Front steering and suspension defeats my logic. I've got this great book called "How to build & modify sportscar and Kitcar Suspension and Brakes" by Des Hammell, but despite reading it about 6 times i still don't understand it!
When you go round a corner at extreme steering angles, the wheels have to turn at a different angles to account for the diffrent radius circles. (Patrick, take a look at your Alfa model and you can see it). This is called Ackerman steering and is realised by the steering rack and the offset steering arms.
My normal logic says, increasing the caster angle should improve the self centering (like supermarket trolly wheels) but the book says this also causes "dynamic negative camber" i.e. lots of negative camber on full lock on the inside wheeel, which may not help? I know my Sportster does something strange at full lock.
Increasing the tyre pressure should reduce friction and make it easier to self centre.
The book says that self centering on rear wheel drive cars is achieved by the addition of toe-in, but that can cause understeer at speed.
So...
I think the plan should be to set maximum caster angle with the washers, pump up the tyres and keep increasing the toe-in equally each side until it self centres from full lock.
If that doesn't work you could try Robin's suggestion of positive camber to off-set the dynamic negative camber.
Another option might be to reduce the range of the steering rack with your hose clip end stops. The book says..." In the normal course of events, the front wheels do not turn (angularly) all that much from the staight ahead position (often not more than 20 degrees)." That's if you can get it to self centre from less than full lock.
Good luck with the trials and it's nice to see the real friendly helpful advice from Marlin hasn't changed. But we wouldn't enjoy the challenge if they told us exactly how to do it, would we?
Oh and just to repeat, I'm no expert on this stuff so all of the above is just ideas!
Just finished writing the news bit for the pictures
