bazpro88 said:
just checked , 38 psi in fronts and 32 in rears.
seems odd.
ive got a set of 17s that came on the car originally which I might use next time as I wont feel guilty about destroying the tyres!!
also am all for reducing understeer but got to have a bit oversteer otherwise its boring
.
so your saying if I disconnect the rear anti roll bar it would oversteer more?
a lsd is out of the question as am guessing a lot of money and putting a welder in it isn't really ideal for using on the road.
Your starting point for tyre pressures should be factory recommendations and then go up, I have found a minimum of factory +4psi is a reliable starting point, buying a tyre pyrometer is a good investment as this tells you exactly how much camber and pressure is working and the temps will give you a good idea when your out of balance at one end.
Disconnecting the rear anti roll bar will reduce oversteer as there is less weight transfer to the outside loaded tyre it will also improve traction out of tight corners (up to a point) it's no substitute for an LSD.
If your car suffers understeer increase the front tyre pressures or if they are already starting to feel light due to high pressures disconnect the front bar and adjust the front - rear balance on the dampers and pressures (if you have adjustable dampers).
It's well worth experimenting by playing with pressures and bars just to see how your car behaves with your driving and the tyres it has, once you have an understanding of what changes in the balance when you make these big adjustments then you will be able to figure out what you want and tune the handling, but it's always a compromise, a car that works great through the fast corners may be less predictable in the slower corners and vice versa.
A simple guide is-
1, increase pressures +4 and try it to see how it feels
2, attempt to balance any understeer or oversteer by raising or lowering the pressures in small 2psi steps, try a couple of laps after each adjustment
3, if you have understeer and pressures are not balancing it, disconnect the front bar and drop your front pressures by 2psi then try again, for oversteer do the same at the rear.
4, some times the only way to cure an imbalance is to "spoil" the other end, if for instance you have oversteer because the front end is turning in really well but the back can't follow you may have to dial in counter understeer to balance the car, on track days your lap time is not really important but having a predictable car that gives confidence certainly is.
The ideal balance for me was turn in oversteer so I could rotate the car through the corner with the back just starting to slide then power on understeer so I could get on the throttle just before the apex with the front just starting to slide, but that was for my driving style and you have to find what works for you it's also very difficult to achieve and you often have to compromise.
Remember to make notes with each change and note what difference it made, temp on the day will be a very important factor as the next time you go on a cooler or hotter day you may have to tweek your settings.
for chrissake do NOT weld up a diff, the whole point of a diff is to let the wheels rotate at different speeds on the same axle, if you drive the car round a roundabout the outside wheel is travelling further than the inside one as the diameter of it's circle is smaller due to the width of the cars track, it's not hard to realise how much stress this would put on the drive shafts and the horrendous understeer you will cause! as both wheels try to push the car against each other!
Drifters weld up the diff to prevent the power being sent solely to the unloaded wheel, but they flick the car into a drift and then maintain it by allowing the wheels to spin, it might look cool but it's slow as hell!
An LSD works like a clutch by allowing a portion of the power to be sent to the loaded wheel before the clutch slips, you hear of LSD's being set in percentage term such as 40%, that's the amount of power of it's normal 50% share sent to the loaded wheel, A welded diff being 100% ie 50% to each wheel, the tighter the diff (higher the percentage) the greater the power split and traction but the greater the understeer normally.
