DESIGN AND INNOVATION
But we know everything about our design and so can adjust it the way we want. We saved a lot of money because most of the manufacturing was sponsored.’ But GFR is a big team with major sponsorship, so has the resources available to design and make its own differential.
A team with a smaller budget
that is also in the process of developing its own active torque system is Oxford Brookes Racing, but for different reasons: ‘The Drexler is very expensive. We’re sick of it. Every team runs one. We want to get away from that and start to innovate instead.’ Ultimately, the choice
The Quaife differential can be supplied in component form, allowing teams to adapt it to suit their requirements
be the cost – at least depending on the country of origin of the competing team.
QUAIFE Unlike Drexler and Torsen, Quaife do not offer a ‘university special’ differential, instead supplying teams with the same unit as they do for their mainstream motorsport applications, which means teams then have to make their own modifications. Len Unwin from Quaife Engineering: ‘The automatic torque-biasing (ATB) characteristic automatically adjusts the ratio at which the differential locks up. However, it never locks up completely, so acts like an open differential and doesn’t upset handling, whereas when using a plate differential, the handling has to be adjusted. Another benefit to the ATB is there is no friction affecting the performance and no wearing parts.
‘Our differential gives the
Formula Student team a chance to experiment, and it won’t affect the rest of the capabilities of the car. It gives a lot of scope for the students to modify for their own use. It’s nice for us to encourage students, but hopefully they’ll get a good opinion of Quaife and want to use us again throughout their careers in motorsport. We
have given them a unit that works, and works very well, but also one they can use their own imagination and their engineering skills on, which is what it’s all about.’
One team that used Quaife
differentials is Mobil 1 Team Sussex. ‘We know Quaife offer a lifetime guarantee so we knew it was a good product to have. Also, in previous years we’ve had good support and technical advice from them and we’ve never had a problem with their differentials. It’s a very compact unit, which is easy to fit and to design around. We had to get the right driveshafts and we didn’t custom make those but instead got them off an actual car and modified them. In terms of moulding around the differential, because there was so much detail from the product itself and the size of the drawings it was easy to put it all together. It comes sealed as one package and all we had to do was add the grease. The differential is probably the most expensive part of our car but Quaife offer a very reasonable discount.’ As expected, price plays its part again, but also the time available. Some teams admitted they didn’t have time to make the necessary modifications and so had chosen to purchase the more expensive Drexler unit instead.
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www.racecar-engineering.com • September 2011
HOMEMADE DIFFS Is it more effective to modify and design your own differential because a Formula Student car is so specialised? Global Formula Racing made
its own clutch pack differential. ‘It’s externally adjustable with a pre-load, which is something we’ve been developing for a while. We looked at differential suppliers and it was something we strongly considered because there is a lot less effort involved.
between Drexler, Torsen, Quaife or a custom made differential comes down to two things: the time available and the budget. If a team has money and little time then the Drexler is suitable. The Torsen seems to be used by teams with less time and less money, while the Quaife is cheaper still but takes longer to adapt. Looking at the success of GFR, it seems that if a team has plenty of both time and money they should certainly consider designing their own unit. Alternatively, teams could go
the Cardiff Racing route and run without a differential altogether, simply choosing to use a solid spool because they ‘found it much better than a differential in a car with this short wheelbase.’
Hamburg worked with GKN to develop its own differential. A rare choice
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