Samthomasracing wrote:We are currently building a 427 coil spring car to race in FIA championships, FIA are happy along as a car competed in an International FIA event, so can't be a 10 lap sprint at Spa but more like 1000km of Nurburgring or Sebring etc etc. This is how TVR Griffiths race at an FIA level now. Note their reintroduction to Goodwood this year.
I'd stay away from sticky tyres on Cobras, even on slicks the power will always break through the tyres & if the tyres are too sticky the car will become very nervous on corner entry and it will twitch on exit, we set them up to slide which is the fastest way in these old cars, set the nose up before the corner, steer with the throttle. Blockley tyres are really good, a lot of people run the Avon tyres too, i can get serial numbers if anyone wants to try them out.
Shock absorber revalving, spring rates & anti roll bars are key on these cars, there's a weight percentage which can be calculated, and makes the car extremely planted especially on the roads.
Saying this, isn't all the fun in oversteer out of roundabouts ?
I'll be really interested to see how that goes Sam. I believe the 427 Cobras raced in the FIA Sports category in period, which put them directly up against the likes of McLarens, Chaparrals and GT40's etc.
Did you watch Top Gear last night Roger? They test drove an electric car that was specifically designed to hang the tail out.
Yes, I did. It wasn't driving itself though, was it? Can you imagine a self-driving car that allowed you to do that? Switching off the self-drive would probably automatically invalidate your insurance...
Nobody's thought this through, and until they sort out the legal aspects these things are dead in the water. The lawyers always, always win.
But please - I bow out of this discussion now as I know where it will lead and this is not the right place for it! A pub with padded walls and floor and no sharp objects might be best...
Thanks for the all the replies and insight into the different driving styles. This car is going to be predominantly for road use, though I may try a few sprints with it. I want a car that has good road manners and is predictable in what it's going to do when pushed hard, hence my initial question as to which is the best all round performer, the coilsprung or leaf sprung chassis, bearing in mind that this is an original style chassis and not a Hawk. I don't want a car that shakes your fillings out on uneven surfaces, or becomes too tiresome to drive on long journeys. Yeah, I know it's a Cobra, I must just be getting old I guess, but I want to enjoy the driving experience and not have a car that I have to fight with .
If you're building a "replica" 289 from scratch, then you might as well try to get as close as you can to an original, which would mean transverse leaf suspension. There is no reason why it shouldn't be comfortable and civilised within the scope of what's possible. Colin took his 289 to Italy in 2015 and I didn't hear any complaints from him about his car in that respect.
I presume your decision comes down to 'what do I build a replica of?' I guess the choice is leafspring 289 (known as 'slabside') or later AC 289, with coil springs and different chassis design. Both are 'original' in design terms, and I'd say neither is 'better' than the other, they're just different.
The coil sprung car feels more 'modern', and my reasons for referring to the Hawk chassis are that as far as I am aware the chassis dimensions etc. of the Hawk are similar to the later AC289, although the Hawk frame 'kicks up' towards the front whereas I don't think the AC289 does. I am the first to admit that I know a lot less about the later AC289 than I do about the earlier cars so hopefully someone else can give more complete advice.
As far as I know, the AC289 coil sprung chassis is the same as the 427, but with different engine/chassis mounts for the smaller motor.
There are differences between the 427 chassis' in that the "Street" chassis has slightly different pick up points for the rear upper structure to allow room for the underslung exhausts to pass up behind the rear bulkhead and over the axle. (I am not referring here to the GRP boot internals, but the main steel chassis structure.)
Samthomasracing wrote:We are currently building a 427 coil spring car to race in FIA championships, FIA are happy along as a car competed in an International FIA event, so can't be a 10 lap sprint at Spa but more like 1000km of Nurburgring or Sebring etc etc. This is how TVR Griffiths race at an FIA level now. Note their reintroduction to Goodwood this year.
I'd stay away from sticky tyres on Cobras, even on slicks the power will always break through the tyres & if the tyres are too sticky the car will become very nervous on corner entry and it will twitch on exit, we set them up to slide which is the fastest way in these old cars, set the nose up before the corner, steer with the throttle. Blockley tyres are really good, a lot of people run the Avon tyres too, i can get serial numbers if anyone wants to try them out.
Shock absorber revalving, spring rates & anti roll bars are key on these cars, there's a weight percentage which can be calculated, and makes the car extremely planted especially on the roads.
Saying this, isn't all the fun in oversteer out of roundabouts ?
I'll be really interested to see how that goes Sam. I believe the 427 Cobras raced in the FIA Sports category in period, which put them directly up against the likes of McLarens, Chaparrals and GT40's etc.
Did you watch Top Gear last night Roger? They test drove an electric car that was specifically designed to hang the tail out.
Hi Paul
Yes homologated December 3rd 1965 in the over 2ltr Group 4, also allowed to run in pre66 FIA events now such as Goodwood Revival / Members meeting, Silverstone Classic etc so very much looking forward to that.
It will be fascinating to see how competitive 427 Cobras are against some of the other more established cars. It will probably take a little while to iron out the wrinkles and bring them up to date, but I would expect a well sorted 427 to be quick from the outset.
If they were homologated in 1965, why didn't they start racing then? Overshadowed by the GT40, I guess, but I'm surprised a few smaller teams didn't try them. Maybe back to the aerodynamics issues of the 289 that prompted the Daytona?
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