Spitfire Blade Arb + Suspension Setup

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

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 Walshy 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. 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.

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.

That has been my impression of what is going on with most of these setups too.

I look forward to hearing some preliminary results!

Paul, will be following this with much interest

I'm 'downgrading' my springs to 400F 500R shortly I'll be following this too There was a good thread recently about understeer induced by use of a stiffer ARB

Fair play for applying a bit of science to your VX setup and I'll be watching with interest. If you think you are treading new ground though you may want to have a look around and see what us guys who have been racing these cars for many years (from LOTRDC to Britcar, to Brit GT) have been doing. Couple of comments to make. I like blade type ARB's as they are easy to adjust but personally I wouldn't choose one for a tin-top race car as their spring rate isn't typicaly linear at high roll angles. Also, the soft springs and firm damping doesn't work well on an Elise at all. You will find that you will have a nice positive response through the wheel with a car setup like that but you will diminish outright grip and also the car will get snatchy.

Yes that seems quite possible, it's why you need to look at the overall effect it has on the car. It's all that cornering force do, setting up cars in this way so I'm sure they know what they're doing.

Chris, I'm aware I won't have been the only person to do this, but I can't recall anyone else with a VX doing it, especially not on a road car. As I say, it's only their inclination without looking at any data yet. I do think that my current Nitrons may well be too harsh for some roads, on most they are fine but on some average B roads you have to slow down a lot as the car bounces around too much, even in a straight line.

Chris, I'm aware I won't have been the only person to do this, but I can't recall anyone else with a VX doing it, especially not on a road car.

As I say, it's only their inclination without looking at any data yet. I do think that my current Nitrons may well be too harsh for some roads, on most they are fine but on some average B roads you have to slow down a lot as the car bounces around too much, even in a straight line.

Which Nitron's do you have?

As you may or may not know I have recently fitted Hofmanns 2 way Nitrons. After bedding them in for a couple of weeks I gave the car a thrash around the North Yorkshire moors and Nidderdale where the roads vary from smooth fast A's to rippled B's. The car is so far away from what it was it's a little surprising. I'm happy with the re-bound but think the compression may need a subtle tweak.

I'll do a full report in the thread I started. Sorry for the hi-jack.

Hope to see Simon soon. Good luck with this.

Currently got a set of one way Walshy spec Nitrons, the new type, with similar spring rates to those Randy uses (I think) something like 600/750. Maybe the roads are just worse round here?

Currently got a set of one way Walshy spec Nitrons, the new type, with similar spring rates to those Randy uses (I think) something like 600/750. Maybe the roads are just worse round here?

See here:
http://www.vx220.org...873#entry922873

ps next time you're in Harrogate give me a shout.

Edited by Nikov, 16 September 2009 - 11:01 AM.

Currently got a set of one way Walshy spec Nitrons, the new type, with similar spring rates to those Randy uses (I think) something like 600/750. Maybe the roads are just worse round here?

See here:
http://www.vx220.org...873#entry922873

ps next time you're in Harrogate give me a shout.

I'll be about at about midday on Saturday, then some time in about 3 weeks time to pick it up.

Fair play for applying a bit of science to your VX setup and I'll be watching with interest. If you think you are treading new ground though you may want to have a look around and see what us guys who have been racing these cars for many years (from LOTRDC to Britcar, to Brit GT) have been doing.

Couple of comments to make. I like blade type ARB's as they are easy to adjust but personally I wouldn't choose one for a tin-top race car as their spring rate isn't typicaly linear at high roll angles. Also, the soft springs and firm damping doesn't work well on an Elise at all. You will find that you will have a nice positive response through the wheel with a car setup like that but you will diminish outright grip and also the car will get snatchy.

Too much damping just doesnt work.

The really good information doesnt always make it into the public domain. It will be really interesting to see your findings.

As I say, it's only their inclination without looking at any data yet. I do think that my current Nitrons may well be too harsh for some roads, on most they are fine but on some average B roads you have to slow down a lot as the car bounces around too much, even in a straight line.

I think you can write off B/white roads with the rates your running. You can be quite stiff and get it to work well with the right damping but it's so violant becuse of the frequencies you'd slow down.

Will these chaps take into account tyre rates? It does make a significant difference.

Currently got a set of one way Walshy spec Nitrons, the new type, with similar spring rates to those Randy uses (I think) something like 600/750. Maybe the roads are just worse round here?

See here:
http://www.vx220.org...873#entry922873

ps next time you're in Harrogate give me a shout.

I'll be about at about midday on Saturday, then some time in about 3 weeks time to pick it up.

I'm not going to be about on Saturday but I'll make a point of trying for 3 weeks at Simon's, then we can chat plastic cars.

Just on my way back from York now, having dropped the car off. It's going to be set up with the datalogging and tyre temperature monitoring kit, have that done then it's going to be tested on a circuit by a racing driver. They will then analyse what they believe the best spring damper and arb rates to work together as a package. It will have further testing then back to the circuit for a racing driver to drive again. Simon will be posting on here in due course but the plan is to offer for sale a complete handling package which is designed to work together to get the absolute maximum from the car. The data supporting this and the thinking behind the setup will be made available.

Any chance of getting some lap times from the testing? You do realise that there is only so much you can get done in one test session?

There will be a lot of datalogging, they have the car for 3 weeks so there will be multiple track and testing sessions.

The car's been stripped down today and they're hopeful that a rear antirollbar can also be fitted. The next 2 days are probably going to be taken up fitting the datalogging equipment, then initial testing with a racing driver on friday.

I would avoid a rear ARB... it will make the car snappy.

I would avoid a rear ARB... it will make the car snappy.

Have you tried one before?

Yes... there isn't much I haven't tried on these little cars when it comes to suspension setup!