All About S550 Mustang Vertical Links and Toe Rods

Vertical links are essentially rear lower control arms for IRS cars. Due to the design of the IRS system, traditional control arms don’t fit/have the same impact. Instead, vertical links are used to keep the rear wheels planted. Their primary purpose is to reduce knuckle deflection under load, limiting the fore and aft movement of the knuckle. This prevents the knuckle from binding up as the axles turn, allowing you to put your power to the pavement more efficiently. You may also see these referred to as integral links. They function almost identically to lower control arms and are responsible for reducing wheel hop in an S550 Mustang. From the factory, the Mustang is equipped with stamped steel pieces which are weak and can deflect under load. Some aftermarket solutions are fully adjustable allowing more tweaking to your vehicle's handling. By switching to an adjustable link, you are able to precisely dial in your camber. This is another critical step when lowering your Mustang, as extreme camber can cause uneven tire wear or poor handling characteristics.

Non-adjustable camber links can still offer rigidity and reduced deflection over the OEM links. If your camber is in spec without needing adjustable links, a set of non-adjustable links can reduce suspension deflection and prevent camber excessive camber changes during suspension travel.

Anyone who is planning on doing performance driving with their Mustang should replace their vertical links with an upgraded set. Having a more robust set of vertical links will help to reduce knuckle oscillation, deflection, and provide you with more consistent rear suspension characteristics. With the reduction in deflection also comes more consistent geometry changes, a more predictable rear suspension, and a reduction in wheel hop. Wheel hop is the enemy of traction and performance, so anything you can do to reduce it will help your Mustang have more consistent traction. Eliminating wheel hop will also prevent axle shafts from snapping and causing damage to your Mustang.

Vertical links come in three different types, bearing/bearing, Delrin/bearing, and Delrin/Delrin. Bearing/bearing vertical links have spherical bearings on both ends and allow articulation while eliminating deflection. These are a popular choice for street cars because they still allow for movement over uneven surfaces. Delrin/bearing arms are also a popular choice for the street since they reduce knuckle wrap further, but still allow some articulation. The Delrin may be more prone to squeaking than a bearing/bearing link. Delrin/Delrin vertical links should be reserved for race applications only. They completely eliminate knuckle wrap, but increase the chance of damaging your suspension on the street. The solid nature of Delrin also will lead to more noise, vibration, and harshness (NVH) over a bearing/bearing arm.

Toe links work like a bump steer kit and help to keep the toe angle of your rear wheels within spec. Toe links optimize and improve traction, especially off of the line, and provide a more balanced ride. When toe settings are set incorrectly, your tire will drag or skip along the road surface instead of smoothly rolling. From the factory, Mustangs have stamped steel rear toe rods with rubber bushings. These factory rods will deflect under heavy loading, allowing the rear wheels to toe in or toe out. This can lead to erratic handling characteristics or uneven tire wear. Installing adjustable toe rods are an excellent idea when lowering the vehicle. It allows you to correct rear end geometry after lowering and keeps the toe settings locked in place by reducing deflection. Non-adjustable toe rods can be used as well, but should be reserved for Mustang owners who don’t plan on lowering their cars. Without the adjustability from the toe rod, your alignment specs may be stuck in an unfavorable position.

An upgrade to an adjustable rear toe link offers many improvements:

• Stiffer steel tubing with Heim joint construction
• Fully adjustable to dial in handling
• Reduced deflection helps to eliminate wheel-hop
• Bolt lockout plates to prevent bolt slip and changing alignment specs after they have been set

Elimination of flex in the chassis is a goal of any owner who wants to get the best handling from their Mustang. Any flex will affect alignment angles leading to decreased control and steering feel. When shopping for a toe rod, be sure to choose one with a threaded adjuster. Threaded adjusters are more accurate, easier to use, have greater adjustment range, and are not prone to slip like toe rods that utilize eccentric bolts. You should also consider choosing a toe rod that has a bearing on it instead of a polyurethane bushing. This will allow the toe rod to properly articulate and will reduce toe deflection during suspension travel. Keeping your toe consistent will go a long way to maintaining proper steering properties of your Mustang.

Finally, a quality set of toe rods should include, a set of lockout plates for the bolts. These plates prevent bolt slip after installation, which would ruin your alignment settings. They eliminate the factory adjustment bolts; all adjustments are then made on the toe rod. Lockout plates are used to minimize to change and deflection from the factory bolt slipping and losing adjustment. We recommend lockout plates if you have more than stock horsepower, or if you're running soft compound tires.

Factory toe rods were designed with the intention of maintaining alignment with factory suspension components. When you modify your Mustang's suspension with products like lowering springs, you may end up needing adjustment outside of the range of the factory toe rods. Stock toe rods have a very small range of adjustment and can be prone to slipping if not installed and set correctly. By upgrading to a set of adjustable toe rods, you give the person performing your alignment greater control over the end result, and making it easier for them to hit their target alignment specs accurately.