Well I know it wont be everyone’s cup of tea but i believe a car of this caliber deserves to have power steering so I’m going to have a go at putting something together. The tidy choice seems to be to go for a fully electronic version or EPAS – a lot of cars have this now and it has several advantages. No messy hydraulics, ecu controlled and mappable to provide the correct balance of assist (no or little assistance at high speed, full assistance at low speed), compact and dare i say, relatively easy to install. There are quite a few choices out there either new or second hand new systems are quite pricey and will run from a few thousand pounds. A very popular choice for several years has been those from Vauxhalls corsa range – they have been used on all sorts of conversions kit cars and rally cars etc., so there is a fair bit of knowledge out there on how the system works. I found a particularly helpful write up at.http://www.super7thheaven.co.uk/blog/corsa-c-electric-power-steering-epas/ This covers a great deal of the background on the ecu and maps etc – all very helpful stuff, and not the sort of info you will find in a Haynes manual – or from a Vauxhall technician for that matter.
Electronic Control
It seems the majority of the units get fitted with simplified dial in electronics that either set the amount of assistance by dialing a knob or use other methods of timing such as allows power assist for first 20 seconds after engine start or after pushing a button. Most of these systems look like a compromise on how the system is supposed to work so I’m aiming at a properly speed related self adjusting system.
A few companies seem to do their own variants of aftermarket kits but essentially rely on the stock Vauxhall Corsa B or C column. example below.
The good thing is the units are still readily available and can be purchased for as little as £50 or £60. Try to get a good low mileage one if possible and it seems the tilt steering version will be an advantage to gain a bit of “inclination” on the steering wheel – more of that later.
Geometry
The biggest challenge will be getting the geometry correct and making sure it has a substantially engineered bracket system to attach to the car. (power steering can exert a lot of torque to its mounting points. I’m sure the GD monocoque shell will be more than man enough to handle it but the bracket that transfers it to the shell will have to be equal to the task. Keith A was incredibly helpful in providing me with some accurate dims to ascertain the standard position of the steering splined shaft, kindly removing his steering wheel and checking a few dimensions for me – great photos and great help – its gonna save me a lot of head scratching. With his photos and dimensions i can be pretty certain of the desired X Y and Z position of the steering wheel.
I firstly roughed up the position of the steering column into the body shell by a bit of temporary joinery work acting as support battens and props. Once I had the column in the correct position I can take a few measurements to make up the final bracketry. It soon becomes apparent that i wont be able to use the GD windscreen support cross bracket as it slightly interferes with electronics on the column, but that’s not a bad thing as it allows me to beef up the cross over assembly that will be transferring the power assistance loads.
It will be getting some additional fixtures to the body work around the gearbox tunnel as it develops… more pics and details to follow…
Marks Cobra Build 