Querlenker: Der ultimative Leitfaden

control arm the ultimate guide
control arm the ultimate guide

In a vehicle suspension system, there is one part that serves more than one purpose- the Kontrollarm. You may have heard people call it different names, such as “A” arm or wishbone. Control arms are one of the most common vehicle parts, and you will find it in almost every automobile on the road.

This article contains information about this crucial component. It aims to help you ensure safe driving and smooth rides as a bad control arm affects both drivability and safety. The guide contains these topics.

  • Control arm definition and its location in the suspension
  • Control arm function
  • The different types of control arms
  • Bad control arm symptoms
  • Control arm diagnosis and troubleshooting
  • The procedure to replace a bad control arm, and
  • How to purchase a control arm

Whether a car owner or intending to become one, you will find the information contained here useful. Control arms are among the most ignored car parts. These components look simple, with no moving parts, and many people mistakenly think a bad control arm cannot affect vehicle performance.

Reading through the whole guide will make you fully knowledgeable about this suspension system component. You can also choose to go straight to the topic that you are curious about or which will help solve a problem such as control arm replacement. To get us started, a look at what a control arm is.


Chapter 1: Definition of Control Arm

Control Arm Function

Control Arm Designs

Chapter 2: Control Arm Material and Assembly Types

Control Arm Materials

Control Arm Assemblies

Chapter 3: Control Arm Problems and Causes

Probleme mit dem Querlenker

Causes of Control Arm Problems

Chapter 4: Bad Control Arm Symptoms

Signs that a Control Arm is Bad

Chapter 5: Control Arm Diagnosis and Troubleshooting

Control Arm Diagnosis Tests

Control Arm Troubleshooting

Chapter 6: Control Arm Replacement

Lower and Upper Control Arm Replacement Procedure

Control Arm Replacement Questions Commonly Asked

Chapter 7: How to Buy a Control Arm

How to Buy the Right Control Arm for Your Type of Vehicle

Kapitel 1

Control Arm Definition

The control arm image sample
Source: http://tunersmotorsports.com

A control arm is the part that forms the link between the suspension of a car and the chassis. Although control arms come in different shapes and sizes, they are easy to recognize or spot. They are the visible metal structures that run from the vehicle body to the wheel assembly.

On the chassis side, a control arm mounts by means of bolts. It hinges on rubber or polyurethane bushings called control arm bushings. The wheel assembly end of the control arm features a ball joint. That way, the component moves on both ends.

You will mostly find control arms in the front axles where they attach to the steering knuckle. Some heavy and high-end vehicles will have control arms in the rear axle as well. Most control arm car parts are broad at one end and narrow at the other. They can be an “A” or “L” shape, but some feature a simple shaft.

The number of control arms on a single wheel varies depending on the type of vehicle. Some have two control arms on either side- an upper and lower one. These can be seen attached to the wheel assembly through ball joints while the other ends bolt to the vehicle frame. This type of suspension system is called double “wishbone suspension,” and for reasons we will see shortly.

Modern, inexpensive cars mostly have a single control arm at each wheel- a lower control arm. These are vehicles that use the MacPherson strut suspension. This type of suspension supports most of the weight on a strut, and the reason for the lack of an upper control arm. It has its advantages and disadvantages (we will see about that in a minute).

Control arms feature three main parts: bushings and sleeves, main body, and ball joint. Control arm bushings help to reduce friction and vibrations while the control arm ball joint forms the pivot at the steering knuckle or wheel assembly. The main body is the control arm link that connects the component to either end. It can be stamped steel, cast iron, or aluminum.

Here is a control arm diagram showing the different parts.

The control Arm Diagram

Control Arm Function

What does a control arm do in an automobile? The component serves several purposes.

It connects the wheels to the frame, which adds to a vehicle’s stability. During the times when you drive over rough surfaces on the road, it is the control arms that help to make the ride smooth. The components synchronize the movements of the wheels with that of the frame, helping to dampen vibrations. It does that with the help of the jointed ends.

The control arm purpose does not end there. These components enhance control of a vehicle. By allowing for rotation of the steering knuckle at the ball joint, a driver can steer a vehicle while still moving forward. Control arms allow the wheels to move up and down while keeping them in contact with the ground and stabilizing the vehicle. That way, you do not feel the severity of potholes or bumps. The lower control arm function is not different from that of the upper. Both allow for vehicle control and make rides smooth.

Control Arm Designs

Control arms come in different designs. There are the “A” shaped types, which also gave rise to the other name such as  “A” arm, “A” frame,” and “wishbone.” These appear like a triangle and are one of the most common designs for these vehicle components. “A” shaped control arms have the narrow end attach to the wheel assembly and the broader one the frame of the car. The narrow end usually features a ball joint as a pivot point and the broader one bushings.

Design of Control Arms
Source: zoneoffroad.com

Some control arms are an “L” Shape. Like the “A” shaped design, they also connect to the steering knuckle on one end and pivot on a ball joint on the opposite end. The other control arm design is a single shaft. It uses the same connections as the other control arms, that is, a ball joint at one end and bushings on the other.

Control Arm's Design
Source: http://1autoshop.com

For many years, the double wishbone suspension was the norm or standard for most vehicles. This came in the form of two control arms, one on the upper side of the suspension and another the lower. The two control arms required two ball joints, an upper and lower ball joint.

As you can guess, the double control arm design meant more maintenance. There were two ball joints to worry about, the lower and upper control arm joint. Because the ball joints bore most of the car’s weight, it also meant fast wear rate of the control arm assembly and shorter service intervals. There were also bushings to worry about- those on the upper and lower control arm.

Then came the MacPherson suspension. This had a strut to support the weight of the car. That meant doing away with the upper control arm and, therefore, the ball joint. This type of suspension was minus several components- an upper control arm bushing, ball joint and the arm itself. As a result, it was less costly or tasking to maintain.

Vehicle manufacturers quickly adopted to the MacPherson or strut suspension and the reason for its popularity in most cars today. These suspensions feature fewer parts, which means less cost to manufacture them. They also allow for compactness and less weight in the steering parts, which results in better vehicle handling.

The double wishbone suspension is still common today. Reasons for that include the better handling capabilities and efficient control. In modern automobiles, you will mostly find this type of suspension used in high-end cars. These are vehicles where performance is necessary. Their owners also do not mind the repair or replacement costs of the suspension.

Away from the different suspensions, let us look at a different type of control arm auto parts you might come across.

Einstellbare Querlenker

Einstellbare Querlenker
Source: http://www.roughcountry.com

These are used to adjust wheel camber or vertical alignment. In automotive language, positive camber means a wheel that has tipped outward while negative camber refers to a wheel tipped inwards. Properly adjusted camber allows even tire wear. It also enables proper traction when driving.

Next, we let us discuss the different materials used in the manufacture of control arms and the up and downsides of each.

Kapitel 2

Control Arm Material And Assembly Types

Material's Component
Source: http://switchsuspension.com

Control arms are important components in a vehicle. As we have seen, these auto parts ensure smooth driving and passenger or driver comfort. Because they hold the wheels to the frame, they need to be sturdy enough. A broken or bent control arm is not desirable when driving. That means manufacturers have to choose control arm materials carefully. Not only that but also use the right manufacturing process. Control arms must be checked to satisfy different requirements.

In this chapter of the control arm guide, we will look at the manufacture of control arms and the various materials used.

Control Arm Materials

What are control arms made of? Different materials can be used to construct them. They include:

Steel Control Arms
Source: http://www.speedwaymotors.com

Steel– this has been the main material for control arms in the history of vehicles. Stamped steel was (and still is) used. Steel control arms cost less to manufacture. That means they can be mass-produced, and one of the reasons for their low price on the market.

Steel control arms are inexpensive, a reason for a car owner to prefer them when replacing a bad one. Steel flexes under stress, which is an advantage when used for a suspension part. It means fewer cases of breakage or cracking of the control arm when off-roading or driving with heavy loads. Steel control arms are also strong enough to be used on the average car.

A major disadvantage of steel control arms is their inability to resist rusting. With these components hanging low and exposed to wet conditions and salts, rust is almost inevitable when steel used to make them. That would mean reduced lifespan. In a rusted condition, the ball joint and bushings would present a challenge to remove.

Steel also produces heavy components. Weight in the steering system parts can reduce the ease to handle a vehicle. Many car manufacturers strive to make lighter components today and the reason they may not use stamped steel control arms.

Aluminum Control Arms
Source: http://iconvehicledynamics.com

Aluminum– using this material offers several advantages. Aluminum is lightweight. For the components that connect to the steering system of a vehicle, too much weight affects handling characteristics. Aluminum control arms help to reduce weight, which results in easier steering.

Aluminum control arms are made from cast aluminum. They are quite sturdy, a necessary characteristic for suspension parts. Some aluminum control arms can even be stronger than steel ones. Another major advantage of aluminum when used to manufacturer control arms is the ability to resist corrosion. Aluminum does not rust, which means a longer lifespan even when the components are subjected to extremely wet conditions.

A disadvantage of using cast aluminum is its reduced ability to flex under pressure. While control arms made from steel will bend if exposed to stress or impact, aluminum control arms would crack or break. Another disadvantage of aluminum is its soft nature that would cause accelerated wear, especially at the ball joint end.

Querlenker aus Gusseisen
Source: http://www.everydayautoparts.com

Cast Iron– cast iron is a popular material for the control arms used in most modern vehicles. This material offers several benefits. It is sturdy, which makes cast iron control arms suitable for conditions where a lot of weight has to be supported. That makes cast iron control arms the most used in trucks and SUVs.

These types of control arms can withstand several other environments and driving conditions to give the component a longer life. Compared to steel, cast iron control arms are lighter. That means enhanced steering or vehicle handling.

Control Arm Assemblies

Control arm assemblies come in different types. These are discussed below.

Bolt in– this kind of assembly uses bolts to connect the different parts of the control arm. MacPherson suspensions usually use bolt-in assemblies. Bolt-in control arms allow dismantling of the parts. However, it also means more work.

Unitized– in this control arm assembly, the control arm comes with a ball joint. Because the ball joint and the control arm form one part, you cannot replace only the control arm or ball joint. It requires you to remove the whole assembly.

These types of assemblies are better when it comes to replacing a bad one. You will not have many parts to remove, and the process takes a shorter time. You can also use simple tools for the task.

Press in– these are also integrated with a ball joint. Press-in control arms are commonly used in large vehicles. As the unitized type, press-in assemblies make replacing worn or damaged control arms easy.

Regardless of the material or assembly, a control arm will eventually age and go bad. Sometimes, it can be as a result of rough driving or accidentally hitting the wheels on something. Control arm damage or wear can take many forms. It also happens to different parts of the control arm as we will see in the next chapter.

Kapitel 3

Control Arm Problems And Causes

Problems of Control Arms
Source: http://eibach.com

Automotive control arms are simple components but which are prone to damage. Malfunction mostly happens at the control arm bushings and ball joint, and rarely the main body. In such cases, replacing the affected parts solves the problem. But not all control arms allow the bushings to be replaced. Some come with built-in ball joints and require changing the whole assembly if the ball joint wears out. This chapter examines the different forms control arm failure as well as the causes.

Probleme mit dem Querlenker

Problems are different for the different parts of this auto part. Control arm bushings break down and cause the metal parts to come into contact. Ball joints wear down and produce excessive play. The main body may rust, bend or break to cause drivability issues. Let us look at the possible problem for each part.

Main body damage- depending on the type of material used, a control arm’s body may rust. This happens if the component comes into contact with water or moisture over a long period. Rust affects the structural integrity of a control arm. It also makes replacing the components at either end difficult.

The body of a control arm may also crack, bend, or break under extreme conditions. These include collisions, excessive vehicle abuse, or the wheels hitting a curb. A control arm can also damage if wrongly hooked when being towed.

Damages Image of Control Arms

Control arm bushings damage– control arm bushings are mostly rubber and susceptible to breakage and wear. Over time and if subjected to extreme usage, the bushings can fail to allow the metal components of the suspension to touch.

Bad control arm bushings are loose and cannot restrict the movement of the control arm they are mounted to. They also do not absorb vibrations to dampen off the noise. That leads to rough rides and difficulties controlling the vehicle. The vehicle makes unusual and annoying noises while driving.

Control arm ball joint damage–at the end of control arms where they attach to the steering knuckle or wheel assembly mounts a ball joint. Some control arms come with a built-in or permanent ball joint, while others use a separate joint. If the ball joint is permanently attached, its damage would mean having to replace the control arm.

Control Arm Ball Joint Image
Source: http://forums.quattroworld.com

Ball joints, especially those of lower control arms, support a lot of weight. They, therefore, do wear out quickly. It can make vehicle control a challenge. Driving a vehicle whose control arm ball joint is faulty can even be a safety risk.

Causes Of Control Arm Problems

Other than time, some conditions can cause premature damage to a vehicle’s control arms. These are situations that incline the component to rust, the bushings or ball joints to rapid wear, and extreme environments that cause breakage or bending. The causes of a bad control arm include:

Quick Take Off

Going into drive and gas immediately after starting the car takes a toll on the suspension, particularly the control arm bushings and ball joint. Having this driving habit causes rapid wear and breakdown on these ends of the control arm. If the bushings are the irreplaceable type and the ball joint built-in, it can mean having to install a control arm sooner than normal.

To avoid early damage, it is advisable to be gradual in transitioning from vehicle start to gas. In other words, accelerate gradually to allow the suspension to move in time with the car frame. It improves the life of the control arm considerably.

Rough Terrain

Bumps and potholes cause stress to the control arms. If the weight of the vehicle is always high and the road conditions rough, the effects can be control arms that break down before the usual lifespan. It mostly damages the main body of the control arm by causing cracks and breakages.

Severe road conditions also ruin the ball joints at the end of the control arms, and can even cause it to break free and become a driving risk. The bushings would break, too, and reduce the suspension’s ability to reduce vibrations or friction. Avoiding rough conditions of the road is recommended. If impossible, it is advisable to drive over potholes and bumps slowly and carefully.

Wet Conditions

During Wet Conditions
Source: http://www.audiworld.com

Moisture causes the surfaces of a control arm to rust. Over time, the rust wears off the metal and causes destructive corrosion. Moisture or water will also cause the protective dust boots of the ball joints to break down and allow the entry of debris into the joint. Dirt and debris are the main causes of accelerated wear and eventual joint failure.

Water coming into contact with the control arm bushings would also cause damage that affects the usefulness of the component. Water breaks down the rubber that makes the bushings.

Bad Driving Habits

Every vehicle requires careful driving and handling to protect the various components. In the case of moving auto parts such as control arms, extreme care is necessary. Collisions would cause the arm to distort, the bushings to crack, and the ball joints to break down.

Some common rough driving habits include situations where the wheels hit a raised part of the road or parking, causing physical impact to the ball joints, bushings, and control arm. It can also be situations where you have to brake hard. Braking a speeding car suddenly puts stress on the control arm and its components.


During control arm installation, under-tightening of the mounting bolts is possible. Should that happen, any slight stress or strain on the component would result in excessive movement at the under-tightened ends. In the case of the ends that attach to the chassis, the movements would cause wear and damage to the bushings. On the opposite side, a loose mounting would lead to damage to the ball joint. The frame of the control arm would not be spared either, and the possibility of cracks would be higher.

As long as a vehicle is being driven, its control arms will eventually age and go bad. Sometimes, damage can happen to relatively new control arms due to various reasons such as impacts. Luckily, a bad control arm will show signs. The symptoms can be seen with the eyes, felt while driving, or even heard. In the next chapter is a list of these signs and an explanation for each.

Kapitel 4

Bad Control Arm Symptoms

Bad Control Arms Symptoms
Source: http://www.howacarworks.com

Except in situations where a control arm breaks or bends while driving, most faults show gradual signs. Knowing the symptoms of a bad control arm is an essential skill for a vehicle owner. These components hold the wheels to the car frame, and their failure can compromise vehicle safety.

Bad control arms can make rides a most uncomfortable experience, especially if driving on rough terrain. A driver would also struggle to control a vehicle whose control arms have gone bad. The good thing is that you can tell when the control arms in a vehicle are faulty.

Signs That A Control Arm Is Bad

The following are the symptoms to watch out for.

Quelle: http://www.youtube.com


Worn control arm bushings cause the wheels to vibrate when you step on the gas pedal. Also, when taking a corner. The wheel shimmy may transmit all the way to the steering wheel. Should you experience a trembling steering wheel, you may want to check the control arms to see if the bushings are worn. Other car components can also cause the steering wheel to vibrate. Find out if they are responsible before confirming a damaged control arm.

Wandering Steering Wheel

Apart from the vibrations, bad control arms maker the Lenkrad to move from side to side. Steering wandering could be a sign that the bushings or ball joints are worn and moving too much. It takes driving comfort away and could also result in loss of vehicle control. Replacing the damaged parts of the control arm is highly advised as soon as you experience this symptom.

Unusual Noises
Source: http://vehicle-tipsninfo.blogspot.com

Unusual Noises

Again, this sign indicates excessively control arm bushings and ball joints. Usually, bushings restrict the movement of a control arm. Ball joints, too, allowing mostly rotation. Wear increases movement and causes the metal parts of these joints to knock. That results in sounds coming from the suspension, especially when accelerating, going around a bend, or driving in rough road conditions.

Bad control arm noise can be a clunking, popping, or snapping, sound. It can also be a squeak when you bring the car to a halt. These noises are slight at the beginning, and you may be tempted to ignore them at first. They will increase in intensity if you do not take action and reach a point where they openly indicate badly damaged suspension parts.

Steering Wheel Pulling to the Side

Control arms allow efficient steering and the up/down movement of the car body. If faulty, they cannot serve that purpose as intended. You will experience the car pull to one side while driving and have to use force to bring it back to course. While this may also be a sign of fault in other components, damaged control arm parts could be the reason. Checking the control arms on either side would help you confirm the problem.

If the steering wheels feels too stiff at times, it could mean the ball joints are too dry. Lost lubrication would cause the control arm not to pivot freely, affecting steering ease. It can bring drivability issues and even be a safety concern. This problem mainly affects the serviceable ball joints, especially when you have forgotten to lube them. Unless the joints are badly worn and causing other symptoms, applying lubrication would restore their function.

Wobbly Wheels
Source: http://en.wikipedia.org

Wobbly Wheels

Wobbly wheels can be a result of damage at the wheel hub but also due to bad control arms. In a vehicle, control arms attach the wheels to the chassis. They must do so firmly, or the wheels will not rotate in a true plane. Bent control arms or those with worn ball joints and bushings will distort wheel alignment and lead to a wobble. In addition to making affecting drivability, wobbly wheels can be unsafe at high speeds.

Sudden Change in Braking

As odd as it may be, bad control arms can make the brakes to assume sudden and unexpected improvement. It happens when bushings have worn and do not allow for the back and forth oscillation of the control arm. The improvement is often only temporal, though, and does not occur every time you depress the brake pedal. The erratic brake performance can be a drivability and safety concern if not checked. Immediate action would, therefore, be necessary if you notice this symptom.

Uncomfortable Rides

Control arms are hinged on bushings that dampen vibrations and help to reduce the severity of bumps or rough terrain. The other end pivots on a ball joint that smooths the wheel up and down movements. When these parts get damaged, passengers start to feel the potholes and bumps on the road.

Bad control arms will also cause a vehicle to lean too much at corners, especially sharp ones. When taking off from a stationary state, the rear of the vehicle experiences a backward movement. If you notice these signs, it could be about time you installed new control arms.

Uneven Tire Wire
Source: http://www.audiworld.com

Uneven Tire Wear

There are many causes of uneven tire wear. Bad control arms is one of them. Worn bushings and ball joints can throw the wheels out of alignment, causing inner edges to wear excessively. Bent control arms, too. While damaged bushings and ball joints are easy to detect, a slight bend of the control arm would not be. It requires precise measurements to be able to determine that.

A bad control arm may be as a result of damage to the parts it hinges on, or the control arm itself. It could be worn or broken bushings, bad ball joint(s), or a bend. The symptoms listed here show that something may be wrong with the component. But how do you determine the kind of damage or even the faulty part of the control arm? That is the topic of the next chapter.

Kapitel 5

Control Arm Diagnosis And Troubleshooting

Control Arm Diagnosis
Quelle: http://www.youtube.com

Suspecting that a control arm is bad is one thing, and knowing where the problem is another. Automotive experts advise that you stay alert to any symptoms that may affect suspension components so you can take action early.

While signs may not be apparent at first, carrying out tests can help find out faults. A bad control arm will be bent, cracked, or broken. Severe bends, cracks, and breakages are easy to spot through a visual inspection. Tiny bends would be hard to detect, the same for worn control arm bushings or ball joints.

In this chapter, we will look at the tests to diagnose both upper and lower control arms. We will also see the actions to take for each problem. Some of the diagnostic procedures involve visual inspections, while others require tools. They are easy to carry out, though, and will only take a short time.

Control Arm Diagnosis Tests

Things will need: a floor jack to raise the car and allow you to access the control arm and its components, jack blocks for safety, a pry bar to push aside the control arm during control, and protective gear to prevent injuries.

Test Drive
Quelle: http://www.youtube.com

Step 1 : Test Drive

This test aims to subject the suspension to driving extremes that would make symptoms clearer. To perform it, find an empty road stretch or empty parking lot. The area to test drive on should allow you to speed up safely, turn at any time, and take your hands off the steering wheel for a second or two.

Start the vehicle and accelerate quickly. Listen out for unusual control arm noise or sounds. Observe to see if there is backward movement of the vehicle’s rear. Those are signs of bad control arms. While speeding, turn sharply. Again, listen for clunking sounds. These will indicate worn control arm bushings or ball joints. Vibrations of the wheel, too.

Take your hands off the steering wheel for a moment. Does it move from side to side on its own? If it does, you could be having bad control arms. Feel for vibrations, one of the signs that the bushings of the control arm are worn.

While driving straight on, check to see if the steering wheel or the car pulls to one side. That would indicate a bent control arm that has thrown the suspension or wheels out of alignment. It could also be that the bushings are bad.

Assess, the ease of working the steering wheel. A stiff one often means bushings that have dried out or broken down. It could also indicate ball joints that have not been lubed for a long time and that are causing the control arms to fail.

Examine the Wheel and Tires
Source: http://www.fourwheeler.com

Step 2 : Examine the Wheel and Tires

Use a jack to raise the vehicle or hoist it on a lifting platform. Check the wheel wobble by pressing each with your hands. Excessive play could indicate several problems, and one of them is issues with the control arm or arms. Worn bushings or ball joints usually cause wheels to wobble.

Check the tires. Excessive wear on the inner edge can be as a result of misalignment. Ruling out other causes, the reason for that could be a bent control arm, worn bushings, or ball joints that have deteriorated.

Step 3 : Perform the Axle Slip Test

With the vehicle raised and the wheels spinning, have someone apply the brakes. If the axle slips for a moment on braking, you have damaged control arms. The bushings may be broken down and allowing too much movement of the control arm.

Perform Axle Slip Test
Source: http://www.fourwheeler.com

Step 4 : Inspect the Control Arm

Jack up the vehicle to access the control arm. Using an 18-inch pry bar or handle bar, push the control arm from one side to the other. If in good condition, the control arm should return to its earlier position or spring back on releasing it. If it does not, it is likely that you have a bad control arm that needs to be changed.

Look out from any sign of bending such as a wrinkle on the control arms. Small bends may be hard to detect. You may need to take measurements to ascertain that. Measure the distance between the wheel and control arm on either side of the car. The distances should be identical. If it is not, you may be having a bent control arm.

Examine the control arm for breakage or cracks. A few cracks may not be a cause for concern but would if pronounced and several. If the control arm is aluminum, watch out for cracks. This material is known for that problem. Breakage is not common unless the component just experienced a severe impact. But even then, it would be easy to see the problem. Lower control arms contain the load carrying joint, which means it may be wearing out a a faster rate compared to the upper one.

Inspect the Control Arms
Quelle: http://www.youtube.com

Step 5 : Check the Bushings for Damage

Control arm bushings are part and parcel of the control arm. The bushings are mostly rubber, which makes them prone to damage. Heat, salts, loads, and the movements of the control arm will take a toll on these essential parts over time. Eventually, the bushings deteriorate and the control arm does not cushion the vehicle anymore.

To check the bushings, remove the wheels to access the control arms. Examine them visually for damage. Signs include cracking, oil saturation and any other hint of poor condition. While still at it, check the ball joint for damage also. Look to see that the dust boot is intact. Ensure, too, that there is not too much movement of the ball stud in the socket.

Control Arm Troubleshooting

Once you have determined the problem, the next step is to fix it. There are two ways to it. You may replace the affected part or replace the control arm itself. Some bushings are replaceable. If they are damaged, all you need to do is find new ones and install them. Some ball joints may also be replaced. These are the press-in or bolt-on types and which can be changed without having to replace the control arm.

Control Arms Troubleshooting
Source: pmmonline.com

If the bushings are not replaceable, install a new control arm. Also, if the damaged or worn ball joint is built into the control arm to make one piece. Bent control arm symptoms include alignment issues that affect vehicle control. The only remedy is to remove them and place new ones in their place. Replace control arms that are showing signs of cracking or those that have broken.

When looking to install new control arms to take the place of bad ones, you are faced with two choices; to take the car to a repair shop or do it yourself. Control arms are simple auto parts, accessible and easy to remove or mount. The next chapter contains steps on how to replace a lower control arm for MacPherson suspension and both upper and lower for double wishbone suspensions.

Kapitel 6

Control Arm Replacement

Control Arm Replacement
Quelle: http://ricksfreeautorepairadvice.com

Most of the time, a bad control arm calls for the installation of a new one. Bad bushings cannot be repaired, the same with worn ball joints. If the control arm is cracked or bent, the only option would be to replace it. Control arm replacement can cost several hundred dollars average, which is why one would choose the DIY route.

The process to replace a damaged control arm is simple and straightforward. Almost every car owner can do it with only a few simple tools. However, you may need to be conversant with some auto skills, such as removing the wheels and correct torque when replacing bolts.

Lower And Upper Control Arm Replacement Procedure

The procedure explained below applies to most vehicles. Ensure you wear protective gear to avoid injuring your body, especially the eyes. These include googles and gloves. Ensure, too, that the vehicles is secured and safe to work on.

NB: In some vehicles, removing the load-carrying ball joint and control arm, leaves the weight resting on the coiled spring. It is a dangerous situation. If the jack slipped from its hold, the spring would fly out forcefully and cause fatal injuries. Because of this, you need to ensure the body of the vehicle is properly jacked and the wheels secured. Ensure also that the ground is flat and free of any interference.

Here are the things you will need.

Your new control arm(s), floor jack and jack stands, ball joint separating tool, mallet, crowbar, braked bar, torque wrench, ratchet wrench and sockets, penetrating fluid and brake clean.

Replacing the Control Arm
Source: http://www.ifixit.com

Schritt 1

Find a secure flat ground and loosen the lug nuts in readiness to remove the wheel or wheels.

Schritt 2

Safely jack up the vehicle and remove the wheel where the control arm to be replaced is.

Removing the lower control arm
Source: http://www.f150online.com

Schritt 3

With the vehicle raised and the wheel removed, locate the end of the control arm where it pivots on a ball joint. This is the joint that connects the steering knuckle and the control arm. You will need to force the ball joint out so it can separate from the control arm.

Spray all the bolts that you will need to remove with penetrating fluid. It will make them easy to unfasten.

Schritt 4

Remove the cotter pin and the castle nut holding the ball joint to the control arm. Use the ball joint separator tool and hammer to remove the ball from its mounting if it is the removable type. If you have a press, use that. If the unremovable type, taking out the bolt that mounts the ball joint to the steering knuckle is enough.

Schritt 5

Using a wrench, unfasten and remove the bolts that hold the control arm to the frame. Once the bolts are out, you can easily remove the control arm by pulling it out.

Removing the Upper Control Arm
Quelle: http://www.youtube.com

If your car uses a double wishbone suspension, it will have an upper control arm. Use this procedure to remove it.

Schritt 6

Remove the bolt that holds the upper ball joint in place

Schritt 7

Use a crowbar to lift the ball joint from the steering knuckle.

Schritt 8

Unbolt the other end of the upper control arm where it attaches to the vehicle frame. If the ball joint is the removable type, use the ball joint separator to release it from the control arm. If it is permanently built or mounted, leave it on.

New Contro Arm Installation
Quelle: http://www.clublexus.com

New Control Arm Installation

Some vehicles use ball joints and control arm bushings that can be replaced. If this is the case with yours, replace them at this point. You will need to use tools to press in the ball joints and the bushings. Once everything is set, use this procedure to mount the new control arms.

Step 9

Slide the new lower control arm into its mounting place on the frame of the vehicle. Insert and fasten the bolts partially, using your hands.

Step 10

Lift and insert the ball joint at the end of the control arm into the steering knuckle. Fasten the castle nut with the hands. If you had removed an upper control arm, replace it using the reverse of the procedure to remove it. Do so before tightening the lower control arm.

Once done, tighten the nuts and bolts fully and to the correct torque. Replace the wheel or wheels and lower the car. Test drive it to ensure the new control arm or arms are correctly mounted.

Test Drive
Source: http://forums.macresource.com

Control Arm Replacement Questions Commonly Asked

Vehicle owners with control arms that have gone bad usually have many questions to ask. Also, those looking to replace the components without help. We compiled and answered the most common questions regarding the installation of new control arms.

Question 1. How Often Do I Need To Replace Control Arms?

Answer. It depends on many factors, such as driving conditions, how gently or roughly your driving is, and the quality of the control arms. The average lifetime of new control arms lies between 90 000 miles to 100 00 miles.

Question 2. Is It Easy To Replace Control Arms?

Answer. It is. The process to replace control arms should present no difficulty. On average, removing an old control arm and mounting a new one would take one or two hours.

You do not need special tools. However, access to some of them such as control arm bushings tool or ball joint press would make the task easier.

Question 3. Is Driving With A Bad Control Arm Dangerous?

Answer. Unless it is badly damaged, a bad control arm will only cause awkward driving. It will also produce noises on rough terrain and when accelerating or braking.

If a control arm is severely bent, cracked, or if the bushings and ball joints are excessively worn, it can be unsafe to drive.

Badly damaged control arms can cause loss of control or the vehicle or even snap at the ball joint and result in a wheel caving in. So, yes, driving with a broken control arm can be risky. Driving on bad ball joints is even riskier. The joint could separate from the control arm and cause a safety concern.

Question 4. Do I Need To Replace Both Control Arms?

Answer. For a double wishbone suspension, yes. Both the upper and lower control arms will likely have been installed at the same time. Even if one of them does not show signs of damage, it may within no time.

It is also advisable to replace control arms on the other side of the axle for both double wishbone and MacPherson suspensions. You do not want a situation where you have a performing control arm(s) on one side and a bad one on the other.

Question 5. How Much Does It Cost To Replace A Control Arm?

Answer. The component itself costs less than a dollar, and labor to install it between a hundred and three hundred dollars. Combining the two amounts, you can expect control arm replacement cost from $150 to $350 to have a new control arm on your vehicle.

If you opt to replace a control arm yourself, the only cost to worry about would be the purchase price. It can be a huge saving when you have to install several new control arms at a go.

Speaking of the cost to replace this suspension component, you can see that doing the job yourself help reduce the costs involved. You would only spend around $50. But then, how do you go about buying the right control arm for your type of vehicle and budget? That is what we look at next.

Chapter 7

How To Buy Control Arm

How to Buy a Control Arm
Source: https://gmc.risna.co

Just like other types of car parts, purchasing a control arm requires careful evaluation of the options. Apart from finding a control arm that fits your specific vehicle, other factors will come into play and dictate the direction to take. There will be many control arm manufacturers if you choose aftermarket types, different control arm prices, and a wide range of features.

You want a control arm that will last you a long time. If you normally drive in harsh road conditions, you will want a control arm material that can withstand such environments. As you can see, there is a lot that you need to look into. We put up a control arm buying guide to help you with selecting the type, model, and brand to go for.

How To Buy The Right Control Arm For Your Type Of Vehicle

Here are the factors to consider

  1. Vehicle Type, Model and Year of Manufacture

To ensure the right control arm, you need to have this information with you. The auto parts dealer will ask for it to choose the model that will fit the description of your vehicle. If looking for the control arm online, you can easily find the type and model to buy easily.

Many auto parts websites provide spaces to input the information, from big ones such as advance autoparts or autozone to the smaller ones. It allows users to search online catalogs quickly and without difficulty.

You also need to have with you information regarding the position of the control arm to be replaced. That is because control arms are different depending on where they are used in a vehicle. There are lower control arms, upper control arms, and those used in the rear.

Steel and ALuminum Style Control
Source: http://www.ipdusa.com

  1. Decide on the Control Arm Material

Control arms are made using three different materials. They can be cast iron, cast aluminum or stamped steel. When choosing the control arm material to go for, it is recommended that you consider your driving conditions. Some harsh environments call particular control arms unless you want them not to last for long enough.

Aluminum control arms perform well in tough conditions. They are sturdy, sometimes even more robust than steel control arms. Aluminum does not rust, which makes control arm made from the material resistant to corrosion and durable. One of the main disadvantages of aluminum is in the way it gets damaged.

Under extreme stress such as collision or unusual load, an aluminum control arm would crack instead of bending. This increases the chances of breakage, whichcan be dangerous when cruising down a freeway at high speed.

Cast iron is sturdy and can stand up to a variety of harsh driving conditions. Cast iron is one of the most common materials for control arms. Control arms made from this material are also lightweight when compared to steel ones.

Steel control arms are inexpensive. They are also strong enough to be used in different conditions. However, steel is prone to rusting and will corrode if driving conditions are mostly wet.

OEM vs Aftermarket
Source: http://goldentouchnj.com

  1. OEM Vs. Aftermarket

This is one of the dilemmas that vehicle owners face when purchasing different vehicle parts. OEM control arms will have the characteristic of the original arms you may be replacing, both in style and performance. That means they will not have additional benefits. OEM control arms will also be expensive when compared to aftermarket types.

Aftermarket parts are designed to offer better performance in most cases. They may be more durable, sturdier, and more giving in different conditions. Aftermarket control arm manufacturers will also choose to make cheaper parts by trading off some features. As you can see, aftermarket control arms offer a wide range of choice for quality and price.

Single Control Arm or Full Kit
Source: http://www.chaosfab.com

  1. Single Control Arm or Full Kit?

When looking to buy a control arm, you will have the option to buy a single unit or complete control arm kit. Auto experts recommend full kits. The reason is that it is more convenient to replace the control arms on both sides and not only one. And if you have rear control arms as well, replace them on all four sides at the same time.

With a full control arm kit, it will be a long time before you need to worry about these suspension parts again. Considering the high control arm replacement cost, it can be more economical in the long run. Full kits also come with all the required fastening parts, which means you will not need to purchase anything separately when replacing control arms in your car.

  1. The Various Features

You will need to assess the features that the control arm comes with. Some will aim to make the component durable, others easy control arm installation. To get the best control arm, consider the technologies used to manufacture it. Powder-covered control arms, for example, will resist corrosion and last for a long time.

Other considerations include the brand, price, and warranty. Reputable auto parts manufacturers are known to produce quality components. If a company offers a lengthy warranty for their control arms, it can signify they are confident about its quality.

Consider also the different control arm prices. While too high prices do not always indicate quality, extremely low ones will not either. Choose control arms that are moderately priced. These will offer decent quality without denting your pocket. However, prices will vary depending on the material, type of control arm, and other aspects. Aim to buy a quality control arm without having to part with a lot of money.

Buying a control arm requires a careful weighing of the options available. There are so many of these components on the market today, which would make finding the right one for your vehicle a challenge. However, some research and knowledge about what to look for can help.

You may look up the parts online or visit an auto parts shop. Regardless of where you choose to shop, consider the different control arms that would fit your vehicle. Then, choose the one that offers better features and sells at a reasonable price.


Automotive control arms enable smooth rides, efficient steering and other drivability benefits. Not many vehicle owners understand that. As a result, they neglect these components and end up with uncomfortable cars that also also difficult to control. At times, bad control arms may even cause a break down of the suspension system while driving- a dangerous situation that could have been avoided.

Reading this guide means increasing your knowledge about control arms. You can now tell the component’s purpose, and why it is essential for it to remain in good condition always. Not only that but also how to pick the signs of control arm failure early enough. The guide contains information about how to troubleshoot the component. This should help you confirm the observed symptoms.

We also included a step by step procedure to change a damaged control arm. Using it, you will perform the task on your own and save money. Lastly, it is essential that you know how to buy a quality control arm. The article helps you to do that by explaining the factors to consider. In a nutshell, it is a comprehensive guide that will help you care for the control arm and experience driving comfort and steering efficiency.

1 Kommentar

    Is there suppose to be a small bracket on front control arms on a 1991 Mercury Capri base model?
    If so, what is it called? Thank you

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