My mini came with coil springs, hi lo's and adjustable bilsteins. It is my company car which I drive to work everyday and I club race it. Our club championship is based on 4 different events. Circuit sprints, hillclimbs, motorkhana and autocross.
My Sons also pinch it on Saturday nights and cruise with 2 of their mates. The suspension was set at a reasonable height. Apart from driving to work in peak hour traffic I would compress the coil suspension in some way that would compromise the vehicle. Diving under brakes, scraping tyres on flares on cornering or too many people in the car. The worst feeling is a flat out corner at the top of the back straight at our Sandown race track where the suspension would hit the bump stop and suddenly stiffen the car and send it into a massive drift at 160 kph. Played with ride heights, bilstein settings and the like and completed many events with varying settings, cambers, castors and toe angles at both ends of the car.
Fact 1- there is no such thing as a rising rate coil spring only progressive rate springs which rely on coil stacking of a tightly wound group of coils (soft rate) before a wider wound section of the same spring (stiffer rate) comes into play.
Fact 2- the coil length of a mini coil spring is not long enough to have the progressive wound sections and is essentially a single rate coil.
It is entirely practical to fit stiffer springs to suit the event and I had considered this. I decided to try rubber cones and went with the red dots. Kept the bilsteins.
The ride was harsh but the handling was dramatically improved in all situations and with the same ride height it doesn't scrape anywhere.
The improvement in braking was also dramatic with no squat or dive to speak of.
I swapped out the red dots in the rear for standard cones in order to soften the rise. It didn't make a huge difference.
Fact 3- Mini rubber cones are true rising rate suspension mediums and a car like the mini absolutely needs rising rate suspension. What other car can almost double its kerb weight by adding passengers. A single rate coil cannot adapt to the massive increase to the sprung weight to kerb weight ratio. Any coil has therefore got to be a compromise.
With the uses I have for my car rubber cones have given me a set and forget suspension that copes with everything I do.
This is the right answer for me but perhaps the wrong answer for someone else who just want to take their mini out on a pleasant Sunday.
I have become very adept at scanning the road ahead and dodging holes, drain covers etc, etc.
The raised "cats eye" reflectors on our Freeways drive me mad because they seem to crash through the car worse than ant pothole.
Nothing a Nigel Mansell lane change cant fix.
Allan Sainforth writes a book called "Race & Rally Car Source Book" which has numerous references to the mini and its rubber suspension.
Please read if you can get a copy and draw your own conclusions.
