Tuesday, March 11, 2008

Some thoughts on safety

"Do you ride motorcycles because of their proximity to death, or in spite of their proximity to death?"
This was the opening question posed by Matt Chambers, CEO of Confederate Motorcycles, during a recent presentation on American design.

I don't ride motorcycles, but if I did I'd have to answer "in spite". I'm lucky in that I have an abnormally high sense of self-preservation. I usually lift off the throttle well before the limits of my car and I always instinctively slow when rounding a blind corner. That's why I'll probably never be a great racer, and why I pay next to nothing for insurance!

I'm a father and a husband, and I don't particularly want to get killed or maimed for my hobby. Worse, I don't want to take someone out with me. So when a recent discussion with co-workers turned to the subject of the safety of my home-built car, it led me to make a few more decisions on what my car will be about.

I don't expect this car to be as safe as a real car, period. I plan on using 6-point racing harnesses, but I won't have airbags, ABS or even side-impact door beams. If I get t-boned by an Escalade, it'll probably put me in the hospital (or worse). I take my safety seriously, but I also lament the time where cars weren't loaded down with 1000 lbs. of safety features. I'm starting to get fanatical about weight, and a line has to be drawn between safety and the purpose of the car.

That being said, the primary approach I'm taking with regards to the safety of the vehicle is to prevent a loss of control of the vehicle or dangerous vehicle dynamics while on the road. I'll have to practice "active safety" (aka paying attention and driving defensively) with regards to threats from other vehicles on the road.

To me, loss of control usually falls into 3 areas: structural failure, loss of brakes, and loss of steering. There's also the terrible threat of a fire.


Carroll Smiths "Prepare to Win" is an awesome book, and I think all builders should read it. It outlines his fanatical attention to car preparation to minimize mechanical failures. I won't go over all the details covered, but here are a few "high points" I'll focus on during the design and build:
  • Use aircraft grade hardware to secure anything that'll hose you if it fails. Lock washers, nylock nuts and loctite just don't cut it.
  • Safety wire or cotter pin all hardware that may vibrate loose.
  • Redesign stress points (like suspension mounts) to maximize weld area and to prevent loading welds in tension. This is a major issue (to me) with the current Locost design.
Additionally, I'm planning on integrating the roll-bar into the frame (like Moti did on the LocostUSA forums). I'm not really impressed with the way the roll bar mounts on the current Locost design.

Finally, I just need to pay attention when designing and building the suspension. I don't plan on cutting corners with the structural integrity of the suspension bits and mounting points.


Mark Rivera's crash at Mid-Ohio really opened my eyes to what could happen in my car. In his case, a fastener worked free on his brake pedal and he lost brake control.

Thankfully again he was on a track with enough run-off to contain the accident. My worry is that my car will careen out of control on the street. I've made a few decisions regarding the brake system.
  • I'm going to use a commercial pedal set w/dual cylinders. I don't want to make my own when so many proven systems are out there.
  • I intend to run brake lines away from heat and sources of puncture. The brake lines to the rear will have to run past the driveshaft, so I'll have to think of a way to protect them.
  • I'm going to run hanging pedals, if possible. As one commenter on the LocostUSA forums pointed out, hanging pedals are less vulnerable to debris clogging the works.

There have been many posts on the forums concerning steering rack modifications to reduce bump steer. I get the willies when I think about welding my steering rack. Especially because once welded and reinstalled, there's almost no way to quickly inspect the welded area over the life of the car. If at all possible, I'd like a professional solution, either an off-the-shelf rack or something modified by a pro.

I'm considering using a removable steering wheel, but I need to do some research regarding the safety of these on the street.


This really scares me, and it should scare everyone else, too. It's going to be friggin expensive, but I want to use a real fuel cell for my car. I intend to mount the cell in the rear above the differential to give as much crumple room as possible in the event of a rear impact.

I'm going to have a fire extinguisher in the passenger compartment and battery cutoffs on the dash. I intend to run fuel lines in the same "protected" zone as the brake lines.

In closing, safety isn't just a punch list of features, it's a design approach. As I design and build this car I'm just going to have to be diligent about building something fun and light, but not dangerous.

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