A control arm is basically the part of the suspension that links the frame or body of the vehicle to the steering knuckle assemblies. The control arms have rubber bushings to allow them to absorb road forces and to travel up and down with bumps. There are many variations on how this is done and many varieties of control arms. They can also have various names; they can be called lateral links, trailing arms, radius rods, swing arms, etc.
Control arms can be made of stamped steel, or cast iron, or aluminium, and will usually have two or more rubber bushings pressed in at the ends where the arm attaches to the frame, knuckle, or axle. The most common kind of control arm is used on the front of almost all front-wheel-drive vehicles with a McPherson strut suspension. In this case, there is a front lower control arm with three corners; on one, a large webbed bushing is oriented horizontally, which is called a compliance bushing. This can twist to allow suspension movement while also absorbing braking and cornering forces. And there is a second bushing that usually lies sideways, secured to the frame in a way that allows the arm to pivot up and down with the suspension. On the third corner is a ball joint, which is sometimes integrated or pressed into the arm, and sometimes bolts on as a separate piece.
Some vehicles use an upper control arm on the front as well, and some vehicles have a lower control arm or an upper and a lower control arm in the rear suspension, or various arrangements of controlling links. On a modern multi-link suspension, there can be 6 or 8 control arms per corner. The inspection and service of these are all pretty similar, as are construction and pricing generally.
Most often, if a control arm is removed to service the bushings, both bushings on the arm will be replaced. Most shops have a press and the adapters necessary to drive out the old bushings and press in new ones.
Cost of Control Arm Bushing Replacement
On average, for most vehicles, it costs about £205 to replace a pair of control arm bushings.
For some more specific estimates on common vehicles, using £70 an hour as a labour rate:
For a 2009 Dodge 1500 with four-wheel drive, the labour time to replace a pair of lower control arm bushings on one arm is 1.6 hours. Factory lower control arm bushings are unavailable, but aftermarket control arm bushings cost about £55. This would make the job about £165 using aftermarket parts.
For a 2010 Nissan Altima, the labour time to replace the front lower control arm bushings on one arm is 1.8 hours. Factory lower control arm bushings are unavailable, but non-OE bushings cost about £38. This would make the job about £165 using aftermarket parts.
For a 2008 Chevrolet Malibu, the labour time to replace the front lower control arm bushings is 2.2 hours. A pair of factory bushings cost about £145, or aftermarket bushings cost about £70. This would make the job about £300 using OE parts, or about £225 using aftermarket parts.
Labour in all cases includes removing and re-installing the control arm, plus about 0.2 of an hour per bushing. In many cases, a new control arm can be comparable in price and sometimes a better choice, and many vehicle manufacturers don’t make bushings available, only whole control arms.
Cost of Control Arm Replacement
For a 2009 Dodge 1500, the labour time to replace a control arm is 1.2 hours. A factory lower control arm lists for £405, or a non-OE arm costs about £110. This would make the job about £490 using OE parts, or about £195 using aftermarket parts.
For a 2010 Nissan Altima, the labour time to replace a lower control arm is 1.2 hours. A factory-lowered arm lists for £260, or a non-OE part costs about £130. This would make the job about £345 using OE parts, or about £215 using aftermarket parts.
For a 2008 Chevrolet Malibu, the labour time to replace a lower control arm is 1.9 hours. A factory arm lists for £255, or an aftermarket arm costs about £95. This would cost the job about £390 using OE parts, or about £230 using aftermarket parts.
As can be seen, the cost of replacing a control arm, especially using aftermarket parts, is pretty comparable to the cost of just replacing the bushings. Two advantages, to the mechanic and to the customer, are that it takes less time to replace the whole arm and that the whole arm is covered under a parts warranty.
In almost all cases, whether the whole arm is replaced or just the bushings, it is necessary to check the alignment after the work. That adds about £90 to the cost of the job.
Common Problems with Control Arm Bushings
The main thing that goes wrong is the rubber degrades. Even if the vehicle isn’t driven, rubber ages and hardens and becomes prone to cracks. The compliance bushing usually cracks first, and generally, they are allowed to have cracks up to 3/8ths of an inch deep before they are considered to be compromised and need to be replaced. Very old rubber can also just crumble when asked to flex as a control arm bushing needs to.
Most types of rubber also react poorly when exposed to petroleum products, such as engine oil. If a vehicle has an oil leak that has coated rubber parts, it is common for them to need replacement. If a bushing is replaced because it has been oil damaged, the oil leak should be repaired and cleaned up as well, of course.
One of the more common reasons for replacing a control arm has nothing to do with the bushings, though; the lower control arms, especially in a front suspension, are designed to absorb impacts to protect other parts. In a front or side impact or curb hit, the lower arm is designed to crush in a controlled manner, rather than transmit impact forces into the much more costly subframe.
Symptoms can be clunking when braking, cornering, or changing direction. In most cases, a visual inspection can be done, or a tool used to check the bushings for play.
Yes, control arm bushings have a direct effect on the alignment and it definitely should be checked after replacement.
For the most part, it doesn’t matter, and the decision can be made based on which way offers the best price and availability.