Traction Control Bushes with Fitting Position Rear Axle

Traction bushes are the suspension bushes that decide whether an axle stays put when torque hits it, or twists, hops and shunts instead. The name causes confusion. They have nothing to do with the electronic traction control system that cuts power or brakes a spinning wheel. They are mechanical parts: firmer or purpose-designed bushes in the links, spring eyes and mounts that locate the axle, chosen to reduce the movement that robs a 4WD of grip under load. On a 4WD climbing a loose hill, towing a heavy van away from a standstill or crawling over rock in low range, that movement shows up as axle wrap, wheel hop and clunks. Use the vehicle search to find traction control bushes to suit your 4WD.

Traction Bushes and Electronic Traction Control

Electronic traction control is a system built into the vehicle. It reads wheel speed sensors, and when a wheel spins faster than the others it reduces engine power or applies the brake to that wheel. It has no bushes.

Traction bushes are a mechanical approach to a different problem. They limit the movement of the axle or suspension so the tyres stay in more consistent contact with the ground under torque. The two can work alongside each other, but one does not replace the other.

What Axle Wind-Up and Wheel Hop Do to Traction

When torque reaches an axle, the axle housing tries to rotate in the opposite direction to the wheels. On the way up a steep climb or pulling away with a trailer, that force is large.

On a leaf sprung axle, the springs resist that rotation, but they can twist into an S shape under heavy torque. This is axle wrap. When the springs reach their limit, they snap back, the axle rotates the other way, and the cycle repeats. The result is wheel hop: the tyres bounce on and off the ground instead of driving steadily.

On a coil sprung axle, the trailing arms or links resist the rotation through their bushes. Worn or soft bushes let the axle wind up further before the links take the load.

Either way, every time a tyre unloads, it loses grip. On loose surfaces, that can mean spinning instead of climbing.

Where Traction Bushes Sit on a 4WD

There is no single part called a traction bush on most 4WDs. The bushes that affect traction are the ones that locate the axle against torque.

Leaf spring eye bushes. On a leaf sprung ute, the front spring eye bush carries the drive and braking forces into the chassis. A soft or worn front eye bush lets the axle move fore and aft and rotate further under torque.

Trailing arm and link bushes. On a coil sprung axle, the bushes at each end of the lower trailing arms and upper links control how far the axle can rotate. Firmer bushes here reduce wind-up.

Diff mounts. On independent front or rear suspension, the diff mounts carry the reaction to drive torque. Worn diff mounts let the diff twist, which can cause clunks and affect drive.

Traction kits. On some vehicles, purpose-made traction kits combine firmer bushes, inserts or extra links to control axle or subframe movement under hard acceleration.

Signs Your Axle Is Moving Too Much

A clunk or shunt on take-off is the most common sign. The axle rotates or shifts in its bushes until the slack is taken up, and the knock comes through the vehicle.

Wheel hop on a steep climb or when pulling away with a heavy trailer is another. The rear of the vehicle shudders or bounces as the axle winds up and releases.

A clunk when changing between drive and reverse, or when backing a trailer up a slope, can point to the same movement.

On inspection, worn bushes in the spring eyes, links or diff mounts usually show cracking, splitting or rubber squashed out of the housing. Levering the link or spring eye can show how much movement there is.

Driveline joints, engine and gearbox mounts and the diff itself can cause similar symptoms, so a full inspection is worth doing first.

Towing, Low Range and Loaded Vehicles

Towing

Pulling away with a heavy caravan or trailer, especially uphill, is one of the hardest jobs a 4WD's rear axle does. The torque needed is high and applied from a standstill, which is the ideal recipe for axle wrap and wheel hop. Firm, healthy bushes help the axle stay planted.

Low Range

Low range multiplies the torque reaching the axles. On a steep, loose climb, worn bushes let the axle wind up and hop, and the wheels lose grip just when it is needed most.

Heavy Loads

A loaded 4WD needs more torque to move and more braking to stop. Both increase the forces through the bushes that locate the axle.

Lifted Vehicles

A lift changes the angle of the links and spring shackles, and on leaf sprung utes it can make axle wrap more likely by changing how the spring loads. Tightening bush bolts at the new ride height, and checking the pinion angle, helps keep the axle behaving.

Rubber, Polyurethane and Traction Kits

Factory bushes are usually rubber, which isolates vibration well but deflects under torque. As it ages, it deflects further.

Polyurethane bushes are generally firmer and deflect less, which tends to reduce axle wind-up and the clunk on take-off. They may transmit a little more vibration, and some designs need grease.

Traction kits go further on some vehicles, adding inserts or extra locating parts. They suit vehicles that see repeated hard launches or heavy towing. Whether a kit is available depends on the vehicle.

What Comes in a Traction Bush Kit

Kits vary widely. Some cover a single position, such as the front spring eyes or lower link bushes. Others cover several positions, or include inserts and hardware. Check the product details for which positions the kit covers and what is supplied.

Replace Bushes or Do More?

New or firmer bushes are usually the fix when the clunk or wheel hop comes from worn or soft bushes and the springs, links and mounts are sound.

More is needed when the leaf springs have sagged or lost their rate, when links are bent, or when the diff, tailshaft or joints are worn. Bushes cannot stop a weak spring from wrapping or fix a worn driveline.

Fitting Traction Bushes

Fitting traction bushes means removing links, spring eyes or mounts, so it is a job for a qualified technician. The vehicle is supported on rated stands with the axle supported. Old bushes are pressed out, housings cleaned and checked, and new bushes fitted with any lubricant supplied.

Bolts are tightened with the vehicle at ride height so the bushes start in their neutral position, and all fasteners are torqued to specification. A road test, including take-off under load and some towing or low-range work where relevant, confirms the result.

How Formula 4x4 Can Help

Formula 4x4 works across the whole 4WD suspension and driveline, which matters on a problem with more than one possible cause. A shunt on take-off could be spring eye bushes, link bushes, a tired leaf spring or a driveline joint. The team can help work out which, so the fix targets the actual cause rather than the first part that looks worn.

Find the Right Traction Control Bushes with Formula 4x4

Use the vehicle search, then identify which bushes locate your axle against torque: spring eyes, links or diff mounts. Always check the product details for what is included.

If you are unsure what your 4WD needs, contact the Formula 4x4 team.