1964-1974 [Subscribe to Daily Digest] |
...the changes made to the '73/'74 models. These had beefed-up intrusion protection at the front and rear and in the doors. Seeing how this was done might help you plan how to implement your upgrade. A few thoughts:
-- The big-bumper cars' rear bumpers, in addition to being energy absorbing, are mounted on square-section tubes that tie into the main chassis sections on either side of the trunk well. These are the same sections that absorb suspension loads, so have to be pretty sturdy. This provides an intrusion protection upgrade over the plain fiberglass panel on the older cars. At the front, the bumpers are mounted on long extensions that tie into the same areas of the front platform that support the engine mounts; again, this is a beefy area of the chassis. The bumper mounting arms at both ends consist of one tube inside another, providing some energy-absorbing "controlled deformation" capability.
-- The big-bumper cars have side impact beams in the doors. These consist of 1-inch square-section tubing; not really big, mind you, but better than nothing! Just putting '74 doors on your '72 wouldn't be much of an improvement, though, because the impact beams need to tie into something. What the factory did was attach the beams to a vertical stringer that runs down to the bottom of the door frame and terminates into a flat hook; this hook ties into a flattened rectangular eye that you can see on the door sill. The eye is positioned opposite the crossways "hat-section" reinforcement that runs from one side of the car to the other. All this stuff accomplishes two things: the hook prevents the door from being peeled out of the aperture by an impact, and channels crash loads into compression of a strong part of the floor. This distributes the energy over a wider area and makes it less likely that a side impact will just fold the car up.
-- This feature may be on the earlier cars, too: there's a steel tube bonded into the fiberglass windshield surround and front pillars, providing additional protection against the roof collapsing in a rollover. You can see where this tube runs by the bulge it makes behind the windshield; the rear-view mirror is screwed into it. Although you can't see them, there also are steel blade reinforcements molded into the fiberglass around the door openings.
I'm certainly NOT saying this stuff makes the Sonett as crash-resistant as a heavier, more modern car, but it does show that the factory was trying (which is more than you can say for a lot of competitors' sports cars in the 1970s.) More importantly, it gives you an idea of where the factory thought were the strongest places to attach reinforcements, so you can start thinking about what you might want to do. I'd think that if you started by using the factory mounting points and upgraded the impact structure with heavier materials -- basically converting the existing pieces into a roll cage -- you might be able to make your car significantly more crash-resistant without adding too much weight or subtracting too much space.
You definitely want to work with professionals such as race-car builders, though. As someone else has pointed out, just adding more structure without careful attention to where and how it's attached might actually make the car LESS safe! If you add a big strong crash structure and tie it into points on the chassis that aren't very sturdy, you could increase the risk that a crash would collapse the basic structure of the car, which would fold it up with you inside (ouch!)
I've also wondered about the possibility of some higher-tech solutions, such as filling the rockers with expanding foam, or adding padding along the tops of the doors to reduce the risk of head injuries in side impacts. Anyone done any practical work with concepts like these?
posted by 204.76.11...
, Tue, 28 Mar 2006 16:33:32
, Tue, 28 Mar 2006 12:50:13
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