How to Replace Your Car's Control Arm Assembly?

The function of the suspension control arms of your vehicle is to connect the wheels to the frame and function as an essential part of the suspension system. The control arm acts as a mounting point for the wheel and complete suspension assembly. Due to their location, control arms are constantly subjected to harsh environments, road debris, and shocks. Over time, this leads to wear, and you have to replace your control arms.

However, if you are planning to replace the control arm yourself, it can be difficult and tricky if the parts are corroded or if the ball joint is damaged. Replacing a control arm requires a little experience and some tools, but can be easy if you have worked on your vehicle before. If you are witnessing symptoms of control arm failure, you should install a new control arm. This stepwise control arm replacement guide will help you replace your old, worn-out control arm with a new one.

1. How To Replace The Lower Control Arm?

Replacing your lower control arm is fairly easy and straightforward in most passenger cars. It depends on the suspension design and the type of vehicle you own. For example, it is difficult to work on a vehicle with a torsion bar and should be left to a professional mechanic. In this guide, we will learn how to replace the lower control arm on a vehicle with a MacPherson suspension system or double wishbone suspension system, which is mostly used in off-road vehicles and SUVs. Also, to ensure a hassle-free and perfect installation, it’s important to purchase the correct lower control arm.

2. Remove The Wheel

First, loosen the lug nuts but do not remove them completely. Secure the wheel by leaving a lug nut on so that the wheel doesn’t fall unexpectedly when you lift the car with a jack. Position the jack according to the owner’s manual’s instructions for changing a tire. Lift the car using the jack, and place the jack stands under the car for stability. Remove the bolts that secure the wheel and remove the wheel.

3. Remove The Ball Joint

Removing the wheel will expose the steering knuckle. Start with removing the ball joint. Remove the cotter pin (not every car has it), which is located below the castle nut, and lock the ball joint. Some cars have a pinch bolt instead of a castle nut. Use a wrench to loosen the nut or the pinch bolt after removing the cotter pin. You can use a screwdriver to create space between the pinch bolts so that the fit isn’t tight. Then, by using a hammer, strike the spindle or the control arm to remove the ball joint from the steering knuckle.

4. Remove The Sway Bar or Stabilizer Bar Link

A sway bar, also known as a stabilizer bar, is a long, U-shaped rod that prevents the vehicle from rolling over at corners. These are connected to the control arm with the help of a sway bar link. Remove the nut by holding it with a wrench or a socket and loosening the nut with a socket. After loosening it, you may need to shock it loose, just like you did with the ball joint. Remove it from the lower control arm mount so that plenty of space is available to do the next job.

5. Remove The Control Arm Mounting Bolts

The control arm is mounted to the frame or subframe of the vehicle by two bolts, which can be in a vertical or horizontal position. Some of them may have a nut on the backside, and you can loosen these bolts using a wrench and a breaker bar. After loosening these bolts, the arm may come loose and is ready to be removed from the vehicle. You might have to remove the engine splash shield to gain better access to the control arm bolts.

6. Install The New Control Arm

Grab your new control arm and inspect if the pre-fitted bushings are functioning properly and are greased. When installing the control arm, the first step is to align the bolt holes. It can be a little tricky as the other hole may get out of alignment. Use a screwdriver to align the holes and insert a new set of nuts and bolts. It is critical to replace your old control arm nuts and bolts because they may be rusted and rounded off. Hand-tighten the nuts and bolts.

7. Attach The Sway Bar Link And Ball Joint

Reattach the sway bar link you removed earlier. After doing this, insert the lower ball joint of the control arm into the steering knuckle. Ensure the ball joint is seated on the steering knuckle properly by using a hammer. Hand-tighten the castle nut or the pinch bolt that holds the control arm ball joint to the steering knuckle. Also, hand-tighten the sway bar link and other hardware. Tighten all the control arm ball joints and sway bar nuts and bolts to the recommended torque specifications using a torque wrench. Insert the cotter pin underneath the ball joint and castle nut.

8Reinstall The Wheels And Test Drive

The last step is to align the wheels of your vehicle. It is important to get a wheel alignment done after replacing control arms or changing other suspension components.

9. Upper Control Arm And How To Install It?

Most front-wheel drive vehicles, such as a hatchback or a sedan, are equipped with a lower control arm and a MacPherson strut suspension system. However, vehicles such as SUVs, off-road vehicles, trucks, and 4x4s have both upper and lower control arms to ensure balanced wheel control and stability. Vehicles with upper and lower control arms have a double wishbone suspension setup. The main difference between a double wishbone and a McPherson suspension system is that the MacPherson system makes the suspension very compact and the cabin more spacious, allowing room for passengers, the steering system, etc. MacPherson is mostly used on the front, and double wishbone is used on the rear. However, many SUVs, off-road vehicles, and performance cars use double wishbone suspension in the front because it offers better steering and handling compared to MacPherson struts with a single control arm.

10. How To Install A Upper Control Arm?

• Lift the vehicle and remove the wheels.
• Detach the ball joints situated on the top side by loosening the pinch bolts. You might need a hammer to pop out the ball joint of the control arm.
• Unlike the lower control arm, the sway bars are not connected to the upper control arm.
• Remove the two mounting bolts that connect the upper control arm to the frame.
• After removing the old control arm, make space for new ones. Check the pre-installed bushings on the new upper control arm.
• Install the new upper control arms and tighten them to the manufacturer’s recommended torque specification.
• Take out the vehicle for a short spin and look out for weird noises, which should be rectified soon.