Glenn R

I have a spare set of control arms for my early 85 944. I am going to try my hand at box welding them for strength. Any recommendations on what gauge steel to use? Or other advice, for that matter?

aussie944cab

My advice is Don't do it, you need to make sure you don't induce any stress points as no flex is a bad thing, if you stiffen a certain section, where that meets a standard section creates a stress point
Usually I am all for "giving it a go" but in this case the potential cost (of life/health) is too much

tempest411

But haven't people been doing this for a long time on these cars, with no ill effects? Steel doesn't fail catastrophically, like the alloy arms can.

harveyf

I have heard the philosophy that the control arm is the weak link. Better to bend this part and just replace it. It would be very hard to break this part.

That said, I boxed the control arms on my track car. The gauge of the material is really not the important parameter. The fact that you are boxing the section is where the strength comes from.

Bottom line: 1/16" material.

StoogeMoe

It's required to box the a-arms in my PCA region. They are known to fail at the track. I've been running them on my car for the last 10 years. No stress cracks. Lol.

aussie944cab

I stand corrected

V2Rocket

As long as the welder is competent and aware of the metal gauge of the arms and the reinforcing piece and gets the "heat" right I think it is OK.
Looking at my A-arms I wonder if you'd gain anything by using a round tube (~1" OD?) to "fill the gap" rather than a simple flat stock triangulating the "box".
Round tube would probably fit the "valley" nicely and give lots of surface area to weld to, and it's stiffer than flat bar.

T&T Racing

Sold a pair of reinforced gusset steel lowet control arms to a customer in Australia. The outside web was welded with 1/8 " steel strap and key areas where the sway bar mounted were reinforced.

Customer was very 😊, Harvey Ferris post is also supportive for steel strap aka flat bar stock.

The steel arms were on a race car for 7 years and NO stress cracks. Just control the heat, tig weld or mig weld

MAGK944

Curious how the factory did it on their race cars, certainly doesn’t look stock from this angle.

V2Rocket

Looks like a stock 924 arm to.me.

They had the swaybar mount on the arm., that's the round thing sticking forward.

MAGK944

Ah yes I see now, that round bump made me think it was modified when in fact the early 924 arms were built like that

Glenn R

So, 16 gauge (1/16") steel, Mig welded should do the trick, right?