trackday setup

[Tim Smith]

I did a trackday at Brands on Friday and had a few handling problems that I've not encountered before. Although I've just had the car Supersport R'd and it therefore has more power than previously, it felt lacking in rear grip, particularly through Clearways

 

After each session there was considerably more heat in the left rear tyre than in the right rear and the left rear was getting seriously chewed up. The tyres are CR500s which I run at 18psi cold. I suspect the left rear was overheating as by the end of a session there appeared to be very little grip.

 

So over to the track and race setup experts:

 

1) If I want to reduce the tyre temperature do I need to raise or lower the tyre pressure?

 

2) I am currently running with the rear anti rollbar on its miniumum setting as I found this makes for a slightly less choppy ride and better traction on the road where there tend to be lots of bumps. What effect on rear grip does the anti roll bar have? Any ideas on what sort of setting works best?

 

3) Anyone got any other ideas on how to get a more balanced setup with the car. Front end grip seemed good with even tyre wear through the day.

 

Tim

[Trevor Newman]

If the tyres are similar to 048's then you want them set to app 21-22psi when hot

starting at 18psi seems rather high. Adjust the tyres as soon as you come off track not 5 minutes later when you get round to it

 

try starting at

15psi n/s rear

16psi o/s rear and n/s front

17psi o/s front

 

Try the Rear ARB fully stiff to see if you can induce some understeer rather than oversteer, if you only move one notch at a time you may not be able to detect the effect this has on the car. By going to the other extreme you should be able to detect how the handling has changed.

 

what front ARB are you using

[Tim Smith]

Thanks Trevor,

 

I presume CR500s have a similar construction to 048s so I'll try those pressures at the next trackday along with the rear ARB adjustment. What effect does stiffening the rear ARB usually have?

 

I'm currently using the medium front ARB, front end grip doesn't seem to be an issue, I only get understeer at high speed or when I turn in too hard.

 

Tim

[Shaun_E]

If you are suffering oversteer then surely the rear ARB needs to be softer not stiffer. If you are running it on it's softest setting then just disconnect it (remove one drop link).

The suggestion to run different tyre pressures from left to right should even up the hot pressures to give a bit more grip. When a circuit has most corners going one direction (e.g. mostly rights) then this is a reasonable thing to do. I have been told that the R400 racers were running CR500s at around 22-23psi hot, the rears being a little higher than the fronts.

The other thing you can try is to alter the rake of the car (assumes you have adjustable spring platforms). Lowering the rear a bit should put more weight on the back of the car and therfore give more traction at that end.

 

Yellow SL #32

[MartinWoodham]

in my experience stiffening the rear will promote oversteer. At Brands last year with green front bar and fully stiff rear the car was tailhappy to the point of not being able to get the power down through Clearways. This cost me 3 race positions on each lap ☹️, same 3 cars because I got them into Paddock Hill/ into Druids each time 😬

 

In a corner, weight will transfer to the stiffest end of the car (all other things being equal ie no front/ rear weight transfer through braking, accelerating etc) - in your case the rear. (CC racing advice is forget the rear bar unless you're running green - stiffest - at the front) So your nearside rear is carrying all the weight in cornering - hence the temps.

 

I'd look to getting it a bit more balanced front to rear.

TPs may be a bit adrift but I'd start with reducing the rear bar, since it's fully soft already then disconnect it - remove one drop link is enough - or stiffen the front bar and see how the temps change and whether you prefer the feel of the car.

Of course much is down to individual style - maximum sideways and minimum lap times need different setups...

 

Martin

Roadsports B with upgradeitis

 

typo edited!

 

 

Edited by - mwoodham on 2 May 2006 09:38:53

[Wahey]

I drove caterhams on track for 3 years before ever having one set up properly!

 

It makes a big difference - I wouldn;t get too hung up on trying to deal with it by adjusting tyre pressures & just get it set up properly then play with roll bars & pressures from there.

 

You can fanny around all day trying toget it to handle right by making your own adjustments but it may be way out to start with anyway.

 

Bookatrack have a guy that can do this for you at the side of the track or you could try here www.fauldsport.com who has done my last 2 cars & made them pretty quick with very neutral handling.

[Tim Smith]

Thanks all for the advice, it does sound as if I have been running with too high pressure in the rear tyres. The car was flat floored and set up just before I bought it but I'm beginning to wonder if it might be time to get it done again. I'll also have a look at disconnecting the ARB, what is a drop link and where will I find one?

 

Tim

[MartinWoodham]

there's a drop link either side that connects the arb to the de dion ear - they attach each end with balljoints.

 

Martin

Roadsports B with upgradeitis

 

 

[Shaun_E]

There is a pin/clip affair that holds the ball in the cup. You unclip the pin by pushing it away from you and then pull it down - dont' lose it! The ball can then be pulled out of the cup (needs a bit of force). I just zip tied the drop link to the de dion until needed again. You only need to undo one end of one of the drop links to disconnect the ARB.

 

Yellow SL #32