Understeer

Hi Guys suspension theory suggests softening front ARB stiffness to reduce understeer so I changed the drop links from the middle to the outer ends of the bar but it’s still understeering at the limit. The only way I could stop it was to trail brake into corners. Am I getting it all wrong? I’m going back to Donnington (my favourite circuit) May 22nd so any advice would be very much appreciated. BTW my car is on standard suspension.
Steve

Some have claimed that stiffening it up helps (go figure!), so you may want to try that.

I’m the same as you, my original smooth/safe style was giving loads of understeer. Trail braking is definately the answer. [WARNING: I TAKE NO RESPONSIBILITY FOR THE RESULTS OF TRYING THE NEXT TIP] I’ve also found taking more speed in helps, as the Exiges’ limit are much higher than the brain often comprehends.

If you don’t want to drive it like a go-kart, you may want to get somebody to play with the geo for you.

Ian

Thanks Ian, maybe I’m just being a wuss and not turning in hard/fast enough. I think it’d be interesting to see how Gavan Kershaw or someone of that skill level might deal with it.
Steve

What tire pressures are you running? My car is very sensitive to tire pressure.

I was running 18psi allround cold but that translated to 22psi front and 25psi rear when hot. I’m running Toyo tyres (until they’re worn out) what would you recommend?
Steve

Too low.
I run 19Front 17Rear but on Yoko A048’s. That translates to about 24psi hot all around.
Toyos need higher pressures because the carcass is too soft (made really for the road)
I’s start with 22F 20R, but look for something like 28psi all around hot.

Also, wear pattern and tempeartures might tell you a lot.
Are the edges of the front Toyos more worn than the middle?


Also, ultimately, don’t expect a lot of grip fron Toyos, they’re ok for the road, but not for track.

24psi hot on the 48’s?

I was under the impression we wanted about 28psi hot on 48’s?

I run 048s at 28 hot all round and find the handling fine, with little understeer except on hairpins…

Technically I believe a little understeer is what you actually want. A tyre gives it best grip at the ideal slip angle (about 10o for road tyres, probably less than 2o for F1 and maybe 5 or 6o for ours, I’ve never been able to find out). Slipping the front tyres is of course either understeer or a cracking old slide!

Ian

I want the front tyres and the rear tyres at the right slip angle at the same time… i.e. a slide that you can only just feel…

Hence the driver training mike!

Ian

Meat

Gav Kershaw ran his race car with 28psi (hot) all round. When I tried this, I found it understeered badly - Gav obviously chucked his car into corners at a far greater speed than I was capable of, & those pressures suited his style (& race car set up!). I’ve found 20 psi front, & 23psi rear, when hot, just fine. (In saying that, Gav’s hot is higher than my hot - “hand test” used at various of Gav’s race meetings last year!)

The 48s & individual car settings appear quite sensitive, so it makes sense for everyone to play around with the tyre pressures & find their own optimum.

I got mine playing with a pyrometer and looking at the tyre wear, and you’ve seen me on the track, it seems to work…

I think it’d be interesting to see how Gavan Kershaw or someone of that skill level might deal with it.
Steve

he’d maybe provoke some oversteer to compensate ??

Some have claimed that stiffening it up helps (go figure!), so you may want to try that.

I’m the same as you, my original smooth/safe style was giving loads of understeer. Trail braking is definately the answer.
Ian

IDG

don’t you find trail braking quite scary in tightish corners following fast straights? like the first bend after pit-straights on most circuits??

I was running 18psi allround cold but that translated to 22psi front and 25psi rear when hot. I’m running Toyo tyres (until they’re worn out) what would you recommend?
Steve

icon – i reckon that these pressures are way too low for Toyo tyres (i guess you are talking proxes t1s here?)… I found i needed about 28-30 psi hot at track-days with them… they are still kinda squidgy tho’…

BTW… they will never wear out… so you could be missing out on the real fun for a while yet…

don’t you find trail braking quite scary in tightish corners following fast straights? like the first bend after pit-straights on most circuits??

Yes!

I believe (as in I was taught) the trick is to do the hardest braking early, so you’re coming off the brake when it’s getting tight (controling the tail), not burying the pedal through the floor as the car heads straight for the gravel.

Ian

Technically I believe a little understeer is what you actually want.

This is spot on. What you are looking for is slight understeer on the apex of a corner as this means the rear end has some grip available when you want to hit the loud pedal. You will kill most of the usual Exige understeer by going into the corners deep and fast.

Uldis/Pesky

How do you find tire wear at these pressures? Are you scrubbing the outside edge quite a bit?

I only find understeer an issue on decreasing radius turns when trying to stay on the power. My geo is probably all knackered though - I will be getting one soon.

Meat

I’ve just reread my earlier post, & I meant 20F 22/23R when cold, so for me they get up to about 26-28 when hot (depends on track temp). Really sorry for any confusion caused!

I found the 39 fronts would wear quite quickly on the outside edges when on track. The 48s definately last longer - I put this down to them having a much larger rubber contact patch on the tarmac, than the 39s with their “block” treads.

Having the geo set up properly does make quite a noticable difference to the handling, & is money well spent.

Once again, apologies for the earlier misinformation.