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Discussion Starter · #1 ·
I am not a road racer or even a drag racer, But am going to replace my arm bushing on the rear . The lower i thought i would box them in and put a swaybar on ,all ready have one,whille i had them out . Dang, the thangs are prices, so looking to do it my self , any body got a cheeper place to get the inserts to be welded .looked around and seems to be going for around $40 by the time they ship. Only found two places on ebay. for sale. Any input would be nice.
 

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The stock sway bar will do very little, because of it's veeery 'flexible' mounting arrangement. Much better to fit an aftermarket rear anti roll bar that attaches DIRECT to the frame rails. I used the Hellwig from Summit. Other brands available.
After doing this, not much need for 'better' lower control arms. The factory braces on the lower controls arm used with the factory roll bar are practically useless in terms of reducing twist. Put one end of a piece of rectangular metal in a vice & you will find the other end is easy to twist.....compared to a piece of round tube!

I modified/strengthened my factory arms against twisting by welding in some round steel tube the full length, about 1.25"diam from memory.
 

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Factory lower control arms with the boxing insert installed will work just fine for your use of the vehicle. You will be amazed at the difference the sway bar makes.

The inserts are generally available for around $25.00, welding them in is an easy project and you should be able to find a friend that can do that for you for some beer. This is the process https://www.lever-family-racing.com...rence/create-12-bolt-arms/boxing-control-arms

One caution when you weld them in be sure to run the sway bar mounting bolts through the holes and the "U" channel of the boxing insert. This will insure that the holes and the "U" channels in the inserts line up when you are done.

When I weld inserts in for people I charge $65.00 including the cost of the insert. I weld the full length of the insert and then grind the weld smooth.



This is an easy project that you can take pride in having done it yourself.

As far as "The factory braces on the lower controls arm used with the factory roll bar are practically useless in terms of reducing twist." that is not the stress that is put on the arm. In addition once the arm is boxed you will not twist it. The sway bar will be trying to bend the arm up and down in the middle of the arm, and as a boxed structure is VERY strong.

Glenn
 

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Have you already upgraded your front swaybar? I went with a Hotchkis front 1 3/8" bar and it made an amazing difference in reducing body roll. So much so that I honestly don't see any need for a rear. Lowering my springs is my next step.
 

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:cool: Here's a guy on eBay who's selling a pair of boxed lowers -- he's open to offers. Shoot him a low ball offer and see if he counters with a reasonable price. By the time you ship your arms to someone to be welded and pay for welding and shipping both ways it might be cheaper buying these:

chevelle boxed lower control arms | eBay
 

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Discussion Starter · #6 ·
Thanks all for the post and info, . Already have an 1 1/4" up front fron a T/A,, Still having trouble with this site sence i loged in aweek ago.keeps redirecting me to one of the search site on hear with all the placeses i have been ,but will not let me read much befor it redirects me again, haven't been abale to post with out stoping me over and over. this is #2 times i started this post . thanks again.
 

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I use the classic view of the website, it works alot better for me viewing and posting. Just go to the bottom of the page and theres a box on the left and switch to classic view. Jim
 

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Just buy some aftermarket arms and be done with it. UMI are $150. By the time you put new bushings in and buy the supports you are halfway or more there already. Then you just spent that money on a 50 year old part that could fail at any time. Both my rear lowers cracked.
 

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Glenn,
There was absolutely NO NEED for the factory to box the control arms for use with a rear bar. All they needed to do was weld in bolt spacers for the roll bar bolts....
The boxing of the lower control arms was an attempt to reduce twisting, as it would reduce body roll....the very reason for an anti roll bar.





It is also an engineering FACT that a square/rectangular section will twist more than a round section, all else being equal. Probably why many of the aftermarket arms use round section tube.....
 

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Glenn,
There was absolutely NO NEED for the factory to box the control arms for use with a rear bar. All they needed to do was weld in bolt spacers for the roll bar bolts....
The boxing of the lower control arms was an attempt to reduce twisting, as it would reduce body roll....the very reason for an anti roll bar.





It is also an engineering FACT that a square/rectangular section will twist more than a round section, all else being equal. Probably why many of the aftermarket arms use round section tube.....
I have to disagree with you. Boxing the lower arms adds tremendous strength to the lower arms. Just adding the spacers will only keep the arms from being crushed when you tighten the sway bar bolts.

Just boxing the arms will not reduce body roll.

Companies are driven by profit. If spacers were all that were required, that is how they would have gone. Instead they went through the expense of material and labor to box the arms.

There is a large aftermarket that makes its living off boxing lower arms.

Glenn
 

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Glenn,
There was absolutely NO NEED for the factory to box the control arms for use with a rear bar. All they needed to do was weld in bolt spacers for the roll bar bolts....
The boxing of the lower control arms was an attempt to reduce twisting, as it would reduce body roll....the very reason for an anti roll bar.





It is also an engineering FACT that a square/rectangular section will twist more than a round section, all else being equal. Probably why many of the aftermarket arms use round section tube.....
I disagree too.

Just adding a spacer, would only strengthen the spacer area, you are leaving the rest of the arm with no strength.

Also, your contradicting yourself...
You're talking about only using spacers in the square arm, but then go on about a round arm being stronger.

The insert added the the stock arm does strengthen it more than enough to do the job. The round arm isn't needed.
 

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Shane,

I am not contradicting myself at all & what I said was 100% correct. And I will say it again for just you...& Glenn.

In terms of using the lower control arm to mount the anti roll bar, all the factory needed to do was weld in spacers for the roll bar bolts to go through. Job done, roll bar is now bolted in, start driving.

However the factory ADDED the re-inforcing plates to the arms, to box them, NOT as a requirement for the roll bar mounting, but to help the arms resist twisting. It was a cheap & ready fix, & like most cheap fixes, did little or nothing to fix the problem. If the arms did not twist AT ALL, there would be no body roll & no need for the bar.
So the boxed in lower arms were a bandaid, 'better than nothing', approach to help reduce body roll. Bandaid because a rectangular section will twist much more easily than a round section.
Get a 2 feet long piece of square or rect steel & put one end in a vice. Put a wrench on the other end & try twisting it. Quite easy. Now repeat with ROUND tube about the same diam as the square section. Almost impossible to twist. Get it now?
 

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And Shane...

..try reading the post correctly first before you criticise. NOWHERE did I say the the round tube was stronger. I said round tube resists twisting more than sq/rect section tube. The factory arm has adequate strength, IMO.
 

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Fair enough...with the round arguement...

But the boxing the arms the way they did resists twisting AND strengthens the arm for the bar.
 

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Shane,
Completely agree with the first half of your statement in post #14!!

My point was though, & still is, is that the boxing in the arms did help resist twisting, but not by very much. Nowhere near what arms made of round tube would have done. It was what I call a cosmetic change...looks nice, but does very little.
 

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One thing we can all probably agree on is the stock arm is pretty flimsy. My stock drivers side on the 70 was collapsing into itself. This was a factory 350 4 speed car. Just boxing it would help on the strength but the W bends in the plates probably help stiffen it too. Also the round vs box. Im sure the aftermarket round tube arms are thicker walled too which helps. Ive got the round tubes on my 70. Jim
 

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I looked at various companys Rear Control Arms to replace my stock ones
which were just not good enough to handle the BBC and Wheel Hop on the Street or the Track

Looked at round ones, but did not like the Looks etc.

When I came across UMI Perf Rear Boxed Control Arms I was sold on them
when they arrived at my home and I opened up the box I was more than happy
with the quality/finish/weight and potential strength of them

IMHO these UMI Perf Rear Boxed Control Arms should not Twist easily if at all

64-67 GM A-Body Rear Control Arm Kit, Fully Boxed Lowers, Adjustable Uppers # 402126
 

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I looked at various companys Rear Control Arms to replace my stock ones
which were just not good enough to handle the BBC and Wheel Hop on the Street or the Track

Looked at round ones, but did not like the Looks etc.

When I came across UMI Perf Rear Boxed Control Arms I was sold on them
when they arrived at my home and I opened up the box I was more than happy
with the quality/finish/weight and potential strength of them

IMHO these UMI Perf Rear Boxed Control Arms should not Twist easily if at all

64-67 GM A-Body Rear Control Arm Kit, Fully Boxed Lowers, Adjustable Uppers # 402126

This is the setup going on my car, just in black.
 
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