
The new carbon/magnalium wheels were developed by Dymag for performance cars to achieve new standards of performance by achieving very low wheel weights and moments of inertia whilst retaining great strength and rigidity with the flexibility needed for both road and track use.
The new carbon/magnalium wheels were developed by Dymag for performance cars to achieve new standards of performance by achieving very low wheel weights and moments of inertia whilst retaining great strength and rigidity with the flexibility needed for both road and track use.
The wheels are made of a forged magnalium hub, designed to reduce the normal cast magnalium porosity to zero. The hub is then fastened to a carbon fibre rim by specially coated titanium fasteners, working within specially bonded bushes. The carbon rim is made from a very special process, using aerospace developed carbon fibre within a special injection process developed by Dymag in the UK. The process uses a solid metal mould which ensures that the wheels are consistently made to a very close tolerance of accuracy straight from the tooling. This also gives a very high quality durable finish which is resistant to brake dust, salt, ultra violet light and the usual forms of corrosion encountered by race and road cars. Carbon fibre in this form is not onIy very strong, but is also quite resistant to shock and thus will withstand potholes better than magnalium, it will bend under extreme shock and then return to shape better than most metals. It will not shatter catastrophically as some have predicted – this is why carbon is used in formula one chassis and aeroplane wings!
The low weight but high stiffness of carbon fibre gives a very light weight rim to the wheel, significantly reducing the moment of inertia. This saves a considerable amount of power in turning the wheel. Consider that a standard Porsche GT3 RS 18” wheel weighs about 14kg, the Dymag carbon/magnalium equivalent weighs around 6.5kg saving about 30kg per car.
The effect on the car however, is much more than the static weight saving. The moment of inertia calculation is based on the ratio of the mass multiplied by the square of the radius, meaning that as the diameter of the wheel increases then the greater the energy consumption of increased weight becomes. Therefore with the Dymag carbon/magnalium wheel the much reduced rim weight has the effect of at least 5 times the static weight reduction, meaning that the feel on the car performance is of taking out 3 adult passengers!
The wheels are not cheap, but then the performance advantages are the best value tuning to be bought for any vehicle, the materials used are of the highest quality and are new to the car market.
Care and maintenance of the wheels is very easy, the carbon rim needs only normal car washing procedures with detergents in water. The finish responds well to car body polishes and waxes. Scratches can be polished or even re-lacquered if required. The magnalium centre needs careful examination on a regular basis to avoid exposure of the metal to the environment. Any exposed or scratched areas should be repainted as soon as possible. The painted finish can then be treated the same as the rim.
If used for track days one difference between the carbon wheel when compared to metal wheels is that the carbon wheel does not heat up as quickly as metal wheels, therefore the cold tyre pressure should be greater than experienced with metal wheels. The best way to achieve the correct pressures is by the old fashioned method of measuring the pressure once the tyres have achieved the recommended hot pressure and then re measuring when cold to determine the rise in pressure. Conversely the wheels hold temperatures well, so that the tyres do not cool as quickly as tyres mounted onto metal wheels, therefore slow laps or a pit stop have less cooling effect on the tire.
To complete the ultimate in wheel technology Dymag also offer the wheels fitted with Tire Watch wireless tire temperature and pressure monitoring, using real time transducers within the tire to alert the driver to punctures, overheating, freezing road conditions etc.
The effect of carbon/magnalium wheels when fitted to the car is to reduce the gyroscope effect of the wheel this gives the following effects: