Nissan Spec-V: Part 6: Protecting the Driver
8/20/2006
Safety is very important, so we have taken precautions to ensure we can safety take this car to the limit. The first main piece of safety equipment is the driver’s seat. The seat is important because it holds the driver in place in an accident, absorbs shock and keeps the harnesses in place in a bad crash.
We chose a pretty state-of-the-art seat, a Sparco Circuit. The Circuit is FIA approved and features head protectors. To get FIA approval the seat must undergo a stringent series of tests to assure it can take a big hit without breaking and absorb some of the shock of an impact. Not too many seats have this approval, so it’s an indication of safety.
Most FIA-approved seats are side mounted. Side mounting puts the seat mounts closer to the driver’s center of gravity, reducing stress on the shell of the seat and making for a much stronger mount. Most seats will only keep their FIA certification when side mounted. We used Sparco’s side mounts, which are cut from lightweight aluminum plate.
Since our car may need to be driven by drivers of several different heights, we needed to use adjustable seat rails. We used Sparco FIA-certified rails which have dual locks to firmly hold the seat in place. Most seat rails only have one locking tab which can shear off in a bad accident. Dual tabs are quite a bit stronger and safer.
It is also critical to properly mount the seat. To give the driver the best possible protection, we mounted the seat as low and as far to the middle as possible to get the driver’s head away from the roof and to give as much side crush area as possible. This also helps the weight distribution as the driver is the second heaviest component, only the engine weights more. This helps lower the CG and gets the weight more centered between the wheels.
We mounted the seat on a fabricated subframe which is welded to the cage. This is safer, as a bad impact is less likely to deform the cage and the seat mount separately. This helps ensure the harnesses tension will not change too much in a bad crash. An impact bad enough to deform the cage will result in the seat and cage moving together. The subframe is also much stronger than the factory seat mounts.
We also chose Sparco as the supplier of our safety harness, pedals and steering wheel. The Sparco harnesses are cam locked and FIA approved. We chose a six-point harness as we feel this is the safest. We liked the feel of the Sparco steering wheel and the larger pedals make heel-and-toe shifting easier.
At this point we decided to get rid of the stock, heavy steering column, replacing it with a cool billet unit from Sweet Manufacturing. The Sweet steering column is adjustable for position via a machined billet aluminum mounting clamp that bolts to the forward cross member of our cage. The Sweet column also has an important safety feature in that it can collapse about 10 inches. This is so the steering column won’t spear you in a bad accident.
We topped off our steering column with one of Sweets’ steering wheel quick release mounts designed especially for Sparco steering wheels. The quick release mount is important; we can remove the steering wheel instantly so it does not get in the way when entering or exiting. This is important for safety as one can exit quickly in an emergency.
To finish off the cage, we welded in tabs for our window nets. The nets help keep body in and debris out in a bad accident. We also mounted our Longacre master kill switch. This switch shuts off all of the power at once. The switch must be easily accessed by both the driver and emergency workers so we mounted right by the driver’s side mirror.
We also added a unique feature to the cage, our impact-absorbing structure. This structure is made of lighter-gauge tubing and is designed to crush inward in a severe side impact, taking up a lot of the side loads that can injure or even kill a driver. The cage’s stiff X-bars act like the final protection.
We chose Sparco for our seats, pedals, steering wheel and harnesses. Sparco is fashionable and functional.
Richie Watanabe welds in our seat rails.
To mount our seat lower and closer to the center, our seat mounting rails tunnel through the floor crossmembers, which are channeled and boxed in to reinforce the channel.
The seat rails weld directly to the cage in the rear.
The seat rails weld directly to the unibody’s main frame rails in the front.
The entire seat support structure is shown here.
The seat is as low and as far toward the center as possible for the best protection and the best possible weight distribution.
The Sweet steering column sheds about 30 pounds and gives an infinite amount of adjustment for steering wheel location.
An important safety feature is Sweets’ collapsible column, which prevents the driver from being speared in a bad crash.
Sweets’ quick release mechanism allows the steering wheel to be removed in seconds while holding the wheel securely to the steering column in normal use.
Our driver’s compartment is safe and comfortable.
Longacre supplied our master kill switch, which shuts off all power to the electrical system.
This structure is designed to crush and absorb energy in a bad side impact before it can harm the driver.