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 also can 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 aluminum, and will usually have two or more rubber bushings pressed in at the ends where the arm attaches to the frame or 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 lays sideways secured at 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 bushings.
Cost of Control Arm Bushing Replacement
On average for most vehicles, it costs about $225 to replace a pair of control arm bushings.
For some more specific estimates on common vehicles, using $100 an hour as a labor rate:
For a 2009 Dodge 1500 with four-wheel drive, the labor 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 Moog control arm bushings cost about $60. This would make the job about $220 using aftermarket parts.
For a 2010 Nissan Altima, the labor time to replace front lower control arm bushings on one arm is 1.8 hours. Factory lower control arm bushings are unavailable, but MAS bushings cost about $42. This would make the job about $222 using aftermarket parts.
For a 2008 Chevrolet Malibu, the labor time to replace front lower control arm bushings is 2.2 hours. A pair of factory bushings costs about $155, or Delphi bushings cost about $75. This would make the job about $375 using OE parts, or about $295 using aftermarket parts.
Labor in all cases includes removing and re-installing the control arm, plus about .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 labor time to replace a control arm is 1.2 hours. A factory lower control arm lists for $439, or a Mevotech arm costs about $120. This would make the job about $559 using OE parts, or about $240 using aftermarket parts.
For a 2010 Nissan Altima, the labor time to replace a lower control arm is 1.2 hours. A factory lower arm lists for $279, or a Beck/Arnley part costs about $140. This would make the job about $399 using OE parts, or about $260 using aftermarket parts.
For a 2008 Chevrolet Malibu, the labor time to replace a lower control arm is 1.9 hours. A factory arm lists for $276, or a Moog arm costs about $105. This would make the job about $466 using OE parts, or about $295 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, is that it takes less time to replace the whole arm, and then 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 $100 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 to replace 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 I 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 affect 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.