Jaguar XJR-9

Grand designs

1988 was Jaguar’s third attempt at lifting the biggest prize in sportscar racing; the rival Porsche was ageing, but quite capable of winning. Both camps recall an epic battle
Words: Keith Howard. Photography: Benedict Redgrove

Le Mans 1988 was a story of ageing titan versus past hero resurrected. Porsche’s 962C was over the hill — all it had going for it was proven reliability and the fact that low-downforce Le Mans cancelled out much of its aerodynamic inferiority. This was a last stand to keep Jaguar from its prize.

For Jaguar and Tom Walkinshaw’s TWR it was the third attempt; pressure was intense for a win. With Lammers, Dumfries and Wallace in car 2, it did, despite the efforts of the works Porsche of Bell, Ludwig and Stuck. The two finished on the same lap, only about two and a half minutes apart.

We spoke first to Tony Southgate, designer of the XJR-9, who was responsible for the car’s carbonfibre chassis and its superior ground effects. Porsche’s story is given by Norbert Singer, who headed up the 962’s development programme.

Aerodynamics
TS: “The Jaguar benefited from the C100 Mk3 I designed for Ford. It had a similar tail and wing configuration and a side radiator fed from a NACA duct. It never raced, but it was very good except that it didn’t cool well enough and had a bit of understeer. I thought the easiest way to correct that on the Jaguar was to put the radiator at the front. It’s the most efficient place for cooling, which means you can use a smaller radiator, and ducting the outflow upwards adds downforce.”

NS: “It was a couple of years after we started to do ground effect aerodynamics in 1981/82 that we got our own tunnel. It had no moving belt but it had a sophisticated boundary layer suction system beneath the car as well as ahead of it, so you could test a full-size car just by rolling it in and turning the wind on. We could check the aerodynamics and be out again in half an hour. With a moving belt you can’t do that.”

Engine
TS: “The Jaguar engine had a lot of horsepower — up to 740bhp when we won in 1988. Biggest problem was its size. I put it as far forward and as low as possible to improve weight distribution, but the centre of gravity was still higher than you’d want.”

NS: “The flat engine influenced the ground effect we could achieve. Around the gearbox, ahead of the rear wheels, we had a disadvantage in the width of the underfloor duct. This lost us 10-15 per cent downforce. Our engine also couldn’t be used as a stressed member; we had to have a tubular frame round it, up to the gearbox, which was a stressed member.”

Structure
NS: “Our car had an aluminium chassis but others built composite chassis for it. If we’d made a complete new composite chassis we’d have changed the shape to make it more effective. If you copy an aluminium chassis in composite you don’t achieve the best result — it’s not optimised.”

TS: “With my Formula One experience, I never considered anything other than a carbon monocoque. I drew the tub and specified section thicknesses and Advanced Composites decided the weave type and alignment. It was super-stiff. Overall the car was around 6000lb/ft per degree between axles but the tub itself was more like 40,000lb/ft. All the deflection took place in the engine bay. I’d be surprised if the Porsche 962C achieved more than 20001b/ft per degree.”

Transmission
TS: “Near the end of the 1988 race Lammers felt something happen in the transmission, so he was very careful changing gears. He stayed in the car at the final pit stop because he wouldn’t trust anybody else with it. When we stripped the ‘box down we found the main shaft in two pieces. It had sheared across a lubricating hole but luckily bang in the middle of one of the splined gear hubs, which held it together. Tom [Walkinshaw] made us keep it quiet. But you need a bit of luck in racing, and that was ours.”

NS: “The PDK double-clutch gearbox was not reliable, so we only had it on one car at Le Mans, and had problems with it. This was our only technical development in ’87/’88, and the only development budget we had. We did a test at Paul Ricard where PDK was nearly 1 sec faster a lap, even though it added over 30kg. But it was ahead of its time. You had to do things mechanically that today you do electronically, so we had no chance of getting it to work properly. If we hadn’t done PDK but spent the budget developing an evolution 962, I’m sure we would have got that 1sec improvement out of the car.”

The race
NS: “Klaus Ludwig made a mistake trying to do two laps on the reserve fuel tank, which was impossible. But at least he made it to the Ford chicane, just before the start/finish line. The last 200m he drove on the starter motor. This dropped the car two laps, which would have been enough to win. Technical problems happen in a race but a driver error like that shouldn’t.”

TS: “We started down the grid because the Porsches turned the boost up for qualifying. But Lammers soon passed Stuck to take the lead on the Mulsanne; so as far as I was concerned I’d succeeded. I’d done everything to make the car quick on the straights and it had paid off. Stuck came up to me after the race and said, ‘You know, that cheeky Lammers was waving as he passed me!’ We then just had to last the 24 hours, and it was nail-biting. Changing the screen on the Lammers car was the worst bit. We were comfortably in the lead and if we’d lost it then it would have been tricky to get it back.”