You want to know why the car is oversteering on corner entry, or corner exit?

If it's corner exit, then coast locking isn't important.

If it's corner entry, increasing the coast locking could help cure the problem, but I'd look at the cause of the oversteer (i.e. setup or driver induced) rather than try to fix it by adding understeer somewhere else.

Quote from PudelHH :

Okay ...sorry I mixed up something....when I said I want to know why my car is stepping out of a corner with LOW coast lock....of course my car is massively OVERSTEERING....(not understeering...sorry)....and I want to know why the car is doing that.

Post a replay, then we can see if it's the setup or you're driving.

hi....i am talking only about corner entry....Maybe its possible to give me an idea what process(es) makes the car more vulnerable for oversteer in corner entry with low coast lock.

I understand thats also a question of driver skills, but also for a very good driver its harder to get a corner under low coast lock as with high coast lock. I simply want to know why its harder?

Hope you can understand me and sorry for bothering.

thanks

I think with low coast lock the driver wheels are not forced so much to travel at the same rates. Thus the braking (or engine braking) can cause one of the wheels to lock up more easily, causing snap oversteer. A highly locked coast diff will have the effect of pseudo-antilock, as the torque required to lock one wheel isn't sufficient to lock both wheels, but the trade off is more corner entry understeer.

I have a small question about the LSD-diffs.
Is the resistance to different turn-speeds fluent or instant? That means, will the inner wheel begin turning at a different rate than the outer at one point because a "limit"-torque has been achieved in the diff or will the diff fluently allow more and more difference in speed (much like the viscous diff, to my knowledge).

My experiene is that the LSD-diff "switches" between "locked" and "open" at a specific point, but the area where the diff opens might just be very small. That's why I ask.

I can't seem to be able to drive rather open diffs, because I want the diff to stay locked while accelerating out of a corner and while trail-braking. 70-80% on both coast and power is the only way I can drive LSD-diffs, and still I'd like the diff to stay locked in some situations where it opens.

Hopefully the LSD-diffs will be preloaded after the patch. It's getting strange when I have to put down gas at corner entry where I'd normaly coast with neither gas nor brake, just to keep load in the diff.

Vain

Without preload you have two defined cases (afaik), engine loaded (power) and road loaded (coast). The change is instant, which is one of the main problems with LFS's diff.

With a preload on the diff, the change is slightly more gradual, as the load from the engine and load from the road get close the preload has more and more of an effect. So you can have, say, 40% coast, x preload and 70% power lock. I don't really know in much more detail though, but Colcob (or Bob, or something of a like mind) will be here soon to put us all straight

I am mostly interested wether the switch between locked and open is fluent or instant on the LSD-diff, but I appreciate the clarification, Tristan.

Vain

It's instant at the moment, but might not be tomorrow

Edit: Aha, Forbin has pointed out that I might have misunderstood you. Mine applies to changing between coast and power states, not between same wheel speed to differing wheel speeds.

If I understand you correctly, you're refering to a situation where you are not changing diff state (power to coast or coast to power) as described by tristancliffe and you are doing something like entering a turn where the wheels begin to rotate at different speeds. I believe the word you are looking for is fluid, or progressive.

In LFS, assume the diff is in coast mode and no power is being applied. When you are going straight, the diff is essentially open due to a lack of preload. When you begin to turn in to a corner and the wheels begin to rotate at different speeds, the diff progressively locks, but never completely like a fully locked differential.

I believe in real life there is a certain type of diff that is normally open, and when one wheel begins to slip a significant amount, the diff locks completely. In the United States (maybe elsewhere too, I don't know), this is known as a Detroit Locker.

Quote from PudelHH :

Okay ...sorry I mixed up something....when I said I want to know why my car is stepping out of a corner with LOW coast lock....of course my car is massively OVERSTEERING....(not understeering...sorry)....and I want to know why the car is doing that.

depends on how much you oversteer really ... if its snap oversteer that happens under engine braking (try clutching while braking into the corner to see the change) it might be the lack of preload that causes one wheel to lock the moment you lift off and too little coast lock to get the wheel to turn again

Quote from Vain :

I have a small question about the LSD-diffs.
Is the resistance to different turn-speeds fluent or instant? That means, will the inner wheel begin turning at a different rate than the outer at one point because a "limit"-torque has been achieved in the diff or will the diff fluently allow more and more difference in speed (much like the viscous diff, to my knowledge).

if im not mistaken a clutchpack diff will act more or less exactly like a locked one up to the point where the torque difference reaches the point to brake static fricton which should cause a sudden drop in the amount of torque that can be transfered through the clutches

Quote from Shotglass :

if im not mistaken a clutchpack diff will act more or less exactly like a locked one up to the point where the torque difference reaches the point to brake static fricton which should cause a sudden drop in the amount of torque that can be transfered through the clutches

I doubt it takes very much torque at all to break clutches' static friction. Obviously it'd take a bit more with more preload.

seeing as this thread has revived...

i just want to clarify if anything has changed with the new patch? i dont see it on Scawens list anyway.

also, an XRT set i was given still had a locked diff, so i assume things are the same.

are the lift-off oversteer problems less noticable now with the improved trye physics?

Quote :

i just want to clarify if anything has changed with the new patch?

no, it is as crap as it was when it came in the demo time iirc .

Quote from wheel4hummer :

In a jeep wrangler with locked diffs on painted cement (with water on the ground) you can hear the inside tire "scrubbing" < DOn't know what else to call it.

It happens because the rear wheels have 50 percent power each.
when the inside wheel looses grip(while turning) it will spin in the same speed as the tire with grip(outside)
This gives a scrubbing effect as you can call it

Im 14 years old and cant explain it further....

Sorry for reviving an old thread but someone asked about diffs in general discussion and got linked here and ive read the thread but ive got one question.

I Understand that coast lock means when the car is coasting (under braking etc) then it is the figure of how much the wheels lock. So 0% would be open diff and 100% would be a locked diff under coasting conditions. Those figures aren'tt available in lfs but my question is why does having a higher coast lock help stability. I understand under braking where the traction rubber of the tyre is the factor. So if open diff one wheel can lock, if locked both wheels would have to lock so a higher force(?) needed to lock the wheels under braking. So under braking it helps but surely a high coast lock while turning wuld cause the car to be more unstable? looking at a rwd, as the car is turning with say 80% coast lock then surely it would cause oversteer under coast conditions?
Is that right? and its a case of finding a balance between stabilty under braking and the possible (in rwd) oversteer during cornering?
Or is it what ive said is a load of tosh if so can you explain please.

Thanks.

I think the reason why high coast lock is beneficial for stability under braking is because it causes the car to resist yawing/rotating, perhaps by equalizing braking effort on both sides of the car. I think if we had a preload adjustment, we wouldn't need quite as much coast lock as we're using now.

Sorry maybe i didnt make it clear, i understand under braking it resists causing the car to yaw, but surely a high cost lock cause the car to yaw during turning.
I no a with clutch pack lsd 100% lock isnt available but using 100% coast lock for example.
Under braking the diff is locked increase the braking force needed to lock the driven wheels (Again use rwd as example) but during turning surely it would create oversteer as the rear wheels would be rotating at the same speed. So surely a high coast lock helps under braking but hinders under turning?

Edit: Just had brainwave - A high high coast lock increase stability under braking and a high cost lock though locks the rear wheels (which under power conditions could cause oversteer) under coast conditions causes understeer.

So with clutch pack LSD's the balance is between coasting stability, so under braking conditions and understeer generated in corners.
So low coast causes an instability under braking but means good corner (possible oversteer?)
High coast lock creates stability under braking but causes understeer.

Have i got this right?

Quote from Greboth :

High coast lock creates stability under braking but causes understeer.

...during normal cornering. Yes it can. Use as little coast lock as you can get away with, but without a little pre-load you generally always need high values.

The power lock ive understood for a while but now i get the coast lock to. Thanks bob

Great thread. I'm glad this was revived.

I found that whatever I did with my LX6 setups I still had the back end snap out on corner entry when trail braking. I eventually realised I had been neglecting the diff, stuck the coast lock up a bit and it handled like a dream!

I'd like to raise a question related to our un-preloaded diffs:
How should one go about this problem when tweaking the setup?
Personally I try to ignore this problem in low-powered cars by leaving 10% throttle on. That way power-lock applies and I don't have to care for preload. But in the more powerful car this is risky. A FZR doesn't react always react well to throttle in mid-corner. Also, right foot brakers always have a small timeframe of neither throttle nor brake while switching. The unloaded diff causes a lot of wheelspin unless the driver is extremely careful.
So how would one decrease this tendency in the setups? The damper-setting could be of assistance here, because we (nearly) always enter the neither-throttle-nor-brakes area by going off the throttle.
Any other hints for frustrated LFS drivers who have to live with un-preloaded diffs since ages and begin to think Scawen enjoys the player's suffering in mid-corner?

By the way I really don't understand how the preloaded diffs can take so long. I always look at the GTR class, thinking "So many people drive it, it can't be that bad", get sideways every 2 races because of lacking preload and stop racing GTRs for some weeks. Repeat.
Thanks for listening to my ranting.

Vain

@Vain: In Patch Q, I raced the FZR a bit and just always had to be very careful on the brakes going into a corner. If I tried braking too hard, the rear end would come around. Once at the apex, however, I could put my foot down hard on the gas.

sry, didnt check page number

very interesting thread!

my setups have tended to suffer from twitchiness under braking, which i've tried to tune out using the brake bias, toe, and bump damping, but i've ended up with cars that are stable under throttle and nimble in corners, but with a terrifying transitition between the two states, where the car has great potential to get squirly.

so as soon as i get home, i'm going to reduce my power lock and increase my coast lock and see how that works for me.

Yes, great thread.

A quick question about power lock: if one driver has 20% power locking and the other has 80% power locking, does this mean that if the 80% guy can keep it together and apply throttle smoothly to avoid oversteer, he can expect to out-accelerate the 20% guy on corner exit?

Or is this only theoretically true, and might the opposite be true in practice, that the 20% guy can mash the throttle so early and so confidently that he can be faster out of the corner than the 80% guy who will be worried about oversteer?