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Stock boxed lowers--good enough?

2313 Views 23 Replies 12 Participants Last post by  Texas70
I'm debating getting a set of stock boxed lower arms to replace the original open ones. Do they work well enough or should I consider something else? The car will be mostly a cruiser...no canyon carver or strip machine.
Thanks.
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FYI.. there are kits available to box your original stock "open" lower arms. I just completed a set recently for the '72 convert, replacing the bushings at the same time. Did the same thing to the '67 Sedan. Works well!
I can take a photo and post it here if that would help...
BillsCamino said:
FYI.. there are kits available to box your original stock "open" lower arms.
I can take a photo and post it here if that would help...
I'd like to see a photo and info on the kit, where to buy, price, ease of installation etc.
Thanks, Robert
That would be helpful, Bill, along with the info Robert asked for, too, if you have it.
Mr Chevelle said:
Mine are a little different than the method described...
I bought item #C-5382-130A from page 39 of the latest NPD catalog.
Looks just like the factory boxed arms when installed...cost $39.95
Use the drilling dimensions as outlined in the Tech Reference.
I'll post a pic later today when I get home...

EDIT: As promised, here's a pic...the inserts are not welded in yet, only set in place.
Just go to home depot and buy some 1/8" steel, and box them in yourself :)
I bought the same kit as mentioned but from OPG. I sandblasted them first. Welded in the inserts, then had them powder-coated and finally, installed new rubber bushings.
69boo307 said:
Just go to home depot and buy some 1/8" steel, and box them in yourself :)
True Brian but the inserts are formed to give better support around the sway bar bolt area.
Hughski said:
I'm debating getting a set of stock boxed lower arms to replace the original open ones. Do they work well enough or should I consider something else? The car will be mostly a cruiser...no canyon carver or strip machine.
Thanks.
I don't think boxing will be noticeable or needed if you're not planning a sway bar, just make sure your control arm bushing are in good condition.

If you box using the "Tech Reference" method be sure to do the sway bar mounting hole support part even if you're not planning a bar now. You may want one in the future and then it's just plug and play.

If you box and run a sway bar also consider control arm braces, if you don't already have them.
The only reason to box them that I can see is if you want to upgrade your suspension with a rear swaybar. Otherwise do not bother. The suggestion about new bushings is a good one; every time you replace the old worn out stuff your car will be noticeably better to drive.
Box the uppers while your at it. No such thing as too strong. Also UMI performance makes a nice set of rear control arms for a fraction of the price hotchkis charges.Just paid like $250 for boxed upper and lowers with energy bushings.And they come powdercoated.
chevfan_1 said:
Box the uppers while your at it. No such thing as too strong.
Not true... The uppers need to flex to be able to go through their range of motion without binding up. The bushings do not flex enough, so the arms need to have some flexibility. If poly bushings are used, and the arms are rigid, that flexibility has to come from either the frame (bad) or the axle housing (worse).
Derek69SS said:
Not true... The uppers need to flex to be able to go through their range of motion without binding up. The bushings do not flex enough, so the arms need to have some flexibility. If poly bushings are used, and the arms are rigid, that flexibility has to come from either the frame (bad) or the axle housing (worse).
or tire grip even worse
So you guys can tell hotchkis their uppers are worthless and poorly engineered.
chevfan_1 said:
So you guys can tell hotchkis their uppers are worthless and poorly engineered.
They probably already know it, but they're making money, so they don't care.

Global West's rear suspension is even worse.
A while back there was a long discussion about boxing upper control arms. I tried to find the post but gave up. I think it was about a year ago.

If my memory serves me correctly the discussion went something like this: Because of GM's 4 link control arm configuration something needs to flex when the differential moves. The best place for this flexing is the upper control arms. Boxing the upper control will eliminate it.

If poly-urethane bushings are used in the upper and lower control arms at least one rubber bushing should be used in each upper control arm, perferably the one in the differential housing.

The one acceptable place to use both upper and lower boxed control arms is drag racing because the differential movement is very limited. They even sell solid bushings for this type of use.

Some suspension companies like Edelbrock are offering upper control arms with spherical ball assemblies that allow the suspension to move freely.
Mr Chevelle said:
A while back there was a long discussion about boxing upper control arms. I tried to find the post but gave up. I think it was about a year ago.

If my memory serves me correctly the discussion went something like this: Because of GM's 4 link control arm configuration something needs to flex when the differential moves. The best place for this flexing is the upper control arms. Boxing the upper control will eliminate it.

If poly-urethane bushings are used in the upper and lower control arms at least one rubber bushing should be used in each upper control arm, perferably the one in the differential housing.

The one acceptable place to use both upper and lower boxed control arms is drag racing because the differential movement is very limited. They even sell solid bushings for this type of use.

Some suspension companies like Edelbrock are offering upper control arms with spherical ball assemblies that allow the suspension to move freely.
That's pretty-much right-on :thumbsup: I'm going to try spherical in all 8 pivots in the rear.
Derek69SS said:
I'm going to try spherical in all 8 pivots in the rear.
Hmm...sounds like a good idea...
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