Rallying in New Zealand has experienced some serious accidents which have resulted in extensive damage to vehicles and injury to crew. While we need to accept that vehicle damage is an ever-present risk in a sport which pushes the boundaries, we must do all we can to reduce the likelihood of injury to crew. Fortunately, we can reduce or eliminate injury with sensible seat selection, well engineered and sensible seat mounting , well thought out harness mounting , use of head & neck restraints and good well placed rollcage padding .
Motorsport safety is David Black's passion. Over the last 8 years, David has been involved with numerous crash-testing programs for the FIA standard, along with development testing with race teams and car manufacturers. During this time, David has continuously strived to learn from this experience so Racetech can offer product that continually enhances crew safety.
Some simple philosophies & facts about motorsport crashes.
• If you support the human body well enough in the right places and keep all parts of the body in the same relationship to each other - it can withstand enormous decelerations with minimal or no injuries. 100G is quite survivable.
• Lateral/side impacts cause more injuries than frontal.
• The 4 parts of the body which need this support are the HEAD, SHOULDERS, PELVIS & THIGH
• The body should be stopped as close to the Chassis deceleration as possible.
• Only 20% of body movement in a frontal deceleration is in belt stretch – the balance is body reconfiguration.
• Using a crash recorder in the field, we have measured an 81G lateral impact during use of a Racetech seat in NZ Motorsport. The driver had no injury – and the seat had no damage.
Seat and head restraint advancements
With current technology and availability of seats with side head restraint you would need very good reasons not to use a good Head Restraint seat and a Hans device. The Hans device works 20 deg each side of frontal and the seat does the rest. The current FIA standard require the seat to withstand 20G rearward, 15G sideways & then another 10G rearward. For these advancements to be fully realized, it is essential that the seat and brackets are mounted appropriately.
Seat Brackets and Mounting
The FIA standard requires the seat to be mounted using 5mm thick aluminium brackets, bolted into place with ISO 8.8 bolts. Seats are required to have plates of specific dimension engineered into the seat for fixing. Surprisingly, there is however, no requirement for the seat bracket to match this plate size on the outside of the seat.
Testing has shown us that enormous loads go onto all mounting hardware - and at relatively low decelerations. These loads will bend brackets and pull captive nuts through 3mm steel. In the field we have seen 50mm x 6mm steel plate bend in shoulder mounts. We have seen both small spacers between seats, and bolts with small or no washers pull through brackets. This testing and field analysis proves the need for good mounting practice.
Racetech recommend the use of washers (22mm Dia x 3mm thick) and provides these along with grade 12.9 cap screws. The seat brackets should at least cover an area similar to that of the plate inside the seat (55mm dia) at each bolt point but really support of the full side of the seat is a good idea. We don't recommend spacers but if you need a spacer between seat and bracket then make it at least this size also (55mm Dia). Bolting the bracket to the car is also very important and we don't recommend adjustable seat mounts in rally cars. Again you should use large washers and grade 12.9 bolts. If a seat has no back fixing/support at the shoulder level then we recommend you support the full length of the bracket if possible and use 2 bolts on each side at the front and 1 bolt at each side at the back. It is important the seat is well anchored; the loads in a rear impact are multiplied by the leverage of the length of the back of the seat - if the seat lets go then the belts won't do anything either!
The shoulder belts should be mounted as close to the back of the seat as possible – within 100 to150mm. There should be a bar at this point to mount the belts and the seat if using a back mounted Racetech seat.
The belts should also be mounted close together to ensure they stay on the shoulder of the Hans device. Always ensure your belts are tight and in a long stage check them as you will compress down and hence the belts will loosen.
The lap belts should be fitted with click in eyebolt fittings with angles and location to manufacturers' instructions. Again ensure these are tight as any movement can result in injury.
Ensure that if using a crotch strap that it either is mounted directly below the crotch hole in the seat or passes around a bar at this point. Race seats are not designed to take loads from the belts in a roll over.
Head & Neck Restraint
In the last few years HANS Devices have become widely used and are in fact mandatory in many forms of our sport including WRC, F1, NZV8's, V8 Supercars etc. With what the safety experts know now – the use of a HANS device is a very smart thing to do. If selected correctly with good choice of helmet and harnesses correctly mounted both close together and close to the back of the seat these devices are a very smart investment. The drivers we spoke to initially had some issues, but got used to it very quickly, so much so – “It is now just another piece of safety gear they put on.”
Remember in a crash you have little if any control over your body movements and the distances you move even when fully restrained are amazing. The rollcage is particularly hard even when you hit it with a helmet on. The High density FIA approved padding should be placed on the potential head impact side of the rollcage anywhere the head could potentially hit. We are not trying to protect the expensive helmet when you getting in and out – the padding is there to protect your helmet/head in an impact and with bars so close to your head/helmet you will hit them.
for most of us Motorsport is “FUN” - let's keep it that way and keep doing what we enjoy.