PACKAGE ‘A’  - Full Analysis - £985 + VAT

Details of Service

Our objective is to provide you with the maximum possible

improvement - with minimum cost and ‘hassle’.

Our experienced  vehicle dynamics  engineer, Nigel Rees BSc, will

visit your premises for a full day, to ‘measure’, assess and analyse

your car. Before the visit, we will ask you for the make, type and

size of tyres. Usually, we will have full performance test data for

the tyres available, but if not, we will contact the manufacturer to

obtain test data. We will also ask you for CWP ratio, range of gear

ratios, engine power/torque curve (or simply max. Power and revs)

and whether or not the car has a limited slip differential.  We will

also ask you for any restrictions imposed by your particular

championship/category regulations.

Note:-  Aerodynamics. If your car generates significant aerodynamic

downforce, we have three possibilities:

Post 1990 Tatuus, Dallara, Lola etc. single seaters and sports racing

cars are generally  supplied with wind tunnel data.

You, the client, may consider selecting ‘Package C’, whereby we,

GSD RaceDyn, generate accurate aerodynamic data through track/datalogger testing

(See details in Package C)

In the absence of either a) or b), we (GSD RaceDyn) will make an

estimate of Lift Coefficient (downforce curve v speed)and centre

of pressure position from prior knowledge and experience and apply

this to the cornering and braking analyses.  Fine aerodynamic balance

can then be achieved during testing – GSD can assist if required.

During his visit to your car, our engineer will initially:-

• Take measurements of track, wheelbase and 3 dimensional positions of all suspension ‘pick up’ points.
• Accurately measure wheel to spring/damper motion ratios.
• Accurately measure anti roll bar system and motion ratios.
• Measure longitudinal Cof G position. (Weight distribution).
• Measure ride heights and rake.
• Generally assess the car’s structure, mechanical systems and any issues which may affect performance and handling.

This measurement process generally takes 3-4 hours.

At this stage, we will take an initial view of weight distribution compared to tyre sizes / characteristics. This will be refined during the ‘cornering dynamics analysis’ phase.

Once the measurement process is complete, our engineer will enter the data into our ‘RaceDyn’ vehicle dynamics system on a laptop computer and conduct the following analyses:

• Suspension Geometry:-
• Camber change with bump and droop.
• Roll Centre location and movement with bump, droop and roll.
• Virtual swing axle length and change with bump, droop and roll.
• Track change (contact patch displacement) with bump and droop.
• King post inclination.
• Scrub radius.
• ‘Jacking’ potential (particularly rear).
• Anti dive and anti squat coefficients (pitch centre/pitch resistance, rake control).

At this stage, we will assess an optimal geometry solution. This may suggest the ‘movement’ of suspension pick up points. In many cases, this is easily and cheaply achieved. However, regulations and/or practical/structural constraints may preclude pick up point changes. Should this be the case, compromises in spring rates, anti roll bar stiffnesses, ride heights etc. will be introduced at the ‘cornering dynamics’ stage to achieve the best possible compromise.

• Braking Analysis

Utilising tyre data, the output from the geometry analysis above and, where appropriate, aerodynamic data, we simulate the cars behaviour under heavy braking, particularly ride height/pitch/rake changes. This enables us to select optimal spring rates (stiffness) / wheel rates . We also assess suspension ‘frequency’.

• Cornering Analysis, power off and power on

Utilising tyre data, the output from the geometry analysis above, spring rates selected from the braking analysis and, where appropriate, aerodynamic data, we now simulate the car’s behaviour when cornering ‘on the limit’ in low speed, medium speed and high speed corners. Behaviour is analysed with and without the application of engine power.

Output from this phase includes:

• Lateral acceleration (g force)
• Roll angle
• Vertical wheel loads
• Lateral wheel/contact patch forces generated by tyres.
• Traction and linear acceleration under power
• Front/rear balance (understeer/oversteer)
• Dynamic camber
• Yaw moments under power and overall stability

We then  re-run this cornering analysis several times with varying front and rear anti roll bar stiffnesses until we have achieved optimum performance, handling balance, stability and  traction.

• Anti Roll Bar selection /design

Having selected optimal anti roll bar stiffness (front and rear), we will run our anti roll bar design programme to either:

• Select settings for your existing anti roll bar system
• Design a new anti roll bar system (torsional length, bar/tube diameter/wall thickness and lever arm length.
• Select Belleville disc stiffness for monoshock/shuttle systems.

• Engineer’s Report and Recommendations

Generally, our engineer will  provide you with a set of recommendations before he leaves your premises.

Within 3 days, you will receive a full report covering all aspects of our analysis and data generated, in detail.

The report will include a set of recommendations including, but not limited to, the following:

• Spring Rates front and rear
• Anti Roll Bar sizes/settings front and rear (or revised antiroll bar system  design)
• Front and rear static ride height settings
• Front and rear static camber settings
• Static castor
• Static ‘Toe in’ Front and rear
• Dampers – if we consider that your dampers require ‘revalving’ due to our revised spring rate recommendation, we will provide you with a ‘Data Pack’ which provides your damper manufacturer or service agent with sufficient information to select and fit appropriate ‘valving’.

It is possible that we may recommend small changes to weight distribution to optimise performance. We will only recommend weight distribution changes if this can be accomplished easily and safely by relocating components such as battery or extinguisher system, or by making minor changes to the driver’s seating position.

If we find significant suspension geometry problems, we may recommend revised ‘pick up point’ positions, but only if:

We cannot overcome the problem by other means.

The problem is sufficiently serious to have a major adverse effect on handling and performance.

Changes can be accomplished relatively easily, safely and at reasonable cost.

Such changes are permitted within the regulations for your particular race series.

GSD will provide a telephone support service for 6 months from date of analysis, including advice on damper settings for varying circuits. A set up advisory manual will also  be

CONTACT

Nigel Rees BSc on 07766 761702 or nlr784@yahoo.co.uk