Someone gave you some very bad information. First, there is no such thing as a "cold" weld that is still structurally sound. Aluminum melts at around 1100ºF, so no matter what, it's going to get that hot or hotter and that heat has no choice but to go in to the surrounding area of the weld (HAZ or Heat Affected Zone). Annealing temperature of aluminum alloys is roughly 650ºF, depending on alloy and original temper, so anything over that you're going to destroy the temper, which for a suspension component is very bad news. If you weld AT ALL on this, you will, at the minimum, need to have it re heat treated to restore the temper.
Second, Helium is generally used to produce a HOTTER arc. It's used a lot in welding thick plates and for DC aluminum welding, because the extra energy produced by Helium will get through aluminum oxide in the absence of AC cycle cleaning properties and produce a deeper, more narrow weld.
Third, the way you say that you can weld aluminum on a "good day" is troubling. This is not a project for a hobbiest.
Overall, a very bad idea for you.