Try talking to a certified airplane mechanic at a local airport.
DanO
good suggestion from dan o. i am an aircraft structural engineer, and a licensed Airframe & Powerplant mechanic.
you need to be careful what you're welding on your car. welding heat-treated aluminum introduces enough heat to locally anneal the aluminum adjacent to the weld. so, unless you can re-heat treat the whole piece you're welding, you'll be introducing a soft spot into the structure, losing strength rather than gaining it. spotwelding heat-treated aluminum generally does not introduce these deleterious effects.
also, once alloyed aluminum is bent, straightening it usually results in cracking due to work-hardening. bending will also create openings in the anodized surfaces, which can cause corrosion problems. however, i think the alloys used in the X are already pretty corrosion resistant in their heat-treated condition.
on the X, you don't want to cut and weld channels or crossmembers, spring/shock attachments, A & B pillars, or motor mounts. and definitely do not EVER do a weld or straighten on the suspension components. if it's bent or cracked, throw it away and get a new one. it's not worth the risk just to save a couple of bucks.
there may be other areas that could reduce strength in crash safety zones, but the items just listed are under cyclic loads every time you drive, resulting in fatigue (cracking) problems if not repaired correctly.
or, you can assume that there's a high enough factor of safety in the design to tolerate some damage, and that i'm just gas-baggin, and besides, it's just a friggin car. on aircraft, we work with a 50% safety factor (1.5), so there's not much room for error. on a car, i'm sure it's much higher.
these are general instructions, not intended for use on any aircraft installation without FAA approval.
