There really is no point going into how the ROLL AXIS Vs Mass centroid Axis works !!!!
There are technical seminars available and university degrees for those people who wish to study the physics of automotive suspension, it can be a very difficult subject to understand nevermind explain to people from scratch, everything affects everything else, I personally have several books and notes of reference, and at any point if any terminolgy is mentioned and not explained properly then people should not feel shy or embarassed to ask if they don't understand.
laymans terms are much better.
HANDLING (A summary)
Handling is a term used but also it's a range between comfort and traction. Lets look at this really simple because it's much more fun that way:
Comfort is what you have in an armchair, comfort can also be had in a chair or seat of your car.
If you want to travel 4 hours in a car, a softly sprung (Compliant and forgiving) car will allow you to not feel knackered at the end of your journey
If you want a car to go round a corner really really fast, with lots of forces (on your body and the car) you're gonna have to brace yourself in your seat, and / or hold on tight and obviously this is not going to be a comfortable experience and you probably couldn't sustain this for 4 hours without some pain!
These are 2 extremes and some cars of course have "in between" characteristics with some compromises between the two above scenarios.
You can only corner at high forces, if the tyres can grip the tarmac well enough.
The tyre can only do this as long as it has all it's rubber molecules available to grip the surface and it stays flat and / or has enough of it's rubber molecules to hang on.
If it can't sustain the load it's having to deal with because of lots of reasons, it will loose grip and slide.
The suspension on the car is all connected to this tyre, and it's job is to keep the tyre flat on all road surfaces to retain this maximum adhesion.
It's a difficult job because it is subjected to many forces and different conditions on typical roads.
It's so difficult keeping this short because it's a complex subject,
The tyre has to deal with the car's body effectively tipping over (cornering) and you can imagine at a certain point the tyre has absorbed some of the bodyroll because it's made from flexible rubber, but then it can not stay flat if more force is tipping it and hence the tread contact patch starts to lift off the floor (on the inside) and the (outside is becoming more deformed) so you may then only have 75% of the availble tyre tread on the road. Because this is less than it should be, there are less molecules on the road and they are having a much harder time holding on. This is described as the camber of the tyre, which is best leaning more inwards (Negative) than outwards (positive) If the cornering forces continue and the tyre can not cope it will slip and loose grip. (Understeer at the front, and oversteer at the rear)
The job of a road cars suspension is designed so that when the wheel moves up and down from undulations in the road and / or cornering , braking and acceleration forces it can stay firmly planted on the tarmac giving the road user enough grip to not have an accident.
There are then loads of different angles of dangle, calculations, and characteristics of what tyres and suspension do and don't do, which would be a full time occupation..........and not light reading for a forum!
Handling Vs Ride Quality
A shock absorber opens and closes, and a spring compresses under force and this has resistance which wants to return to its natural unsprung state.
Not all springs are wrapped around the shock absorber Called a (Coil over) but in this case the Elan is..........
If a car had springs but no shock absorbers, the car would bounce over a bump in the road and then osciliate up and down again and again until it stopped eventually!, this would be most uncomfortable and the car uncontrollable . A shock absorber opens and closes with some resistance, which means when the car body weight compresses into a bump in the road, it not only compresses the spring, but also the shock offers a little resistance, and then when the car comes out of the bump in the road the the spring extends pushing the wheel down, and the shock absorber also opens under resistance and hence the car will be controlled under compression and rebound whilst tackling road irregualr surfaces.
When a car goes down a dip in the road the car's body pushes (Compresses) the springs down, the shock absorber also compresses and this resistance is called BUMP, I remember it by thinking you're going DOWN into a BUMP, when the car comes out the dip the body starts to rise, the spring force has held the cars weight and force whilst going down and now it is pushing the wheel down and the car back up. The shock absorber then starts to open itself from being compressed and this motion is called REBOUND.
The BUMP and REBOUND resistances (Ratios) in the shock absorber are different, usually on road cars a one third BUMP resistance and a two thirds REBOUND, this is because the spring does most of the work in BUMP, but on the REBOUND a stronger resistance is required to stop the rise being too quickly is as the spring has a force to extend itself.
Weight Transfer
Weight does not move about the car when cornering but the mass of the vehicle does tip and apply forces on to the tyres, EG the front and rear left side wheels when cornering right, also weight transfer occusrs when braking and accelerating EG Braking = stronger forces to the 2 front tyres . The weight 's force can upset and make each tyre have too work work to cope with!. If the car has very little resistance (EG: soft springs and not much shock absorber resisitance) then the car bodies weight will shift itself very quickly to the front of the car if an emergency stop is performed for example. This amount of weight and more importantly the speed (Too fast) that it all loaded on the front axle may be is too exessive and could cause the tyres to lock up and skid.
If this car was then fitted with a stronger rate springs and also higher resistance (Stiffer) shock absorbers they would not allow the car to tip itself forwards so quickly and hence tslow down the weight transfer speed. A slower shift of weight is much better as the poor front tyres do not now have have a sudden rush of force. The result of having a loading applied to them slowly gives the car body better control and a much better chance for the tyres to bite into the road and stop the car better without skidding.
Stiff Shocks and Springs
The answer for high cornering, braking and also accelerating then is to have as stiff shock absorbers and springs as possible................because the slower the weight transfer the better...........
WRONG.
Moderation is needed ! Too stiff suspension especially for road use, causes all sorts of problems for the tyres traction: it does not allow the wheel to rise and fall enough to cope with a dip in the road and hence the wheel comes off the floor!! which means zero traction and if this is the driven wheel (Front in the Elan's case) it's no drive and possibly wheelspin!
Ride Quality
The major compromise of having a stiffer spring and shock is the ride quality suffers. This may be acceptable on the racetrack for 10 laps, but not as an every day vehicle or even a weekend car becasue it will not be nice to drive.
As modern technology gets better, designers are finding better ways of getting good suspension control without much bodyroll but also good comfort.This has been acheived with good success and especailly using electronics in such vehicles from BMW, Mercedes, Aston Martin, Jaguar etc.... The car either senses the loading automatically EG when you throw the car hard into a bend the suspension stiffens, and then when you're cruising at 75 mph on the motorway it's under not as much loading and is in it's softest setting for comfort.
There are no such systems availble yet for the Elan, hence the only solutions at the moment are purely mechanical shock absorbers and a coil spring.
Lesson over.
PS There are lots and lots of differences to these theory;s, just in case I've slipped up somewhere (I'm only Human) and it's not a good idea to get too technical and deep because it only switches people off, and doesn't help anyone
I would welcome all feedback and questions from anyone who wants to improve their car and the reasons for what's why ? .
Please answer thess on its own seperate thread named AVO Protech suspension, this discusses products and ideas for those that want to improve the handling for the road but also those that have even upgraded already ? (protech or AVO dampers) and / or (SJ Springs) but are either unhappy (whats the Reason?) or do you still want more............
I would like to see a set up made or modified that reduced the standard set-up bodyroll but more importantly that also retained 90% of the ride comfort.
Or the ultimate challenge for me would be an improved ride quality over standard but also better body control.
The other thread on shocks and springs I believe will be more track day biased and I believe the ride will not be that nice for the road???
An improvement in the ride and body control will however not be done through one component, the components and characteristics that control these are:
The Wheel width, diameter and offset, weight and tyre pressures
The Tyre width, profile, compound, and condition.
The shock absorber
The coil Spring
The Anti (Sway) roll bars
The condition of the mounts, bushes and ball joints etc..
The cars natural static geometry (EG how all the angles of the 4 wheels are sitting naturally and in relation to each other)
