I've been wanting to have me a little rant about this for a while now - I've become more and more frustrated with most setups I get lately. Everyone seems to use locked diffs, or if not a clutch pack with high coast locking factor and high preload. To make my point first, some physics.

Locked diffs keep both wheels at a constant speed. With weight transfer taken into account, this means that the outside wheel produces more longitudinal force than the inside one. Open diffs, at the other extreme, result in equal longitudinal forces for both wheels. The clutch pack is somewhere between these extremes depending on where you set it.

When considering clutch packs, we also have to distinguish between coast and power. Coast is while the engine speed is decreasing (ie. braking or... coasting, funnily enough). Power is while engine speed is increasing (ie. your thorttle is greater than neutral throttle). Coast locking factor has no effect while on the power and vice-versa.

Preload simply makes the diff behave as if it were locked over a certain range of torque difference between the wheels.

The other important piece of physics that one has to be familiar with is torque (not from the engine, just the rotational effect caused by a force). Torque is proportional to the magnitude of the force and the perpendicular distance to the center of rotation (in our case, the center of gravity of the car). See the attatched Torque.png.

Imagining a tractive (forward) longitudinal force from an outside wheel, you can see this results in a torque in the direction in which the car is turning (ie. more oversteer). A braking force on the other hand results in a torque in the opposite direction and thus more understeer. The opposite is true for the inside wheel.

So to recap: we've established that a stiffer differential results in more longitudinal force on the outside wheel and less on the inside. An open differential results in equal longitudinal forces on both wheels. Thus, from the points regarding torque, it is obvious that a more locked diff results in more oversteer while accelerating and more understeer while coasting/braking. If this is confusing, see Diffs.png.

So, what's wrong? Well, people tend to use huge coast locking factors (70%+ often) or high preload (so high that often you might as well be driving a locked diff) or a locked diff. With some setup tweaking, this isn't so bad out of the corner and power is controllable. Also, using anti-roll bars, which affect immediate turn-in behaviour (while load is transferring a stiffer rear roll bar or a softer front will increase relative turn-in grip at the front, due to load sensitivity of tyres), people can dial out the inherent coast understeer. However, between turn-in and apex (once the weight has tranferred to the ouside wheels and you are coasting), 90% of setups just understeer and understeer and understeer some more. There's no sensible way to dial this out.

So stop using these retarded locked diffs in the RWD cars especially. And with clutch packs, keep coast locking and preload AS LOW AS POSSIBLE. If you are running more than 30% coast locking, you are probably driving a shitty setup. As a general rule, try to aim for below 20%. And try to keep preload below 60Nm.

Neutral setups +1

Wholeheartedly agree. Personally I refuse to use any setups with locked differentials. They might be the fastest if combined with ridiculous setups and silly driving techniques, but boy they feel so unnatural and revolting :mad:

They also result in people complaining about "low grip problems" with the prime example of "go very slow, turn and listen how your tyres screech and you understeer all over the place, see how weird LFS is?". The fault lies IMO mainly in the current setup options, that allow a far too wide range of adjustments. I think if those were finally fixed, half of the realism issues or weird-driving-technique concerns would go away.

For now, I will simply blame the non perfect physics for being 1.5 seconds per minute off the pace. I try to make reasonably believable setups, and I'm a Driving God of course, yet I still loose time.

Then I see a WR and disagree with how those times are achieved, both looking at the setup and the driving style.

Once I have all the WRs, the physics are completed and I will instruct Scawen to stop working on them......



But seriously, yeah there are some oddities, not the least of which is the diffs. However I suspect the reason we get away with them is in the tyres.

The fastest laps look odd to me, almost like slow motion, the (road) car rarely being snappy or having trouble to accept the attitude desired by the driver.

I'm not sure LFS is advanced enough yet to call for the use of realistic diffs. Mind you its pretty advanced; but tyres are so tricky that the chances of a few fair flaws still being there are considerable.

One more reason to enjoy from viscous coupling, it just works Well for me it is the one that works

+1. I thought we would see more natural setups when the clutch pack was introduced but no.

i think the main reason locked diff still remains so popular is the stability, its very predictable.

I'm an oddball. I find locked diffs, or extremely high clutch lock undriveable. It is drift/spin city for me if I use a high lock.

Axus states "above 30% coast...." With coast, I use higher percentage for the same reason as lower power lock, drift/spin on throttle lift-off.

I don't set for what's fastest, I set for what I'm capable of driving. First thing I do with a downloaded or server given set is go to the drivetrain and turn the power lock down to around 35-40% and the coast up to around 60-65%, depending on car/track combo.

Unrealistic, realistic, fast, slow, I don't care. It's about driveability for me. I can't win, place, or just generally have a good battle midfield if I'm spinning out on the first lap.

I must agree mrodgers, low locking (after new patch) or viscous is one that I can drive, all of sudden spins with locked or high locking, I don't drive by speedo, I got wheel and windscreen there to be used and I do feel when car is about to slip and when not, as I use low locking or viscous coupling.

It really does not matter if I can't be fastest, it is much better to be in control and have lot of fun racing as I don't spin out at T1.

Can't understand popularity of locked diff any other way, but wrong driving styles, my guess is these are drivers that look speedo and drive at certain corner at certain speed speedo shows that they have learned to be max speed for that corner, not much to do with driving, imo.

That is why I like that digital speedo is no more, people need to drive more correct methods, for some it is quite lot of learning, but I believe when they learn not to look speedo and stop using unrealistic diff options, they will find more enjoyable racing and new better LFS

Quote from JTbo :

I must agree mrodgers, low locking (after new patch)

I wasn't talking just about this patch though. I was talking about after patch.... 0.3H, which is where I entered into the LFS world

I've never ran locked/high lock diff. It's just throttle.... spin..... for me with high lock.

I agree with your thinking on this, although I don't know enough to suggest LSD clutch settings.

However, the reason I end up using a locked diff sometimes is the engine bog down problems. You hit your brakes, the engine bogs down, and you end up with this weird skid problem. It only happens on LSD cars and usually only happens if you are turning just a little bit (ie trail braking or a slight bend in the brake zone). It is not so bad if you are going perfectly straight.

I try to use LSD (the diff that is) whenever I can, but I find in the GTR cars, even with setups I have made from scratch using some of Bob's tools, I still have this strange braking problem. I have tried reducing the amount of brakes to the point where you can't lock up the tires, I have tried moving the brake bias mostly to the front, which helps, but also severely handicaps you in a race. Nothing really works effectively, so I end up using a locked diff.

Quote from Hallen :

However, the reason I end up using a locked diff sometimes is the engine bog down problems. You hit your brakes, the engine bogs down, and you end up with this weird skid problem. It only happens on LSD cars and usually only happens if you are turning just a little bit (ie trail braking or a slight bend in the brake zone). It is not so bad if you are going perfectly straight.

That was a major problem for me with the LSD before patch X30, I used to use high preload to avoid it (i.e. 200 - 400)

With the new engine intertia improvements I have found this problem to be almost non existent now Since X30 I've been setting up the LSD with 20-30 Power Locking, 30-40 coast locking and 20-60 Prload with very good results.

That is the aspect of the new patch that caught most of my attention initially

I personally think we must be pretty close to phasing out the Locked Diff from LFS as the LSD seems pretty good since X30. It was only ever put in there for comparison, it wasn't ever ment to be a viable alternative to the LSD There is simply no need for it anymore. People will not like it though as it will take some time for people to relearn how to setup up a car

So I agree fully with Axus, I suspect he might know that though

Quote from Glenn67 :

With the new engine intertia improvements I have found this problem to be almost non existent now Since X30 I've been setting up the LSD with 20-30 Power Locking, 30-40 coast locking and 20-60 Prload with very good results.

I was hoping the engine inertia would help with the problem. I think you are right, it has helped. I have been trying it out with LSD setting now too. I only brought the issue up because I wnated to point out one of the reasons, however unrealistic, that locked diffs get use.
I think... hope... that patch Y will allow us to use LSD's and make locked diffs a thing of the past.

This thread is a good read!

I wonder what Scawen's thoughts are on this?

TBH I tend to go for quite high coast-side locking (70%-ish) and a low preload value. I don't like all the mid-corner understeer, but I prefer it to being completely unable to turn and brake at the same time which is what seems to happen with a low coast lock.

Quote from mrodgers :

I wasn't talking just about this patch though. I was talking about after patch.... 0.3H, which is where I entered into the LFS world

I've never ran locked/high lock diff. It's just throttle.... spin..... for me with high lock.

I meant that with new patch, I can use clutch pack with low locking, before new patch virtually any setting of clutch pack was impossible to use, same spin'o'matic effect with any setting

well I just tried my current S06 set with 30/40 lock, keeping my preload at 50mn and it instantly improved the set by half a second on a rather tame lap. The controllability is awesome now, I can have confidence under throttle whilst still steering which makes my avg cornering speed much higher

thanks!

i've always worked on the principal of having the lowest power lock figure i can get away with without suffering wheel spin when accelerating away from the slowest corner on the track, i always tend to run a low coast figure as i'm just not comfortable with the understeer that ensues up to the apex with my driving style of slowing till apex, i know i can allow for it by aiming inside the apex but it always seems an inexact style. as a result of these two figures i always tend to use a low preload, when i'm concentrating on setup i'll set the power and coast and then run the preload as low as i can without getting that strange jump between the two states that we used to get before preload was available.

must admit i havent really done a lot with this patch but i also have enjoyed the benefits of the viscous diff in the past, i think that one reason for its lack of popularity and the glut of high diff lock setups is that most people value absalute speed over drivability, if this was real life and they had to face repair bills and possible injuries i suspect that drivability would become a more pressing concern

I haven't checked this with LFS but diff lock can be deceiving. It could well be that anything beyond 40% or 50% is basically resulting in a locked diff. Does anyone actually look at telemetry to find the rotational speed difference between the two driven tyres?

Keep in mind that you can't just loosen the coast factor by 50% and hope the setup still works. The rest of the setup has to be designed accordingly too. Here's one of my LX6 setups (pre X30, so it might need some gear ratio tweaking but the handling is still fine). I can do low 21s and high 20s on Blackwood with it... and it's not like I'm all that fast. I find it very enjoyable and easy to control.

I'll test some LX4 setups from before the patch too and upload those. Perhaps it would be nice if people who have put some decent low coast locking factor setups together post them here to show people who struggle just what must be done.

Edit: Niels, I can definitely feel a difference (and, qualitatively the correct one) while progressively increasing locking right up to 80%, and then a difference between that and a locked diff. I can't be sure if it's quantitatively correct but as I understand it, you'll have a pretty hard time doing all the maths and checking.

Yeah I've tried some of your LX4 setups before axus and quite liked them. I can't stand setups with really locked diffs, I find they just understeer way too much on both corner entry and exit. However I don't really know enough about setups to adjust the suspension on one that's setup for a locked diff.

I think the reason people use the locked diff is, the suspenssion they are using. People seem to use the suspension to get rid of all of the understeer of the car by lifting the inside rear tire, wich also causes the engine to bog down on the breaks because the rear break are still effecting the rear wheels on turn in. Once I started using "those sets" is when I figured out what the driving style was and why it looke dso unnatural. However, the reason people can pull it off is Imo, the longitudinal grip on slip is just a tad too high, only a little.

This exta grip while sliding is what allows it. 'Cause with a locked diff should make the inside wheel start sliding on power, it would force the outside to slid, also causing more wheelspin and more slide, wich LFS doesn't do. Dont get me wrong I still think LFS has the grip closest to how it should be IMO.

So If the longitudinal grip where a bit less, we wouldnt have this problem of weird sets and driving styles. Also it will fix the burnout starts problem.

Quote from Hallen :

I try to use LSD (the diff that is) whenever I can, but I find in the GTR cars, even with setups I have made from scratch using some of Bob's tools, I still have this strange braking problem. I have tried reducing the amount of brakes to the point where you can't lock up the tires, I have tried moving the brake bias mostly to the front, which helps, but also severely handicaps you in a race. Nothing really works effectively, so I end up using a locked diff.

It is caused by the suspenssion being to soft in the front via spring or anti roll, causing the inside rear to lift.

As said in the post above.

When ever I watch racin i usually see the inside front lift not the rear.

Just an example:

http://www.youtube.com/watch?v=s3mrcjKUxtU

another reason to have a "forced standard setup" option

Quote from danben7 :

another reason to have a "forced standard setup" option

says who?

Quite a few people actualy