Don Terrill’s Speed-Talk

The rims I want to fit on the front of my car fouls the front suspension upright by about 5mm. I would need to take some material out of the upright to make the wheel fit. The upright is made of aluminium and I was thinking that I could take whatever material I needed out of the upright and reinforce it by welding aluminium plate in this weakened area.

I can weld aluminium (on my good days) and was thinking of using straight Helium to weld the plate on as this would keep the weld area stone cold and should not affect the strength of the cast bit. I got a big watercooled TIG also.

Any advice appreciated as to whether its a good idea or not.

Without a picture, it's impossible to answer properly. Just keep in mind that if you reduce the depth of a cross-section, it reduces its stiffness and strength in bending, even if it has the same amount of material in it. For example, a 1" square tube with 1/16" walls has less material in it than a 1" by 1/4" flat bar but it is a lot stronger in bending along the minor axis.

For a street vehicle, I wouldn't do it.

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.

Uh, narrower rims, less backspace or a spacer?

The set of rims I want just foul the arm. They dont have any other size. I might get away with a 3mm spacer and a little grinding of the arm and a 245 tyre. If I manage to find a cheap secondhand set of uprights I will give it a go. If the ally welds up nice I would get them heat treated. Its probably an idea to speak to the heat treater to see what he thinks.

On my good days I can weld ally. I just got to set myself up right, not rush things and not be stressed. As they say in painting, preparation is 90%, ally welding is much the same for me.

Some aluminum alloys are a nightmare in regards to cracking and porosity.
A little water absorbed by the alcohol used for cleaning, tiny lint fibers from cleaning, and just plain atmospheric moisture can really mess up the tricky ones. 7000 and 2000 series.

I wonder what yours are made of.

I watched a guy try to weld an aluminum rim that had cracked, because of the contamination and even though he had cleaned it every way he thought appropriate, it would not weld. Turned out to be a nasty waste of time.

mbrooks wrote:I watched a guy try to weld an aluminum rim that had cracked, because of the contamination and even though he had cleaned it every way he thought appropriate, it would not weld. Turned out to be a nasty waste of time.

With used castings and forgings, it's pretty normal to clean, weld, grind out weld, weld, grind, weld, etc. until all of the contaminants have been boiled out, ground out and finally a solid weld put in. Wheels are the same as any other structural aluminum component; They will never be the same unless sent off for heat treat.

Some recommend all "grinding' be done with carbide burrs, not grinding stones, to reduce contamination.

Almost in every case a normal high strength Heat treated Alum Alloy, say 6061, (since 7075/2024/etc don't weld well), will be considerably weaker after welding, no matter what the welders skill set/prep/equip/materials/etc he uses, and the welded area will become a natural stress riser due to the effects of welding as base alum sees all the different heat variations in the process. Next thing to consider, is the item redundant, or is its failure catastrophic, and then, is the item repeatedly stressed, since all alum has a limited fatigue life with ANY stress, and higher stresses lowers that life.

Bottom line, as others have mentioned, not a good idea.

Does anybody offer a tubular control arm for your car? They quite often have more clearance than
the stamped factory arms and with the 3 mil spacers you just might clear your wheels.
Trying to modify any aluminum suspension component is a bad idea on the best of days. Buying
different wheels is still your best option.
Like the Stones said, You can't always get what you want.........

Ken