Suspension Arms

Suspension arms hold your wheels where the alignment says they should be. Springs carry the weight and dampers control the movement, but the arms set the geometry, and geometry is what keeps the tyre on the road at the angle it was designed to work at.

This range covers control arms, camber and toe arms, trailing arms, radius arms and panhard rods, in replacement and adjustable forms.

Control Arms, Trailing Arms, Radius Arms and Panhard Rods

Suspension arms are named after the job they do, which makes the range easier to navigate once you know what each one is holding.

A control arm is the general term for the link between the chassis and the hub. On most front ends there is a lower control arm doing the main work, and where a vehicle uses upper and lower control arms together, the two share the load and give finer control over how camber changes through travel. Front lower control arms take braking and cornering load directly, which is why they are the first to wear.

A camber arm changes the lateral position of the hub, so lengthening or shortening it leans the top of the wheel in or out. A toe arm does the same job in the fore and aft plane at the rear of the hub, pointing the wheel slightly in or out. The two are usually sold together because changing one moves the reading on the other.

A trailing arm runs lengthwise and holds the wheel against acceleration and braking load. A radius arm does the same job on a solid front axle and also controls how far the housing rotates, which means it sets caster, and you will see it listed as a caster arm for that reason.

A panhard rod is the odd one out. It runs across the vehicle rather than along it, and its only job is stopping the axle moving sideways underneath the body.

Why Factory Suspension Arms Run Out of Adjustment

Manufacturers build in just enough adjustment to correct production tolerances, and not a millimetre more. That is fine on a standard vehicle sitting at standard height.

Change the ride height in either direction and the arms swing through a different part of their arc. Camber goes negative on a lowered car and positive on a raised one, caster washes off as the geometry rotates, and toe follows both. On plenty of vehicles the result is an alignment outside specification with nothing actually worn, and the workshop has nothing left to adjust with.

That is not a fault the aligner can fix. The numbers are out of range and something has to physically move a mounting point before the machine has anything to work with.

Worn bushes do the same thing by a different route. Even when the static numbers read correctly, a soft bush lets the arm deflect under load, so the geometry is only right while the vehicle is standing still. That is why a car can measure perfectly on the rack and still wander, follow ruts and wear tyres unevenly.

Adjustable Control Arms and Camber Arms

An adjustable arm lets the length be set, which hands the aligner range that did not previously exist.

Adjustable camber arms and toe arms bring a lowered vehicle back into specification, and they let you set the geometry deliberately rather than accepting whatever the drop left behind. Adjustable upper control arms recover caster and camber on a raised 4WD where the factory arm has nothing left to give.

Because each side adjusts independently, they also fix problems a symmetrical correction cannot. A vehicle that has settled unevenly, or one that pulls to one side with tyres and pressures ruled out, gets corrected side to side rather than split down the middle.

Fixed offset arms are the alternative to all of that, with the correction built into the shape of the arm, so it is right the moment it is bolted in and nothing can move or work loose afterward. On a vehicle at a known ride height that reliability is often the better choice.

Panhard Rod Bushes and the Axle That Sits Off Centre After a Lift

On a solid axle, the panhard rod is the only thing stopping the axle sliding sideways under the body, and there are just two panhard rod bushes holding that location.

When they soften, the axle gains lateral movement. The back end shuffles sideways over mid corner bumps, the vehicle feels like it is moving underneath you on rough roads, and it wanders at speed in a way nothing else explains. Fresh bushes are one of the cheapest fixes in the whole suspension for the change they make.

Raising the vehicle is a different problem entirely. The rod sits at a steeper angle, which pushes the axle across and holds it there, so the axle ends up off centre in the wheel arches with more tyre clearance on one side than the other. Bushes will not bring that back, because the rod is now the wrong length for the new ride height. An adjustable panhard rod is what re-centres it.

Radius Arms, Caster Arms and Solid Front Axles

On a solid front axle the radius arm does two jobs at once, holding the axle against braking and acceleration load while resisting the housing rotating under brake torque.

That second job is what sets caster, and it is why radius arm bushes have such an outsized effect on how a 4WD steers. When they soften, the housing rotates slightly under load, caster changes every time you brake, and the vehicle wanders and needs constant correction at highway speed.

Lifting the vehicle causes the same loss by a different route, because the arms sit at a steeper angle and rotate the housing permanently. Offset caster bushes recover a degree or two, which covers a modest lift. Beyond that the correction has to come from an arm built with the offset designed into it.

Trailing Arm Bushes and the Rear End That Steers Itself

Trailing arms take everything the throttle and the brake pedal apply to the rear of the vehicle, which is a harder life than most suspension positions.

Because the arm holds the wheel in its fore and aft position, anything that lets the arm move lets the wheel move with it. On an independent rear end that shows up as rear toe changing under load. On a live axle it shows up as the axle stepping slightly out of square.

Either way the rear of the vehicle is steering itself in small amounts you never asked for. It feels loose over a bumpy corner, wanders when loaded or towing, and wears rear tyres faster than it should. A wheel alignment reads correctly because the workshop measures the vehicle standing still, which is exactly why rear trailing arm bushes go undiagnosed for years.

Symptoms of Worn Suspension Arms and Bushes

• Clunking, knocking or squeaking from the suspension over bumps and driveways
• Steering that feels vague and wanders, needing constant correction
• More vehicle sway through corners, with the body slower to settle
• The vehicle pulling to one side under braking
• Uneven tyre wear that returns after every alignment
• An alignment that will not hold specification, or one the workshop cannot reach
• The axle sitting off centre in the wheel arches on a solid axle vehicle
• Cracked, split or squeezed out bushing material at a mounting point
• Play at a pivot when the arm is levered against its mount
• A roadworthy or inspection report listing suspension play

Suspension Arm Bushes or the Complete Arm

The right purchase depends on what has actually failed, so it is worth diagnosing before ordering.

Bushes alone make sense when the arm is straight, the mounting eyes are round, the ball joint is tight and the ride height has not changed. That is the cheapest route and it fixes the deflection without touching the geometry.

The arm itself is the answer when ride height has changed and you need correction the factory never provided, when the arm is bent or corroded, when a mounting eye has worn oval and will no longer hold a bush, or when an integral ball joint has failed.

The arm has to come off the vehicle for either job, so once more than one thing is due, a complete arm frequently works out better value than rebuilding it.

Torque Suspension Arms at Ride Height, Not on the Hoist

Most arms bolt into the factory mounting locations and arrive assembled, so this is a spanner job rather than press work.

Support the vehicle properly and take the load off the suspension before separating a ball joint, since a joint under spring load releases suddenly. Use a proper separator rather than a hammer.

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

Torque with the vehicle on its wheels at ride height rather than hanging at full droop, because whatever position a bush is clamped in becomes its neutral position and one tightened at droop binds from the first kilometre.

Book the wheel alignment for the same visit. The entire point of an adjustable or corrected arm is to give the aligner range, so driving away unaligned wastes the exercise.

Find Suspension Arms for Your Vehicle

The range also covers alignment arms for fixing camber, and suspension arm service kits for repairing an arm instead of replacing it. It all sits within our suspension parts range.

Select your vehicle to see the control arms, camber and toe arms, radius arms, trailing arms and panhard rods available for it, and check each listing for the adjustment range it offers. Every Nolathane component is backed by our warranty, a fitment guarantee and 60 day returns.