still confused about a arms..

[davidimurray]

I think you need to consider the context in which the Haynes Roadster is designed - i.e. it is a 'sporty' road car, for occasional track use, based around a single donor.

As such you begin with a number of design constraints, in terms of suspension you have the uprights and brakes to contend with as a starter. In an ideal world you start at the tyre and design backwards, through the upright design , wishbone and then finally the chassis, which at the end of the day is only there to connect everything together. Of course to do all this you need a set of target design parameters to aim for - to do this you have to make a number of assumptions, such as the CoG. There will be a number of driving conditions to then consider - e.g. high speed cornering, low speed cornering, braking, acceleration and all the combined load. A car setup for low-speed autocrossing would be totally different to a high speed circuit racer.

Unfortunately for us we want the roadster to be all things to all men using a number of predefined parts - so the poor car is up against it to start with.

There are plenty of possible improvements you could make - e.g.
Re-designed wishbones with rod ends - although you would need to redesign to prevent rod ends in bending. Also for correct adjustment rather than having adjustable rod ends, staked in bearings would be better along with packers on brackets at the upright - so now you need new uprights.
Then of course there is the round tube chassis - but why even use tube when you could build a excelite monocoque. You can go on and on for ever!

Having been lucky enough to be involved in project managing the build of a simple single seater, while not a designer myself, I've been invovled in quite a few discussions and basically every decision is a compromise of time, money and engineering.

So having been involved in building such a car - why build a roadster?? Because I want a good fun road car that I can have some fun on track in and more importantly build it all myself.

Ramble over