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-arm
significantly 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.
Source Hotchkis Performance: 866-983-2706, www.hotchkis.net
Comments
I'm a Ford man but this is just one of the best body style trucks Chevy made. They had some good ones and I wish they could find it again.
Awesome article, but one problem-C and K aren't the difference between Chevrolet and GMC models, it's the difference between 2WD and 4WD versions.
"C/K trucks (C means Chevrolet, K means GMC)"
Wow! Really! As Don Hornby just mentioned, it's the difference between 4x2 and 4x4 versions.
Good job on the DIY articles , keep them coming!
Keep these coming,I like reading these..as I do all my own work and its a nice change for this site...You can only look/read about the new stuff so much,for those of us who work on stuff ourselves really appreciate these (though some stories on other sites are a bit overboard and dramatic about the so-called propper way to do things) How about some of engine swaps/rebuilds and even newer truck computer upgrades/exhaust ect...even body work for the poor souls who live in the rust belt,bet they would like some quick rust saving tips or repair how to do's....
Funny,I just changed the Idler Arm on my 1968 Charger R/T last night..A month ago I completely went through a 1964 Chev 1/2 ton long box front suspension,including the A-Arms and pulled the mildly bent frame just off a little,actually love chaining the frame to anchors in the ground and pulling,great fun ! Its now just painted ready for final touches and then sale(need a new front bumper),added a slightly built,by my standards 327 4bbl (solid cam love the thump of a solid cam).The previous owned had too many wobbly pops and took out some home owners fancy from yard sculptures / large rocks and tore up the underside of the truck ,so the story goes !
How about an article on what causes the funny noise / slight vibration found on some Ford SD in the left front tire area on 4x4 models. After disassembly and replacing front wheel hub with new bearings its still there... and the ball joints are good. This is driving me and a lot of others crazy.
Shawn: I once worked at an excavating co. that had a fleet of SD's and every one of them had the same problem after about 48K on them, and we did replace almost everything we could think of, in every one of them, and guess what? it was the manual hub lockout device, we found that out when one of them fail completely, and had to be replaced, and when we did that, BINGO! the noise/slight vibration disapered, so we replaced them all, and guess what? all noises were gone!, try this, and when you do use a good/better after market locking device, like Warn, but not from the dealer!
Also Don is correct all the C/K ment was 4x2(C) and 4X4(K), I believe the Chevy's were called C/K-10 for 1/2t and the GMC were called C/K15 for 1/2t, that was also the way they designated the S-10 ans S-15's mid size trucks later on.
I am seventy four. I bought a new 1972 Chevy C-10.
Worse vehicle any one could own. After a year the paint blistered on the hood and roof. After two years the bed had rusted to pieces . It was a pile of rust by the time I made the
last payment. (3 years) Paid $2200. new.
@Shawn - I have to agree with Sandman4x4. The stub shaft is rattling around inside the wheel hub, or the locking hub itself could be the culprit.
I agrere with the comments that C/K meant 4x2 or 4x4.
Cool old Chevy.
These DIY projects can be very rewarding and empowering. Not to mention money saving! You still need to be mechanically inclined for them to go smoothly though.
Davy; Did you live near the ocean or snow in the '70's ?
My '77 C/5 Jimmy had thin paint down the center of the roof, a textured, flat white on all Blazer/Jimmy models, resulting in a rusty stripe after a few years. Many others had this issue.
The only other rust problem I had was in the front fenders collecting leaves inside the cavity behind the wheelwells where the windshield drain dumped out. That rusted from the inside out.
I ordered that C/5 from the factory in '76 and owned it for 27 yrs. (Dealers only stocked K/5's). I always ran it through the bottom spray car wash whenever I took it to the Gulf Coast.
GM started using galvanized steel in the early '80's I think, but the improvements in paint tech probably put the brakes on rust issues after that. Unless you deal with salt or acid rain.
For the record: It cost $7,600 in 1976!
Lou---
I live in the salt belt (snow)
Stevadore-------------
I paid $2200. For the base base model, no radio
only option 10 inch clutch.
A worthwhile mod, but real handling will never be achieved with 70-series all season tires.
I am probably in the minority, but on my cars, I run extreme performance tires in the warm weather and snow tires in the bad.
Also, there is a typo or mistake--it notes 16" wheels with 15" tires.
hotchkis makes some cool stuff. i installed a full Hotchkis TVS kit on my 86 Grand National. the kit included new adjusting sleeve tubes for the tie rods, a new larger front sway bar, new front springs, new lower boxed rear trailing arms, new adjustable upper rear trailing arms, new larger rear sway bar, and new rear springs. put that together with new bilstein shocks and the ole girl drives competely different than she used to. it would be SWEET to add upper and lower a-arms to that list! good stuff keep the DIY's comin
How do you fit a 15" Toyo tire on a 16" wheel? Mr. Kiewicz sharpen your pencil...C = 2x4 K = 4x4
this chevy is beautiful! i love the vibrant green color
My 69 Chevy was the same color, although faded, and same configuration. I had two friends that had these old trucks, one I blelieve a 70 shortbed, the other a 71 longbed, the 70 had a 454, the 71 had a 402. They benifitted from their dad racing dirt cars, so some racing parts and suspension work got done on their trucks. They made them corner really good, and although one person that posts on here things teens should be limited on their power, NEITHER OF THEM EVER WERE INVOLVED IN A WRECK! They drove them hard...I would think nowadays, SCCA autocross would be better.
It's not the same world as it was 28 or 30 years ago when if the police caught you after trying to outrun them, they would laugh an say," Yeah, we got you!" Nowadys, guns drawn, police dogs...yada yada yada...better off at the track!
Do you have the paint code for this? My husband bought me a 1971 stepside c10 and this is the color I want.
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