15-02-2018, 01:25 AM
(15-02-2018, 12:11 AM)Phil Kingdom Wrote: Another point to remember is chassis flex, with a lightweight special body chassis stiffness could be greatly reduced as opposed to the original car. So although one setup may work on one car in may not work as well on another, not that chassis twist is always a bad thing in fact in the world of go-carts some racers have hard and soft chassis to suit the tracks they are going to, a hard setup and tight shocks with a bit of flex in the chassis/body may handle in a similar manner to a softer setup with very little flex. Unless your are building an exact copy of an existing car it is really a case of trial and error.
My car would patter going round the long right hander before going down the hill at Cadwell (Chris Curve before Gooseneck) which was quite scary. My memory says the wheels looked like they were jumping 4ins off the ground in turn, but it was twenty years back.
The car wasn't raced for long enough to develop it, it had (and still has) the original type damper at the front which was (is...) high up the "to do" list. What I came to blame was just how floppy the chassis was as the body was (is) very light. A friend built a heavier car and I can remember the flitch plates (not 100pct sure that's the right word for them, the bits below the bonnet from scuttle to rad shell) added a LOT of stiffness. With an axle stand under the middle of my front spring I could bounce a wheel like a basket ball, his felt like a car...
I just looked at the http://www.oxfordshiresevens.co.uk/ site where there are body component diagrams. There's a lot of structure my car lacks. The chassis is boxed as are the cross members but no extra stiffness in the nose or spring mounts which I remember from the John Miles experiments "recently" make a tremendous difference. I was always pondering some sort of structure hidden in the rad shell with "sturdy" bracing from the filler cap area back to the corners of the scuttle.
What I'm only now wondering is if I have short chassis steering arms on a long chassis. From memory the king pin inclination was quite steep (that's how it came out with the drop links I had/have). It used to be on 15in wheels so perhaps the offset came into the mix as well? (Its now on 19in wheels).
As least at the back I've got "short" damper arms, beefier springs in the dampers, the leaf springs flat, stiff, and bound. On the hills it used to be a progressive understeer, I think on the circuits as well unless really REALLY wet, which it mostly was those summers.