I picked up a spare rear and it came with control arms. I was thinking of boxing the lowers and swapping them in. I tried to search on here to see if it was a good or bad idea and couldn’t come up with a solid answer.
Boxing lower control arms
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boxing is a good idea but if you have the a stock sway car in rear I think that stiffens up the lowers
I think boxing them is not a bad solution. It's still better than your typical stock stamped lower control arms. However, I do like the aftermarket tubular control arms. I boxed my lowers and didn't bother doing the uppers. I would also suggest installing new bushings as well. I used the Camaro 1LE bushings on mine.
I don't think they're available any longer, but there's other options out there.
I don't think they're available any longer, but there's other options out there.
It couldn’t hurt, especially with a stiffer rear sway bar. But I’d keep rubber bushings in the arms, after seeing some of the stuff UNGN went through with road racing- I don’t feel it’s worth the risk with northern backroads IMO.
If the arms are in good shape , use them. For my Malibu, I went to the yard and cherry picked a set off a 2000 Camaro. Rust free and twenty year newer bushings.
timo22
timo22
Boxing the stock lower arms is a bad idea as they are designed to flex on purpose to prevent suspension binding and damage to the weak LCA mounts on the frame. The rear 4 link suspension relies on control arm flex and bushing deflection to operate correctly. Boxed arms and especially poly bushings induce binding issues. The only way to run box or tube rear arms is to use ones with spherical joints. Also its a good idea to weld on gussets to reinforce the LCA mounts. Even the stock rear sway bar causes binding, which is why the frame mount aftermarket sway bars are better.
I'll disagree with that.
The uppers need to flex; the lowers do not. If you do box them, weld some sleeves in for the sway bar bolts, so it doesn't collapse when you tighten the bolts.
The uppers need to flex; the lowers do not. If you do box them, weld some sleeves in for the sway bar bolts, so it doesn't collapse when you tighten the bolts.
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I boxed the uppers and lowers on my cutlass, since i havent road tested it yet i cant say what that will be like however i cycled the suspension pretty hard from side to side with a floor jack under the axles and it seemed to travel fine and i didnt see much of any binding to speak of. I wont be running the factory sway bar however but i personally dont see the difference in boxing the stock arms vs a set of tubular arms that would be even more rigid and a lot of people run those on the street with no issues at all.
There is a distinct difference between "no issues" and not knowing any better. One may not notice it on 'day one' or during the initial miles driven, but in time there will likely be an issue if put to the limits.
These suspensions were intended to have some flex as part of their functionality to survive on the road for x-amount of miles. If it doesn't get put to the limits, there really isn't a need to upgrade. If you upgrade for other reasons, anything that inhibits the suspensions ability to articulate smoothly will promote binding sooner than a stock suspension that could flex would. Again, in normal driving situations it won't be a big deal so binding while cruising around like a typical driver won't be an issue.
Binding while driving beyond 'normal range' (higher speeds + higher lateral loading) can cause the suspension to be upset during maneuvers. The moment it gets upset, it can be very unpredictable thus uncontrolled. That is NOT something you want to happen in those circumstances.
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