A vehicle’s suspension is made up of numerous components, and the list varies with the type of suspension used and the specific engineering of the vehicle. The weak points of suspension components are typically at their points of movement.
Because of this, the repair can be costly and very meticulous as you may not only be dealing with a single part but possibly a whole system.
Costs of Suspension Repairs
Car suspension costs can be affected by several factors. These include the type of vehicle and model being serviced, the quality and source of the parts used, and the labour cost being applied, which depends on the auto shop’s location.
To be able to demonstrate the variations in the suspension repair costs, three common vehicles are used as an example, using a labour rate of £70 per hour:
- 2007 Jeep Grand Cherokee 4WD with a 4.7-liter engine
The rear solid axle uses an upper and lower control arm on each side. The labour time to replace a lower arm is estimated at 0.4 of an hour, 0.5 of an hour to replace the right upper arm, and 1.2 hours to replace the left upper.
A factory upper arm costs about £100, and a factory lower arm costs about £120. A non-OE upper arm costs about £47, and the lower one is about £48. The total cost to replace a rear lower arm would be about £150 using OE parts or about £76 using aftermarket parts.
To replace the right upper arm, the cost is about £135 using OE parts and about £82 using aftermarket parts. The additional labour to replace the left upper arm would cost about £65 either way.
- 2011 Subaru Forester
The front suspension is a Macpherson strut type and uses a lower control arm with a press-in ball joint. The labour time to replace the front lower control arm is estimated at 1.9 hours.
A factory replacement part costs about £280, and a non-OE replacement part costs about £75. The total cost to complete the job would be about £415 using OE parts or about £210 using aftermarket parts.
The rear suspension is a simple multi-link design using two lower lateral arms and one upper arm. One lower arm, the rearward, bears most of the burden of control, while the second is adjustable for toe angle.
The upper arm holds the camber stable. The labour time to replace an upper arm is estimated at 0.8 of an hour, and a factory replacement costs about £255, making the job cost about £310. There is no general aftermarket availability for the upper arm.
The lower arms have more aftermarket sources as they are more prone to rust and/or collision damage and replacement. The rearward lower arm costs about £110, and the forward lower arm costs about £84; both through Mevotech and other manufacturers. Labour time is estimated at 0.8 for each, making the replacement of the rearward arm job cost about £165, and about £140 for the forward arm.
- 2005 Chevrolet Silverado 4WD with a torsion-bar type independent front suspension
The labour time to replace a lower control arm is estimated at 1.6 hours. A factory replacement part costs about £335, and a non-OE part costs about £166. This makes the job for a lower arm replacement cost about £447 using factory parts, and about £278 using aftermarket parts.
The labour time to replace the upper control arm is estimated at 1 hour. A factory replacement part costs about £282, and a non-factory part costs about £70. The total cost to complete the job would be about £352 using factory parts and about £140 using aftermarket parts.
In either case, if the upper or lower arm is replaced, a new ball joint is pre-installed in the new part. If an upper ball joint needs to be replaced, it is typically replaced with the control arm. If it’s the lower ball joint that needs replacement, that can be replaced separately without the whole arm.
A factory lower ball joint costs about £140, and a non-OE replacement costs about £40, while the estimated book time for replacement is estimated at around 1.2 hours. The total cost to complete the job would be about £225 using factory parts or about £125 using aftermarket parts.
Below is a list of some of the parts involved:
These support the weight of the vehicle, holding the weight of the chassis and frame assembly up off the suspension. Springs are typically non-wear items, but they establish the ride height of the vehicle and can, in some cases, weaken with age.
If there is a problem with a vehicle’s ride height, it’s almost always a problem with the springs. Sometimes, this only becomes evident during alignment, as worn springs can lead to a vehicle’s suspension being out of spec and then, tyre wear.
- Shocks and struts
These absorb road forces and control the oscillation of the springs. The main problems they develop are internally in their dampening mechanisms.
Another common problem is popping noises when steering, which can happen when the bearings in the upper strut mounts become worn and don’t allow the wheels to turn smoothly.
- Steering knuckle or rear knuckle
The knuckle connects various suspension members together. On the front, it has a steering arm to which the tie rod attaches and is called a steering knuckle.
Typically, it is a non-wearing item made of cast iron or cast aluminium. Ordinarily, short of collision damage, there shouldn’t be any reason to replace a knuckle.
- Tie Rod Ends
This is the connection from the steering rack or gearbox that transfers steering forces to the steering arm on the knuckle. The inner and outer tie rod ends use ball sockets to allow for suspension movements, and the ball sockets can wear and cause tyre wear and play in the steering.
- Ball Joints
These are the ball sockets that the front knuckles rotate on as the vehicle is steered. On an independent front suspension, there are two ball joints: an upper and a lower.
On a Macpherson strut suspension, there is only a lower ball joint; the upper function is provided for by a bearing on top of the strut. A ball joint is typically secured at the steering knuckle with a tapered pin and is connected to the frame by a control arm. Ball joints can wear out and develop play.
As a broken or separated ball joint typically leads to loss of control of the vehicle, they are considered to be important safety items. Vehicle manufacturers provide specifications for inspecting them and for the allowable amounts of wear before they need to be replaced.
The most common specification is zero measurable play. However, on some designs, a small amount is allowable.
Some ball joints press into the control arm or knuckle, and the replacement involves removing the arm or knuckle and installing a new ball joint in a press.
Some ball joints bolt on to the arm and the replacement is simply breaking the tapered pin from the knuckle and unbolting it from the arm. On some designs, the ball joint is permanently installed in the control arm, and replacing the ball joint is done by replacing the whole control arm.
- Control Arms
They are the members that fix the position and control the movements of various suspension parts. There are several kinds of control arm.
Control arms that locate ball joints on the front suspension are the most common, and most vehicles have a lower control arm. This is designed to pivot up and down on two bushings where the arm bolts to the frame, and have a ball joint either pressed or bolted on at the knuckle attachment. Exceptions include some cases where the ball joint presses into the knuckle and then bolts to the control arm.
There are a few ways that a lower control arm can fail. The rubber bushings at the frame have to flex, and as rubber ages, it becomes stiffer and less resilient, and more prone to cracking.
When the rubber cracks and deteriorates, it can allow the arm to move excessively, which causes steering issues and tyre wear. Sometimes, control arm bushings can be replaced, but more often, the labour involved is greater than simply installing a new arm with bushings already installed.
In some cases, a new arm will come with a new ball joint, and generally, if an arm is being replaced, that’s a good time to replace the ball joint as well. This isn’t included but is a small additional cost. If an oil leak has caused deterioration in a rubber bushing, the leak should be repaired at the same time as the rubber part is replaced.
Control arms are also very susceptible to collision damage, being generally the weak point that absorbs damage and protects other parts from damage. Even in a small collision, if the alignment has to be rechecked or set afterward, it is a good idea to closely inspect the lower control arm for damage. A part that is bent even slightly is inherently weaker and should be replaced.
On an independent suspension vehicle with an upper control arm, the same things apply. The arm will pivot on two rubber bushings at the frame and have a ball joint attached to the steering knuckle.
Rubber bushings can crack and wear, allowing play, tyre wear, and steering issues. When control arms that control knuckle positioning are replaced, it is usually necessary to adjust the vehicle’s alignment afterward.
Another type of control arm is used on solid axle vehicles where they are used to hold the axle in a stable position centred in the wheel well. Typically, this arrangement has both upper and lower arms on both sides. In this case, on a solid axle suspension, it’s not necessary to recheck the alignment after control arm replacement.
- Multi-link Suspensions
Some suspensions use multiple arms to link the knuckles to the suspension and control movements. An arm with a ball joint is typically called a control arm, while an arm that connects a knuckle and the frame using a rubber bushing at each end can be used with various terms.
Longitudinal arms, lateral arms, radius rods, control links, and trailing arms are some of the names used. Some multi-link suspensions don’t use ball joints at all, relying instead on the flexing of the rubber bushings to allow for steering knuckle rotation.
Multi-link arms are subject to the same failure modes as control arms; rubber ages and can crack or deteriorate. One common issue is a rear arm that establishes the camber, bearing the weight of the upper knuckle away from the frame.
Age can lead to the compression of the rubber and the top of the wheel leaning in. Multi-link arms are usually fairly simple to replace, having just a bolt at each end.