RRS Technical Section

Motion ration is the rate of movement of the spring and or shock absorber to wheel movement.

0 points poor (over 2:1 ratio) 1 point average (below 2:1 ratio) 2 points excellent (1:1 ratio)

Unsprung weight is the weight of the components hanging off the vehicle's suspension mounts such as wheels, rotors, control arms & shocks. The comparison will evaluate how the different suspension systems react to irregularities cause this mass to move.

0 points poor

1 point for average

2 points for excellent

Shock design & adjustability play a key role in your suspension's ability to compensate for differing road surface conditions.

0 points poor (cheap)

1 point (good design, no adjustment)

2 points (good design & adjustability)

Your springs are affected by three main factors: manufacturing process, materials, and adjustability.

0 points poor OE replacement spring

1 point average economy spring

2 points excellent race engineered spring

Articulation joints are your suspensions ball joints & control arm bushings. These joints contribute to unsprung weight via friction & or resistance to movement.

0 points for poor (high friction)

1 point for average (low friction)

2 points for excellent (near-zero friction)

Is the angle determined principally by the location of the outer tie rod end in relation to the lower ball joint , so that the inside wheel on a turn will turn a proportionally smaller radius than the outside wheel ,to both match wheel base & wheel track .

0 points for incorrect Ackerman angle

1 point for good Ackerman angle

2 points for good and adjustable Ackerman angle (Ackerman angle can be adjusted by one of two ways:

a) adjustable outer tie rod end location

b) Adjustable inner tie rod end location

Angle between vertical & a line connecting top & bottom pivots of a front suspension upright, seen from head on. Not to be confused with caster angle which is lean back angle on the top pivot behind the bottom pivot of a front upright, seen from the side of the car.

The amount of steering axis inclination is vital to suit modern radial design tyres.

0 points for incorrect steering axis inclination

1 point for acceptable steering axis inclination

2 points for acceptable & adjustable steering axis inclination

Caster angle is the lean back angle of the top pivot behind the bottom pivot of a front upright, seen from the side of a car. The caster angle for modern tyres typically fall in the range of 2`-6` positive caster for a street car and 41/2- 81/2 positive caster for a race set up. The higher the caster angle the more self centering action will occur that helps a car run straight at high speeds, and will also pull the wheels back to straight ahead coming out of a corner.

0 points for lack of adjustment to reach 6`

1 point for lack of adjustment to reach 8.5`

2 points for an adjustment range from factory 1.5` to 8.5`

A jacking effect is created to either raise or lower the outside wheel opposite to the inside wheel to either increase body roll or decrease body roll. When body roll is decreased by this method a less stiff anti roll bar would be required.

0 points for a jacking effect that increases body roll

1 point for no jacking effect

2 points for a jacking effect that decreases body rollYour springs are affected by three main factors: manufacturing process, materials, and adjustability.

0 points poor OE replacement spring, 1 point average economy spring, 2 points excellent race engineered spring

This is the invisible moving point about which a vehicle is considered to rotate in a corner. Easy to plot in a static situation but far from easy once the vehicle is moving. The relationship between the roll center & center of gravity determine the roll moment .The roll moment is the leverage exerted by a vehicle attempting to roll,

0 points for either excessively high or low roll center positioning

1 point for either moderate, high or low roll center positioning

2 points for a tightly positioned roll center as low as possible before an increase in body roll is caused.

Roll moment once calculated, helps determine how the sprung weight of the vehicle can be transferred to either end of the vehicle and can help determine the springs, roll bars strengths and the leverage with which they are applied.

0 points for a roll moment that will make a vehicle dangerous at high speeds corners

1 point for a roll moment that will make a vehicle stable in high speed corners but will lack cornering grip.

2 points for a roll moment that makes a vehicle stable in high speed corners and will increase grip

Geometric method of reducing a vehicles tendency to nose dive under braking by tilting inboard suspension pick up points and or mounting the brake calipers front or rear of the axle center line

0 points for bad anti dive characteristics

1 point for moderate anti dive characteristics

2 points for optimum anti dive characteristics

Scrub radius has been a loose term which is most commonly understood to apply to a radius of movement of the tyre contact patch on the horizontal plane .When there is too much movement caused by high scrub radius, typically the vehicle will either increase or decrease with wheel movement (Scrub radius is a result of a close relationship between wheel center line and suspension pivot points)

0 points for poor scrub radius characteristics

1 point for moderate scrub radius characteristics

2 points for optimum scrub radius characteristics

Beaming & torsioning

Beaming is the bending of the vehicle end to end .Torsioning is the twist of the vehicle end to end

0 points for increasing beaming & torsioning

1 point for maintaining beaming & torsioning

2 points for decreasing beaming & torsioning

Different suspension formats create loads in different suspension pivot points (where the sprung weight is carried). Fatiguing is typically a high stressed suspension pivot point or a reduction of the manufactures intended chassis integrity (OEM, uni-body chassis rely heavily on the integration of bolt on exterior body panels and frame welded panels)

0 points for changing the chassis design or incorrectly loading a pivot point

1 point for maintaining original chassis design and original loading pivot points

2 points for maintaining original chassis design and decreasing loading at pivot points

Space in relationship to engine bay size (Mustang II can remove entire shock tower, RRS strut allows the option of shock tower notching to achieve an identical effect of useable space) and space in relation to the ease of serviceability of the suspension and steering components.

0 points for no improvement of space

1 point for improvement in space that requires additional modifications

2 points for improvement in space that does not require any additional modifications

The gross vehicle mass ideally for any performance application should be as light as possible with no loss of chassis integrity

0 points for increased weight

1 point for maintaining weight

2 points for decreasing weight

Chassis integrity is affected by age, original design, modifications and skill of the tradesman who carries out the modifications. This will determine the duty cycle (lifespan) and safety of the vehicle

0 points for decreasing chassis integrity (the likely hood of failure)

1 point for maintaining chassis integrity

2 points for increasing chassis integrity