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Tuesday 6th August 2013


CAR SET-UP BASICS: PART ONE

Back to school for PH's man as he gets to grips with the fundamentals of car set-up


The black art of car set-up - we hear about it week-in, week-out from the likes of Vettel and his cronies, complaining of too much understeer or not enough traction. On an ultra-adjustable multi-million pound Formula 1 car millimetres make the difference, but for the amateur track driver can a few turns here and a couple of clicks there really make a noticeable change?

Sean's MK Indy R has plenty of tweakability
Sean's MK Indy R has plenty of tweakability
I am very much that amateur track driver with limited knowledge on how to set a car up. So can improving your grounding in this area actually make you faster and, if so, where do you start?

I own a 'Seven-a-like'. You see, I couldn't afford a proper Caterham (still can't...) and wanted something with decent performance, so I went down the bike-engined route and chose an MK Indy R.

While the powertrain might be a contentious issue for some, it's the chassis I bought it for. It boasts plenty of adjustability - camber, caster, spring preload, ride height, as well as compression and rebound damping - which gives two possible outcomes: deriving the perfect setup for your chosen track, or tying yourself in knots when it comes to clicks and turns.

Learning how to make the most of it is the goal
Learning how to make the most of it is the goal
That's why I took a trip to BR Racing's Essex base to get a better idea. The company will soon run experience days for enthusiasts, teaching and showing them the difference between good and bad car set-up on track with extreme understeer and oversteer, for example. They'll run through the different adjustable parts, what they do and how altering them affects the car. So that's a good place for me to begin.

Going sideways
My first run in the car was a disaster - but it was meant to be. I was going sideways everywhere, and not in the manner you might expect from PH...

The team had set the car up to crab badly, hunting for cambers and pulling the wheel in your hands. It's the perfect example of how not to do it and rams home how bad car set-up can lose you time. A quick exploration lap was enough, so back to the pits it was to make some changes.

BR's Rally Sport Trainer is an excellent teacher
BR's Rally Sport Trainer is an excellent teacher
The Ford-built tubular spaceframe cars the firm uses were originally developed to help train racing drivers, allowing massive geometry changes to show future stars how different parameters can effect car behaviour.

BR Racing has kept that aspect, throwing into the mix a set of GAZ coilovers - adjustable for compression and rebound damping - a bigger 125hp 1.7-litre Ford motor (enough for a 650kg car) and a Quaife ATB limited-slip diff.

Back to basics
Back in the paddock and it's sucking eggs time with a general recap of areas I can adjust. And let's not be squeamish - this is real back to basics stuff. First up, camber. This is the angle the wheel makes to the vertical - for track driving, negative camber (where the wheels lean 'in' towards the car) is generally what you're looking for.

It's a hands-on experience in the literal sense
It's a hands-on experience in the literal sense
Next up is toe. Toe in (tyres pointing towards each other) gives extra stability, while toe out gives improved turn in.

Ride height does exactly what it says on the tin - by making the car sit higher at the back, say, you effectively put more weight over the front end, aiding grip to neutralise understeer.

Compression and rebound damping control the rate at which the wheel moves up and how quickly or slowly it returns to its equilibrium position. Think of it like pumping iron in the gym - you've got to be as smooth and controlled lifting the weight as lowering it. Your suspension needs to do the same. It's all about keeping the tyre in contact with the road surface, that way it can find the most grip possible.

Neutral ground
Zero is a good place to work from when you're trying to find a set-up. So with neutral settings dialled in (no camber, zero toe, even ride height all round and the dampers in the middle of their range of adjustment) it's back onto the course. Immediately it's better.

Initial set-up shows how not to do it
Initial set-up shows how not to do it
The surface is a mix of concrete, mud and grass, so it's always going to be a compromise, but turn in feels positive. The car's too soft on the rear, however - through high speed direction changes there's a fair amount of weight transfer causing the car to lapse into roll oversteer and initiate some big tank slappers. My passenger, James Saggers, former British GT driver and Radical SR4 champion nips out for a spin and (broadly) agrees with what I'm saying, so if nothing else, I've learnt how to diagnose a problem. Now, how to fix it?

I'm interloping a student day, where motorsport and engineering colleges come to learn about set-up, too. Following Saggers' feedback the students dial in six clicks of damping on the front and 10 at the rear to make it firmer, while dropping the rear tyre pressures by 2psi when hot.

The rear is better but the front is now worse, locking up on the brakes on the loose and the bumpy concrete. It's more unsettled on turn in as well and there's less compliance. More air out of the tyres to 28psi from 34 (it's amazing what difference this makes) and three fewer clicks on the front dampers yield an improvement, but it's still not perfect.

Everything to zero creates a baseline setting
Everything to zero creates a baseline setting
Maybe it's time to think about some geometry changes, then? More rake (higher rear ride height) and some more negative camber on the front would certainly improve things, but I'm only here for a taster session and I don't get to weigh up the difference.

No matter though. What's important is the knowledge I've gained - something that experience day punters will pick up, too. And now I'm free to transfer it to my car and experiment with it. I'll be breaking out the spanners on the MK this weekend, so stay tuned for the results. It's going to be fun.





   
   
   
Author: Sean Carson