Suspension setup and suspension settings tuning.

Suspension tuning.

On the track the lower you go the better. This works well because tracks are fairly flat and you do not have a carrier bag full of eggs in the car from your return trip to the supermarket. Manufacturers have to take speed bumps, uneven road surface, passenger comfort and road noise into consideration when setting up a cars suspension. Most production cars have soft comfortable suspension that does little to maximise handling and driving experience. Track cars are set up for driver preference and style so there perfect setting is not just different for each model of car it is also a subjective thing.

Common mistakes. Going into the local part store and buying a suspension kit that lowers the car 30mm and expecting this to be the perfect set up. Most kits are very general in nature and imply that they can be fitted to all models in a cars range. Different engine weights, wheel sizes and car weights need different suspension characteristics. If you go too low you risk grinding the tyres in the wheelarch requiring a rolling of the arches (making them bigger by folding the metal underneath) you also risk damaging the drive shaft and gearbox if the angle from the final drive to wheel hub is wrong.

Ride Height adjustment
Cars look good when slammed to the ground. You reduce your ground clearance and can cause problems with tyres rubbing in the wheelarches. Remember that roads have speed bumps and instead of slowing a lowered car down they will grab the sump and rip off the bottom of the engine and most of your front skirt.

For most road cars I would not recommend going lower than 35mm for hot hatches which tend to have uprated suspension I recommend just 30mm. If you have changed the wheel size then these tolerances could be much lower a car fitted with standard suspension and 17” rims would be OK but if you lower it as well you may get all manner of problems. The aim should always be to improve handling and with the car being lower there will be less air going under the car and this can help with stability. Remember lower springs should be fitted to matched shocks and just cutting the springs is really bad idea – you are asking a piece of metal designed to a tolerance to work effectively with a big chunk of its structure missing.

(Damper – the shock absorber).
Bound & Rebound settings
This is the dampening force of the shock absorber. Bound is the rate at which the shock allows compression and rebound is the rate at which the shock releases the compression. If your suspension has a dampening control then you can play with these settings and get the optimum setting. Electronic in car adjustments is now possible and if you are considering drifting your car you really should invest in one of these set-ups.

The shocks are generally a piston inside a liquid and some have an additional gas chamber to absorb shocks (gas compresses whereas liquid does not compress under pressure.) Shocks can have a fairly complicated structure. Testing the shocks on your car you bounce the car – if you get more than one bounce then your shock are on the way out. Without shocks the car would drive like a thing on a spring and just bounce everywhere.

Camber
This is the angle of the wheel to the road. If you put all of your weight on the outside of your feet you would have a negative camber and if you rolled your feet inwards so all your weight is on the inside you get positive camber. As the car rolls into a corner the camber can make a big difference to handling and also tyre life. Sadly the best camber setting for handling will cause premature wear to the tyres! Front wheels are set up to get positive camber as the wheel is deflected up. The camber setting is the angle of the wheel to the road as well as the angle of the wheel to the chassis. As the car corners and rolls the suspension geometry must maintain the best angle of contact of the tyre to the road.

This is why manufacturers go to such great lengths to set up their cars correctly and when you make suspension modifications it should be your aim to keep as close to the makers spec as possible. Generally the more tuned the suspension set-up the less variation there is under stress and the less room you have to play with. Start off with the manufacturers settings and alter these slightly and test the results. If you can’t feel any difference then why are you bothering!

Remember that kerbing wheels and hitting bumps can knock out the camber setting. Tyre temperature alters the camber so the camber is best set with warm tyres!

Caster
Imagine it is a windy day and you lean forwards – your legs now have a negative castor. The angle of the wheel hub in relation to the suspension arm is described as the angle of castor. The positive castor keeps the wheel straight when going along – a bit like a pram wheel the connecting arm to the hub is set slightly back. Stability results whereas a neutral camber would result in the wheel wobbling around the axis. The angle a car wheel is set at generates more camber when the wheel is turned.

Toe
Stand like Charlie chaplain with your heels together and your toes out. Now imagine your cars tyres are at this angle too – this is known as Toe Out. Toes in is where your heels are apart and the toes are together. Obviously the angle of Toe in a car is barely perceptible. The effect of this setting on the car is stability – toe in gives great stability on the straight and the car resists a turn to the right or left. Toes out gives a much quicker steering response. Toe in is a road car setting and Toe out is a track setting – it is up to you to decide how much Toe you want. Toes applies equally to the rear tyres although they are generally set as a lower angle than the fronts.

Roll
Eliminating roll in corners helps cornering stability and keeps all four wheels on the ground. When pushed really hard most production cars will lift a rear wheel of the ground and when cornering you really need as much rubber in contact with the black stuff as possible.

The roll bar also known as a sway bar helps to keep the car level in a corner by taking the lift from one side and trying to move it to the other. As this is not possible the lift is effectively pulled down and everything is kept in contact with the road.

Strut braces stiffen the top of the suspension mountings and help reduce flex when you are pushing the car hard so also have a minor benefit at reducing roll.

Spring stiffness
If the springs are too stiff the car will bounce over humps and lumps in the road. If it is too soft the car will just wallow along (it’ll be a really comfortable ride though). The best shocks are adjustable on the car and let you get the set up perfect to match your driving style. If you have slightly softer springs on the front the nose of the car will grip in corners and you will have more oversteer (back gets lighter and tends to go wide in corners). If the soft springs are on the back you will get understeer, which is how most production cars are set up nowadays because the inexperienced driver reacts better to understeer than oversteer.

Bushes
These connect the suspension components to the chassis of the car. The rubber ones deteriorate in time. New polyurethane bushes last longer and keep the handling much tighter but because they are harder they can make the ride a little more bumpy.

Suspension Setup

Shocking and Absorbing stuff!

Suspension tuning.

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