Quote from AndroidXP :

Only that the exploit setups use stiff ARB at the front.

That depends on the patch version you talk about, there have been wr sets with high rear ARB in the past and currently most UF1 WR sets use max rear spring and damper settings.

What the aim of the extreme high ARB whichever end it is on is to cause one wheel to lift on turn in (turning towards the appex under braking) thus causing oversteer when you would expect understeer.

If you look at flotches sets for the UFR at AS2 for example you can find versions were he uses high ARB at the rear as well as the front.

Quote from Glenn67 :

What the aim of the extreme high ARB whichever end it is on is to cause one wheel to lift on turn in (turning towards the appex under braking) thus causing oversteer when you would expect understeer.

It’s causing oversteed only when you apply throttle and that because of the high power locking factor of the diff.

The problem here is the tire physics that allow the outside tire hold such a high amount of pressure giving the appropriate grip so you don't need the inside tire at all...

I have tried many times to make a FWD setup with a proper amount of overseer in both springs and ARB.
In that situation both front wheels work together (still the ouside is way more loaded but there is sufficient load on the inside too) but the grip you have on corner exit is clearly lower than what you have when you fully load the front outside tire with a hard front ARB... despite the "understeer" you get at corner entry... (the grip generated buy the inside tire is not enough to replace the lost grip by the less loaded outside tire (cause of the softer front end) and that’s not the way it really is IRL…)

The tire model lacks attention on the load sensitivity curves and unfortunately this is greatly spotted on the fwd cars because simply by accelerating you unload the front wheels making that great force transfer that the front ARB causes to the front outside wheel really advantageous on the corner exit…

Quote from kaynd :

The problem here is the tire physics that allow the outside tire hold such a high amount of pressure giving the appropriate grip so you don't need the inside tire at all...

Hmm yes I tend to agree, although there is definately tyre load sensitivity at play in LFS but it does apear to need work.

i dont know if we are still talking about low lock setups, but i have a pretty good one for the LX6 that i can share.
the tire pressures are currently set to heat up quickly in a normal race.
its basically a qualifying set.
with higher pressures, it is super fun tho.

I agree almost completely with everything here said. I'm afraid, if it's not a land rover, it shouldn't be locked. Remove locked diffs completely, they're not needed with this level of physics being thrown at the cars. Also, i agree with the bizarre FWD/AWD suspension setups (that quite possibly have just survived the patches). Everywhere I go playing TBO class cars and GT2 class cars, I hear the same thing

Quote :

Ahh, My FXO won't last a lap on tyres, how do I change this

Previously I put it down to driving style, but yea, looking at their setups, they always have locked setups, and the tyres don't last more than 5 laps, even taking the thing gently around the skid pad....

Locked Diffs are fine for drag setups, you can get away with them in off-road and drift setups, but for a responsive track car that doesn't chew up tyres? It's gotta be more open. In fact, the FXO is stable enough to have open diffs IMO...

EDIT: I will be posting an FXO setup with an open diff when i get home from work.....

Right, here they are, an open diff setup for SO1 and likewise a low-locking Clutchpack setup for SO1 (both work in reverse, too, unlike most setups going around) Have a play with them see if you can improve them, note how they comfortably do 10 laps without running the tyres above 65 degrees...

Well, it can't be that bad, nobodies complained yet.....

lols

Open Diff FTW

Ok there is no traction whatsoever at the corner exit with open diff.
It is easy to make setups that are nice to drive but not competitive at all.
With the cplsd it's a bit better, and it could easily get more lock at the power side.
Generally the setup needs a bit more attention; there is no need for such overseer in the ARB settings. (even in real life there is no way you will find in a road sports car, the front ARB 12 times softer than the rear comparing the absolute stiffness value… let alone stiffness/mass)
Also the suspension travel is not enough for that spring stiffness and the front bottoms out while cornering, which is not that good for traction over bumps. If you want it that soft you need to make it higher.
After you reconfigure the suspension settings, take a look at camber values cause you need a bit more at the rear... Ass dragging in an FWD car is = lots of traction lost in both sides, unless you want it to go fast around hairpins or certain autocross layouts.

Ok, I was actually thinking of tightening the rear up to increase the oversteer myself. Intrigued over your thoughts on corner exit traction, but of course the open diff will be lower than the clutch pack. I generally found the setup quite quick, especially in the hairpin-chicane sequence of SO1. I've not noticed the suspension bottoming out myself, but I'll increase the height in the front and maybe up the spring slightly.

And yes, the arse-dragging rear camber is nice through the hairpin, isn't it...

I am going to play with the setup right now, I might try losing some ARB on the rear although that oversteer twitch is a really nice feature. Right I'm off to get my low 51s times

Wow I just finished reading every post and so far all I have to say is thanks for explaining everything so well, I learned alot. I think that maybe there should be an option on some servers that forbids the use of locked diffs instead of completly erasing them from LFS, because I use them for drag racing.

*Bump*

The subject of grip being too low in LFS came up in a conversation the other day, so, in defense of the point that the reason LFS "seems" to not have enough grip, because of the setups, these setups were born. These setups emulate cars that would be "fresh off the lot" stock, however slightly adjusted to in order suite the performance of the XFG and XRG.


The main cause of excess wheel spin is close final drive ratio. If the ratio is closer to 1 the wheels will spin faster but have less torque. It the ratio is father from 1 wheels will spin slower but have more torque. The final drive ratios of both cars have are similar to real life cars.

XFG: '88 to '91 civic/CRX - final: 4.250

XRG:'86 to '88 RX7 S4(N/A) - final: 4.1

Did you also adjust the individual gear ratios? Because just setting the final drive to what a similar real life car has without adjusting the others is nonsense. If you don't have the data, then you can get them roughly right by making the 1st go to about 40km/h, 2nd to 80, 3rd to 120, 4th to 160 and 5th for the rest.

The final drive ratio itself is irrelevant, btw. You always have to multiply the final drive with the individual gear ratio to get a meaningful value. In game it doesn't matter at all if you have a final drive of 4 and a 1st of 3.5 or a final drive of 2 and a 1st of 7.

If all your adjustments were to make the wheels have less torque by making the gears unrealistically long then you achieved nothing, I'm sorry.

Quote from legoflamb :

XFG: '88 to '91 civic/CRX - final: 4.250

XRG:'86 to '88 RX7 S4(N/A) - final: 4.1

I really liked your miata sets so I'll give these a whirl sometime soon

Well I don’t find that in lfs there is a low grip problem in general. You can see that there isn’t just from the high enough g-forces the car generates.

There is a problem thought seeing how the grip alters in different tire loads.
The low vertically forced tire generates too low grip and the high loaded tire generates too much.
Many have referred to that just saying that tire load sensitivity combined with slip ratios is not working great yet.

That makes antiroll bars and front-rear stifness differences in general, useless in defying the over-under steer characteristics of a car.
Right now stiffness changes in ARB and springs have an effect on the differential-s and damping “synchronization” between front and rear.

It doesn’t matter what stiffness relation is there between front and rear… as soon as you tune the dampers right with the appropriate arb fine tuning, you have almost the same grip limits front and rear in any combination… The only thing that changes is the weight transfer between the front and the rear tires, depending on the roll and pitch stiffness, making some differences in behavior while turning in or accelerating out of a corner.

That’s why rear heavy FZR’s are much more stable with theoretically over steering setups judging from the stiffness. (I am not talking about exact numbers but about stiffness/mass relations) And fwds get even to understeer more with higher real spring and arb rate… and I am not talking only about locked diff sets where that is normal. This happens even with open diff. The only reason that an fwd in LFS might get unstable with a high rear ARB or spring stiffness, is because you have messed the damping balance…

Why I am telling all this?
The inside spinning front wheel in an fwd car has to do with that inside low loaded tire with no grip at all… no matter how hard you try in LFS setting the stiffness in any way, the inside wheel is going to spin even going in 5th gear, having the xfg with 115ps with open diff pooling anything more than 0.8g lateral force… not to mention the 55ps of the uf1.

Of cource gear ratios have to do with the torque that goes to front wheels and their willingness to spin, but that's not the real problem here.

PS [edit]
Anyway there seems to be a working tire load sensitivity model.
That’s why weight transfers during acceleration and deceleration work in the right way. (The heavily loaded end, tends to loose grip first… eg adding weight makes the car loose grip earlier etc.) That's why damping works in the right way (well ok... most of the times ).
But there seems to be a problem on the load “scale” in which that model is effective.

Quote from AndroidXP :

Did you also adjust the individual gear ratios?

Actually i the individual gears were adjusted, however the cars were unable to reach peak RPM even down the longest straight in 4th gear with the gearing of the cars chosen(RX7,CRX), so I mucked with those a bit just for drive ability.

But your probably right

If anything, real gear ratios should be used, and then final drive adjusted for any difference in the rolling radius of the tyres.

Quote from Bob Smith :

If anything, real gear ratios should be used, and then final drive adjusted for any difference in the rolling radius of the tyres.

The problem with that is that the engine power curve in the XRG is different than you would find in an RX7 (or E30 325is in my case). So, the actual gearing from the real car does not work very well even if you go with the highest diff ratio that came with the real car. To make the car drivable without an LFSTweak, you pretty much have to adjust the gearing and diff settings.

Secondly, it does feel strange because most street car gearing is set for comfort and gas mileage, not necessarily for performance. 5th gear is for saving gas for the most part and unless your final drive gearing is really high, you will never need to use 5th at all. The RX7 set was topping out at around 120mph in 4th gear on KY3 and still had RPM's left to go faster. This is about right for the real car, but you can see how long it takes to get to that speed.

In my 325is, I can hit about 120mph indicated down the back straight at Portland International Raceway with my 3.73 diff in 4th gear (it's probably about 115mph actual though). There is no need to shift to 5th. With a 4.10 diff, you do need to shift to 5th on the back straight. In LFS using the intake restrictor and weight handicaps to mimic my BMW, you can never make it to 5th gear with the factory gearing and the 4.10 diff. Well, you can shift to 5th, but there is never a need to shift. This just shows that the engine type in the XRG is just not matched well with the factory gearing.

I know I'm resurrecting an old thread that has no point now because of the patch that might come out, but I have some more setups. I have been having the most fun with LFS racing the XRT/XRG with these setups on IHR's server recently. I have actually beat most of my old PB's with these setups because there are no special exploits to drive them fast.

Driving these setups quickly is very straight forward. Reading the grip with these setups is really easy. This is what makes the setups easy to drive. When maximum grip is not obtained or has been slightly exceeded, it is easy to notice. Small mistakes are obvious therefore it is easy to correct them on the next lap. However, racing them precisely and competitively is a challenge. The challenge to learn and drive these setups competitively makes for great fun. Each lap completed without making a mistake gives a feeling of great satisfaction.

The focus is on the suspension and geometry so that they dictate all or most of the way the car performs. The cars are tuned to stabilize on partial throttle with a little bit of "push". When the cars starts to push too much mid-corner, lifting the throttle a bit will set the car back into the corner. Stabbing or blipping the throttle will also counteract under-steer. In high-speed corners the cars are stable to hold the rear end on line at full throttle. Trail-braking the cars into corners can be challenging. Any mistake will put the car off line when the rear end steps out.

To drive these setups with the proper feel; a steering ratio of 14.4:1 is required. The steering ratio is set to 14.4:1 at 720 degrees. Too little steering degrees; the car will be very unstable and extremely twitchy on the brakes. Too many steering degrees; the car will under-steer, but when it slides it will be difficult to manage. If the steering degrees are changed, a 14.4:1 steering ratio must be maintained (by adjusting max lock) to keep the same feel. (minimum of 540 degrees of steering. 400:~14, 300:~10, or 200:~7 have too small max lock)

[900 deg:~31 max lock =14.5:1 ; 540 deg:~19 max lock =14.2;1]

I don't know if anybody will like these setups, or even drive them for that matter. But if this thread is stumbled upon, and my "long" essay has been read to this point, I hope somebody gets the same enjoyment and satisfaction that I get while racing with these setups. For me there is new life breathed into LFS, even without the new patch.

I'll give these a spin. Let you know in a day or so.

I've been looking for a general sets anyway.

Quote from Vain :

Unfortunately I never had the opportunity to drive a FWD with anything but an open differential so my thought are purely theoretical, but shouldn't a locked diff cause horrible, horrible, horrible torque steering?

I don't know about totally locked-diff FWD, but i have drive few times with FWD N-series rally car with quite stiff clutch-pack LSD. Not on tarmac, but on ice (rally tyres) and gravel. It has some kind of power steering.

You really have to be ready to hold the wheel when you apply throttle on corner. It's (for me at least) totally impossible to hold it steady with one hand, and you need to have good grip even with both hands on wheel or it will slip. That's one reason why seats tend to be very close to wheel on racing cars, you have much more power when there is good angle in your elbows and you can use your big arm muscles to hold the wheel.

And that was on gravel and ice, and with LSD.. Hard to imagine what FWD 100% locked diff on tarmac would do, probably you break your steering in first corner if you flat the throttle. If you somehow manage to hold the wheel.

That's waaay over the torque G25 will produce with 100% force.

Combine that with commonly used unrealistic 270deg lock, which will almost triple the steering torque when compared to 700deg lock.

If power steerings breaks on FWD car with nothing stiffer than open-diff, it's very very hard to drive and you lose a lot of time.. Basicly you can't throttle on corners anymore. Or at least have to be very gently.

I think it would be pretty easy to calculate the pure steering force (without power steering), from the amount of force going from wheels to track, steering lock and car width. From there you can calculate how powerful power steering you would need to make it driveable.

While racing there is psychological pressure to drive faster which makes driving precisely harder. Trail-braking into corners is a bit difficult, and while racing it is more so. I decided to add more parallel steer which has added a bit more stability to more than just trail-braking with both cars.

Also, for the XRT, the suspension was stiffer than I wanted it to be. After readjusting the suspension, the car transitioned into slides more gradually making it easier to manage exit over-steer.

I would like to make low differential lock setups for the front wheel drive cars, but low lock is too much of a disadvantage compared to high lock.