm
- Harness slot height: suitable for a wide range of driver heights
These dimensions make it clear why this seat isn’t commonly found in small, closed-off cockpits, but the Spire GTR makes it work thanks to its open layout and racing-focused interior. For most road or track cars, we recommend the Sprint L for those who want maximum comfort and support without compromising on FIA compliance.
Installation & Bolt Patterns
The Spire GTR uses a custom-built base plate rather than OEM subframes. Thankfully, the Sprint L uses a 345mm universal bolt pattern on the base, making it drop-in compatible with most aftermarket frames, aside from Cobra’s narrower 291mm sub-frame range.
Want adjustability? You can side-mount the Sprint L; however, once side-mounted, this does increase the bolt pattern to a wider 405mm fitment that reduces the amount of frames compatible with this setup. We recommend using OMP or Planted Technology sub-frame brackets because they feature a wider 405mm bolt pattern. Want to use sliding runners with side mounts? Use Corbeau’s XL 405mm sliding runner to be compatible with the wider side mount fitment that lines everything up perfectly.
For perfection, we recommend our Endurance Multi-Point or Sparco Multi-Point side mounts, thanks to their multiple bolt placements for fine-tuning seating angle and position.
Recommended Fitting Equipment
To get the most out of your Sparco Sprint L bucket seat, choosing the right fitting equipment is just as important as selecting the seat itself. The Sprint L is versatile in its mounting compatibility, supporting both base mount and side mount configurations, giving drivers plenty of flexibility when setting up their cockpit.
Base Mount Setup – Sparco, Corbeau, Planted Technology, OMP sub-frame + (Optional) Sparco Runner
For the most straightforward and widely compatible fitment, base mounting the Sprint L is ideal. This configuration uses the seat’s 345mm bolt pattern, which is the standard for aftermarket seat fittings. We recommend using high-quality vehicle-specific sub-frames from trusted brands like Sparco, OMP, Corbeau, and Planted Technology. These sub-frames are engineered to work seamlessly with base-mounted seats and make installation quick and secure.
Side Mount Setup – Planted Technology, OMP sub-frame + Side Mount + (Optional) Corbeau Runner
If you’re opting to side mount your Sparco Sprint L to allow for greater adjustment in tilt and driving angle, you’ll need side mounts and sub-frames that support the increased 405mm bolt spacing of the Sprint L. Pairing these with OMP or Planted Technology sub-frames is a winning combo, as they feature wider base bolt spacing to accommodate side mount setups. We recommend our Sparco or Endurance side mounts as they provide a high amount of bolt points for more adjustability with the tilt of the seat for an optimal driving position.
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OMP sub-frames, by contrast, are focused purely on motorsport use. They do not feature mounts for factory seat belts, as they are designed to be paired with racing harnesses instead. This makes them ideal for full race cars and track builds where a harness belt system is already in place, but less suitable for cars that still rely on standard seat belt hardware.
Sparco, Corbeau, and Planted Technology sub-frames are ideal for Motorsport and road/track day use, as they include provisions for transferring your factory seat belt buckle to the new frame. This allows you to retain your OEM seat belt setup with your new seat, ensuring legal compliance and day-to-day usability.
Final Thoughts – “Form, Fit, Fearless”
Watching the Sparco Sprint L nestle into the Spire GTR was a rewarding sight, big support in a tiny cockpit. It shows when you get your measurements right and fit trusted equipment, even an XL bucket seat can work wonders in a track-day rocket.
Planning your seat fitment? Pay close attention to bolt patterns (345mm vs 405mm), your car’s internal width, and mounting angles. With the right subframe, side mounts, or optional runners, plus the Sprint L’s inclusive design, you’re setting up for performance, safety, and real driving confidence.
Thinking about a similar upgrade? Check out our range of Sparco Sprint L seats, brackets, and runners. We’d love to help you transform your cockpit.