DIY Special: A Simple A-arm Upgrade
This 1971 Chevrolet C10 was already upgraded with stiffer/lower springs (2-inch drop in front, 4-inch drop in the rear), new front and rear anti-roll bars, performance shock absorbers, a close-ratio steering box, and 16-inch wheels and tires. Then a set of new Hotchkis upper A-arms were installed.
Text and photography by John Kiewicz
Without question, the 1967-1972 GMC C/K pickup is the most popular classic truck around. Adding to its popularity is the wide variety of restoration and aftermarket parts available for these C/K trucks (C means 2WD, K means 4WD). While a new, high-performance engine, aftermarket wheels/tires and rejuvenating paint job are the top upgrades, suspension upgrades are becoming increasingly popular so that the old pickups don't handle like, well, a truck.
As delivered from the factory, the C/K trucks had a lofty ride height with a somewhat spongy suspension. Upgrading to lower/stiffer springs and performance shock absorbers is a straightforward upgrade that provides excellent results – not just for improved performance, but for improved looks as well. Now, aftermarket companies such as Hotchkis Performance are offering performance-minded tubular front A-arms that drastically improve the suspension geometry to deliver better handling and steering feel.
We recently installed a set of Hotchkis upper A-arms on a 1971 Chevrolet C10 truck to improve its handling performance. The installation was easy and was accomplished in just a few hours using everyday tools. Here's how we did it:
What They Do
The Hotchkis tubular upper A-arms improve handling through a revised suspension geometry and a reduced suspension component distortion.
The design of the Hotchkis upper A-arms delivers increased "negative camber gain," which is a fancy way of saying that there's a larger contact patch for the tire on the road during cornering. When a vehicle with stock upper A-arms corners, the tire leans over, causing much less of the tire to meet the road. The Hotchkis upper A-arms use unique tubing geometry and an offset-style cross shaft to create that contact patch. As a result, when the suspension travels upward (during cornering or going over a bump), the Hotchkis upper A-arm travels along a revised arc that allows the A-arm to pull the upper ball joint inboard. The result: better handling because more of the tire makes contact with the road.
In addition, the Hotchkis upper A-arms allow for increased caster angle that significantly improves mid- to high-speed stability. With the Hotchkis upper A-arms, the caster angle can be set to about 8 degrees as opposed to about 1 degree from the stock A-arms.
Constructed of laser-cut 1.125-inch diameter tubular steel that has been tungsten-inert-gas welded, the Hotchkis upper A-arms greatly reduce flex compared to stock A-arms constructed of lightweight, stamped steel. With lower A-arm flex comes reduced geometry changes during cornering and therefore better tire contact with the road and improved steering feel. In addition, the Hotchkis A-arms use Delrin bushings that also significantly reduce flex.
That increased strength also helps improve braking and makes braking more consistent, because the reduced flex lets the tire achieve a flatter, more consistent contact patch.
What's interesting is that even though the Hotchkis A-arms are significantly stronger, they are less than a pound heavier than the stock A-arms. In addition, they're more compact in size. Notice the difference between the Hotchkis (above left)and the stock (above right) upper A-arms. Not only is the Hotchkis A-armsignificantly stronger, but it is more compact as well.
How to Install Them
Begin by lifting the front of the truck off the ground, and then remove the front wheel. Note: This 1971 C10 uses a set of aftermarket 16-by-8-inch rally wheels fitted with P235/70R16 tires.
Because the front coil springs do not attach to the upper A-arms, removing the upper A-arm on a 1967-1972 Chevrolet/GMC truck is easy. Remove the cotter key and castle nut that connects the upper ball joint to the spindle. Then, use a ball joint separator to release the ball joint from the spindle.
Raise the upper A-arm to access to the two cross shaft retaining nuts that connect the A-arm to the truck frame.
With the two nuts removed, the upper A-arm should easily pull off. Be sure to note the amount of alignment shims used on each mounting stud. Later you will want to reinstall them the same way to keep a relatively correct alignment until you can have the suspension professionally realigned. Once the upper A-arm is removed, spend some time cleaning the dirt and grime that's accumulated over the years.
The Hotchkis upper A-arms mount just as the stock A-arms did. Position the cross shaft on the original mounting studs, then thread on the two retaining nuts.
Clean the alignment shims, then reinstall them in their original location. Afterward, use a torque wrench to tighten the two nuts to 65 pounds-feet.
Insert the mounting shaft of the new, heavy-duty ball joint into the top of the spindle. Then thread on the castle nut, and install the new cotter key. Reinstall the front wheel, lower the vehicle and then torque the lug nuts to spec. This is the fully installed Hotchkis upper A-arm assembly. Truth be told, it took longer to clean the frame and suspension components than it took to install the Hotchkis A-arms.
After the new upper A-arms are installed, the front suspension will need to be professionally aligned. Hotchkis offers a range of specifications to share with your mechanic as specs differ slightly depending on how you plan to use the truck.
SourceHotchkis Performance: 866-983-2706, www.hotchkis.net
