electric power steering
Discussion
Dont need to go to the expense of fitting power steering, just reduce front wheel castor by 2 degrees. Makes a world of difference even with fat tyres. No adverse affect to steering geometry or tyre wear. Happy with mine and I have fitted 17.0 x 9.0 rims with 235 x 40 tyres on front. No PAS fitted.
CHGRIFF said:
Dont need to go to the expense of fitting power steering, just reduce front wheel castor by 2 degrees. Makes a world of difference even with fat tyres. No adverse affect to steering geometry or tyre wear. Happy with mine and I have fitted 17.0 x 9.0 rims with 235 x 40 tyres on front. No PAS fitted.
??Expand please.
Hi, I spent alot of time looking into the options for power steering on my Griff. The corsa column B or C option sounds great but there are some significant problems/hurdles including properly mounting it under the dash and the relative sensitivity/feel of the steering which is difficult to get right and requires a separate ECU that does not come with a Corsa column (well not off ebay anyway). The feel can be unervingly light especially at speed. The whole option got so complicated and expensive that I gave up and adopted a different route.
In the end I fitted a standard Griff power steering rack and used a Citroen saxo electric power steering pump that is used on the tuscans tamoras etc - they are £60 off ebay. It all fitted in beautifully and it feels great. It is also a fraction of the cost of going the corsa electric route.
I even have a spare power steering rack (which are like rocking horse sh*t) if you need one. Jes
In the end I fitted a standard Griff power steering rack and used a Citroen saxo electric power steering pump that is used on the tuscans tamoras etc - they are £60 off ebay. It all fitted in beautifully and it feels great. It is also a fraction of the cost of going the corsa electric route.
I even have a spare power steering rack (which are like rocking horse sh*t) if you need one. Jes
As part of total steering geometry Castor is set to provide straight line steering sensitivity and steering centralisation when exiting a curve, without castor steering would be a pig.
By setting a castor angle you are in affect pushing the wheel into the ground or lifting it as the wheel is turned around the effective kingpin intersection point with the ground. This sensitivity is sometimes referred to as steering weight. Same logic applies to Bike forks.
Generqally at ground level the cenreline of wheel intersection point is I believe 10-15mm from the Kingpin intersection point. When the kingpin angle is inclined (castor), as you turn the wheel rearward the wheel bites into the ground, when turning the wheel forward the wheel actualy lifts. Its this that gives you the sense of feel when driving.
Castor is preset by TVR using the upper wishbone hub spigot mounting. The wishbone width is about 48mm, the spigot width is about 40mm. TVR use a steel spacer of 8mm to fill the gap, the spacer being placed forward of the spigot to preset the castor.
I cant remeber the castor degree range within the spigot but I think it went from 12-18 Degrees (When moving spacer from front to rear)
We carried out several experiments changig the castor, driving the car and judging steering sensitivity. First we moved the spacer behind the spigot but this was a pig to drive. We replaced the spacer with 4 x 2mm thick stainless washers about 25mm diameter and placed 3 washers on the front of the spigot and 1 behind, reducing castor by about 2 degrees. This reduced steering weight to power steering levels and is totally acceptable, straight line steering is good as is steering centralisation. IMO there has been no negative to doing this, a cheap solution.
As mentioned I have now fitted max wheels and tyres to the front end without further changes and am pleased with the result. You can either use washers or buy pre-set steel spacers from SC Power.
By setting a castor angle you are in affect pushing the wheel into the ground or lifting it as the wheel is turned around the effective kingpin intersection point with the ground. This sensitivity is sometimes referred to as steering weight. Same logic applies to Bike forks.
Generqally at ground level the cenreline of wheel intersection point is I believe 10-15mm from the Kingpin intersection point. When the kingpin angle is inclined (castor), as you turn the wheel rearward the wheel bites into the ground, when turning the wheel forward the wheel actualy lifts. Its this that gives you the sense of feel when driving.
Castor is preset by TVR using the upper wishbone hub spigot mounting. The wishbone width is about 48mm, the spigot width is about 40mm. TVR use a steel spacer of 8mm to fill the gap, the spacer being placed forward of the spigot to preset the castor.
I cant remeber the castor degree range within the spigot but I think it went from 12-18 Degrees (When moving spacer from front to rear)
We carried out several experiments changig the castor, driving the car and judging steering sensitivity. First we moved the spacer behind the spigot but this was a pig to drive. We replaced the spacer with 4 x 2mm thick stainless washers about 25mm diameter and placed 3 washers on the front of the spigot and 1 behind, reducing castor by about 2 degrees. This reduced steering weight to power steering levels and is totally acceptable, straight line steering is good as is steering centralisation. IMO there has been no negative to doing this, a cheap solution.
As mentioned I have now fitted max wheels and tyres to the front end without further changes and am pleased with the result. You can either use washers or buy pre-set steel spacers from SC Power.
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