3.8. The rear most part of the Spaceframe must be at least 100mm forward the rear most part of the rear bumper( App. 12 Drawing 8.5).
3.9. The roof must be of either minimum 10mm composite, 1mm steel or 2mm alloy to be fixed to the top of the upper surface to protect the driver as defined in App. 12 Drawing 8.3.
4. Main cage 4.1. The bulkheads( Ch. 7 App. 2 Arts. 6.1 – 6.4) must extend across the full width of the Spaceframe. 4.2. Bulkheads must be made of minimum 1mm steel and be welded to the Spaceframe. 4.3. For front bulkheads App. 9 Art. 21 of this Chapter applies. 4.4. No part of the rear bulkhead must be further forward than the rearmost part of the driver’ s seat.
4.5. Cars with a front engine location must be constructed so that the rearmost part of the engine is at least 25mm in front of the front bulkhead.
4.6. In rear-engine cars the bulkhead must extend vertically to at least the same height as the highest part of the engine. From this point a polycarbonate window, minimum thickness 5mm may complete it, extending to the full height of the interior space as well as a horizontal cover extending to the rearmost part of the interior space( Ch. 7 App. 2 Arts. 6.5 – 6.6).
4.7. In either case the full bulkhead must completely isolate the driver from the engine compartment. 4.8. A similar bulkhead must isolate the engine and exhaust system from the fuel tank Ch. 7 App. 2 Arts. 6.1 – 6.4). 4.9. No part of the engine may protrude through either the front or rear bulkheads( Ch. 7 App. 2 Arts. 6.5 – 6.6). 4.10. Power Transmission System / Flywheel Protection
4.11. The transmission tunnel frame will be fabricated from steel tubing with minimum dimensions of 25mm x 2mm( App. 12 Drawing 8.4).
4.12. This frame to be reinforced( on the drivers’ side and top of tunnel), at the rear of the gearbox and at the clutch / flywheel area, for a minimum distance of 200mm( centre lines based on the front propshaft flange and 25mm rearward from the gearbox to engine mounting face) using minimum 2.6mm steel extensively welded to the inside of the frame. Using the same centre line for 300mm minimum 1.2mm steel will be extensively welded to the outside of the tunnel. The remainder of the tunnel may be covered by minimum 1mm steel or minimum 1.5mm aluminium.
4.13. Front wheel drive, the front bulkhead must be reinforced where the flywheel and drive shafts are directly in line with the driver.
5. Aerodynamic Devices 5.1. Must not exceed the overall limits of the original bodywork dimensions( Ch. 7 App. 2 Arts. 6.10 – 6.14). 5.2. Must not be wider than the widest part of the car’ s bodywork or higher than the highest part of the roof. 5.3. Within these restrictions their design is free
6. Body panels 6.1. Door hinges must be of adequate strength. 6.2. Body material is free subject to Art. 1.1 and Art. 3.4 above.
7. Engine 7.1. App. 9 Arts. 3.1 and 3.3 apply.
7.2. Forced Induction engines must be fitted with a restrictor in compliance with FIA Appendix J, Article 279, Article 3.7.
Motorsport UK National Competition Rules 2026 Edition 1
Chapter 16 Part B( Rallycross) Appendix 11- Rallycross Spaceframe Technical Regulations
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