Weekend Workshop

Rebuild your worm-and-roller steering box at home for £10

How to overhaul a steering box.

Is there play in your steering? Or is it stiff, graunchy or otherwise peculiar? If so, start by checking the steering joints and the balljoints or kingpins. Then, have a look at the steering idler (on the left chassis rail in the mirror position to the steering box), which may need lubrication and adjustment. With the steering rods disconnected, it should have no play but present only very slight resistance to turning. If all these seem fine, turn your attention to the steering box.

Start by checking the box’s adjustment. Most have an adjuster screw in the top plate that raises and lowers the drop shaft to alter the mesh of the worm and roller. Others have shims under the top plate that can be removed to serve the same purpose.

The quick method of adjustment is to rock the steering wheel in the straightahead position while watching the wheel rims (not tyres) for movement. Tighten the adjuster until there’s no lost movement. Be very careful not to overtighten it.

A better method, though, is to disconnect the steering rods from the Pitman arm on the box. Centre the steering by counting turns of the steering wheel. Now turn the steering wheel 30° and adjust the box until play in the arm is just eliminated. This will give the box a very slight over-tightness at dead centre. Play increases towards full lock at each side, which is designed-in.

It’s vital that the centre position of the steering shaft (and worm gear) corresponds to the straight-ahead position of the road wheels. If it doesn’t, adjust the trackrods equally on each side until it does, then reposition the steering wheel, if necessary.

If adjustment fails to remove play, action is needed. Start by removing the box. This is often a pain, but the pleasure of working on it on a bench makes it worthwhile. If you follow this guide and keep on top of lubrication and adjustment, it’s unlikely that you’ll ever have to do it again.