Chimaera Suspension
Discussion
steve - you should get a job with nasa or something. 
thanks for the insight with your own car - most helpful to avoid me wasting time in certain areas. I am going to get under the car at the weekend and fit the TVR lip and then look into the corner splitters. Will test both before and after and see what happens.
I must say I am loathe to go much over 100 with the roof on as the noise eminating from the front edge makes me nervous its going to pop off and the frequency of the folks loosing their roof when considering a lot of these cars dont see big 3 figure speeds is rather condemning.
thanks for the insight with your own car - most helpful to avoid me wasting time in certain areas. I am going to get under the car at the weekend and fit the TVR lip and then look into the corner splitters. Will test both before and after and see what happens.
I must say I am loathe to go much over 100 with the roof on as the noise eminating from the front edge makes me nervous its going to pop off and the frequency of the folks loosing their roof when considering a lot of these cars dont see big 3 figure speeds is rather condemning.
There are some very significant questions there and I would say that if you are serious about improving the aerodynamics you are considering the right areas. However, its a very complex area as Steve says, and common sense and trial and error are not enough on their own, it is going to take a sound understanding of the theory to get anywhere with this.
The roof on / roof off question I think is a bi of a red herring. Taking the roof off changes the air flow dramatically for the worse. It increases the size of the wake, and lift and drag over the rear of the car, a well as making a real mess of your hair unless you keep the cap well pulled down. I haven't tried to measure the extra lift and drag on the V8S because I never drive it top down when I am after performance.
It is much harder to generate downforce at the rear than at the front, without pretty unsubtle changes. The separation zone behind the cockpit prevents attached air flow over any of the boot except the outer corners, so for any wing to work it would need to be right up level with the top of the roof, or way out the back of the car. A gurney flap as Steve has does work to some extend in the separation zone, although nothing like as well as it would work out in fresh air. Bigger is better, and it is going to be quite intrusive before it is big enough to have a significant effect. Basically, the air flow over the top of the car is knackered by the cockpit and there is not a great deal you can do with it.
Underbody aerodynamics are a different matter altogether. If you can arrange for an attached flow over a smooth underbody, with a significant amount of extraction at the back, you can get very significant amounts of downforce. The key to this, is avoiding any disruption to the air flow so that it will stay attached to the extractor, so that you can achieve a pressure rise across the extractor. The twin wishbone rear suspension you have at the rear is quite low and prevents you from getting much extraction at the back. The V8S is quite a bit better in this respect because it does not have any suspension low down at the back (trailing arms had to be good for something!) but the exhausts are still lower than you would like.
If you can achieve smooth underbody flow and good extraction then the way to make this work is to remove the air dams and splitters from the front and get as much clean air as possible under the car. Done right, in combination with a rear wing to put the extractor outlet into a low pressure zone, this is how you achieve multiple Gs worth of downforce. However, if you get it wrong and end up with turbulent air flow that wont stay attached in the extractor then instead of downforce you get large amounts of lift, it is also sensitive to right height changes and other effects which can mean that although you do get lots of downforce, the car is undriveable because the downforce is ot consistent. You need to be very confident that you know what you are doing before you take this approach. The alternative of simply 'blocking off' the front of the car with air dams and splitters doesn't produce large downforce but also can't go badly wrong however you do it.
The roof on / roof off question I think is a bi of a red herring. Taking the roof off changes the air flow dramatically for the worse. It increases the size of the wake, and lift and drag over the rear of the car, a well as making a real mess of your hair unless you keep the cap well pulled down. I haven't tried to measure the extra lift and drag on the V8S because I never drive it top down when I am after performance.
It is much harder to generate downforce at the rear than at the front, without pretty unsubtle changes. The separation zone behind the cockpit prevents attached air flow over any of the boot except the outer corners, so for any wing to work it would need to be right up level with the top of the roof, or way out the back of the car. A gurney flap as Steve has does work to some extend in the separation zone, although nothing like as well as it would work out in fresh air. Bigger is better, and it is going to be quite intrusive before it is big enough to have a significant effect. Basically, the air flow over the top of the car is knackered by the cockpit and there is not a great deal you can do with it.
Underbody aerodynamics are a different matter altogether. If you can arrange for an attached flow over a smooth underbody, with a significant amount of extraction at the back, you can get very significant amounts of downforce. The key to this, is avoiding any disruption to the air flow so that it will stay attached to the extractor, so that you can achieve a pressure rise across the extractor. The twin wishbone rear suspension you have at the rear is quite low and prevents you from getting much extraction at the back. The V8S is quite a bit better in this respect because it does not have any suspension low down at the back (trailing arms had to be good for something!) but the exhausts are still lower than you would like.
If you can achieve smooth underbody flow and good extraction then the way to make this work is to remove the air dams and splitters from the front and get as much clean air as possible under the car. Done right, in combination with a rear wing to put the extractor outlet into a low pressure zone, this is how you achieve multiple Gs worth of downforce. However, if you get it wrong and end up with turbulent air flow that wont stay attached in the extractor then instead of downforce you get large amounts of lift, it is also sensitive to right height changes and other effects which can mean that although you do get lots of downforce, the car is undriveable because the downforce is ot consistent. You need to be very confident that you know what you are doing before you take this approach. The alternative of simply 'blocking off' the front of the car with air dams and splitters doesn't produce large downforce but also can't go badly wrong however you do it.
Which is why you need the air tunnel and the load cells to measure what is happening. There must be a college chappie out there who is a sports car anorak who can be invegialed into doing the testing for a pint or two.
How about suggesting this as a research project for a post grad student in one of our ivory towers?
Which university could be interested? They have all the resources but are short on decent projects.
Surely someone knows someone who can be accosted?
I am not denigrating the hands on approach suggested by several of you successful racers, more that your approach in tandem with a technical approach will be to the benefit of all!
I will report back on what is happening on my duff shoch absorbers (they started this amazing post) but giving the garage time to respond.
How about suggesting this as a research project for a post grad student in one of our ivory towers?
Which university could be interested? They have all the resources but are short on decent projects.
Surely someone knows someone who can be accosted?
I am not denigrating the hands on approach suggested by several of you successful racers, more that your approach in tandem with a technical approach will be to the benefit of all!
I will report back on what is happening on my duff shoch absorbers (they started this amazing post) but giving the garage time to respond.
Ditto! I have GGP all round on my 400 and I'm happy as larry!
With 14 clicks (rear), 12 clicks (front) on standard springs compared to the bilsteins, I no longer have excessive lurching in corners and now the back end is very planted in the bends but when it breaks loose its easier to bring back in.
In short they've come on alot in 9 years.
With 14 clicks (rear), 12 clicks (front) on standard springs compared to the bilsteins, I no longer have excessive lurching in corners and now the back end is very planted in the bends but when it breaks loose its easier to bring back in.
In short they've come on alot in 9 years.
QBee said:
Gaz dampers now bear no resemblance to the ones he described. I have Gaz Gold Pros on mine and love them.
His original post had me immediately thinking "that car needs four wheel aligning and corner weighting"
Same^ His original post had me immediately thinking "that car needs four wheel aligning and corner weighting"
The Chim handles well, less roll but still pliant. Can be adjusted to suit too.
mgjc said:
Ditto! I have GGP all round on my 400 and I'm happy as larry!
With 14 clicks (rear), 12 clicks (front) on standard springs compared to the bilsteins, I no longer have excessive lurching in corners and now the back end is very planted in the bends but when it breaks loose its easier to bring back in.
In short they've come on alot in 9 years.
Is that 14 and 12 up from soft, or down from hard?With 14 clicks (rear), 12 clicks (front) on standard springs compared to the bilsteins, I no longer have excessive lurching in corners and now the back end is very planted in the bends but when it breaks loose its easier to bring back in.
In short they've come on alot in 9 years.
I have 400/375 lb T350 springs, so run the dampers on 6 clicks up from soft on the road. Any harder on the road and I feel every matchstick and my fillings fall out!
20 clicks top to bottom. So my setting is the same as yours if you measured from hard.
I tighten the front up as hard as it will go for the track, but having tried a harder rear setting, I found the car hopped round hairpin bends on the track, so softened the rears back down to the road setting and the car was really planted.
Next track day I had a free corner weighting - my wife passengered at Cadwell. Car was really planted, so off for a proper corner weighting set up soon. Set off home on the track settings, picked my fillings out of my lap after two miles and adjusted the fronts dampers back to 6 clicks up from soft.
You can check them yourself easily. Jack up a corner to have a look. The adjuster is a small round knob on the inside, near the bottom end of the damper. Clockwise to tighten, anti clock to soften. Soften it off, counting the clicks, then you will know your setting. Then tighten it up again, counting as you go. You can actually do the adjusting without jacking the car up, just reach round the front wheel while lying on your back beside the car.
Standard springs are something like 325/300, so your dampers will need to be set harder than mine to compensate for the softer springs.
Standard springs are something like 325/300, so your dampers will need to be set harder than mine to compensate for the softer springs.
That's good re setting them, and it would be interesting to know what your spring rates are.
Mine came with the dampers, which I bought off a T350 owner. Car feels good on them, though I think my rear ones are not quite right, as I am getting some tail slippage on ordinary roads, which might just be down to greasy autumn roads and my heavy right foot. Nothing I couldn't catch, anyway
Mine came with the dampers, which I bought off a T350 owner. Car feels good on them, though I think my rear ones are not quite right, as I am getting some tail slippage on ordinary roads, which might just be down to greasy autumn roads and my heavy right foot. Nothing I couldn't catch, anyway
One aspect on the original post that I noticed was the Poly bushes because I had a very nice handling Chim on Gaz nickels until I re-bushed it with a well known brand of polybushes, I tried everything to stop the jittery ride until in the end I replaced all the bushes with rubber------- Guess what, back to a nice ride and still is 7 years on.
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