Tyres at 45psi for track days!
Discussion
Last Sunday on cold wet Doni i was getting extra 7 1bs at the rear on 993 rs , very hard susp , not extreme but some neg camber , on a hot, dry 9 .........this is on Dunlop SSR
I aim for 30 hot all 4 corners .......sums are easy
with MSCups as per manufacturs recomendation to run at 36 hot all round similar diference cold to hot , different end result ..................also 993 chassis nearly double power of rs .................
May help ........................?
I aim for 30 hot all 4 corners .......sums are easy
with MSCups as per manufacturs recomendation to run at 36 hot all round similar diference cold to hot , different end result ..................also 993 chassis nearly double power of rs .................
May help ........................?
Be careful - my comment about reducing tyre pressures relates not only to a 911 but also to my Caterham. If I were to increase tyre pressures on the Caterham I'd certainly get more understeer as a result.
With so little weight, the Caterham does take time to warm its tyres up properly and the sidewall flexibility has never been an issue for me either.
My (admittedly limited) experience of 4wd cars on track days has shown that to kill understeer, it's better to be more brutal with the approach into corners. I guess that raising tyre pressures ought to assist in letting the car drift before turning in?
With so little weight, the Caterham does take time to warm its tyres up properly and the sidewall flexibility has never been an issue for me either.
My (admittedly limited) experience of 4wd cars on track days has shown that to kill understeer, it's better to be more brutal with the approach into corners. I guess that raising tyre pressures ought to assist in letting the car drift before turning in?
This is interesting. I always followed the let air out rule on my 944 .
Particualy on the 944 which wore track boots the front types were scrubbed all the way round to the rims. I mentioned the problem one of the old touring Ccr guys who used to drive 944s I think (Andy Rouse) who said I should be running the fronts at mid 40s pressure (hot) rather than the 34-36 I was using, essentially to gain greater stiffness as mentioned in a previous post.
Would this mean raising the back as well or is a 10psi differencial front to back reasonable.
I have to admit I haven't tried it and tend to run about 34/36 hot with my SO2s on the 968 I have now
Particualy on the 944 which wore track boots the front types were scrubbed all the way round to the rims. I mentioned the problem one of the old touring Ccr guys who used to drive 944s I think (Andy Rouse) who said I should be running the fronts at mid 40s pressure (hot) rather than the 34-36 I was using, essentially to gain greater stiffness as mentioned in a previous post.
Would this mean raising the back as well or is a 10psi differencial front to back reasonable.
I have to admit I haven't tried it and tend to run about 34/36 hot with my SO2s on the 968 I have now
vic cohen said:
Last Sunday on cold wet Doni i was getting extra 7 1bs at the rear on 993 rs , very hard susp , not extreme but some neg camber , on a hot, dry 9 .........this is on Dunlop SSR
I aim for 30 hot all 4 corners .......sums are easy
So Vic on your 993RS you aim for 30 hot all round? Whereas I was told to aim for 34 to 36 hot all round? What difference would this make to handling etc?
Piers
993RS
My rs is a very stiff Clubsport with Bilstein sport suspension........Dunlop SSR are not that far offa road tyre , object of course to get as much footprint as poss on the road ......at 30 hot all round i believe with this type of compound i am at best compromise [ excluding race tyres / slicks softer stuff]Higher temps i feel the car moving around at the back plus more understeer for luck IMHO not what i want ......... alot is personal pref but i ave based the decision a lot on what Porsche track people recomend ......Steve Winter Jaz Motorsport is a good source as he puts out any number of Porkas every w/end for races in the summer of all ages 30 all round hot is most peoples choice
Other compounds as pointed out diff story
I know ur car , fro Peter T , ask him what he uses ......looks a lot nicer than when Mr F had it !!!
>> Edited by vic cohen on Wednesday 9th February 07:50
Other compounds as pointed out diff story
I know ur car , fro Peter T , ask him what he uses ......looks a lot nicer than when Mr F had it !!!
>> Edited by vic cohen on Wednesday 9th February 07:50
heard loads of different opinions from very experienced drivers over the years on this one....
The conclusion I came to was that people are told to up the pressures when they are relative novices...this is because they are unlikley to go that quickly thus pressures wont rise that much, anf it prevents flexing of the sidewall....
however if you are quick, and you dont drive your GT3 like a Diablo owner, you are likely to heat the tyres and raise the pressures quite high.....
Therefore you should lower the pressures...but only after they have been raised by some quick laps and you will be lowering them to the Porsche recommended pressures...i.e. GT3 32/37 ...996 36/44.
So even when the tyres are running hot, they are at the recommended pressures. Obviously they will drop after a rest and at the end of the day will probably need reinflating for the way home
This seems to work for me, whether on the GT3 or the Integra...
IMHO
>> Edited by peterpeter on Tuesday 8th February 20:33
The conclusion I came to was that people are told to up the pressures when they are relative novices...this is because they are unlikley to go that quickly thus pressures wont rise that much, anf it prevents flexing of the sidewall....
however if you are quick, and you dont drive your GT3 like a Diablo owner, you are likely to heat the tyres and raise the pressures quite high.....
Therefore you should lower the pressures...but only after they have been raised by some quick laps and you will be lowering them to the Porsche recommended pressures...i.e. GT3 32/37 ...996 36/44.
So even when the tyres are running hot, they are at the recommended pressures. Obviously they will drop after a rest and at the end of the day will probably need reinflating for the way home
This seems to work for me, whether on the GT3 or the Integra...
IMHO
>> Edited by peterpeter on Tuesday 8th February 20:33
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