Excessive wheelspin on corner exit!!!

[Gupster74]

I'd appreciate anyones constructive help on this one. I consider myself quite a good tuner of my cars being on board GT from the very start. I have recently delved into Scaff's tunning guides and have also learned a couple of mistakes i was makin with the set-up of my cars. I have recently set up my Nismo R-Tune with this new found knowledge and its a peach!! But it has a LOT of rear slip exiting corners!!! This is my set up:
@600bhp
Lsd(fr/rear)
torque: 10/30
acc: 30/30
dec: 10/10
Suspension(fr/rear)
Ride height: 0/0
Springs: 10.0/10.5
Damp-ext: 7/6
Damp-comp: 5/4
Anti r/bar: 3/4
Camb: 2.0/3.0
Toe: 0.00/0.20
Aero: 15(rear) - max!
Traction: 1
Abs:1
The car is just how i like it but i'd like extra traction!!! Im running sport softs and dont really wanna put racing tires on as i feel this is cheating somewhat in the races i use the car in!! What would be the best aspect to alter without resorting to the dreaded power-sapping traction control??? btw, the rear suspension will only go down to 10.0 min as i would've tried this route already!!! Any help will be appreciated!!

 

[Blade2322]

https://www.gtplanet.net/forum/showthread.php?t=169943&page=2

Check out my tuning garage i have a tune for that car although it is set-up w/rt but it still might convert well. Id suggest using 35/65 on your power transfer, as well as setting your lsd to something more like.

T- F- 10 / R- 20
Acc- F- 20 / R- 20
dec- F- 10 / R- 10.

Try and see if that helps.

 

[budious]

A few things come to mind, lower the rear dampers by one click each and they will get better grip with the surface; retune the suspension, the rear spring may be too stiff or make A/R 3/3; lastly, use a higher LSD acceleration value at rear, try 40/45/50 and note handling differences.

 

[zodicus]

more LSD in the rear under accel, less rear comp, less front extention. more rear pos toe, less rear camber. all of those should help. not saying you have to do all of that but any one or combination should help. if you like how the car handels id say go for the LSD settings first, then the toe if thats not enuf.

 

[Gupster74]

Thanks everyone. Will try trial & error a few of these ideas to get to where i wanna be !!! btw Budious, not sure a 0.5 change in the rear springs will change much & need the fexibility of the fully adjustable package!!!! Thanks again tho:-)

 

[budious]

Thanks everyone. Will try trial & error a few of these ideas to get to where i wanna be !!! btw Budious, not sure a 0.5 change in the rear springs will change much & need the fexibility of the fully adjustable package!!!! Thanks again tho:-)

Think smaller, try them .1 at a time, it can make a huge difference just to go 6.5R to 6.4R sometimes, etc.

 

[Gupster74]

Think smaller, try them .1 at a time, it can make a huge difference just to go 6.5R to 6.4R sometimes, etc.

Cheers!! Will give it a go. Had GT4 tunnng down pat but there are subtle differences and still getting to grips!!!
BTW all, is it just me or does everyones loading screens still take an age even after the big install?????

 

[BlueShift]

Camb: (...)/3.0

Your main problem, 50% of your spining comes from this. Half it, at least. Best to be quaterred. (both front and rear).

torque: 10/30
acc: 30/30

Your second problem (25%), but I can't help if you don't give the torque sensing center differential setting.

From your initial, I guess you chose something around 25%/75%, from your accel, you chose around 50%/50%. One of these (rear intial or front accel) is set too high, or one of these (front initial or rear accel) is set too low.

Damp-ext: 7/6
Damp-comp: 5/4

Well... 15%.

I won't say the reason again for the 10th time in a row (ext and spring work in the same direction, comp and springs work the opposite), but if you played older games, you should have set the opposite (ext < comp). Now, I'm alone to think that on this forums.

The last 10% comes from your brakes I guess. What did you choose in rear ? More than 5 ?

 

[Gupster74]

Your main problem. Half it, at least. Best to be quaterred. (both front and rear).


Your second problem, but I can't help if you don't give the torque sensing center differential setting.

Soz, i did somehow leave that out!!!:-S
I like my cars as RWD as poss so its 10 / 90 fr/ rear.

 

[budious]

Soz, i did somehow leave that out!!!:-S
I like my cars as RWD as poss so its 10 / 90 fr/ rear.

Not really optimal, but then again I haven't played with 4WD to as great an extent as FR and MR cars. From my limited experience somewhere around 30/70 split was closer to optimal, then place a higher LSD accel on rear so that it will have a bit of a power oversteer through corners and the front has just enough power to pull the nose into position.

 

[Gupster74]

A - i asked for CONSTRUCTIVE HELP , so any one feeling like being a patronising, sarcastic c**t, **** off bk over the channel, and
B - Stiffening the compression is only going to harden the suspension leading to MORE slip, not less!!! SOME TUNNING GURU!!!!

 

[Gupster74]

Plus, what the **** has brakes got to do with it??? I'm talkin about accelerating OUT of a corner, NOT braking INTO!!!! fyi, the brakes are set at 5(fr) - 3(r) . Pretty optimal you will find!!!

 

[budious]

This is constructive help, I don't see any patronizing or sarcasm here, everything posted so far has been valid advice. Use it or don't bug us for help if you gonna whine about it.

I would disagree a bit with the DE < DC also though, this is typically only the case in my experience if the spring was too soft for it to show a positive effect on ride quality.

 

[Gupster74]

"i wont say the reason for the 10th time in a row...."
Pretty sure that accounts for sarcasm especially as i dont recall seeing the other 9times it was mentioned on this thread!!!!
Anyway, wasn't whining and i am grateful for the advice so thanks. I was actually thinkin that prob the camber was TOO severe on the rear and that the lsd needed tweakin so it was as much a needed 2nd (or 3rd, etc) opinion as much as anythin!!! Plus i aso understand that 600brake with little downforce will cause a bit of slip especially in the slower corners

 

[BlueShift]

wtf what happened with the op ?

You ask some help because you don't understand something. if someone tries to learn you something (with brakes) no need to **** talk like that.

If you had set it to x/8, you'd ask too much torque difference from the rear from the braking phase to the acceleration phase. That is the reason.

"fyi" no need to shout.

edit -

"i wont say the reason for the 10th time in a row...."

omg that was what made you angry.
I speak engrish just in case you don't know. I am not Shakespeare. And I told everywhere in this forum why I keep tuning with ext<comp, that's the meaning of this sentence.
I just hope a precise word I used here won't make you shout more...

I didn't asked to stiffen comp, I asked to reverse comp and ext settings.

 

[oppositelock]

I like my cars as RWD as poss so its 10 / 90 fr/ rear.

That's your problem.

 

[Rotary Junkie]

I won't say the reason again for the 10th time in a row (ext and spring work in the same direction, comp and springs work the opposite), but if you played older games, you should have set the opposite (ext < comp). Now, I'm alone to think that on this forums.

Higher extension on the front will help with corner exit traction... Faster extension = faster rearward weight shift. Lower extension on the rear will do fairly little for it unless the car certifiably has "too much" and is therefore dribbling the rear tires when one hits a bump.

I've fairly extensively tested running less extension than compression... ~50% of the time it works well, other times (ex: Kia Impreza for the tuner challenge) it causes nasty reactions to sudden suspension compression as the suspension isn't allowed to expand quickly enough, resulting in some handling problems.






To OP: The torque bias is most definitely your issue... By virtue of the fact that there is SOME power going to the front tires at all times, you're not getting the full benefits of RWD (lower losses, less stress on the front tires, etc), but nor are you getting the benefits of AWD (greater traction resulting in the ability to take different lines in low speed corners without sacrificing exit speed, being able to hit the throttle whenever you please, etc). I'd try 30/70 at LEAST given it's an FAWD... Though since it's an R34, I'd also suggest trying it without any LSD or VCD installed at all (go back to the factory units) as the factory AWD system cannot be matched by the very simple (though effective) clutch-type differentials used for the LSD and VCD.

 

[zodicus]

"Higher extension on the front will help with corner exit traction... Faster extension = faster rearward weight shift. Lower extension on the rear will do fairly little for it unless the car certifiably has "too much" and is therefore dribbling the rear tires when one hits a bump. "

iam i looking at it backwards? more extention on the dampers would slow the extention of the shock, there by slowing weight transfer, or did i just misunderstand what you said?

p.s. readding the last few post i would think most of the problem is the front to rear bias in the center diff and the rear camber, lower the rear camber and put the center diff at mabye 25-75 or 30-70 and see if that helps. if i understeers on power out of the corner after you make those changes try adjusting the front limited slip, like lowering the accel and initial before you put the center back.

 

[budious]

When you run lower settings the car becomes loser so weight transfer is being thrown around more, the higher the number the slower it transfers. Think what he meant was since this is 4WD slowing the weight transfer to the back would keep more weight on the front wheels pulling and exiting the corner cleanly. I had a hard time reading his response also.

 

[zodicus]

yeah i kinda get that but with a 10-90 front rear split, the fronts arnt doing much.
i do use a higher setting sometims if i feel the nose pulling up to fast, accompanied with understeer. for me any way it seams to make oversteer more of a problem with the higher setting, especially right after i apply the throttle.

 

[budious]

I think the general consensus here was that he should try 30/70 and if that was the case, keeping weight at the front after transfer from the braking into the corner would make sense.

 

[BlueShift]

Higher extension on the front will help with corner exit traction... Faster extension = faster rearward weight shift. Lower extension on the rear will do fairly little for it unless the car certifiably has "too much" and is therefore dribbling the rear tires when one hits a bump.

I don't agree. I think your springs are set too low.

I've fairly extensively tested running less extension than compression... ~50% of the time it works well, other times (ex: Kia Impreza for the tuner challenge) it causes nasty reactions to sudden suspension compression as the suspension isn't allowed to expand quickly enough, resulting in some handling problems.

Yeah, I run into a wall with that car too. I agree on the denomination, the car is a pig.
This morning, I'm testing this, but I've got only a few time this week.
I think that theory don't work because springs are too low, and I can't determine real RH, and the weigth lift by springs, since the car is 2010.

Did you do spiral speed tests ?

I think the general consensus here was that he should try 30/70 and if that was the case, keeping weight at the front after transfer from the braking into the corner would make sense.

If the weigth of the car is ~35%/65%, yes. If it's 50/50, no : it should be ~45/55.
10/90 is "a choice". This completly remove the 4wr benefits, but still with a 4WD transmision device that weigth some extra % in front.

 

[budious]

A 50/50 weight would still shift backwards though on acceleration and on inclines so putting more at 30/70 split would still benefit the push over pull.

 

[BlueShift]

50/50 need more traction than 40/60...

 

[Rotary Junkie]

"Higher extension on the front will help with corner exit traction... Faster extension = faster rearward weight shift. Lower extension on the rear will do fairly little for it unless the car certifiably has "too much" and is therefore dribbling the rear tires when one hits a bump. "

iam i looking at it backwards? more extention on the dampers would slow the extention of the shock, there by slowing weight transfer, or did i just misunderstand what you said?

p.s. readding the last few post i would think most of the problem is the front to rear bias in the center diff and the rear camber, lower the rear camber and put the center diff at mabye 25-75 or 30-70 and see if that helps. if i understeers on power out of the corner after you make those changes try adjusting the front limited slip, like lowering the accel and initial before you put the center back.

The extension is known to be backwards at this point; a higher number results in faster extension and therefore less damping force. Completely backwards but yeah...

When you run lower settings the car becomes loser so weight transfer is being thrown around more, the higher the number the slower it transfers. Think what he meant was since this is 4WD slowing the weight transfer to the back would keep more weight on the front wheels pulling and exiting the corner cleanly. I had a hard time reading his response also.

Higher settings on bound = slower transfer towards that end. Higher settings on extension = faster transfer away from that end.

I don't agree. I think your springs are set too low.

Here's something for you... Softer front springs will, much like higher front extension, help rear tire traction on corner exit.

Yeah, I run into a wall with that car too. I agree on the denomination, the car is a pig.
This morning, I'm testing this, but I've got only a few time this week.
I think that theory don't work because springs are too low, and I can't determine real RH, and the weigth lift by springs, since the car is 2010.

I've based my springs off of a theoretical 60/40 weight distribution (which is roughly accurate, true weight distribution in real-life is 58/42... Though I find that weight reduction changes weight distribution somewhat).

Did you do spiral speed tests ?

I did some; results pointed somewhat towards your school of thought on the dampers (1mph or so difference at best though) but once I took the car to Trial Mountain... It became very obvious that the track is completely unforgiving of such a setup, particularly through the first three corners and the last two. The Trial Mountain testing also showed me that you're wrong about how anti-roll should be set . You've mentioned that it should, like the springs, be set in-line with the weight distribution... I contest that it should be softer at the end that needs the grip the most and stiffer at the end that needs it less.

If the weigth of the car is ~35%/65%, yes. If it's 50/50, no : it should be ~45/55.
10/90 is "a choice". This completly remove the 4wr benefits, but still with a 4WD transmision device that weigth some extra % in front.

I'd still say to try the factory differentials instead of the adjustable ones.

Nissan's system actually sends 100% of power to the rear tires until they slip, at which point power gets fed to the fronts. This can cause, to some, "inconsistent" handling... But once you know how it works you will be astounded by what it can achieve.

 

[BlueShift]

I've based my springs off of a theoretical 60/40 weight distribution (which is roughly accurate, true weight distribution in real-life is 58/42... Though I find that weight reduction changes weight distribution somewhat).

I used 47/53, as all spring devices says, by not tracking weigth reduction distribution for the initial tests. I need a few more day on the car before being sure, my tuning entry won't be finished.

I think real lvl3 weigth is between 47/53 and 50/50. So "less/more" or "even/even", that is quite different of "more/less" that you choosed. (that's why it's a pig btw)

I did some; results pointed somewhat towards your school of thought on the dampers (1mph or so difference at best though) but once I took the car to Trial Mountain... It became very obvious that the track is completely unforgiving of such a setup, particularly through the first three corners and the last two. The Trial Mountain testing also showed me that you're wrong about how anti-roll should be set . You've mentioned that it should, like the springs, be set in-line with the weight distribution... I contest that it should be softer at the end that needs the grip the most and stiffer at the end that needs it less.

I don't really understand. If you used 60/40 you should have set a-roll bar like that : more/less. Are you saying that less/more or even/even is better ?
What if you were wrong with your weigth ?
I used more/less.
About the dampers, i've got 178km/h with a flat SR/RH @ 47%/53%, and flat dampers and a-roll bars : 5/5/ - 5/5 - 4/4 and 184km/h with my classic dampers, so no, I won't change a line in my moto : that's 3.5% more speed for me, or a chrono @ 1'40 vs a chrono @ 1'36.5

=>
You are holding the curve at more speed, so you are quicker around the track (less needs to brakes and more speed after curving), maybe what you saw is speed problems.
Braking, even less, at higher speed is more violent than braking at lower speeds but you enter into the "torque function" differently, more smoothly, with low torque @ high rpm (torque for engine brakes) going to high torque at middle range rpm than @ midrange rpm with high torque allready going to low torque at low range rpm then low torque @ high rpm. Watch your decel settings. I guess they are set low just for that curve.

Hence first 0.3 second braking stability in first curve after the long straigth line. So people won't shoot the wall there. And low ext help a lot braking too.

Aero set @ 0/20 is the fundamental problem there. aka "understeer land".

I'd still say to try the factory differentials instead of the adjustable ones.

Nissan's system actually sends 100% of power to the rear tires until they slip, at which point power gets fed to the fronts. This can cause, to some, "inconsistent" handling... But once you know how it works you will be astounded by what it can achieve.

For susp/aero settup-ing default lsd is "l'enfance de l'art", as we say in french.

Of course I did that. I don't even watch or touch the lsd yet.

 

[budious]

Higher settings on bound = slower transfer towards that end. Higher settings on extension = faster transfer away from that end.

Sounds completely absurd, that's why I believe it. I've seen enough inconsistencies between the differences in clutches, flywheels, center differentials, typos in car descriptions, and silly puddy damage modeling that this is the best half baked game I ever played.

 

[Rotary Junkie]

I used 47/53, as all spring devices says, by not tracking weigth reduction distribution for the initial tests. I need a few more day on the car before being sure, my tuning entry won't be finished.

I think real lvl3 weigth is between 47/53 and 55/45.

Spring rate is never correct for the weight balance of the car to start with.

Unless you mean to tell me R32-34 Skylines have rearward weight distribution with a cast-iron block inline 6 in the front?

I don't really understand. If you used 60/40 you should have set a-roll bar like that : more/less. You are saying less/more is better, that's it ?

I'm running less/more on my anti-roll and a 60:40 ratio on springs. It works, and works well. Very low 1:27 lap times say volumes.

What if you were wrong with your weigth ?

lolohwell. I care less for theory than for results. So far, I'm getting results. As they say, in theory, theory and practice are the same. In practice, they are not.

For susp/aero settup-ing default lsd is "l'enfance de l'art", as we say in french.

Of course I did that. I don't even touch the lsd yet.

I was referring to the OP's car at that point of the post; the Impreza however can benefit greatly from well-set LSD and VCD. And actually, for optimal suspension testing conditions, you want VCD at 50/50 and LSD at 5/5/5 on both ends.

Sounds completely absurd, that's why I believe it. I've seen enough inconsistencies between the differences in clutches, flywheels, center differentials, typos in car descriptions, and silly puddy damage modeling that this is the best half baked game I ever played.

It's been that way since GT4 at least.

Then again, I do believe GT5 is GT4 with a new coat of paint and fresh tires. (Prettier graphics and a new tire model to be more exact)

 

[Scottster]

The Higher the numerical setting on extension, the stiffer (harder to pull apart) the setting. Therefore, the slower the weight transfer is when the shock is seperating.

 

[Rotary Junkie]

The Higher the numerical setting on extension, the stiffer (harder to pull apart) the setting. Therefore, the slower the weight transfer is when the shock is seperating.

That would be the way you'd hope for it to be...

But it is not the case.