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jimmyb_84
31-05-2015, 11:13
Hi all,

I had a go at tuning the Ginetta GT3 on Donington GP circuit.

I softened most areas so it's a little more forgiving and I'm comfortable with the car in the main apart from high speed snap oversteer, I have made it a little easier to get the power down on corner exit, turn in is fine but the problem appears to Craner Curves (last part) massive oversteer.

I changed rear toe a little too (could this be causing it?)

I think I need to get a better understanding of the tyres but it's mainly fronts that overheat, tears are at a stable 90c +.

I think my next move is to reduce rear ride height slightly.

I will post a picture of the setup later, cannot get on PS4 at the moment.

Your thoughts

JeyD02
31-05-2015, 14:55
Antil roll bar, balance them and for high speed maybe put more rear dwonforce as well.

jimmyb_84
31-05-2015, 15:00
Antil roll bar, balance them and for high speed maybe put more rear dwonforce as well.

I already have full downforce ill try anti roll bar next cheers

JeyD02
31-05-2015, 15:12
I already have full downforce ill try anti roll bar next cheers

If there is too much stiffness on rear ARB it'll snap the rear, you could try softening slow rear rebound too. Find your sweet spot :)

hkraft300
31-05-2015, 17:44
Maybe try a stiffer spring rate (same ratio F/R). I was having problems running soft at Bathurst but I stiffened up the car all round and found massive improvements.

Rear toe in (~0.2-0.4) should help but not a lot at high speed. that's a quick area of the track reckon you might be bottoming out, zero your bumpstops, raise ride height and try stiffer springs, and what JeyD02 said above.

SVO360
27-07-2015, 03:32
are you guys able to post your best setups? i started driving this car the other night and enjoyed at one track had a go at Monza and another track and its beyond comprehension no matter what angle the car is in besides straight its spins even breaking turning in the corner its spins. i am a very hard late breaker and some cars hate it Im guessing as the rear gets lite or the brakes lock i don't know

Jussi Viljami Karjalainen
27-07-2015, 03:46
If there is too much stiffness on rear ARB it'll snap the rear, you could try softening slow rear rebound too. Find your sweet spot :)FWIW Personally I'd never run anything other than full max on all the damper settings apart from the slow bump (which I'd set to around 15 400 at the front, along with stiffer front springs, and 11 500 or so at the rear), even with the rear slow rebound and both fast settings set to max you get very little damping, barely enough for the softest spring options.
Maybe try a stiffer spring rate (same ratio F/R). I was having problems running soft at Bathurst but I stiffened up the car all round and found massive improvements.

Rear toe in (~0.2-0.4) should help but not a lot at high speed. that's a quick area of the track reckon you might be bottoming out, zero your bumpstops, raise ride height and try stiffer springs, and what JeyD02 said above.Also personally, I've found little use in running anything other than maximum front and minimum rear springs, the default bias on the car is almost the same frequency front and rear, which on a street car usually translates to oversteer, with max front and minimum rear you get about 12% higher frequency at the front which is more along the lines of most of the other GT3 cars, and the dampers are just barely enough for those springs.

This car is probably my favorite GT3 car off the whole lineup, the lightest and most agile one of the lot. On most tracks I've tried I've gotten it to within a few tenths of all the other GT3 cars but it requires a massively different approach, a lot more hard, on the edge style during cornering, since it can't really do much anything on the straights. Diff settings are also important for balancing the car on the throttle and preventing overrotation on entry. =)

wearymick
28-07-2015, 03:22
From memory I just kept the decel diff up and was careful about trail braking. Otherwise it goes like a bought one right out of the box. Love that little car. Particularly good on the less slippery tracks like Oulton Park. You can really chuck it about and it just comes back for more. ;)

hkraft300
28-07-2015, 07:32
Thanks Jussi. Is that spring rate and damping advice specific to the Ginetta GT3? It's only the R18 TDI and Lotus 98T that I've significantly stiffened the slow bump. Otherwise with minor tweAks most cars feel great.
As for the spring rate ratio front:rear it's the Ruf GT3 and Lotus 98T that I've found a sweet spot much different to the defaults.
I have a bad habit of fiddling with the setup before I've learnt to drive the particular car properly, otherwise the defaults are generally really good.

Jussi Viljami Karjalainen
28-07-2015, 10:36
Thanks Jussi. Is that spring rate and damping advice specific to the Ginetta GT3? It's only the R18 TDI and Lotus 98T that I've significantly stiffened the slow bump. Otherwise with minor tweAks most cars feel great.
As for the spring rate ratio front:rear it's the Ruf GT3 and Lotus 98T that I've found a sweet spot much different to the defaults.
I have a bad habit of fiddling with the setup before I've learnt to drive the particular car properly, otherwise the defaults are generally really good.Yeah, it's G55 GT3 specific, the dampers and spring sets on that car really tend towards surprisingly rear biased springs for a racing car (unless using max front and min rear) and low amounts of damping. According to the devs they're right on with the specs of the parts the car was homologated with, so they're realistic, just surprising.

The R18 TDI already runs stiff low speed damping, and the fast damping overshoots my usual ranges by a bit, should be fine on smooth tracks and high DF, but I'd expect it to get a bit twitchy over bumpy surfaces, particularly at low speeds. The Lotus 98T... Yeah I'm not sure I have the correct default setup in my spreadsheet, but if I still have it then the setup is really rear biased in the springs and swaybars (meaning oversteery) and the dampers are really stiff as well, making it not just oversteery overall but also sudden. When setting it up for myself I'd probably revamp it completely, a slight front bias in both the springs and swaybars, and softening up the damping to allow the suspension to move and absorb a bit better. Might do initial calculations once I'm back home...

EDIT: Also on the spring rate ratio front/rear: Unless you use a calculator or do the maths yourself while taking into account the front and rear motion ratios, the spring rates are essentially just meaningless numbers. The R8 LMS Ultra for example has over twice as stiff front springs as it has rear springs, but because the motion ratios are different the front is actually only slightly stiffer than the rear. And on many cars the front is stiffer than the rear while also having much lower spring rates. Or vice versa. Point is unless you know the motion ratios or use a calculator that already includes them, you have no idea what sort of wheel rates (the effective spring rates) the car is actually running on. I made my suspension calculator exactly because this caused so much confusion to me during development.

hkraft300
28-07-2015, 14:55
I don't tend to change the spring rate ratio much - if I increase the front by 20% I'll do the same for rear, then maybe a click of adjustment according to how I want the car to behave. The R8 LMS spring rates seemed way off until I drove it - now I know why - motion ratio! Thanks for taking my arse back to school haha
I've had to make the fast bump a lot softer than default to get the TDI manageable. I've also had to increase the Lotus front springs and dampers a fair way forward to get the response necessary to keep up with the back end. Get it roughly in the zone and that thing is a proper beast and so exciting to drive. Awesome rig.
You get precise numbers with your calculator and I get roughly, sort of in the ball park, by feel - all credit to the dev team for how real the cars feel and behave even through a controller.

PCars fanboyism at its finest ;)

Jussi Viljami Karjalainen
28-07-2015, 15:14
I don't tend to change the spring rate ratio much - if I increase the front by 20% I'll do the same for rear, then maybe a click of adjustment according to how I want the car to behave. The R8 LMS spring rates seemed way off until I drove it - now I know why - motion ratio! Thanks for taking my arse back to school haha
I've had to make the fast bump a lot softer than default to get the TDI manageable. I've also had to increase the Lotus front springs and dampers a fair way forward to get the response necessary to keep up with the back end. Get it roughly in the zone and that thing is a proper beast and so exciting to drive. Awesome rig.
You get precise numbers with your calculator and I get roughly, sort of in the ball park, by feel - all credit to the dev team for how real the cars feel and behave even through a controller.

PCars fanboyism at its finest ;)If you're eager to try out something, I looked at the 98T's springs, swaybars and dampers and came up with something I'd start testing with (can't really play the game currently, so actual testing will have to wait), you could give them a go and see if they work at all. The following settings are intended to make the front end slightly stiffer than the rear end overall (weight etc. taken into account) and to get the damping set up to absorb and smooth out the track to some extent. If all goes well the car should be pretty responsive, but less oversteer happy and more progressive on the limit (though the wastegate setting plays heavily into this, as does the differential). If not, well, it needs more iterations then. =)

The springs, sway bars and damper settings are filled into the green cells on the spreadsheet:

213660

And here's what I'd do to the R18 TDI as a first go, reducing the fast damping dramatically to improve the bump handling and bringing the total damping forces down to sub 70% critical levels on average. Would have liked to get the fast bump setting down to 30% critical instead of the almost 40% critical the current minimum is, but unfortunately ran out of range. Naturally diff, aero and alignment affects things a lot as well.

213661

hkraft300
28-07-2015, 15:42
Will give them a crack when I'm home tomorrow afternoon. Thanks mate, love your work. The lotus has been far easier to tame than the TDI, funny enough. Your spring and damping rates look interesting.
Gonna have to give the G55 a crack as well.
Suddenly my pCars test list is growing huge and I'm finding increasingly less time to play it.
Separation anxiety...

jimmyb_84
28-07-2015, 15:47
some great info here, I will try out the Ginetta too, I found a good baseline setup on your setups website wonder how it compares?

my test list is also getting larger by the day

Jussi Viljami Karjalainen
28-07-2015, 17:55
some great info here, I will try out the Ginetta too, I found a good baseline setup on your setups website wonder how it compares?The "My G55 GT3 baseline setup" or something? That should be mine as well, I think.

jimmyb_84
28-07-2015, 18:10
The "My G55 GT3 baseline setup" or something? That should be mine as well, I think.

That explains why it's pretty good, seem to remember front and rear spring rates being at opposite ends, I need to fine tune it but a very good start.

Jussi Viljami Karjalainen
28-07-2015, 19:09
That explains why it's pretty good, seem to remember front and rear spring rates being at opposite ends, I need to fine tune it but a very good start.The front and rear spring rates are indeed at opposite ends, and for a reason. That only gives you a 12% higher front frequency, which is not that much, it's about where I'd put a GT3 car most times (stiffer front helps give the car a more stable aero platform at the front, and improves responsiveness, while the slightly softer rear allows the car more mechanical grip when accelerating out of corners, and prevents oversteer tendencies to some extent).

For comparison the modern GT cars have the following biases in their default setups:

Aston Martin Vantage GT3: 21% higher front frequency (340/190 springs)
Aston Martin Vantage GT4: 15% higher front frequency (240/150 springs)
Audi R8 LMS Ultra: 16% higher front frequency (450/200 springs)
Bentley Continental GT3: 3% higher front frequency (300/140 springs)
BMW M3 GT: 29% higher front frequency (260/160 springs)
BMW M3 GT4: 21% higher front frequency (180/150 springs)
BMW Z4 GT3: 1% higher front frequency (220/120 springs)
Ford Mustang Boss 302R1: 26% higher front frequency in roll, 1% higher front frequency in heave (113/70 springs, live rear axle causes roll and heave balance to be different)
Ginetta G55 GT3: 4% higher front frequency (210/183 springs)
Ginetta G55 GT4: 8% higher front frequency (140/113 springs)
McLaren MP4-12C GT3: 23% higher front frequency (175/227 springs)
Mercedes-Benz SLS AMG GT3: 25% higher front frequency (300/240 springs)
Ruf RGT-8 GT3: 60% higher front frequency (240/200 springs)

You can see a definite trend, the only cars below 10% degrees are the Bentley GT3 (known to be tail happy when pushed), the Z4 GT3 (likewise, at least to some), and the Ginettas (likewise), and the only car above 30% is the RGT-8 GT3, which has a weird setup if you ask me (very low damping, particularly almost no bump damping at all, massive front bias on the springs, I got it running much better for me with the front adjusted to 20% or so, and the damping made to fit the springs, plus a bit of diff adjustments). For me at least the cars with below 10% higher front frequency tend to want to dart into corners quite well and are eager to rotate, but can be really tricky on the edge. Cars in the 10-25% zone tend to be the most balanced, and cars above 30% start to feel somewhat understeery in steady state situations, plus the front end feels less progressive, and gives up grip more suddenly. The RGT-8 was (at least the last time I drove it with the default) pretty understeery in steady state cornering, but kind of made up for it by rotating very quickly when off the throttle (helped by the pretty open differential) and then understeering under throttle, so you could brake hard, quickly rotate the car, then stomp on the throttle. Trickier in longer sweepers though, and the low amount of damping made the car bouncy and easy to upset over bumps (didn't settle down quick enough). Adjusting the springs and dampers made the car more balanced overall for me.