Hey guys has anyone boxed their upper trailing arms is this good/bad to do and what about fabing up a set maybe use heim joints any ideas/pics? Also my lowers have 2 holes drilled in them but i boxed them myself are the holes for a sway bar and do they go toward the front or rear? Thanks Ralph

There is some debate over boxing the upper arms. Some will say to leave then unboxed to allow them to flex. I forget why you'd want that but Global West follows that philosophy.

I know it's suggested to run rubber or spherical joints on one end of the upper arms to prevent suspension bind.

I went with a tubualar upper and spherical joints on the housing end.

The holes for the swaybar in your lower arms go towards the rear. Did you reinforce the arms around those holes when you boxed them? If you put a sway bar on without correct support, you can crush the arms.

There is some debate over boxing the upper arms. Some will say to leave then unboxed to allow
them to flex. I forget why you'd want that but Global West follows that philosophy.

I know it's suggested to run rubber or spherical joints on one end of the upper arms to prevent
suspension bind.The upper arms need to flex to allow the suspension to travel without binding... If you look at/ think about the layout of the upper arms, it becomes apparent (think of the geometry of the suspension layout).

For example, look at the upper arms without the rear axle housing. If you swing the arms, you will notice that the distance between the bushings on the axle side of the arms changes dramatically. This is due to the dissimilar arcs that the arms swing through. If you hold the arms level, and measure that distance, then let the arms sag and remeasure that distance, and you will see it is pretty significant... Then think about when those arms are bolted to the axle housing, where the distance between those pivot points cannot change... since the frame and axle mounting points are not moving (hopefully), the arms/bushing must flex to allow the rear suspension to travel through its motion.

Boxed lower arms/ stiff bushing do not affect this as much as the uppers, because the arms swing through arcs that are similar, reducing the negative effects.

I had previously run stock upper arms with the poly bushings, and the rearend was very stiff. I used tt think stiff = better handling, but the rear of the car would tend to "skip" sometimes in hard cornering. The suspension was so stiff (because of the upperarms/bushings) that it was also difficult to remove the rear springs (axle wouldn't drop down enough by gravity alone).

I recently switched to the Global lower arms with the spherical joints, and put new rubber bushings in the stock upper arms. No other changes (same springs and shocks, etc...). The ride quality improved dramatically, and the handling seems to be better as well (no quantifiable evidence, just the way it feels), as the car seems to hold the road better on windy/bumpy roads...

I plan to add Edelbrock/Currie upper arms in the future, but I plan on retaining the rubber bushings in the axle housing because, despite the spherical joint at one end, the arms still need to flex.


This is all for handling aspects, as traction for hard launches might be better suited with the really stiff rear suspension (I really don't know).


If the upper arms are built so stiff as to minimize the deflection but yet the loads have no decreased, then something has to give... The upper crossmember on the frame is not very thick, and would be the most likely place to yield. When using the stock uppers with poly, the arms are still relatively weak (compared to the crossmember), but not so with many of the aftermarket boxed uppers.

This is even more critical with a frame that is 32+ years old (metal fatigue, corrosion, etc).

Factory style frame braces will help transfer the loads from the crossmember to the main frame rails by triagulation, and aftermarket bars would be better... When running the stock SS braces and the stock upper arms with Poly for about 7+ years, I found the stock (thin ) braces were beginning to crack around the bolt hole. To me, this indicates that the upper crossmember is possibly flexing. Thankfully I have not seen any cracks forming. I someday plan a frame-off rebuild of this car, and then I will reinforce the upper crossmember.