Either there’s a horrible noise from the front, and you suspect you have a bad control arm. Or you’ve just been told by the garage the control arm is worn. Here’s the problem, you need to drive the car! So can you, and if so, for how long?
Well, it’s not an easy answer to give; however, depending on the severity of the worn arm, presumably its a bush or ball joint attached to the arm, it may be possible to drive about 100 miles, but you do not want risk more than that, and you must keep your speeds down. This is all explained in more detail below.
Some sporty vehicles and SUVs have a multi-link suspension system, meaning there may be more than one control arm on the car. All vehicles have at least one lower arm at a minimum, so this article purely relates to the lower only. However, most of this article’s information relates to the upper and lower arms.
What is a control arm?
A car control arm, also known as an A-arm, lower arm, or wishbone, is a major component in the suspension system. It is typically a metal rod or large frame that connects the chassis via control arm bushes and to the wheel hub assembly connected via a small ball joint.
Its job is to pivot at various points to enable the wheels to move up and down independently. While also absorbing vibrations, keeping the wheel in a fixed position and the tire in contact with the road even when one wheel is going over bumps.
What does it mean if you have a bad control arm
A control arm is a solid lump of metal that is very difficult to bend or brake; however, they sometimes bend in heavy collisions. Most commonly, though, if you have a worn control arm, it means the bushings or ball joint has excessive play and is worn. Like all things, the bushings wear away with age due to constant movement when driving and have an approximate lifespan of around 50,000 miles.
Symptoms of a bad control arm
A bad or failing control arm can exhibit several symptoms, indicating it may need to replace the bushes or ball joint. Here are some common signs to watch out for:
- Vibration or movement in the steering wheel – A worn control arm can lead to vibrations or a noticeable movement in the steering wheel, almost like the steering wheel is loose, especially during acceleration or braking. This occurs because the control arm’s bushings or ball joints may be worn, affecting the wheel’s stability on the road.
- Unusual noises – You may hear clunking noises from the front suspension when turning or driving over bumps and rough roads. These noises can indicate that the control arm bushings or ball joints have deteriorated.
- Alignment problems: Misalignment issues, where the steering wheel isn’t centered when driving straight or the vehicle tends to pull to one side, can be blamed on faulty control arms affecting the wheel’s positioning.
- Uneven tire wear – A worn control arm bush will disrupt the wheel alignment, causing uneven tire wear. If your tires have uneven tread wear, especially on the inner or outer edges, it can signify a worn arm or bush.
- Poor handling – Worn control arm bushes will lead to poor handling and difficulty maintaining vehicle control, especially when cornering. You may experience the car feeling like it is snatching you off to one side; this is a usual indication that the lower ball joint attached to the control arm has failed.
- Excessive wheel movement – If you jack up a wheel and can visibly see excessive movement or play in the front wheels if you attempt to wiggle them, it may indicate worn-out ball joints or bushings in the control arm. This is usually the sort of thing picked up during an annual inspection.
How long can you drive with a bad control arm?
Driving with a bad control arm is possible; however, you do want to limit the driving to around 100 miles at most, and you do not want to travel at high speeds.
There are some conditions to this; one is it’s not a bent control arm, damaged from an impact, and the other is a worn bush causing the problem and not the ball joint. The problem with driving on a problematic control arm is the pressure it puts on the ball joint or bushes, which can cause the car to become very unstable, especially at speeds above 60mph.
The other even worse problem is that the ball joint can pop out of the arm, meaning you will have no control over the steering and will most likely be forced off the road. This is not to scare you; that is a worst-case scenario, of course, and the control arm ball joint would need to be quite bad to get to that point. However it is something that happens and something you should be aware of if you decide to drive with a worn ball joint.
Replacing control arms
Replacing control arms is relatively straightforward; however, depending on the vehicle and the design of the arm, the ball joint can be tricky to remove from the hub. You will most likely need a ramp, and you need to be careful not to pull the drive shaft from the transmission, as you will lose transmission fluid. Again, depending on the design of the control arm, the bushings or ball joint can sometimes be replaced independently of the arm, so you aren’t always required to remove and replace the whole thing, just the worn part.
However, you will get a whole arm unit on most cars, which includes pre-pressed in bushes and the ball joint attached. Just remember that regardless of how the control arm is replaced, you must recheck the wheel alignment afterward.
Can you replace just one control arm?
If the control arm comes as a complete unit, i.e. the lower arm, bushes, and ball joint as one piece, then you should replace it as an axle pair. The reason for this is if you have a brand new arm and the other has done, say, 20,000 miles, it will have 20,000 miles of wear. The car can become unbalanced, and you may experience alignment problems that will never be right until you replace the other arm. This might not sound like a problem, but it can become annoying.
If you are replacing the bush or ball joint, it is unnecessary, although it is advised to do them in axle pairs.
It is possible to drive with bad control arm bushes, and it may be possible to do 100 miles or so; however, if the problem is the ball joint, it is not worth risking driving. I have personally seen them pop out of the arm; it is a very dangerous situation to be in, especially when you’re the one driving.
Instead look to replace the ball joint immediately. It, may be possible to replace just the ball joint on its own, and away you go. The control arm often comes as a complete unit, which is not difficult but can be tricky to replace, so you may need a ramp or a mechanic to do this all for you.