Can it be true? Trick handling...
Can it be true? Trick handling suspension pieces for Mopars? The answer is yes, with these tubular control arms from Magnum Force.
Custom handling-oriented suspension components have been a long time coming for Mopar musclecar applications. Over the years, the dedicated enthusiast had little to choose from. Building a custom suspension system meant swapping to up-rated OE parts, modifying components from other applications, or just plain fabrication.
Mopars have traditionally been viewed as straight-line machines, and emphasis on cornering has been outside the mainstream. Be that as it may, some dedicated enthusiasts have long recognized the cornering potential of these machines. In early-'60s compact-car racing, the A-Bodies ruled. Even the '70 Trans Am series showed the potential of the Mopar chassis.
The control arms come with...
The control arms come with RSMX-series spherical rod-ends, which allow a wide range of adjustability compared to a fixed bushing. These rod-ends are manufactured with PTFE liners. Threaded inserts to receive the rod-ends are nicely TIG-welded to the arms' chrome-moly tubing. Magnum Force also produces a similar version of the control arm, which accepts polyurethane bushings instead of the rod-ends.
In comparison to other vehicles of the era, Mopars stacked up well in road-holding ability. Detailed road-test data in magazine evaluations consistently proved Mopars at or near the top of the pack in handling when vehicles from various manufacturers were compared. Even so, technology has moved on in the three decades or so since these machines rolled of the assembly lines, and in order to maintain handling, upgrades are necessary.
Sticky tires, up-rated springs, bushings and sway bars, and a lowered stance is pretty much the formula for a hot-handling Mopar. A potential pitfall is once it's all said and done, lowered, fat-tired Mopars may not have the adjustability in the front suspension to set the alignment to the appropriate specs. The adjustment point for the caster and camber angles is at the inner pivots of the upper control arms, and there is a limited range of travel available there. With a lowered ride height, the factory adjustment is often not enough to obtain the stock settings required for acceptable tire wear, much less aggressive handling. When a Mopar is lowered, the camber angle goes negative. Once the adjusters are set for the static camber specs-if it will even get there-the range of adjustment required to set the caster is lost. Without sufficient caster, high-speed stability is gone. Even with a stock ride height, similar problems can crop up from the chassis settling from years of service.
At the other end, a machined...
At the other end, a machined ball-joint receiver accepts a standard Mopar ball joint, which is pre-assembled to the arm.
There are several potential fixes, including Moog's special offset "problem-solver" bushings, which help some. But, the guys at Magnum Force Racing go one better with a tubular upper control arm designed with performance handling in mind.
Magnum Force Racing markets two basic versions of their DOM seamless-tube A-arms: One is a low-deflection polyurethane bushed unit; the other, the Mac-daddy, is adjustable with spherical rod-ends. Both feature a revised ball-joint position, moving it further out and back. This is exactly where it needs to be to allow for a performance suspension setting. The tubular construction makes for a structure that is more rigid than the stock stamped-steel control arm, and it certainly looks racier. The eye at the bushing end of the bushed version has greater surface area supporting the bushing. This is an area where stock control arms often crack. The Magnum Force control arms come fully assembled with new ball joints and bushings (or rod-ends) and are ready to bolt in.
Our '71 Charger R/T has been previously set up for performance street handling, and we decided to use this vehicle as a test bed for the installation of a set of Magnum Force upper control arms. We opted for the adjustable rod-end-style arms, which offer full adjustability at the control arm as well as the stock adjustment cam, with near-zero deflection. The Magnum Force arms were a simple upgrade and lent a trick custom-performance look to our front suspension.
Weighing in at 4 pounds, 8...
Weighing in at 4 pounds, 8 ounces with hardware, the Magnum Force arms offer only a 10-ounce weight advantage over the stock arms.
The rod-end-style arms pivot...
The rod-end-style arms pivot on the stock adjustment bolts and use machined aluminum spacers to match the stock bushing width. The small tapered end of the spacers bears against the rod-end.
The arms come in bare, unpainted...
The arms come in bare, unpainted steel. We masked the ball joint and shot ours in Hemi Orange urethane for a flashy look.
Our control arms are going...
Our control arms are going into a '71 Charger R/T. To prep for the new arms, measure the distance between the lower control-arm bumpstop and the frame with the car sitting at normal ride height. This will provide a reference for later ballpark settings. Jack up the car and support it with jackstands by the framerails, allowing the suspension to drop. Remove the brake calipers to get the brake line clear of the upper ball-joint stud.
Fully unwind the torsion-bar...
Fully unwind the torsion-bar adjustment screw to unload the torsion bar.
To separate the ball joint,...
To separate the ball joint, first remove the cotter pin and nut. A pickle fork and hammer can be used, but it will destroy the seal and possibly damage the ball joint. Since this one was practically new, we used a ball-joint separator with a short screw to break it loose without damage.
The inner control-arm pivots...
The inner control-arm pivots are attached with special adjustment cam bolts accessible through service plates in the inner fenders. It may take some wiggling to get them out.
The control arm may require...
The control arm may require some persuasion with a prybar to work it out.
The sway bar links need to...
The sway bar links need to be disconnected so the suspension can travel freely.
With such a broad range of...
With such a broad range of adjustment possible, it can be tricky to pick a baseline adjustment for the installation. With the rod-end-style arms, there are two points of adjustment possible: at the stock camber-adjustment cams, and at the rod-end. The idea is to set the rod-ends so the cams are near the center of their travel with the suspension at ride height and the spindle near the desired camber setting. Once installed, the A-arm must be disconnected from the frame mount to make any further adjustment at the rod-ends, so final fine-tuning of the alignment must be accomplished through the stock adjusting cams. We found that a baseline setting of three turns out of the rod-end (from its fully seated position) put us in the ballpark. A short exposure of threads is preferred to minimize the length of rod exposed to bending loads.
Even though it takes a little...
Even though it takes a little finesse to line up the small spacers, the Magnum Force arms slip right into place, and the ball-joint end is bolted to the spindle.
Set the factory adjustment...
Set the factory adjustment cams to center. This is easily gauged by eyeballing the amount of the mounting slot visible past either side of the aluminum spacers. This setting will give the most adjustability for later alignment.
Jack up the suspension by...
Jack up the suspension by the lower control arm to the ride height noted earlier by the distance between the lower control arms and lower bumpstop. With the steering pointed straight ahead, using an angle finder or level, determine the angle of the brake disc in comparison to a vertical angle. You should be between 0 and -2 degrees. If it's way off, the control arm will need to come off the inner mounts, and the rod-ends adjusted in or out as required. Try to keep the adjuster cams in the center of their range when roughly setting camber. This will allow the most adjustability for setting the caster and camber without having to remove the A-arms later.
On our application, a small...
On our application, a small flap of sheetmetal jutted up from the frame and interfered with the control arm at the bottom of travel. This can be cut off or bent down out of the way.
The factory bumpstop location...
The factory bumpstop location ends up nowhere near the new control arm.
Our solution was to fabricate...
Our solution was to fabricate these extension brackets from 1⁄8-inch steel to move the bumpstop under the arm. Note the elongated square hole for mounting the bumpstop, which allows fine-tuning its final position.
We designed our bracket to...
We designed our bracket to attach at the factory bumpstop hole so we could return to the stock configuration later. The lower end can be bolted in by adding a drilled flange to the bottom and drilling a hole in the stock bracket. Or, it can simply be welded in.
Install the grease zerk and...
Install the grease zerk and lube the ball joint with quality chassis grease, and the control-arm conversion is done.
The tubular control arm looks...
The tubular control arm looks trick and lends a light, uncluttered look to the front suspension.