i've been looking through the parts mags i've got, and i'm wondering about the rear control arms, everything i've read says that they help eliminate wheel-hop, faster acceleration off the line, yada yada yada...
what the hello do they do? and what is the point of the adjustable kind? how do they work?

The aftermarket control arms are made from boxed steel, stock are stamped from a sheet metal. With the boxed type there is less deflection of the arm during acceleration and cornering. Think of it like the difference between a metal tube and a sheel or metal. The sheet you can twist and bend, the tube can be also but it's a whole lot harder to do.

The upper adjustable arms allow you set the angle of the pinon for the rearend. This can help to plant the rearend also if set right. But you have to be carefull when you set this. While it can be set to give you really good traction at the track it can really affect how the car drives on the road. Most people seem to go for a happy medium between the 2.

I went with these on my '78: http://www.bmrfabrication.com/G-Body.htm I got the non-adjustable ones. It's hard to say how good they are by themselves because I installed more susp. upgrades at the same time (KYB's and rear sway bar). What I can say is, with the BMR's and the other upgrades, the rear stays planted, and extremely stable! 8) These BMR arms are also about half the price of the overpriced Hotchkis units!

I took my old lowers, boxed them in, and gave them to a friend of mine who has an '84 Elky. After installing them, he said it was alot more stable in the turns. I'm going to box the old uppers and have him install those to see the total effect :D

You can also box yours in if you would like. It is a simple operation adds strength and keeps the tires on the pavement better.

Just a thought.
:-)

Edlebrock also makes some up graded stuff...Anyone use theirs?

I boxed my lowers & installed poly bushings. It did make a big difference. I was told that unless you race the uppers will not make much of a difference like the lowers do.

I bought a complete suspension package from Performance Suspension in Phoenix, AZ. Came with boxed control arms., huge anti-sway bars, all urethane bushings, 2" dropped spindles, front disk conversion, KYB shocks, etc etc.
I can't report on the performance yet as my '71 is not yet finished (LT-1/4L60E), B&M hammer shifter, new paint, custom dash w/ Auto Meter gauges, GTO rearend, posi w/ 3:90 gear, Grant mahogany wheel, smoothed firewall,etc etc.
I am told however that it should corner like it's on rails and should hook-up pretty well.
I'll certainly have a full report on performance and lots of photographs if I get it back b4 it snows! It's been 'under construction' for 4 months now.

I was planning to use the edelbrock stuff on my '67 chevelle including the braces that attach at the frame mounting points to triangulate the frame. Kinda pricey but still cheaper than new factory boxed control arms or hotchkis stuff. My driver '81 elco has boxed lowers from a monte ss. If you want to beef up a rear end you should also think about welding the axle tubes were they press into the pumpkin, I once twisted a 12 bolt rear at that point.

I bought brand new stock rear control arms (upper & lower) from the dealer, they weren't that much and I wanted to keep the stock ride quality. I boxed them myself as well as used Edelbrock's No Hop Bars on the upper control arms and their Frame Mount Braces, it already had a sway bar. I used the No Hop bars on a GTO I once had and they worked well so I gave them a try on my 87 Z15. Plants like a champ no hopping at all.

There is one drawback though, if I put a big load in the back the upper control arms get a little close to the underside of the bed since the no hop bars raise the control arm location. (airshocks were replaced with bilsteins long ago)

Glenn Thompson
87 Black & Silver Z15
392,000 and counting