A drag link is a steering gear item in a vehicle that changes the rotary motion of a crank or the steering box to a second crank or link in a different plane or axis. This is used in a four-link steering system and is not found in a rack and pinion steering system. The drag link converts the sweeping motion of the steering box to the linear motion needed to pull the tie rods, and ultimately turn the vehicle's wheels.
A major component of the steering system, the drag link can also affect the vehicle's toe in or toe out and must be adjusted when aligning the front end of a vehicle. A worn drag link can affect a vehicle's handling and steering properties, making the vehicle wander while driving down the road. A severely worn one can often be confused with a soft tire.
On some four-wheel drive trucks that have been radically lifted, the drag link must be replaced with one of an altered length and often an altered design. This allows the component to operate on the correct plane despite the steering box being raised away from the axle. Correcting the steering geometry is a vital role of this important component.
On vehicles with high mileage or those that have suffered from extreme use, replacement of the steering components can drastically alter the way the vehicle drives. Replacing the steering components can aid in tire wear and even brake wear. Fuel mileage can also be improved by a servicing of the steering components. Any vehicle which has suffered a frontal collision should have its steering components checked and aligned.
Several aftermarket companies have developed drag links that utilize high-performance rod ends in place of the conventional automotive rod ends. These aftermarket items are much stronger and should be used on vehicles that see extreme duty. The factory components are not designed for and were never intended to be used with over-sized tires and lifted suspensions. The aftermarket components can help avoid costly repairs due to a parts failure from over-taxed components.
The drag link is often overlooked when it comes to vehicle maintenance. The drag link should be checked periodically and greased when applicable. Oil change intervals are the proper time to inspect steering components. Check for loose ends by pulling on the rods by hand and taking note of any movement. These parts should be tight and any feeling of movement requires further inspection and proper maintenance up to and including replacement.