Driveability

289, FIA & Daytona topics
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agnoraan
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Driveability

Post by agnoraan »

For those that have been fortunate enough to drive both coil spring and leaf spring Cobras, be they original or replicas, how have you found the driving/handling experiences compares ?? I'm hoping to get back on track with my "Insanity" car in the near future and my original intention was to use independant suspension on it, but now I'm wondering if I should go down the more traditional leaf spring route. What are your thoughts?

Thanks...Nige
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clive
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Re: Driveability

Post by clive »

The biggest handling difference I found between my Hawk and an original 260, was the steering.
Cheers, Clive.

(If I'm not here I'm in my workshop or on the golf course!)
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Roger King
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Re: Driveability

Post by Roger King »

I did 20,000 miles in my coil-sprung Hawk, and have done just over 1000 in my leafspring car. I can't agree with Clive - they are very different cars, in my opinion. Both have rack and pinion steering.
Nige, I think you need to consider more than just the springing medium. The only point in building a leafspring car is to follow originality as closely as possible - therefore you are talking about 3" diameter chassis tubes set at 17.5" centres apart, as opposed to a Hawk with 4" tube diameter set a bit over 21" apart. As you can imagine, this means wishbone pickup points are in a completely different place, suspension stresses act in a completely different part of the chassis, chassis flexibility is vastly different etc. etc.
My current car drives very differently from the Hawk. There is a distinct element of lift-off oversteer - wait for it - in a straight line, when changing gear if giving it the beans. Similar to, but much less, than a Stag or TR6 and is probably caused by a little bit of spline lock in the driveshafts under hard acceleration. There is also a much greater amount of body roll, even with dampers set pretty firm. The ride is excellent and my wife finds it comfortable (draw your own conclusions).
If you want it to drive as nicely as possible, more like a modern car and much more predictable and well-planted, there is no doubt in my mind that the Hawk arrangement is far superior. I have always said the the Hawk drives better than an AC, as indeed it should after all those years of suspension development (which rather begs the question beginning 'then why did you....'). What I cannot tell you is how this would compare with an original coil-sprung Cobra, as I've never driven one. I believe the chassis dimensions etc. are pretty much the same as the Hawk.
BTW, you seem to be confused over the way AC used leafsprings. You say you were thinking of having independent suspension, but are now considering leafsprings. AC, and Kirkham, use transverse leafsprings, across the chassis, front and rear. One spring at the front, one spring at the rear. The leaflspring suspension is completely independent, AC did not use live axles.

Roger
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db replicas
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Re: Driveability

Post by db replicas »

Interesting post Roger.
As you can probably guess I am keen to see what I could do with my new 289 car to be sure I have nailed down as many drivability issues as possible before I hit the road.
Have you tried different size front anti roll bars to control the roll at all? are they even an option???
Do you think more sticky or wider rear tyres might iron out the the straight line over steer?

Cheers.
Dave.
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agnoraan
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Re: Driveability

Post by agnoraan »

Thanks Roger, I meant to say "fully adjustable" independant suspension that you'd get with coil overs, ie able to try out variable spring rates, height adjustability etc, but I'll let you off this time ;-). Thanks for the insight though, its appreciated, I just need to figure out how women like their cars to feel now if your wife feels it's comfortable ;-)
Nige
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clive
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Re: Driveability

Post by clive »

Roger King wrote: Both have rack and pinion steering.
Are you sure Roger? I was told the reason why the 260 steering was a bit wooly was due to it not being rack and pinion steering.
Cheers, Clive.

(If I'm not here I'm in my workshop or on the golf course!)
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Roger King
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Re: Driveability

Post by Roger King »

clive wrote:
Roger King wrote: Both have rack and pinion steering.
Are you sure Roger? I was told the reason why the 260 steering was a bit wooly was due to it not being rack and pinion steering.
No Clive - I meant my car has rack and pinion, like the great majority of 289 Cobras. Only a nutter would build a replica with a steering box, if you could find one.
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Roger King
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Re: Driveability

Post by Roger King »

db replicas wrote:Interesting post Roger.
As you can probably guess I am keen to see what I could do with my new 289 car to be sure I have nailed down as many drivability issues as possible before I hit the road.
Have you tried different size front anti roll bars to control the roll at all? are they even an option???
Do you think more sticky or wider rear tyres might iron out the the straight line over steer?

Cheers.
Dave.
Dave - we haven't met yet, hope we do sometime soon! However a few minutes of my boring you to death will allow you to understand where I'm coming from with my car - I want the closest possible to what you would have picked up in a London showroom in 1964, I don't care how it drives. I like what it does at the moment (characterful?), and the rubber suspension bushes, stock anti-roll bar size (none on the rear - many cars didn't have them) and the stock 205/70 15 Dunlop SP Sports will be staying. However from my TR experience over the years with highly-modified cars I can tell you that stickier tyres don't seem to improve the spline lock-up - cush drives, rubber doughnuts or ball-bearing spline drives do. To be honest, it's pretty minimal so I wouldn't worry too much. Many cars of that era with independent rear ends do similar.

Roger

PS - I would bet, in a track situation on the right rubber, the leafspring car would be a lot easier to drift and control on the throttle. It feels a lot more 'alive' than the Hawk did, whether or not that's a good thing. Over to Colin to test that one out.
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db replicas
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Re: Driveability

Post by db replicas »

Hi Roger.
Understood.
Thanks. :wink: :D
Paul Blore
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Re: Driveability

Post by Paul Blore »

Having driven both, I am absolutely confident that all other things being equal, a Mk.III cool sprung Cobra would run away from a leaf sprung car on the track.
A leaf sprung Cobra feels like an "old" car, whereas a cool sprung Cobra feels much more modern.
I don't know how much they move on a could sprung Cobra, but the splined drive shaft barely move in and out on a coil sprung car, even during full suspension movement, so I doubt that spline lockup is a major factor in the handling characteristics.
Clive is correct about the steering on a 260, but as Roger has said, why on earth you'd want to build a car with a steering box, I have no idea.

Paul
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