Steering Crewe’s ships
Mike Dunn oversaw the development of the wallowy Bentley Mulsanne Turbo into the wieldy Turbo R. He gives his insight into the process
When I joined Rolls-royce Motors Ltd as engineering director in 1983 it was having difficulty selling cars, and building them to stock,’ says Mike Dunn. ‘There was no great demand, and the reputation of its cars had suffered. There were various things that needed to be done, including fixing the design and quality problems to make the products more attractive – the buyers weren’t demanding, they bought them because they were Rolls-royces, but they wanted their cars to stay on the road.’ If the market was difficult for its own models, then it was a time of deprivation for its stablemate Bentley; the famed marque had slipped deeply into its owner’s shadow and lain practically dormant, its vehicles mere facsimiles given minor styling tweaks. In 1981 it sold just 151 cars, compared to 3104 Rolls-royces. And yet a glimmer of hope had arrived the following year, in the form of the 300bhp Mulsanne Turbo.
‘It wasn’t an answer to a particular problem. One or two engineers had simply been working on a turbo installation and were pleased with the engine response. The company realised it could be a very saleable product if put into the existing car. Initially it thought that it could just sell the extra performance, but quickly found out there was more to it than that.’
After Mike’s arrival, running issues including excessive fuel use requiring engines to be tuned for greater economy and increased heat build-up needing increased cooling capacity were targeted.
‘We did sell Turbo Mulsannes; people liked them but there were problems. Very little had been done to the suspension setup and tyres hadn’t been upgraded. It was softly sprung and rolled excessively through corners. The model wasn’t a liability – that would imply it wasn’t safe. There were no horror stories of people running out of road or brakes; it nobly took the extra power, but drivers couldn’t use it very often because of chassis limitations. It had been a case of dropping the engine in and saying “ooh, doesn’t it go” – the model didn’t cause any great shockwaves.’
Having come from Ford, Mike was able to make incisive decisions. ‘I had no loyalty to this softly sprung mammoth. Sensing an opportunity for the new project, I set about giving the engineers some direction. They’d already started to respond to the car rolling too much by increasing roll stiffness by 10 per cent. It wasn’t enough. I suggested we start by doubling it. The engineers didn’t resist at all; credit to them, they responded well when they were told the new objectives and realised that the rules had changed. I didn’t endow them with know-how they didn’t already have.’
As well as drastically increasing roll stiffness – via stiffer anti-roll bars and increased damper settings – they also added a Panhard rod. Next came tyre widths upsized to 255mm, and new cast-alloy wheels. ‘There was no magic in that. The goal was to lessen roll angles and improve cornering abilities. A principle of bigger boots on the road allowed for higher cornering forces. It’s important to realise that we didn’t do it with a new set of suspension – there were no changes to body structure or mountings, which were already substantial – and the original suspension geometry was sound. It was just a case of using its potential and the damping changes to take it to a higher dynamic standard, but doing so economically.’
Mike suggested the Mulsanne name be dropped and, with the development emphasis on road-holding, that the new model be called the Turbo R. ‘People liked the sound of that.’
In retrospect, Mike says, ‘It was a bit of a sleeping giant and responded well to accommodating the extra performance, though if we’d have wanted to create a truly competitive sporting car then the reality is that we wouldn’t have started with a Mulsanne Turbo.’
Bentley sales staff would obediently attempt to sell what the engineers produced, and didn’t try to steer them in any particular direction. ‘They never asked for improved ride and handling – it was entirely an engineering initiative. Indeed, there were no company expectations about what we could produce. We encouraged sales and marketing to try the improved car; they were impressed and as a result more enthusiastic about selling them.’
Dealers and customers were then targeted. ‘The company had been making sedate cars for a long time and that’s what customers expected; they were surprised when they found it could be pushed much harder and realised we had a good projectile. The Turbo R made them think that this is now a luxury sporting saloon. It had no bad handling traits. It was stable and you could do things like travelling at high speed in a straight line and giving the steering some high-energy inputs to see how the car responded.’
Enthusiastic write-ups and praise for the car’s handling in contemporary magazines helped the cause, and clientele flocked to buy them. As a result the image of Bentley gradually returned to that long-lost ideal of its vehicles being viewed as ‘driver’s cars’. By 1990, sales matched those of Rolls Royce, and come 1996 it outsold big brother by 1235 units to 509.
The Turbo R was undoubtedly the first step in the marque’s renaissance. ‘The company bought competitors’ cars to try and learn from and benchmark against, but the cars we would have taken seriously before were different from those after the Turbo R. We realised we were now competing in a much more dynamic field.’
‘I had no loyalty to this softly sprung mammoth. The engineers realised the rules had changed’