Replace an A-frame ball joint


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The ball joint, located on top of the rear axle : credit: © Dave Barker
A worn ball joint will cause noise and handling issues, while damage to its rubber boot will fail the MoT test. Dave Barker shows how it’s renewed

Need to know

Time: Around 2 hours.
Difficulty: 2 out of 5 stars
Models: All 90 and 110 Defender, Discovery 1 and Range Rover Classic, without self-levelling unit.
Tools needed: General workshop tools, including 30 mm and 19 mm spanners and sockets, torque wrench and possibly a grinder.
Parts used: Britpart DA1129G, fulcrum bracket (pivot block) and ball joint assembly, from £72; Two bolts – Britpart DA1129 kit, joint and bracket fitting kit, from £5.
Work safely:
• Before working underneath a vehicle on the floor or on a lift, ensure the lifting and support equipment is correctly rated for the weight of the vehicle and in serviceable condition.
• Ensure the vehicle is securely supported before starting work and check it cannot be dislodged when applying force to tools.
• Wear gloves or barrier cream to protect skin.
• Wear eye protection when working overhead.
• Wear thick gloves and a strong visor when using an angle-grinder or similar tools, and ensure the tool cannot fall on you or rebound. 
Contact: Maddison 4x4,Water House Farm, Station Road, Topcliffe near Thirsk, YO7 3SG.
Tel: 01845 587407,

The rear suspension upper link ball joint, or A-frame ball joint as it’s commonly called, is located on top of the rear axle. The joint is secured in a mounting block attached to the rear axle casing and to the two upper link arms (forming the A-frame) which, in turn, is secured to the chassis. The ball joint allows the axle to pivot on the A-frame.

The condition of this joint is often overlooked. On some vehicles they will last for many years without any problems, on others they tend to wear out in a short time, all depending on usage and environment. Wear is gradual and so it’s often not noticed by the driver. The result is a very loose rear-end, allowing the axle to move excessively, and a clonking sound from the rear of the vehicle.

Replacing the A-frame ball joint looks an easy job. But, being located under the vehicle, road dirt and corrosion builds up and the bolts become badly corroded, so they aren’t going to be easily undone. It’s normal for the two securing bolts to be seized in the pivot block (fulcrum bracket) and you will often need to cut off either the bolt head or the nut, and then knock the remains of the bolt out of the bracket.

On the plus side, the job is now easier than in past years. Originally, the ball joint was available only as a single item, so you needed to press the old ball joint out of the pivot block and then press the new joint into place. That job required a 10-tonne hydraulic press which few people have at home. But now you can buy a complete assembly, with the A-frame ball joint already fitted into a new pivot block. Oddly, this does not come supplied with new bolts, which have to be ordered separately. This complete assembly does cost around twice the price of just the ball joint on its own, but it does make the job easier and much quicker.

Here, we’re replacing the joint on a 300Tdi Defender 90 on which the joint was showing signs of play, and the rubber boot was split. Before starting, we wire brush the exposed threads clean of rust and give all the threads and nuts a good soaking in penetrating oil.


Removing the damaged joint

In front of axle, looking up: The pivot block, holding the A-frame ball joint assembly (arrowed), locates onto a bracket on the rear axle. We’ll start the work from the back of the axle.

Underside from behind axle: The ball joint is held in position to the A-frame mounting bracket on the axle casing by a single castellated nut that is locked with a split-pin.

Easing the nut: After removing the split-pin, the castellated nut is loosened with a 30 mm spanner, but the nut is left on, loose, at this stage.

Badly seized: From ahead of the axle, we attempt to release the two nuts from the bolts holding the pivot block to the upper link A-frame, unsuccessfully…

Serious attack: The ends of these bolts are badly corroded and the nuts would not undo fully. The only option then, was to cut the nuts or bolt heads off.

Give it a tap: Before removing the bolts, and while the castellated nut was slack, the assembly was given a sharp tap with a hammer to release it from its mounting.

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Knock out: Using a drift, the remains of the A-frame arm securing bolts are knocked out of the pivot block, thus releasing the two A-frame suspension arms.

Fully release: The castellated nut is now fully removed from the ball joint, while holding the ball joint shaft with grips to prevent it from turning with the nut.

Confirming the damage: With the ball joint removed, excessive play could be felt by hand. The visible split in the rubber boot would have allowed water and grit into the joint.


Reassembling with the new joint

Replacement part: The new ball joint is supplied already fitted into a new pivot block. A new castellated nut, washer and split-pin are supplied within the kit of parts.

Loosely fit to bracket: The shaft of the ball joint is inserted through the bracket on the axle, and the new washer and castellated nut are fitted loosely at this stage.

Align and bolt up: New securing bolts (with anti-seize grease for easier removal next time) are tapped through A-frame arms and pivot block, and their nylon insert lock nuts tightened.

Final tightening: The two pivot block securing bolts and the A-frame ball joint castellated securing nut are now tightened to a torque of 176 Nm.

Pinned for security: Finally, the new split-pin is fitted to the castellated nut and its ends bent over to lock it. Greasing helps it come out easily next time.


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