Critical to the ride, handling and steering of your vehicle, control arms are an important part of the steering & suspension system.
Made up of a body, ball joint and bushing, the control arm connects to the vehicle frame with the bushing and attaches to the wheel via the ball joint.
Control arms allow the wheels to move up and down to maintain contact with the road, this is key to ensuring that the vehicle moves smoothly while turning and travelling on the road.
Control arms can be found on each side of the front of the vehicle, with many vehicles having an upper and lower control arm. Having two connection points ensure stability and balanced wheel control.
The upper control arm connects to the uppermost area of the front wheel and the lower control arm connects to the lower most area of the front wheel, with both arms then attaching to the frame of the car. If you have independent rear suspension, the design is similar.
What Is a Control Arm?
A control arm, also called a suspension arm, connects the wheel hub assembly or steering knuckle to the vehicle frame. It typically consists of a body, ball joint, and bushing.
The control arm helps the wheels move up and down to keep your car in contact with the road. This gives you maximum control over your vehicle’s movement, especially when driving over bumps or curves.
You may have one pair of control arms or more based on your car’s suspension type. The two common suspension designs are:
- MacPherson strut-type: This has a single lower control arm on the front wheel and is found in newer cars. In this design, the strut’s upper end connects to the vehicle frame, while the lower end is fixed to the steering knuckle with screws.
- Double wishbone: It has an upper control arm that connects to the front wheel’s topmost area, while the lower control arm connects to the lowermost area. Both arms then attach to the car’s frame.
However, like other car parts, the control arm deteriorates eventually.
Bad Control Arm Bushing Symptoms
A couple of rubber bushings hold the control arm in place and soften road vibrations. Over time, these bushings wear out due to moisture or debris impact. As they deteriorate, the control arm becomes loose, exhibiting these signs:
#1. Uneven Tire Wear.
One of the telltale signs of failing control arm bushings is uneven tire wear. When these bushings deteriorate, they can cause the control arms to move excessively, resulting in uneven pressure distribution on the tires.
This uneven wear typically appears as bald spots or excessive tread wear on specific areas of the tires. If you notice irregular tire wear patterns, it may indicate worn control arm bushings.
#2. Vibrations and shaking.
As control arm bushings wear out, they lose their ability to dampen vibrations effectively. Consequently, you may experience increased vibrations and shaking in the steering wheel, floor, or seats while driving.
These vibrations are more noticeable when going over bumps or rough roads. If you sense an unusual amount of shaking, it could indicate deteriorating control arm bushings.
#3. Clunking Noises
When control arm bushings fail, they can create clunking or knocking sounds while driving. The excessive movement and play in the control arm can cause metal-to-metal contact, resulting in these noises.
You may hear clunking sounds when going over bumps, turning, or during sudden stops. If you notice any unusual noises, especially from the front suspension area, it’s essential to have your vehicle inspected promptly.
#4. Poor Handling and Steering Response
Worn control arm bushings can significantly impact your vehicle’s handling and steering response. You may notice increased body roll, where the vehicle leans excessively to one side when cornering.
Additionally, the steering may feel loose or less responsive, making it harder to control the car accurately. These issues can compromise your safety on the road and should be addressed promptly.
#5. Excessive Vibration during Braking.
If your control arm bushings are nearing failure, you may experience increased vibration or shaking during braking. As the bushings deteriorate, they can allow the control arms to move excessively, affecting the alignment of the wheels.
This misalignment can lead to vibrations and shaking, particularly when applying the brakes. If you feel unusual vibrations while braking, it’s crucial to have your vehicle inspected to prevent further damage.
How to Diagnose a Bad Control Arm
To start, you’ll need to raise your vehicle and look for parts like a worn ball joint, tie rod, or control arm bushing. Checking these components requires technical knowledge and expertise, so you should call an auto repair mechanic.
Here’s how they’ll perform the diagnosis:
- Visually inspect the control arm for cracks or rust accumulation.
- Look for tears or cracks on the bushings.
- Check the ball joints for torn boots or grease leaks.
- Inspect other steering and suspension components for any issues.
- Place a pry bar on the control arm near one of the bushings. Use the bar to push and pull the control arm downward to check its movement. If the movement is more than 1/8 of an inch, it indicates excessively worn bushings.
After identifying the issue, your mechanic will proceed to fix it.
How Does a Mechanic Replace a Broken Control Arm?
To replace the control arm, your mechanic will:
- Disconnect the sway bar, ball joint, or other suspension parts.
- Detach the ball joint from the steering knuckle.
- Unscrew the vehicle frame’s bolts.
- Remove the faulty control arm.
- Clean the control arm’s mounting points.
- Install the new control arm and fix the bolts.
- Tighten the bolts and the control arm as per the manufacturer’s specifications.
- Reattach and install the ball joint, sway bar, and other parts that were removed earlier.
- Perform a proper wheel alignment and test the car for odd noises or poor handling.
Changing the control arm is an intricate process best left to an expert. However, if you’re concerned about how much a professional will charge, here’s an estimate.
Control Arm Bushing Replacement Cost
The cost to replace a control arm bushing will vary greatly depending on the make and model of your vehicle.
The cost for a new bushing range between $105 and $126, while the average labor costs are between $145 and $183.
The average cost for a Suspension Control Arm Bushings Replacement is between $250 and $310.
Usually, fees and taxes are added on, and you may need to replace other suspension components at the same time or have an alignment done.
When replacing suspension components, it is possible you may not need an alignment if the ride height stays the same and any eccentric bolts are left alone, but ultimately this is up to the mechanic’s professional opinion (and the factory manual).
To find the best deal, shop around at different auto parts stores. This job can sometimes be done by an experienced home mechanic but it may be difficult to remove the old rubber bushing.
Summery
Recognizing the signs of failing control arm bushings can help you identify potential suspension problems with your vehicle.
Uneven tire wear, vibrations and shaking, clunking noises, poor handling and steering response, and excessive vibration during braking are common indicators of control arm bushing failure. If you notice any of these signs, it’s essential to have your vehicle inspected by a qualified mechanic.
Timely replacement of worn control arm bushings can restore your vehicle’s stability, ensure proper handling, and maintain your safety on the road.