GT4 on track

[BubblesNW]

ChrisW. said:

It will certainly be good exchanging notes --- this is a fun conversation --- and the next track day in only a week away at Knockhill !

I do hope I'm not going to have to put the PSS's back on !!

You might want to invest in some snow chains!!

[LaSource]

So, I notice my fronts are not only worn at the edges, but also the tread blocks are chamfered at an angle with more wear on the edge closest to the outside of the wheel.
I assume this is a classic case of the tyre rolling onto the edges due to insufficient camber?

[ChrisW.]

Yes --- the trade-off is that if you put more negative camber on the car will tend to tramline on the road and you will then wear the inner shoulders in normal use.

The wider the tyre, the bigger the problem ...

The fact is that tyres wear

[isaldiri]

LaSource said:

So, I notice my fronts are not only worn at the edges, but also the tread blocks are chamfered at an angle with more wear on the edge closest to the outside of the wheel.
I assume this is a classic case of the tyre rolling onto the edges due to insufficient camber?

Just wondering, what hot tire pressures are you running...?

[Porsche911R]

ChrisW. said:

Yes --- the trade-off is that if you put more negative camber on the car will tend to tramline on the road and you will then wear the inner shoulders in normal use.

The wider the tyre, the bigger the problem ...

The fact is that tyres wear

you have to go quite big to get road camber tramline issues, my car don't have that problem
It might wear the inners too much for a normal use daily though.

IF the tread is bending back on the outer edge the temps are getting way too much prob >65oc
Oem is no good for any track work imo.

[LaSource]

isaldiri said:

Just wondering, what hot tire pressures are you running...?

I think close to cold level so 29 psi hot at the front.

[LaSource]

ChrisW. said:

Yes --- the trade-off is that if you put more negative camber on the car will tend to tramline on the road and you will then wear the inner shoulders in normal use.

The wider the tyre, the bigger the problem ...

The fact is that tyres wear

Oh more camber please.

My 6gt3 has about 3 deg neg camber and I don't feel any adverse road behaviour. Even tram lining seems minimal which technically doesn't make sense! It's not on std springs or dampers so maybe that helps.

[ChrisW.]

LaSource said:

isaldiri said:

Just wondering, what hot tire pressures are you running...?

I think close to cold level so 29 psi hot at the front.

I try to max at 30psi hot all round, although the Americans seem to run at 32 + ??

The trouble is I'm measuring pressures after two cooling laps ...

[ChrisW.]

LaSource said:

ChrisW. said:

Yes --- the trade-off is that if you put more negative camber on the car will tend to tramline on the road and you will then wear the inner shoulders in normal use.

The wider the tyre, the bigger the problem ...

The fact is that tyres wear

Oh more camber please.

My 6gt3 has about 3 deg neg camber and I don't feel any adverse road behaviour. Even tram lining seems minimal which technically doesn't make sense! It's not on std springs or dampers so maybe that helps.

I wrote off two rear PSCups on a 964RS with 3000 miles of road driving due to worn inner shoulders ... maybe a more modern car would be better ??

[isaldiri]

LaSource said:

I think close to cold level so 29 psi hot at the front.

That's 2 bar...hm.. Someone i met at the ring some time back was saying at oem type camber he was running at 2.3-2.4 bar and found the tyres held up better (on a 991gt3 though but not dissimilar issue with lack of camber without shims etc). Might give that a try rather than running at 2.0-2.1 i guess.

[Porsche911R]

Cups need to be a bit harder than 29psi when hot IMO.

[Steve Rance]

I run mine at 2.1 bar hot front and rear. Should work well on a Cayman also

[jackwood]

Porsche911R said:

you have to go quite big to get road camber tramline issues, my car don't have that problem
It might wear the inners too much for a normal use daily though.

IF the tread is bending back on the outer edge the temps are getting way too much prob >65oc
Oem is no good for any track work imo.

I still disagree.

Why don't we just leave the debate until the 6th when we have some actual data.

Someone asked about tyre pressures. We run 2.2bar all round, hot. No shoulder wear. Very even wear across tread so far.

This is on Cup2's

I have heard from 2 sources now though that the Dunlops do seem to be chewing up the outer shoulders, even on cars with tweaked Geo.

David, what tyres are you running?

[jackwood]

ChrisW. said:

LaSource said:

isaldiri said:

Just wondering, what hot tire pressures are you running...?

I think close to cold level so 29 psi hot at the front.

I try to max at 30psi hot all round, although the Americans seem to run at 32 + ??

The trouble is I'm measuring pressures after two cooling laps ...

Why aren't you using the TPMS, Chris?

[Porsche911R]

jackwood said:

I still disagree.

Why don't we just leave the debate until the 6th when we have some actual data.

Someone asked about tyre pressures. We run 2.2bar all round, hot. No shoulder wear. Very even wear across tread so far.

This is on Cup2's


David, what tyres are you running?

I hate the Dunlops, I am on cups .

[ChrisW.]

Because it spends most of it's time giving me error messages ...

I start at 24 psi where the car sometimes throws error messages and won't then allow me to select a circuit route.

Sometimes it does work ... and then after you've stopped the car for a while and the tyre pressures have dropped, it starts from scratch again.

I also have a good pressure gauge which I know I can trust.

I have seen up to 34psi when it has been working and the car was definitely starting to squirm ... 34 is 2.4Bar ...

[isaldiri]

jackwood said:

Someone asked about tyre pressures. We run 2.2bar all round, hot. No shoulder wear. Very even wear across tread so far.

This is on Cup2's

Good to know thanks.

[jackwood]

So has anyone had a think about what they want to achieve on the 6th?

The person with the fastest lap has the best geo? Is it that simple?

[Porsche911R]

jackwood said:

So has anyone had a think about what they want to achieve on the 6th?

The person with the fastest lap has the best geo? Is it that simple?

I like to learn from other people if they are fast, so a trip out with a fast person is worth more than a geo.

I find the person with the fastest lap has the biggest balls normally, esp down craner curves, but I hope on the 6th no one will be timing them, it's a fun day out.
I have seem many many people come off on craner, I have had people spin in front of me, so I never push down the curves, where others I find love getting their Vmax speed down the curves, or people seem to want to hit that magic 100mph. where I am happy at 90mph. The kink Left upsets most cars and also on that track you never turn left so tyre temps for left turns are never right either.

I think what happens is people go in too hot do the left kink, the car oversteers and the cars gets fired off into a spin at 100mph.
or you lift off just a tad but enough to make the rear go lighter !! net result is the same style of spin.
as always people catch the over steer, but don't catch the tank slapper !!!

this is what normally happens !
https://youtu.be/VnnMx0Kohs4

the book a track hire cars normally spin like that in front of you !!!

I am hoping a nice person will pyro my tyres for me as I pull in the pits to get some Data, we can then pyro a stock car and see what the 2 geo's are doing.
So going forward we have some real data. you have people running 29psi you have people running 34psi they cannot all be right !

I am sure we will all learn something which is what it's all about, be that geo's or driving techniques or lines, there is plenty to learn.

If some ones faster let them by, if you want to know why they are faster go ask them for a ride out.

By the looks of it the cars which do Javlin days are not what I am used to so there will be a lot of slower cars on track, so watch out for the classic craner spin I have showed you guys. As the GT4 will be faster than most cars there(clios, Mazda, Honda) you don't want that spin to happen 2 meters in front of you. (and if it's me spinning DON'T hit me :-) )

And last if a car is holding you up don't bully it, just do a drive though the pits rather than stick on their bumper for 3 laps getting annoyed.
like wise if you are slower and are holding people up let them by asap.

I cannot see the GT4 and Cayman R getting clean laps in looking what's going, it will be a busy day.

I love Clios, Mazda's etc but the GT4 closing speeds on these types of cars are massive.

Edited by Porsche911R on Tuesday 3rd May 09:40

[ChrisW.]

jackwood said:

So has anyone had a think about what they want to achieve on the 6th?

The person with the fastest lap has the best geo? Is it that simple?

I'm very happy to let it happen and see what we get out of it.

A good turnout of cars will be a great start !

Decent weather will be a plus ---

And a bit of GT4 banter will be even better