Porterbuilt Street Rod’s Bolt-On Step Notch and 4-Link Systems Help lay out Your C-10

January 31st, 2011

Text and Photos by Marcel Venable

If necessity is the mother of invention, then she must have wanted to “link” the back of her truck. How do I know that? If she wanted her truck to lay out, then she had to do something with those stock leaf springs. One of the ways to do so would be to remove the leaf springs, replacing them with a link-style rear suspension for more range of axle travel, which increases ride height adjustability.

Out of all of the different types of link systems, the 4-link is the most widely used system, and by definition, there are two different types of 4-link suspensions. The first and most popular style is made of out of five bars (if you count the panhard bar). Based on using four pieces of steel tubing, stacked vertically in pairs, the bars or links mount on both the driver and passenger side of a truck’s frame rails. This system is referred to as a “parallel” system, and is attached to the axle using a bracket on one end of the bars, joined together with a front bracket on the frame closer to the back of the cab.

The four parallel bars will now allow the axle to travel more than the stock leaf springs in both up and down directions. However, when using this style of suspension, a fifth bar must be added, using it to control side-to-side or lateral movement. The most common way to do so is to use a panhard bar, which is attached to a bracket on the frame behind the axle with the other end attached directly to the axle in the opposing side of the frame bracket.

Another style mounts two of the top bars to the frame by the back of the cab. Then, by slanting the upper bars inward towards the center of the axle they will form a triangle. This system is called a triangulated 4-link. When using this type of system, the two bottom bars mount to the outside of the frame and to the axle, again using brackets at all of the attachment points. There is no need for a panhard bar to be used due to the fact that the top bars spread the load of lateral force in a different manner; however, triangulated 4-links are not the best choice with vehicles used during high speed performance driving. They tend to sway more, and an anti-sway bar system might be needed.

There are many different advantages to using a 4-link setup on a vehicle. Traction, weight transfer and pinion adjustment are all benefits of the 4-link system. Some other advantages that most of you here are reading about and stand to benefit from are range of travel and ride comfort. As I mentioned earlier, a 4-link will give you more up and down axle travel, thus allowing the ride height to be more adjustable, and by changing the geometry of the mounting points of the axle to the frame, leverage can be used to your advantage for ride comfort.

Porterbuilt Street Rods in Phoenix has spent many years researching the advantages of the 4-link setup, mostly for GM trucks from of the ‘60s, ‘70s and ‘80s. Its true bolt-on system utilizes a step notch frame replacement section and a bolt-on air bridge, along with all of the outer frame brackets, axle mounts and panhard bar setup.

The system doesn’t require welding at any point during the installation, just the use of general hand tools, a drill motor and bits, a sawzall and the better part of a day. Follow along with with the crew at Porterbuilt during the installation of one of its kits on this square body C-10.

Sources

Porterbuilt Street Rods

www.porterbuiltstreetrods.com (http://www NULL.porterbuiltstreetrods NULL.com/)

J and S Gear

714.841.4545

Eaton Performance Differentials

www.eaton.com (http://www NULL.eaton NULL.com/)

Classic Performance Products

www.classicperform.com

Bonspeed Wheels

www.bonspeedwheels.com (http://www NULL.bonspeedwheels NULL.com/)

Toyo Tires

www.toyotires.com (http://www NULL.toyotires NULL.com/)

SW Powder Coating

480.735.8183

www.swpowdercoating.com (http://www NULL.swpowdercoating NULL.com/)

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