From the RL test driver, in his own words:
There was also a mechanical issue in the rear suspension which caused an unstable camber condition under lateral load, mentioned in the test report but not this interview.
For AC we've granted David his request and put on the wider wheels and tires although they're still meant to be the lesser Dunlops. We improved the brake power/durability issues but left the bias at 61%F as that's what the book says is in the real thing. And we fixed the camber problem at the rear because, well, there's no way to simulate that in AC anyway. And now it does Silverstone 67 in the 33s, so...
I've been through the suspension design today and the roll centers had indeed migrated, although not as far as I'd thought. (1mmF/5mmR) Fixed that, fixed a couple other things I found along the way. Looks like I failed to take that step last time I adjusted the rear suspension... front was basically ok.
Hobbs Yeah. It gave quite a lot of horsepower. It went extremely fast. We went to MIRA about four or five times. Sir William came once .. Mr Heynes used to watch it. Then they made the decision to drive it at Silverstone so they decided to get two drivers – me and Richard Attwood, another apprentice. So off we go to Silverstone and I can’t remember the exact times but I think we did round about a 1:36 – 1:35 – 1:36. [1:35.7 -ag] The lap record at the time was help by Paul Hawkins in his red GT40 – about 32 or 33. So we weren’t all that far off the pace. If you consider it had these old pads, old wheels, old brakes. The suspension flexed far too much of course. And of course it had no attempt at any sort of spoilers on it. Very sleek. It was incredibly quick of course down the straights.
Richard and I gave a job list of things to do. We wanted wider tyres – we wanted modern wide wheels for a start and modern racing tyres. I think those two alone would have seen us down to the lap record. And another … I seem to remember the bias front to rear brakes was poor. It wanted a lot of, you know, a good tidying up. We reckoned it would have been quick.
...
But I really think the car would have been an absolute wow. I mean, at Le Mans, the thing would have had it. Because the GT40 in those days was an iron-block Ford that was only giving about 300 brake horsepower. I mean, this thing gave nearly 200 horsepower more than the GT40. There’s no doubt about it, it wouldn’t have been as quick as the Mark 2s, which of course raced in ’67. But it would have been very fast and, just by updating it, cos I’m sure it had been sitting in the shop for a couple of years – just by updating it.
But they had a problem. You’ve got to use Firestone or Goodyear racing tyres for example … Dunlop weren’t making good racing tyres then … for that type of stuff
There was also a mechanical issue in the rear suspension which caused an unstable camber condition under lateral load, mentioned in the test report but not this interview.
For AC we've granted David his request and put on the wider wheels and tires although they're still meant to be the lesser Dunlops. We improved the brake power/durability issues but left the bias at 61%F as that's what the book says is in the real thing. And we fixed the camber problem at the rear because, well, there's no way to simulate that in AC anyway. And now it does Silverstone 67 in the 33s, so...
I've been through the suspension design today and the roll centers had indeed migrated, although not as far as I'd thought. (1mmF/5mmR) Fixed that, fixed a couple other things I found along the way. Looks like I failed to take that step last time I adjusted the rear suspension... front was basically ok.