dmel

Yesterday I changed my worn-out SO-2's for brand new S0-3's (205x50/16). I also changed my suspension settings because I hadn't checked them for a while. As it turned out the settings were all over the place... I changed them to:

Front: Camber = -1.25 degrees
Toe = 0 mm
Rear: Camber = -1.25 degrees
Toe = 0.5 mm inwards in each wheel (1 mm in total)

I decided to go for more negative camber because the inside region of the old tyres were in near perfect condition (relatively). Furtermore when cornering hard and the front tyres were pushed hard, the outside sidewalls had signs of coning in contact with the tarmac even reaching the "Bridgestone" mark implying that the camber was not negative enough (indeed it was -0,75 degrees).

After the new settings the car seems to oversteer quite a lot. It tends to lift-off oversteer quite easily and at much lower speeds than before. It is generally easy to make the tail-snap out. On the other hand understeer has been reduced considerably and turn-in is sharper.

I am aware that the tyres are new and that they haven't bed-in properly yet (only 200 miles). On the other hand considering that all 4 tyres are in the same condition there shouldn't be in any bias towards understeer or oversteer; just lower limit of adhesion. Therefore since there is no understeer the reason for oversteer should be the new settings and not the tyres.

The questions are:
1. Do I have too much camber in the back-end? This could explain lift-off oversteer. When lifting off the back end is "lighter" and "only" the inside region of the tyre is in contact with the tarmac thus making it prone to oversteer.

2. Is it OK to have a bit of toe-in in the back? Shouldn't in theory provide some stability?

3. Tyre pressures. A new topic on its own. Following the advice of another thread I inflated the tyres slightly higher than S0-2's. I have 35 in front, 33 in the back.

Looking forward to your replies. Dimitris MY99.

johnfelstead

camber seems excesive all round.

I would sugest your front tyre wear patern was down to low presures, not lack of camber. You will also get that if your using more lock than needed. Next time you feel it understeering (please play with this idea in a safe place first!) try reducing the lock a little rather than piling it on, you may find it actually turns in better because you are already over the limit of the tyre and are just making things worse.

toe in at the rear does induce stability in a straight line.

The SO3's are pants compaired to the SO2's when it comes to grip levels. S de B can tell you far more on this than myself.

dmel

This exactly my response to understeering. I agree with you on that.

Having read other threads the camber settings are not excessive. Also the FAQ states that the Prodrive settings for front camber are Max. Equal Negative. -1.25 is not even the maximum.

AJbaseBloke

Try some different tyre pressures m8. Maybe even higher.

And believe it or not, you may not be through the crummy top layer yet me thinks - it took me around 1200kms before finding the sweet stuff. Now very with them (215/45-17 at 36psi/f, 34psi/r - going to 40psi/f, 38psi/r when going for "exercise").

Cheers.

Jza

Just one thing. One day doesnt seem a lot of "bedding in" for the tyres!! Are you sure the problem isnt that they've still got bed in?

Jza

Stelios

What suspension have you got Dimitri and where did u get your car measured?
If you can adjust rear camber try reducing it first at the range -0.75 to -1.00.
Im booked for geometry check on Wednesday after fitting the whiteline kit including ARBs and rear camber bolts.
|Ill go for front -1.00, 0.00 toe, rear -0.75, 1mm 0ut per side.

dmel

Jza, you don't know how many miles one can do in a couple of days

Stelio, I went to 'Rabbit' in Peristeri. He is very well known and "Omada Sigma" goes there too. My suspension is standard although I think it's time for an upgrade...

dmel

I think the answer is rear toe. I have reduced rear toe to zero and the car oversteers even more. Before making any changes rear toe-in was 4mm (2mm in each wheel) and the car snaped its tail with extreme difficulty.
I will now set it to 2mm total. All this with standard suspension. Nevertheless, I think it's time for a suspension upgrade.