Monday 2 August 2021

Rack and pinion steering conversion

After my relative success at the Bo'ness Revival in September I decided it was time to sort out the steering (including caster angle), Front Shockers and rear suspension.

The steering

The A7 steering arrangement made the car down right dangerous to drive. At speeds above 40 mph it is impossible to keep it on the road. There is so much play in the worm and peg steering box arrangement it is impossible to understand the problems. The existing box has run out of adjustment so a crisis looms for any further track days without urgent action. The alternative is I kill myself. I plan to have a long retirement.

Various solutions have been suggested including a VW steering box however my favoured choice is a Hilman Imp rack from the 1960's. It looked even at an early stage that there was room between the sump and the Bowden assembly for such a modification.

Carboard template of mounting plate for the new steering

Surely there is enough space for a Hilman Imp Rack

A project was born, first the rack mountings were machined out of 10mm alloy plate

Next the cardboard template for the mounting was then cut out of 3mm steel sheet

Above plate needed to centralise the rack vs A7 track rods to keep them the same length.

Above Intermediate Plate needed to transfer  the action of the rack to the front to pick up track rods
Side View Intermediate Plate
Side view of Intermediate Plate

The rack bolted in place with the two plates

Additional plate to take the new track rod ends

Two additional plates are required to mate with the front of the Bowden suspension. The first plate centralises the rack vs the track rods (which are the same size) the other function is to make the assembly easier. The second plate has two 80mm standoffs to transfer the action to the front to pick up the track rods.


The steering has improved a lot however there are now further issues with the handling that need to be investigated and remedied like a) A caster angle of the front suspension (it has none at present) and b) The front shockers are completely ineffective.

The final test was on the track see Video

Here is an Index page for the build

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