Pix Explained

Ref. from quadrant; it is just the way I made it; I could have done it differently, but I did not. The front rubbers are 5 1/2 in between the pivots at rest, and 6 3/4 in static at ride height. In a sense the longer their movement the less non-linear they are.
My previous car, similar in many ways, had taller rear uprights, so the Sh.Abs. could go from the upright down to the chassis. On this car I put the upright (I make my own) inside the rear wheel, and so I had to do the rather clumsy additional bell crank for the Sh.Abs. and also for the T bar for the Anti-Roll set up (See .jpg). The rear rubbers are 5in between pivots at rest, and 7 1/4 at ride height: Just under 50% stetch.
I am thinking of making my next car (No 7), and I intend to tidy up and lighten both the bits you have asked about. I am 77, and have been competing and building my own cars for 40 years !
The rubber bands are very definitely rising rate, which I discovered by taking a band and pulling it down between 2 bathroom scales - I will leave you to do that as I have long ago lost the graph I drew. The rubber is Pirelli Extra Flex, which they sell in rolls, but I do not know the spec. I merely used what Alan S was using.
In general I guess that the rubber is more self damping than steel springs so puts less need for Sh.Abs.ers. I have always used Anti-Roll bars (? sway bars to you) as I do not think the rubber has any influence there.
I use Pirelli Extraflex (I think !). I use 1, 1 1/2, and 2 in. wide. (I do not use 1in now).
As the years go by the rubber stiffens up quite a bit; tho' in initial setting up it stretched for a while in use.
I mount the bands in multiples of 2 with a double yoke which has a centre piece for the pull rods. See the pictures when they arrive.
I think Alan's diagram in his book is 'iffy' when he outs the bands round a pivot, even with needle race inside. I have always put my rubbers in straight pull.
I try to get round the rising rate characteristic when working out my wheel rate by sitting that end of the car on bathroom scales, pulling it down 1/2 in, then lifting it 1/2 in, and I assume (!!!) that the difference in the scales is more or less the lb/in figure, obviously divided by 2 for each wheel.
Originally I got multiple bands sewn in about 1/8 in increments: Now I put a single loop in one end and wrap it round the two pivots and lock it with clamping spikes.
If you take a single loop and pull it down against scales you will see the curve; my own guess work is not to stretch it more than 50% on the car.
My weakness is that I still use shock absorbers and the quadrants etc. add to the weight. Part of the reason for the Sh.Abs. is that if the bands broke (they never have in 24 years) then the Sh.Abs. stops me hitting the ground !