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View Full Version : Help with Setup - BMW M3 GT4



MortICi
23-02-2018, 23:07
So I am having some trouble getting the car to behave properly.

I normally don't touch setups, running the default loose for most tracks minus fuel load/bump stop/and toe-in adjustments (very minor). I can be competitive with the loose setup (G25, VR) and top 5 it for the most part, but I am pretty sure i can squeeze out a at least 3-4 more seconds out of the car with a proper setup for the track.

My problem is that at Fuji, T1 and T2 have a tendency to make the car oversteer very easily. T1 mainly on corner exit and T2 on mid corner. I have to be VERY gentle with throttle and steer input on T1 and on T2 i lose a lot of time as it seems to consistently want to spin around and its a rather flat bend, although it seems to be off camber (dipping down on corner exit) which might be upsetting the car.

I have messed with the roll bars and spring rate but usually it does nothing or makes the car worse. The rest of the track the car performs fantastic, the third to last corner (after the 180 chicane) can be tricky sometimes but i think it has the same type of slope as T2 which is causing me problems.

So any one have any tips on setting up the car for a better stability?

I will try to record a video with telemetry.

Track temps 73-80F ambient 63*, clear/cloudy weather. Hard slicks 23PSI front 21PSI rear, after warmed up 27PSI/23PSI

Toein front: -0.2, toein rear 0.4

front sway 150nm
rear sway 10nm

Front ducts for brakes at 60% and rear at 40%

Setup is set to be symmetrical.

hkraft300
23-02-2018, 23:52
Increase power ramp angle on the diff. Open it up a touch.
You might want to reverse any anti-oversteer tuning you've done to mitigate it, too.

MortICi
24-02-2018, 01:55
Increase power ramp angle on the diff. Open it up a touch.
You might want to reverse any anti-oversteer tuning you've done to mitigate it, too.

Ive been decreasing the power ramp, ill do the opposite and tweak out the oversteer corrections i made on the alignment/suspension.

rich1e I
24-02-2018, 14:12
Have you tried more rear aero? T1 oversteer is normal, you have to be careful in any car as the rear end gets very light. I don't like the BMW so I haven't driven it much but try more aero and maybe increase steering ratio as you might turn in to fast. Also slowing down a little bit more might help.

blinkngone
24-02-2018, 16:40
Ive been decreasing the power ramp, ill do the opposite and tweak out the oversteer corrections i made on the alignment/suspension.

On PC the top 3 TT runs are made with the Power Ramp at 70/75 as hkraft suggested. All ran the same front ARB at 150 and 2 ran the rear ARB at 50 and 1 at 25. 2 ran engine braking at 7 and 1 at 5. Front toe was either -0.1 or 0.0, rear toe was all over the place, 1 at +0.6 and 2 at +0.2. Aero was 2 running 6 and 1 running 4. All the runs are within 0.515 seconds with the quickest run at 1:47.985, all Patch 3.0. Camber and dampers differed for each setup but ride heights remained same.

Ok let's look at the run made with the 0.6 rear toe, it also has the lowest Aero at 4.00 so maybe as Ric1ie suggested about T1 the person had lowered the Aero too much and was now trying to compensate by dramatically increasing the rear toe.

The slowest run had the Preload highest at 140 and the most number of clutches at 6 so maybe this LSD was giving problems in the tighter corners where the others had preload at 100/120 and clutches at 4.

rich1e I
24-02-2018, 18:10
Did a couple of laps and tried adjusting the setup a little bit. It seems only slowing down and taking T2 carefully prevents this car from oversteering like crazy. Didn't try soft tyres, they might help a little bit I guess. I tried everything to reduce oversteer: lower the rear to the minimum and raised the front to 1.10, lowered rear springs to minimum, rear anti-roll bars at 10, full rear aero etc. but nothing. So I'd say try soft tyres and set steering ratio to maybe 14.5 or 15, slow down enough and be very gentle with steering input and you'll make it around the corner without spinning out.

Not that the E92 is not a tail happy car. It's actually a very popular drift car, but I think it's just crap ^^. I have the feeling, the only way to get this car not oversteering in T2 is not using it at all!

blinkngone
24-02-2018, 20:31
None of the setups I have looked at have attempted to control the oversteering with the dampers in this car. I changed the slow bump and bump transition which has worked on other cars.

Casey's tire pressure guide, Modern GT & LMP: ~1.8bar front and rear. Maybe down to 1.6bar for a very slow track like Long Beach or higher to 1.90-1.95bar at Le Mans to squeeze a little bit more off the rolling resistance.
250632

hkraft300
24-02-2018, 21:21
I tried everything to reduce oversteer:

If the rear springs are over-damped, it'll still be too stiff and cause oversteer.

dan2312
26-02-2018, 00:24
Increase Caster,
Harder Front Rollbar
Soften the Rear if possible.
Soften the dampers at the front,
Also if possible increase the clutches on the LSD, Also i don't know that TCS settings you have but minimize the slip to help control the car.

MortICi
26-02-2018, 05:28
Did a couple of laps and tried adjusting the setup a little bit. It seems only slowing down and taking T2 carefully prevents this car from oversteering like crazy. Didn't try soft tyres, they might help a little bit I guess. I tried everything to reduce oversteer: lower the rear to the minimum and raised the front to 1.10, lowered rear springs to minimum, rear anti-roll bars at 10, full rear aero etc. but nothing. So I'd say try soft tyres and set steering ratio to maybe 14.5 or 15, slow down enough and be very gentle with steering input and you'll make it around the corner without spinning out.

Not that the E92 is not a tail happy car. It's actually a very popular drift car, but I think it's just crap ^^. I have the feeling, the only way to get this car not oversteering in T2 is not using it at all!

Basically you got the same result I did. Only thing to do is lose time and go slow through that corner.

I looked at other WR setups and saw the same.

The only thing i can see or feel is that the dip mid corner almost forces overrotation of the car, I am not sure if its actually in the dampeners, if you get mad oversteer and tray to correct i have nearly flipped the car as it re catches. I also noticed that hitting kerbs hard makes the car actually "bounce" on that side.

I will work and see if i can adjust the dampeners, its either too soft or too hard. Its annoying me because I don't think the car should have that much trouble in that corner, unless I have to go with asymmetrical setup.

rich1e I
26-02-2018, 10:27
Basically you got the same result I did. Only thing to do is lose time and go slow through that corner.

I looked at other WR setups and saw the same.

The only thing i can see or feel is that the dip mid corner almost forces overrotation of the car, I am not sure if its actually in the dampeners, if you get mad oversteer and tray to correct i have nearly flipped the car as it re catches. I also noticed that hitting kerbs hard makes the car actually "bounce" on that side.

I will work and see if i can adjust the dampeners, its either too soft or too hard. Its annoying me because I don't think the car should have that much trouble in that corner, unless I have to go with asymmetrical setup.

Tried soft tyres and it was a lot better. Decreased rear slow bump and rebound as well and the result was noticeable. I still believe the car itself is just crap imo. With a track temp of 40C+ hard tyres should be ok especially when they're at optimum temp and pressure but they're so slidey. Recorded a very strange behaviour after I made it through T2. Never ever a car should oversteer like that even if you set 8 clutches and 20 degrees power ramp angle. I think something in the car physics is broken.

http://xboxdvr.com/gamer/rich1e%20I/video/44766504