Tuesday, 31 December 2013

Custom steering boss

For the IVA test in June I did not fit the aero screen as the general advice was not to provoke the testing sharp edges rules. I therefore fitted a cheap steering wheel with lots of padding that would give me a good view of the instruments and satisfy the IVA man.

After the IVA test I immediately fitted the aero screen, wanting to take it touring in Scotland and not having to wear a helmet all the time. That is when the trouble started. The 300mm steering wheel now fouled the aero screen. To save having the car off the road in prime blatting season I elected to fit a small 250mm D shaped sports wheel. The clearance and driving position was now fine but the very positive steering and view of the instruments was poor. At that time I decided to put the problem off for another day.

Aero screen with sports wheel

Over the Christmas 2013 break I decided not to put it off any longer. I ordered up a 120mm diameter round billet bar 2" deep from the local metal merchants. This is pretty well the limit of what I can easily turn in my small lathe. To make it easier to mount in the chuck, first off I put a 2" hole down the centre using a Rota-broach hole cutter. (*) see note

The final boss had 18 radial holes:
* 6 to mount the steering wheel flange
* 6 recessed holes to mate with the existing collapsible boss
* 6 to mount the cover plate
However you need a rotary table or indexer to accurately position these holes or an incredible amount of luck.

The resulting wheel is much improved classic style suiting the car and owner.

See clearance S/W to plexiglass

Dashboard side

Profile with additional 20mm clearance


Note(*):For those who have not discovered Rota-broaches you don't know what you are missing. They are precision hole saw (you do need a vertical drill to use them however).


  1. looking good......did you use a 2.4 ratio rack?...how does it feel with the smaller wheel. On of the first things I want to do after IVA is go for a smaller wheel and move it closer.

  2. I think the smaller wheel is better for the track but I got no view of the rev counter or speedo. I guess if I wanted to keep the smaller wheel I would have to redo the dash possibly with a digital thingy.

  3. I used the Rally Design 2.9 rack I don't think I could have coped with the small wheel and a 2.4 rack.