Variable Rate Steering Arm System (VRSAS)

The Original Project Concept Was To Extend The Ratio Capabilities On The Steering Arm Itself And Remove The Need For A Fixed Ratio Quickrack Through Design. At The Same Time A Long Held Thought Experiment Has Been Realised In The Form Of Asymmetric Steering Possibilities As This Can Realistically Only Be Done On The Arm.

The final design was influenced by feedback requests from many owners and most of the quality aftermarket specialist dealers.

The Spitfire manufacturing philosophy is the same as always regarding materials and quality and the VRSAS is expected to offer a service lifetime in excess of the car itself with the minimum of service requirements. 

The following facilities have been designed into a new combined steering arm and bearing assembly package:

1.  Adjustable steering ratio.

2.  Replacement of the track rod ends with a custom bearing.

3.  Quick, easy and accurate bump steer adjustment on the arm itself.

4.  Increasing the camber range to avoid machining the uprights.

5.  To increase the stiffness and remove any distortion under load.

6.  To save weight if possible, though this is not so important considering the massive increase in function and bearing capacity.

 The kit will work on any Elise series or VX vehicle including the V6

The pre-assembled kits will include all components needed including uprated hub carrier bolts, shims, non-locking setup nuts etc.

 VRSAS SPECIFICS

The detailed functions as above are: -

1.    To remove the requirement for a fixed ratio steering rack. Many owners feel the normal quick rack ratio is a compromise, some would prefer higher, some lower (hence the -4% option). Now you can select the ratio you want.

There are 2 design options for the ratio adjustment system:

a)    Several preset positions

b)   An infinitely adjustable steering ratio capability.

 The preset option design is a overlapping 7 hole system which allows the ratio to be changed in approximately 4% increments from -4% to +21%.

Ratio change is simple and easy, requiring the removal and replacement of the securing bolt into a new setting. 

Each setting is clearly marked and safety is designed in, as the retaining bolts cannot slide along the arm but are located into individual, overlapping holes.

 The slotted option has an infinitely variable design specifically targeted for racing at the very top end of the sport.

This design has the ability to finely adjust the steering ratio in very small increments and even allows asymmetric steering* 

Unless you are a race team with specific knowledge and equipment to use this facility then the preset version is far preferable and much easier to use. It is also inherently safer as the bolt is captive and the system will give you all you need in terms of functionality.

Both options will require a minor track adjustment when the ratio is changed due to the change in the effective length of the steering rack arm.

2.  The OE track rod ends are not great in the first place; they vary in quality and can wear quite quickly especially if the boots are damaged. They are a cause of a significant number of MOT failures. They are not adjustable due to the tapered fitting and readily corrode. They also have a nasty habit of not wanting to be removed from the arm when replacements are needed.

The custom bearings we are using for this project are the exact same units we use on the toe link kits, as the forces are reduced in this function you can probably expect to see 10+ years as a minimum service life. Damaged boots can be replaced, and cheaply, the bearings are dry anyway so even if torn they will not fail an MOT.

3. Once the tapered units have been designed out of the system the bump steer correction can now be carried out at the arm itself and not by moving the rackup and down which only allowed for rough adjustment anyway. Adjustment is done quickly and easily by changing the stainless steel shims under the bearing assembly.

The geometry is such that bump steer correction can be set for any achievable ride height on the VX.

The bump steer correction once set is valid for all ratio changes due the advanced geometry of the design; this is not a simple arm replacement!

Plain nuts are supplied with the kit for the initial setup and play, once set the locknut is used.

4. Camber can be increased up to +4mm at the arm, this should negate any need to machine the uprights. Normal camber shims can be used.

5. Machined from 7075 and hard anodised the arms are stronger, stiffer and lighter than the OE arms and much stronger and stiffer than most of the aftermarket arms we have seen to date.

The increased stiffness of the steering arm system reduces the compliancy and increases the accuracy of the steering system.6. Weight is reduced by 40% over the OE arms themselves, the system as whole is just under 20% lighter with 3mm of shims fitted.

6. Weight is reduced by 40% over the OE arms themselves, the system as whole is just under 20% lighter with 3mm of shims fitted. 

The only possible disadvantage to the VRSAS is that at higher ratios the wheels can hit the chassis at the extreme ends of the steering range, this is not going to happen at speed of course (unless you regularly bang up to the steering stops!) but may happen at very low speeds when parking etc.

Considering the driving ability of most owners it will be common sense as there is no difference in the actual road wheel position-to-response only the position of the steering wheel itself, which will be reduced for any given road wheel movement. 

We appreciate a few may find this an issue so we will have available thick Delrin C rings which can be clipped onto the rack just inside the steering rack’s nylon stops on each side, this will restrict the rack’s movement to match the ratio selected so you then have the same situation as with a quickrack but with an option of ratios, etc.

As the V6 front wheels hit the chassis we could claim it’s the same situation as OE!   

* For those who do not know about the potential advantages of asymmetric steering it’s worth remembering the historic steering geo is based around both wheels following a zero slip angle path in turns. This is great for the horse and cart it was designed for but not really relevant for a high speed car with a substantial weight shift to the extent the inner wheel may not even be on the ground!

What would be preferable is if the outer wheel is steered to the optimum slip angle as is normal and the inner wheel is angled to get the most grip possible considering the reduced weight upon it among other factors.

The ability to alter the inner wheel independently can increase the total grip available, however this is very unlikely to be achieved with a suck it and see approach, you will need accurate geo setup equipment, instant tyre temperature readings, lateral G and lap timing data or the advantages are unlikely to be achieved.