Upper Control Arms with Fitting Position Front Axle

An upper control arm holds the top of the steering hub while the lower arm holds the bottom, and between them they set camber and caster. The upper arm also carries the upper ball joint that lets the hub pivot when you steer.

People end up here for two different reasons. Either the upper control arm has worn out and needs replacing, or the vehicle has been raised and the alignment can no longer be brought back into specification.

Where the Upper Control Arm Sits and What It Carries

Not every vehicle has one, because on a strut suspension the strut locates the top of the hub and there is no upper arm at all. Where a vehicle does use one, the layout is a double wishbone and the two arms work together to control how camber changes as the suspension travels, which is why it turns up on pick-ups, 4WDs and a lot of older passenger cars.

The upper control arm carries less vertical load than the lower on most of those designs, because the spring usually sits on the lower arm. What it does carry is the sideways and twisting load from cornering, braking and steering, and all of it feeds through a ball joint that is typically smaller than the one underneath.

That combination explains a lot about how these fail, because an upper control arm can be worn out while the lower arm on the same corner is perfectly serviceable, and the wear concentrates in the joint rather than spreading evenly across the bushes.

Rear upper control arms turn up on independent rear ends doing a related job, setting camber and keeping the hub square under load.

Why the Upper Ball Joint Usually Fails First

The upper ball joint is the part that gives up on most of these arms, and the boot decides its life rather than the kilometres.

While the boot is intact the grease stays where it belongs and the joint wears slowly. Once it splits, water and grit reach the socket, the grease washes out, and an upper control arm ball joint that still feels reasonably tight can be a long way through what is left of its service life.

How the joint is attached determines what you buy. Where it is pressed or riveted into the arm it is not separately serviceable in any practical sense, so a worn joint means a new arm. Some designs allow the joint to come out on its own, which keeps the repair cheaper.

Check the boots whenever the vehicle is in the air for anything else. A torn boot is the cheapest thing to act on and the most expensive thing to ignore, because by the time there is play in the joint the arm is usually going with it.

Upper Control Arm Bushes or the Complete Arm

Worth diagnosing properly before you order, because the cheaper answer is sometimes the right one.

Upper control arm bushes on their own make sense when the ball joint is still tight, the arm is straight and the ride height has not changed. A fresh front upper control arm bushing at each pivot removes the deflection that lets the arm move under load and stop the geometry wandering while you drive.

The complete arm is the answer when the joint has gone as well, when the arm is bent or corroded, when a mounting eye has worn oval and will no longer hold a bush, or when you need correction the factory never provided.

There is a practical side to it as well. Pressing bushes and ball joints out of an upper arm takes a press, correct diameter tooling and a fair amount of time, and the risk of damaging the arm in the process is real. A complete arm arrives assembled and turns the whole thing into a bolt-in job.

What a Lift Does to Upper Control Arms on a 4WD

Raise a pick-up or 4WD and the arms swing through a different part of their arc, which changes camber and caster immediately and permanently.

Caster is what you notice first, and it washes off as the geometry rotates, and caster is what makes the steering settle and return to centre, so losing it gives you a vehicle that wanders at highway speed, needs constant correction and feels lazy turning in. Camber moves at the same time, which is what starts wearing the inside or outside edge of a new set of tyres.

Factory upper control arms have very little adjustment designed into them, and on most vehicles whatever there was has already been used before the lift went in. The workshop will tell you the numbers are out of range and that there is nothing left to adjust.

There is a second problem that gets less attention and often causes more grief. A factory upper ball joint is built around factory suspension travel, so once the vehicle is raised the arm sits at a steeper angle and the joint articulates further than it was designed to at full droop. It binds, tears its boot, and wears out early, which is why people fit a lift and then find themselves replacing upper ball joints every year or two.

Adjustable Upper Control Arms and Fixed Offset

Fixed offset upper control arms have the correction built into the shape of the arm, so they are right the moment they are bolted in, nothing can move or work loose afterward, and there is nothing to check at the next service. For a vehicle at a known lift height that gets used hard, that reliability is usually what you want.

Adjustable upper control arms let the setting be dialled in on the alignment rack and allow each side to be set differently, which matters on a vehicle that has settled unevenly or pulls to one side once tyres and pressures have been ruled out. They also leave room to change ride height later without buying arms a second time.

Either way, check the lift range the arm was designed around, because these are engineered for a band rather than for anything and an arm built for one height fitted to something considerably taller moves the geometry in a direction you did not ask for.

Symptoms of a Worn Upper Control Arm

• Clunking or knocking from the front over bumps, often worse at low speed
• A knock or shudder that comes back through the steering wheel
• Steering that wanders and needs constant correction, worse as speed rises
• Uneven tyre wear across one edge that keeps returning after every alignment
• Play at the ball joint when the wheel is rocked with the suspension unloaded
• A split or torn ball joint boot, or grease thrown around the wheel arch
• Upper ball joints failing repeatedly since a lift was fitted
• Cracked, split or squeezed out material in the upper control arm bushes
• Caster reading low on an alignment printout with nothing worn to explain it
• An alignment the workshop cannot bring into specification at all

Upper arm wear overlaps with the lower arm and with worn tie rods, so the useful distinction is where the play shows up. Rock the wheel top to bottom for a ball joint, side to side for a tie rod end, and lever the arm against its mount for the bushes.

Upper Control Arm Replacement Cost and Where the Money Goes

Upper control arm replacement cost is driven by labour and by what is being fitted rather than by the price of an arm.

The arm comes off the vehicle whichever route you take, and a wheel alignment goes on the end of the job regardless, since replacing an upper arm changes camber and caster immediately. Those two costs are fixed no matter what goes between them.

What changes the number is whether you are fitting a straight replacement or a correction arm, whether both sides are being done, and whether the workshop has quoted the alignment as part of the job or as an extra. A correction arm costs more as a part and exactly the same to fit, which is why doing it once properly usually beats fitting a replacement now and a correction arm later.

Separating the Upper Ball Joint and Torquing at Ride Height

Upper control arms bolt into the factory mounting locations and arrive assembled, so this is a remove and replace job rather than press work.

Support the vehicle properly and take the load off the suspension before separating the ball joint, because a joint under spring load releases suddenly and without any warning. Use a proper separator rather than a hammer, which damages the hub bore and the stud threads.

Fit both sides, because a corrected arm working against a factory one gives you two different geometries and an alignment nobody can balance between them.

Torque the inner fasteners with the vehicle on its wheels at ride height rather than hanging at full droop, since the bushes otherwise sit preloaded in a position the suspension never returns to and will bind from the first kilometre.

Cycle the suspension through full travel before calling it finished, checking clearance against the coil, the strut and the tyre at both extremes. Then book the wheel alignment for the same visit, because the entire purpose of a corrected arm is to give the aligner range and driving away unaligned wastes the exercise.

Find Upper Control Arms for Your Vehicle

When one arm is bent and the other is fine, individual upper control arms save buying a pair. Both sit within the Nolathane control arms range.

Select your vehicle to see the upper control arms and bush kits available for it, and check each listing for the correction it provides and the lift range it suits. Every Nolathane component is backed by our warranty, a fitment guarantee and 60 day returns.