A TR7 for Le Mans

The Janspeed twin turbo TR7 racing project has re-emerged in West London. ADA Engineering, who operate from an innocuous surburban street in the hinterland between Shepherds Bush and Acton, are to field the car at Le Mans, preceded by the Silverstone Six Hours and possibly Monza. 

In a fine piece of co-operative thinking, ADA partner lax Harrower and Janspeed’s Janos Odor have pooled their resources. 

Jan still owns the car (first shown in the winter of 1977/78, when it attracted a lot of favourable comment for its patriotic-liveried and aerodynamic body) and will continue to develop the twin Rotomaster version of the 3½-litre Rover V8. 

ADA have concentrated, since November 1979, on fabricating the basic chassis, suspension and running gear. We went along to see them at work in late March. The basic plot is a Group 5 Triumph weighing around 1,000 kg. and propelled by 450-550 b.h.p. according to boost used. They do not expect to beat the 800 horsepower plus twin turbo Porsche 935s, but with support from a lot of small suppliers and the TR Register, it is hoped to raise sufficient interest to carry on development while waving the flag at the Sarthe circuit. Drivers will be ex-BRM (now BRSCC executive) Mike Wilds, John Sheldon and Harrower himself.

Although a comprehensive roll cage completed the picture of a developed car when the Janspeed TR was shown, a great deal of detail fabrication and design work has gone into the revitalised project. Brabham fan car project engineer David Cox has contributed, especially on the turbocharger cooling side. Not only is there a conventional water-based intercooler at the front, but also a refrigerant unit mounted underneath the bootlid. A normal racing radiator to look after the engine is also nose-mounted, but the coolers for gearbox and differential are neatly mounted in the side panels on the passenger side of this RHD hardtop. 

The front suspension is very different, using a March Formula Two rear hub assembly to cope with the sharply increased stub axle loads, but retaining the MacPherson strut principle as demanded by regulations. 

At the rear more conventional thinking is displayed with a four link Group 4 rallying-style heavy duty axle additionally restrained by Panhard rod. A vertical Bilstein damper with racing spring wrapped around it sits atop the axle, a rather different arrangement to the separate coil spring/damper layout of the TR7 in production trim. 

An enormous amount of work was devoted to the brakes. The discs are AP 12 in. diameter by 1¼ in. thick with detail attention paid to avoiding the tendency toward cracking by radial slots in the disc face inserts. Wheels are 15 in. diameter with 10 in. front width and 14 in. at the rear. The constructors were keen to avoid over-tyring the car, bearing the Mulsanne straight in mind.

Which gearbox is to be installed is as yet undecided. The Rover SD1-based 5-speed was out on the grounds that it would not be able to cope with an engine that is lighter than a Cosworth DFV, but can give more power than the Cosworth under the planned, full 20 lb. boost. A big Jaguar 4-speed looked a real possibility — “heavy, but it should be reliable, judging by its performance in those racing coupés,” we were told. 

Peering at the chassis itself, a massive transverse tube holds both front rails in position rather more rigidly than before, and the roll cage is linked into the front suspension turrets. Double skinning has been employed around the gearbox tunnel.

The rack and pinion steering is centred on the use of a high ratio LHD rack, moved to a new home behind the engine, and mounted upside down. The seat mounting has all been freshly fabricated to lower the driver clear of the roll cage and fit in with the long distance racing controls that ADA have installed. Naturally the wiring is one major task in a car designed for 24-hour racing. Access to fuses and relays is all provided within the cockpit. 

Originally the engine was mounted so far back that the front bulkhead was almost bypassed. Now that bulkhead is restored, though the engine, in dry sump form with a new sump made by ADA, is lower and further rearward than in production trim. Other fabrication includes that of a fuel tank with top contours designed to feed air to that refrigerant unit. The dry sump oil tank also mounts in the boot. 

It is nice to see that ADA and Janspeed have got on with the job, rather than shrieking how they will beat the World. As writers we have become wary of British projects in long distance racing, especially when centred on emotive names like Aston Martin or Jaguar! 

We wish the team luck at Le Mans, but it may well be that they will have managed to race once before you read this. They quietly admitted that they were going to try to have the car ready for Monza in April, though the real target was a Silverstone shakedown (May 11th) for Le Mans in June. — J.W.