Boxing rear arms & sway bars
Authored by Wes Vann, June 28. 1998
This is a preliminary work and is just to start getting the informationdown. I did this on my 64 and found it so easy that I didn't take photos(yes, I have a mig welder). Well, at this point, when I can get anotherarm, I'll do it just for the photos.
Always use jack stands when you work under a car! As long asyou only remove one arm at a time, the rear-end will stay in place. Keepthe shocks attached.
What and Why of Boxing
There are reasons for boxing the arms.
The first thing is to make the arm stronger and less prone to bending.This is done by making a complete box section out of the current "C"channel.
The other thing that should be done at the same time is installationof "spacers" that will prevent the arms from collapsing whena rear sway bar is mounted (and the bolts are tightened down).
There isn't as much to be gained by boxing the upper arms and I don'tthink that it would be of value. The reason is that they are only abouthalf the length of the lower arms and as such are much less prone to buckling.
The REALLY easy thing to do would be to just buy some alreadymade. I guess I'm cheap.
The reason for a rear sway bar is to help balance out the handling ofthe car. Normally you would want a rear bar that is about 2/3 the sizeof the front bar.
On Chevelles (GM A bodies), the bar bolts directly to the lower rearcontrol arms. There are two bolts to each control arm.
The spacing between the lower arms is fixed due to the mounting pointson the frame and at the rear-end. The sway bar is manufactured so thatit fits between the arms and it's width should match the spacing of thearms. However, nothing is perfect and shims may be required. If you don'tuse shims when you should, you would force the control arms inward andpreload the bushings. This would cause the bushings to go bad. Needingthe shims does not mean that the bar is poorly made. More likely,your old car isn't all that exact.
How's it done
You have to put the rear of the car up on jack stands. You don't haveto remove the shocks.
Remove one of the lower arms and rework it, replace it, and then goto the other arm. By removing only one arm at a time, the rear-end willnot come loose and fall on your head.
You don't have to mark the arms in regards to which end faces front.It doesn't matter until you drill the holes for the sway bar.
You will have to drill two holes in each control arm for the sway barbolts. The bolts should be 7/16" diameter. The holes are centeredin the arm height. (if you want to be exact, draw a line from the centerof one of the bushings to the center of the other bushing.
From the center of the bushing that will be the "rear" bushing,measure forward 5". This is the location for one of the holes.
From the center of the rear bushing, measure forward 11". Thisis the location of the second hole.
If you don't have a drill press to drill the holes, I'd recommend thatyou mark both sides of the arm and drill the holes one side at a time.
If you are lucky, you may have gotten the spacers with the sway bar.I got mine from Addco and they provided them already cut to length.
If you want to be trick, go to a metal supply shop and get "thickwall" 7/16" inner diameter tubing and cut it to length (so itfits within the arms).
If you want to be cheap (nobody will see it!), you could just go get7/16" water pipe. Just keep in mind that welding galvanized steelreleases a poisonous gas.
Install the spacers and put bolts through them. Then tack weld the spacersin.
Now you want to add the plate.
I got 1/8" thick, 2" wide plate from Home Depot for about5 bucks.
The plate only has to go from close to one bushing to close to the other.There isn't any structural reason to run it around the ends. It would howeverhelp when the bushings are pressed out and then new ones pressed in.
Grind all of the rust off the arms where the weld is going to go andweld the plate in place. When you weld it, work in sections and don't justrun a continuous long weld.
It you want it to look cool, grind the welds flush.
Take the arms (arm) to a front end shop and have the bushings replaced.
Other stuff to talk about
If you can, sand blast the arms. It really makes working on them a lotcleaner.
Think about different bushings. I personally like using the stock rubberones (less noise), but there are several options.
Paint the arms so that they don't rust! You could always have them powdercoated.
Use grade 8 bolts. Use nylock nuts or lock washers.
Although there isn't any reason, make sure that the sway bar (and stuff)isn't rubbing on anything once the car is back down on it's wheels.
Do the welding with a mig welder so that there isn't that much heatadded.
If there is any question on the new bushings fitting tight, have smalltack welds added.
Good luck and be careful!