Ford Mustang Rear Control Arm Buyer’s Guide

One of the first mods that you look at doing to your Mustang is replacing your control arms. Whether you are purchasing a new S550 Mustang off the showroom or purchasing a new-to-you Fox body Mustang GT, replacing the stock components for something more performance improved or replacing worn control arms with fresh control arms will be on your mind. Depending on the year model of your model year of your Mustang, the style of the rear suspension will vary. Below we will go over some offerings and recommendations on which control arms will best fit your rear-wheel drive Mustang and driving style.

The first thing you will want to consider when looking at replacement control arms will be how the car will be used. The bushing material and style of the control arm will be the biggest determining factor on which control arm you want to put on your Mustang. Use the guide below to help you select the best control arm for your application.

Type Of Control Arms Bushings

There are generally four types of bushings used in Mustang control arms, rubber, polyurethane, Delrin, and spherical. OEM control arms utilize rubber to prevent noise, harness, and vibration (NVH). Polyurethane bushings will provide a harder material (increased durometer) than the factory rubber, decreasing deflection. Deflection will be the ability for the material to not compress under load. Less deflection will result in keeping the rear axle in a neutral position preventing axle twitchiness during cornering or hopping during hard accelerations. The next step up from polyurethane will be Delrin. Delin is a polymer material that provides a hardness of metal with great low-friction and high wear resistance. Its increased harness further prevents deflection compared to rubber and polyurethane. Due to the hardness of Delrin, it can transmit more NVH than rubber and polyurethane, which means you may hear more suspension noises. Lastly, spherical bushings will be the most race-ready control arm bushing. Spherical bushings provide almost zero defection and the ability of the rear axle to manipulate with very little resistance.

Restoration & Stock Replacement

Not always are we looking to make a Mustang a mean track duty Mustang. If you want to replace worn-out stock control arms or take-off performance control arms for factory restoration, Late Model Restoration has factory replacement control arms that will give your Mustang a refreshed control arm without providing additional noise, harnesses, and vibration (NVH). This will use stock durometer rubber bushings designed by Ford Motor Company and construction great for factory restoration projects where performance is not a priority.

Polyurethane Bushing Control Arms

Control arms utilizing urethane bushings greatly improve the stock rubber bushing control arms. Control arms with polyurethane control arms are great for the Mustang that will be used mainly as a daily driver but may see an occasional competition event. Polyurethane is great at dampening NVH but harder than the factory rubber, making it have less deflection, and providing better acceleration and handling characteristics.

Delrin Bushing Control Arms

Control arms utilizing Delrin will be a step up from the polyurethane versions. Delrin is a harder material than polyurethane making it less prone to deflection, which will mean better performance. These control arms are great for a strip car that might see some street duty from time to time.

Spherical Bushing Control Arms

Spherical bushings will be the ultimate control arm for someone looking to get the best lap times in their Mustang. Spherical bushings are generally designed for Mustangs that will be used in road racing, autocross, and drag racing environments. While some people will opt to use them in a serious horsepower street-strip Mustang, they will transmit excessive NVH into the cabin and can be extremely noisy compared to Delrin, polyurethane, and rubber.

Adjustable Vs. Non-Adjustable Control Arms

Solid Axle Control Arms

Once you decide on which upper and rear lower control arm bushing you want to use on your suspension, the next choice will be whether you want to run an adjustable or non-adjustable control arm. This, again, will come down to a couple of different ways of using your Mustang. Generally speaking, if you want an upgrade on a bolt-on Mustang that will mostly be a street-driven Mustang, then non-adjustable control arms will usually suffice. If you want to use sticky tires at a drag strip to prevent wheel hop or dial in a car for handling, adjustable control arms will be the way to go. There is an exception to this rule: if you are lowering a Mustang extremely low (over 1-1/2" on average), adjustable control arms will help you set your pinion angle back within spec. Any time you are lowering your Mustang, it is always best to check your pinion angle to make you that it does not need adjustable control arms to readjust it back into factory specifications.

Independent Rear Control Arms

Most adjustable control arms for the independent rear in the 1999-2004 Mustang Cobra and S550 Mustang will be designed to correct toe or camber as the rear differential is mounted on a fixed location on a subframe. This means that the pinion axle will not be adjustable. When lowering the independent rear suspension, the wheel camber and toe may need to be corrected, and adjustable control arms are made for this purpose. If you want to beef up the stock components and do not need to correct the toe or camber, then the non-adjustable version will be a great choice!

Height Adjustable Control Arms Vs. Fixed Height Control Arms

Height, adjustable control arms found on 1979-2004 solid axle Mustangs are commonly referred to as weight jacker control arms with an adjustable spring perch on the control arm that will allow an adjustment in the height of the rear of the Mustang. These control arms are beneficial in drag racing, road racing setups, or purely cosmetic. If you need to fine-tune the height of the rear of your Mustang, height-adjustable control arms are the best option!

Drag Racing Benefits:

• Raising the rear end raises the instant center, to increase the anti-squat percentage, providing a harder hit to the tire on launch.
• Clearance for taller diameter tires.
• To raise the right rear corner, to increase the weight on that tire, therefore improving launching by reducing right rear tire spin.

Road Racing Benefits:

• To weight jack the car when scaling it, to optimize the diagonal weights for best handling.
• Compensating for added weight, such as added suspension parts like pan hard or torque arm setups.

Deciding On Your Control Arm

Using the above information, you can help decide which control arm is the best control arm for your Mustang. Aftermarket control arms are always a great way to increase traction and handling characteristics on both manual and automatic transmission Mustangs. Adding additional heavy-duty front suspension parts can further increase the handling characteristics of your Mustang coupe, hatchback, fastback, and convertible.

We hope this has helped you evaluate which rear control arms are best for your Mustang. If you want to purchase and install control arms on your Mustang, Late Model Restoration has plenty of installation tech guides to assist you with this. If you still have any further questions, do not forget to contact us here: CONTACT US PAGE.

• MUSTANG UPPER & LOWER REAR CONTROL ARMS INSTALL (79-04)
• HOW TO REMOVE 2005-14 MUSTANG REAR UPPER CONTROL ARMS
• HOW TO REMOVE 2005-14 MUSTANG REAR LOWER CONTROL ARMS

Commonly Asked Questions

What do upgraded rear control arms do?

• Upgrading your rear control arms are a great way to improve the street, track, and racing characteristics of your Mustang. Rear control arms help to reduce axle wrap and hop which will reduce the traction during acceleration. Upgrading your rear control arm also helps reduce axle movements which will provide a more confident feeling during high-speed cornering.

Do aftermarket control arms make a difference?

• Aftermarket rear control arms do provide an increase in performance over the OEM control arms. Aftermarket control arms utilize stiffer materials that prevent unwanted deflection in the suspension.

Which control arm is more important?

• A general and widely accepted answer to this question is that the lower control arms are the more important control arms to change. During acceleration and deceleration, the stock rubber bushings allow for excessive deflections causing the rear axle to maintain the correct position in the Mustang. If you are budget-minded, a lower control arm replacement will greatly increase the performance abilities of your street-driven Mustang. If you are going to a dedicated track car, we recommend replacing both the upper and lower control arm.

Are tubular control arms better?

• Tubular or rectangular aftermarket control arms have performance benefits over the OEM control arms. The OEM control arms are designed to provide the least amount of noise, vibration, and harshness (NVH) and be cost-effective for Ford to manufacture. These aftermarket control arms utilize polyurethane, Delrin, spherical, or combination to help decrease bushing deflection. Be warned that spherical bushings will result in a significant increase in NVH while Delrin and polyurethane will result in a minimal increase in NVH.

Are tubular control arms better?

• Tubular or rectangular aftermarket control arms have performance benefits over the OEM control arms. The OEM control arms are designed to provide the least amount of noise, vibration, and harshness (NVH) and be cost-effective for Ford to manufacture. These aftermarket control arms utilize polyurethane, Delrin, spherical, or combination to help decrease bushing deflection. Be warned that spherical bushings will result in a significant increase in NVH while Delrin and polyurethane will result in a minimal increase in NVH.

Are panhard bars considered control arms?

• Panhard bars are not necessarily considered control arms but are an important part of the 3-link rear suspension found in the 2005-2014 S197 Mustang and the aftermarket 1979-2004 3-link conversion kits.

Do performance variants of the Mustangs need aftermarket control arms?

• While the upper models like the Shelby GT500, GT350, Mach 1, and Bullitt will have increased durometer rubber bushings on some of their suspension components, these models can also benefit from heavy-duty control arms. Whether you have a top-of-the-line GT500 or a base Ecoboost, changing control arms can benefit your Mustang!

Do you have to keep your sway bar on 1979-2004 Mustang control arms?

• Some Mustangs were not equipped with a rear sway bar from Ford, especially the 1994-2004 Mustang V6. Most aftermarket control arms will have the sway bar mounts but some aftermarket control arms will not have the sway bar mounts. Using no sway bar and replacing it with an anti-roll bar is a way for muscle cars with sold rear axles to provide better straight line launching.