Getting serious with the handling...

Soldato
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Ipswich
While the new ~400bhp engine is still waiting for a couple of parts and waiting for me to find time to port the head I am looking at improving the handling further.

On Saturday I travelled up to Yorkshire to leave my car with a company called "Cornering Force" who are working with Spitfire Engineering to develop a blade style antirollbar and possibly a rear antirollbar as well.

All Cornering Force do is advise on suspension setup, mainly for race teams. Their premises aren't really a garage in the conventional sense, there are more laptops and computers there than tools!

One of the benefits of a blade ARB is that it can be adjusted easily using a nob or similar to give very small increments of adjustment, similar to how most adjustable shocks work. It can even be engineered so that the stiffness can be adjusted from the cabin whilst driving.

As part of this exercise the car is going to have pretty extensive datalogging and benchmarking to determine the absolute optimal springweights on the latest spec Nitrons, the ideal valving and of course the optimal range of operation for the ARB. This will involve extensive track testing which I'll get to try once it's all done.

We concentrate on vehicle performance with some Driver performance measures. The data that we typically gather includes;

•Longitudinal/lateral/vertical acceleration
•Inner/middle and outer temperature on each tyre
•Steering angle
•Damper position and velocity
•Speed, track position and lap times using GPS
•Yaw rate

Analysis of this data using sophisticated software enables us to understand how the setup is working on a corner-by-corner basis and help us to optimise;

•Camber and tracking
•Tyre pressures
•Balance for over/under steer at different stages of a corner
•Damper settings
•Tyre operating temperatures

What we check as standard…
Dampers We dyno each damper at current setting and full soft/full hard settings. Provide Force/Velocity and Force/Displacement curves for report (with other curves available on request). We calculate the theoretical optimum damping rates and comment on the suitability of the current settings.
Springs We test the rate of each spring. We calculate the Ride Frequency provided by these springs and comment on their suitability.
Anti-roll bars We measure the rate of each ARB and calculate the combined roll-resistance provided by the springs/ARBs. We assess the suitability of the spring/ARB combination.
Corner Weights We measure the individual corner weights, the sprung and the unsprung weights. We measure the C of G of the sprung mass.
Geometry We measure the camber, caster, tracking and suspension geometry then calculate the effect of both bump and roll on the geometry using kinematics analysis software. We calculate the Kinematic Roll Centre height using analysis software.

Their inclination at the moment is that my car is too heavily sprung and that a stiffer ARB will allow for softer springs with no compromise in performance.

As a result of the testing I'll get a report on the ideal rideheight, geo, spring weights, ARB stiffness, damping, tyre pressures etc. Pretty much going to town on the entire ride and handling setup. The intention is to produce a handling pack as a result, which will only work as a complete unit given a specified set of wheels, tyres and alignment.

No one else has gone through this degree of testing on the Elise that I know of, and certainly not the VX as it doesn't come cheap. By monitoring the real time temperature across the width of the tyre it's possible to see how hard the tyres are being worked and to make the most effective use of the contact patch. For instance on saturday they showed me graphs of tyre temperature through a corner and from entry to exit the surface temperature changes from 50 degrees to 120 degrees, and back down again by the time you have exited the corner.

To be honest a lot of the principles they were trying to explain to me were way over my head, but Simon who runs the company is fanatical about suspension and the physics and engineering behind it.

The car is going to be there for about 3 weeks. First it's going to have some datalogging, involving tyre temperature monitoring and damper movement (with these cool little devices that track minute movement of the damper rod). Then it's off to the testrack for on track testing with a qualified racing driver.

All of this data is then used for calculations to work out the ideal settings which are applied and it's back to the test track again with the same driver for further testing, laptiming, datalogging and driver feedback. A few more tweaks and then I'll collect the car and have a session on the private test track with the racing driver to see what I think and also to get some tuition.
 
salami - it's not really related to the power, I've got my second set of Nitrons on which whilst are an improvement I'm not sure it's made it as compliant as I'd like for the road.

It's not really going to cost me anything at all, other than time, travelling, time without the car and a few other bits. It's another one of those development things where the company doing it is equally as keen to do it as I am for them to do it. It may also appear as a feature in a magazine too. No doubt the true cost would be several thousand pounds.

It's also being done to prove a point that you can't just change one component in isolation without really testing what it actually does to the car. There must be no end of manufacturers selling suspension upgrades that either don't work or aren't as good as they could be because they haven't gone to the lengths to really see how the car responds in a scientific manner.
 
Also, is there a particular problem with the handling you want to 'improve'?

No, not as such, other than how the car responds to poorer road surfaces. The exercise is to take a very good aftermarket setup (new nitrons, TD1.2s, R888s, Spitfire subframe brace) and see just how good it is and how much better it can be made.

For one reason or another I haven't spent a "silly" amount on the car.
 
All well and good until you get a fat passenger and need to recalibrate the lot ;)

I cant help but think its going very OTT now for a fast road/track car, but respect for doing it none the less.

It isn't really that OTT for them when you consider it's what they do exclusively. You can't change anything with any certainty, nor get proof that it works if you don't test it thoroughly. They're confident that there's such an enormous difference between getting it just right and being slightly off that it's worth doing.
 
Aero mods? (not to improve the damping), as a seperate issue I mean.

Probably not, possibly a diffuser but I don't really want a wing. It's one of those things which is a bit "lick your finger and stick it in the air" unless you go to a wind tunnel like a mate did with his Exige. To get any meaningful improvement the wing needs to be pretty enormous and that's a step to far for me in a road car.
 
Can I just ask, what will the ride be after all of this? Is it going to be spine-jarringly stiff, comfortable or somewhere in between?

I want it more comfortable. It will be setup as road/track car, certainly not like a racing car that will only go on billiard table smooth surfaces. The problem with bone jarringly stiff such as when the car is over sprung is that the tyre is battling to stay in contact with the road surface over bumps so you are wasting grip anyway.
 
How would that work? :confused:

If they're adding a blade style ARB then once they've set it exactly right the last thing you want to do is adjust it, unless they design it so that the two main settings are perfectly suited to the car. 'hard' position for track use, and then the 'soft' position for road use. :cool:

For most people it's not an issue, but those racing may want to change the stiffness on a corner by corner basis.
 
On that basis would you say that there are no worthwhile upgrades to any of the tyres, wheels, geometry settings or suspension on any Lotus model?

Of course there are, because as standard everything is built to a price and to sell in the highest number possible.

Seriously, this guy really knows what he's talking about, he's an engineer, not a mechanic. The cars he usually works on are worth, far, far in excess of the VX, some very rare and expensive race cars.

I don't think your comment about the ARB is entirely correct either, it's far more complicated than that.
 
Driver impressions were that the car turned in nicely but under steered considerably through the apex and exit. Although it was clearly sprung hard it did not seem unduly harsh on the track. However, this car is used on the road as well as for track days and we understand that it feels nervous and jittery on the road.
*
The analysis of the set-up shows that;
*
§******** The ride frequency is very high for this type of car.
§******** The damping F/V curves have some issues.
§******** The anti-roll bar provides a very low proportion of the roll resistance.
§******** The percentage of the total roll resistance at the front is low.
§******** The amount of roll (degrees per g of cornering force) looks about right.
§******** Corner weights show a considerable wedge
*
The analysis of the run data shows that;
*
The front tyres need a little more camber but the pressure was good.
The rear tyres need less pressure but the camber was good.
Tyres are running at 80-90oc in corners
The car rolls about 0.9o/g in corners
The car achieves a max of 1g lateral acceleration in corners
The car achieves a max of 0.68g in braking/0.46g accelerating in 2nd.
The damping bump/rebound balance needs some adjustment.
Max front damper displacement is 22mm rebound/16mm bump
Max rear damper displacement is 31mm rebound/36mm bump
*
Based on this I have a few recommendations;
*
Reduce the spring rate and increase the ARB rate to make the car less harsh on the road but keep the same overall roll angle per g of cornering force.
Fit an adjustable front ARB to allow quick adjustment for preference on the track and the road.
Adjust the damping rates for the new spring rates.
Adjust the corner weights
Adjust front camber.
Lower rear tyre pressure.
Probably increase the ride height a little bit but play with this during testing.
*
I am keen to make these changes as I feel that we can make the car a better compromise between road/track use and improve the grip without losing responsiveness. We can address the mid corner-exit understeer with these changes.
 
Here's what I posted on the VX site straight after the Bedford Trackday.

So I have played around with quite a few things. With both sets of Nitrons I had thus far I was never really happy with how they performed on the road, it always felt like the suspension wasn't really "working" to deal with bumps and changes in the surface, on some roads the car would feel very skittish and never as sure footed as I thought it could be. On one particular straight piece of road near me I could probably do 80mph easily in my Golf but the VX would feel distinctly out of control at 60mph, crashing over bumps.

The way the car performed on saturday was just stunning, the ride is so much more compliant with considerably softer springs but the amount of body roll feels even less than before. It remains so responsive to changes in direction and the traction out of corners is just something else. On a cold and wet/damp track with R888s there was so much traction, the power just went down so easily, it was so stable and composed. The balance through the corners was just beautiful. It was clear through the morning that we were just reeling in pretty much every car there and carrying so much more speed through the corners and getting on the power so much earlier on the exit. One notable thing was Charlie (the racing driver/instructor) was telling me to turn into the apex more on some corners that I had got my entry line wrong on, which I wasn't doing because I didn't even think the front end would be able to grip and turn in at that speed and in those conditions as before it would just wash out with understeer but now it just digs in and grips, it was completely neutral.

By altering the front ARB it was so obvious how the balance of the car was subtley changing, moving from oversteer to understeer and via versa.

I think you kind of develop a good understanding of what the car is capable of when you have owned it for a while and tried various things but this just altered my perceptions, it's on completely a different level, I've never been in an Elise, Exige or VX which even came close to what mine seems to be able to do now. I just need a new engine to carrying on playing with it now!

Oh and it's gone from 0.9 lateral G to 1.2 :D That's with no aero effect on road tyres.
 
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Sneak preview, should get some nice shots out of it hopefully.

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