No_OBsT33R's LSD Calc UPDATED Version 1.1

Ive put together this LSD Calculator that will calculate exactly how much power is given to the wheels based on how much power the car has, the minimum amount the wheels can handle and the LSD settings.

Its still rough, so I only have INT and Accel settings working, I'm working on incorporating Deceleration settings.

It works on the Principle that the slider amount in the game represents the percentage amount of available power required to slip the LSD. 0 is a free slipping, or open differential, while 100% is a locked differential.

In the game the closest we can get to an open differential is 95%, and the closest we can get to a locked diff is 40%.

The calculator ONLY shows values for the LSD when activated. Depending on how high the initial torque setting is. The "Usable Power Level" will have to be reduced by more than the initial torque setting. This represents a difference in wheel speed great enough to activate the LSD.

So if your INT setting is 10, your "Usable Power Level" will have to be less than 90% & no more than 90% to simulate activating the LSD. If the int setting is 50, the usable power level can be no more than 50%. If the int setting is 60, the usable torque level can be no more than 40%.

Ill go more in depth when I have a little more time tonight.

The calc works in excel, the working of the LSD is EASILY simulated with very simple math.

People have asked me to prove my theory, I think this will show my "theory" working.

This will even simulate open or locked differentials. I'm not at home now but I'll go over how it can be used for tuning.

This basically able to show you how much power your LSD will be putting down.

It will show what is going on at the wheel.

I'm adding in how much power is applied when the diff is locked and when it's open (displayed at all times). It will show you the crossover point where the loss generated by the LSD eats more power then the access setting can retain & the where thr accel setting begins to retain more then the loss generated by the int torque setting. (this might surprise you)

This will also show you how much potential there is for correction snap.

I'll add instructions to an update also.

I'm a little confused...

Do people disagree with the results?

Not understand the results?

Unsure of how to use the results?

Lol... settle down. Sometimes it takes time for the adults to see whats going on

EivlEvo

Lol... settle down. Sometimes it takes time for the adults to see whats going on

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I'm just wondering, it seems like people don't know what to make of it.

How does this help someone tune the LSD for getting through corners?

So if I lower initial or accel, it somehow cuts torque to both wheels? Are you thinking this acts like a slipper clutch on a dirt R/C car? This is an LSD, right? Not traction control.

What can I do with it? I can enter my LSD settings and then it splits in some numbers? What are these numbers? And ft-lb is something I have never heard before GT5 and this forum. I'm from Europe and we use Nm...

Hi Basilea!
You can convert lbs-ft to Nm... multiply lbs-ft by 0,7376

100Nm = 73 lbs-ft If you like

Motor City Hami

How does this help someone tune the LSD for getting through corners?

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It tells you how much torque us being put to the ground at all times when the LSD is slipping.

Enter the amount of torque you have and the percentage amount of minimum power applicable, then your LSD settings.

If your creative you can check the gear and rpm your at in a corner where you slip, get throttle snap point, if you are experiencing oversteer/understeer, see what the LSD is exactly doing at the time.

You can go further and do weight transfer calculations and see if the amount of applied power exceeds the limit of the tire.

You can get the best starting point for your LSD without ever stepping on a track.

I'm going to finish up some of my other calcs (suspension reduction rate calc, weight transfer calc, spring frequency calc, yaw angle calc, and a few others I'm working on)

It's too bad I got no excel training or experience, I'm just figuring it out as I go.

Motor City Hami

So if I lower initial or accel, it somehow cuts torque to both wheels? Are you thinking this acts like a slipper clutch on a dirt R/C car? This is an LSD, right? Not traction control.

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Yeah, when the LSD is actively slipping the power to the wheels is reduced by the amount needed to slip.
The accel setting retains power but it has to overcome the loss from the initial torque before it makes gains above the loss.

Updated version will display what a locked and open diff would be doing in the situation, so people can see the difference.

Im also working on a tire load calc to work with this and a weight transfer calc. This way it will be easy to see if out settings are too aggressive or too weak.

Well I know that, but I can't get a picture of it in my mind with this unit... probably the same for everyone with unfamiliar units and then I still don't know what I should do with it... let's say 600 ft-lb and 90% (how do you find out this %) and the LSD 10/15/5, that gives me 241.7/241.7 (ft-lb I guess). That's great and now? Is that any good or bad and should I change the LSD now and if then what is better and why?

I'm going to finish up some of my other calcs,weight transfer calc...

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How can you calculate the weight transfer without the height of the center of gravity?I want to know.

You can go on youtube for excel tutorials 👍

No_OBsT33R

Yeah, when the LSD is actively slipping the power to the wheels is reduced by the amount needed to slip.
The accel setting retains power but it has to overcome the loss from the initial torque before it makes gains above the loss.

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I don't buy this part. You talk about an LSD slipping while both tires have good contact with the ground? Is that what you are trying to say? Most LSDs don't slip when both tires have good traction. They'd burn up if they acted like traction control slipper clutches. An LSD slipping is all during cornering to manage wheels trying to turn at different speeds. How does the LSD cut power to both wheels. I'm not understanding?

In your calc, I lowered Accel and it lowered torque on both rear wheels. So in GT5, if you run low accel numbers, your car will be slower out of the corners?

Basilea

Well I know that, but I can't get a picture of it in my mind with this unit... probably the same for everyone with unfamiliar units and then I still don't know what I should do with it... let's say 600 ft-lb and 90% (how do you find out this %) and the LSD 10/15/5, that gives me 241.7/241.7 (ft-lb I guess). That's great and now? Is that any good or bad and should I change the LSD now and if then what is better and why?

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It's how we say torque it's represented, power over time. Feet per pound. Just grab a ft-lb convertor, get the formula, or switch to ft-lb.

It's only the first release so it's still basic. As with anything we do for nothing, I'll put more work into it based on response. Knowledge is power, this tool gives you info previously tuners were only making guesses on.

ok then always run ini 5/accel 60/ decel just what makes the car stable. Leaving 95% useable power and giving the highest value on inside and outside?

Edit:

The unit is not really a problem I just take it as 1=1 this gives me still a impression... I have more problems understanding the bigger meaning.

Motor City Hami

I don't buy this part. You talk about an LSD slipping while both tires have good contact with the ground? Is that what you are trying to say? Most LSDs don't slip when both tires have good traction. They'd burn up if they acted like traction control slipper clutches. An LSD slipping is all during cornering to manage wheels trying to turn at different speeds. How does the LSD cut power to both wheels. I'm not understanding?

In your calc, I lowered Accel and it lowered torque on both rear wheels. So in GT5, if you run low accel numbers, your car will be slower out of the corners?

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Did you read where it states in the op the LSD calc O N L Y simulates an activated LSD, (this means in a corner or whenever there is a difference in wheel speed for any reason) It's is also not activated until the difference in wheel speed exceeds the int torque setting, until then it acts locked.... That means 50% / 50% .


Come on dude read up. Don't be so closed minded, the math is sound, even if you don't get it.

I also NEVER stated it calculates weight transfer (are you guys serious?)

You input the percentage of useable power, so you will have to make those calculations

Or wait for me to release my weight transfer calculator (it calculates neutral weight transfer on top of WR while accelerating and braking), but....

Like I said this is the first release, just to get it out and people understanding it, I'm glad I didn't add everything making it more confusing.

I have a few additions and i will do a write up on how to use the tool.

This is something that more of the pros will be able to take advantage of for the moment. As we see all info as power.

As for the calc itself... It's confusing the hell out of me, as are you. Or maybe it's just you. Your explanation to what each does is entirely unclear; as it stands it seems like you're somehow saying that raising initial torque reduces the power going to either tire (???), raising accel brings it back up.

Or something. It's 4:30 AM, I don't feel like attempting to decipher what you're attempting to say because right now it makes exactly zero sense. All I know is that accel is good until the car starts to snap-oversteer (and even then it's probably quicker to drive around than fix if at all possible but faster for aliens = harder to drive for the rest of us), initial changes how much input torque it takes for it to attempt to lock (as in going into the diff, not acting on it from outside).

If this makes no sense I'll try and clarify sometime tomorrow. I hope.

I think Rotary Junkie is one of the most respected tuners on GT Planet. If he is confused by your description, then I now don't feel so bad that I can't understand a thing you say about LSDs. I think it is you, No_OBsT33R, who is stuck with a one dimentional view of LSDs.

Keep working on your thoeries. You may just land on something useful eventually.

I'll take a look at it.

Edit: So, how does it work? a text file that would explain your idea would be useful. Also, you can't have 0%/completely open diff in GT as the lowest value for each parameter is 5, while largest is 60 for a reason I cannot fathom.

It's too bad you can't see the usefulness of it. If you really don't understand what's going on I'll further explain after work. It's just with a good knowledge of how LSD's work you would understand the tool better.


Yes the initial torque setting causes parasitic power loss ( it takes power to slip the clutches) and the accel setting retains power above the minimum applicable, however the rate of retention still has to overcome the loss caused by the int setting before it makes any gains above it.

If your confused, entertain the thought it might be you that doesn't (fully) understand what the LSD is doing. I'm not being insulting.

Leonidae@MFT

I'll take a look at it.

Edit: So, how does it work? a text file that would explain your idea would be useful. Also, you can't have 0%/completely open diff in GT as the lowest value for each parameter is 5, while largest is 60 for a reason I cannot fathom.

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Yeah, I'm going to include a read me, I explained I would and this is only the first release.

The new version shows what a locked and open diff would also be doing.

The tool will still simulate after the games limitations. I'm still learning excel, once I figure how to set a max and min for the cell I'll have that in play.

It's rough, it's a first release, but the math is sound.

I'll be providing more tuning tools, based on response. They provide information to the tuner, information is power. The more you know.....

I have a good understanding of how everything works in a LSD, open diff, and obviously a spool.

I won’t harp on about what I believe is right and wrong in this thread simply because I cant be bothered right now… I have a PS3 sitting idle with GT5 in it

But could you explain how to use this tool to make a car handle better?

A read me file will be included with the next update. It will also display what a open or locked diff would be doing at the time, this info can be used to decide weather int adjustments or access adjustments need to be made, as well as weather you want to go closer to locked or open (you would be surprised)

Anybody with a good understanding of an LSD want to test the math?

Thanks for sharing your work!

No_OBsT33R

Not understand the results?

Unsure of how to use the results?

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Think you hit the nail on the head there. I think it's slightly above the average user (me included).

In addition to the readme, maybe add some small notes/labels within the excel file itself as extra clarification?

Guess you're aiming at people with quite a high technical knowledge of LSD's but on GTP you're gunna get a lot of people with less knowledge who are curious about it also

I think I get what you're saying. If what you're talking about is that Intial Torque is 10- that means 90% power or torque can be applied before the LSD kicks in? So you can essentially limit the amount of torque or power from the torque to the wheels by the Initial Torque setting? That's what I'm getting from the OP.

freshseth83

I think I get what you're saying. If what you're talking about is that Intial Torque is 10- that means 90% power or torque can be applied before the LSD kicks in? So you can essentially limit the amount of torque or power from the torque to the wheels by the Initial Torque setting? That's what I'm getting from the OP.

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Your on the right track thumbs-up

It's just a little bit reversed.

In a turn the wheels spin at a different speed to make the corner at a given speed.

It takes 10 percent difference in wheel speed before the LSD slips, if your int is set to 10.. Until then it acts locked and gives all available power.

As soon as you pass 10% difference in wheelspeed the LSD starts slipping, but the amount of power required to slip the clutches is lost to slipping the clutch.

From the moment the clutch starts slipping the access setting tries to keep the diff locked but slips anything past 40% of the available power (if set to 40) after the loss from the int setting.

At the transition point you actually make less applicable power then if you had an open diff until the access setting begins to retain more power then the initial loss.

With the tool you need to input the perimeters to initiate the slipping. Since we know the LSD remains "locked" until we pass the int setting, we have to generate the situation with the minimum applicable power variable value.

If it's set to 10 we have to generate a difference in wheel speed. If 1 wheel is spinning at 90% then we have a 10% difference, and an activated LSD. Anything under 90% useable power value will show what the LSD is doing.

I'm working on additional tools to take the info provided and go further with it, it's juts it seams like some people are upset I put in work for nothing to help people, if not tune at least better understand what goes on inside an LSD.

o_O

BarronGeddon

Thanks for sharing your work!

Think you hit the nail on the head there. I think it's slightly above the average user (me included).

In addition to the readme, maybe add some small notes/labels within the excel file itself as extra clarification?

Guess you're aiming at people with quite a high technical knowledge of LSD's but on GTP you're gunna get a lot of people with less knowledge who are curious about it also

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Thanks! Glad somebody isn't mad at me for contributing something for free. It's like if you explain something, unless it falls in line with the Holly Grail Skaff tuning guide (that is riddled with inaccuracies, misinformed interpretations, and uninformed opinions) while it's got great info the line of fact and fiction is invisible. It seams some have studied it at go by it like it fact, and something more then Scaff's interpretations of things he's read. If you attempt to bring real info that doesn't fall in line with the guide, it's dismissed as wrong.

I mean somebody told me increasing weight reduces a tires ability to grip (what!!?!?!) ahh it could APPEAR that way if you don't really know what's going on (it's the exact opposite) but it's near impossible here to point out a set of collective errors.

Funny enough, that's life when on a forum & playing a video game. I can't wait for the season to start...

Yeah I guess, GT can be a great learning tool. More info = better decisions (value of tool) I'm taking all suggestions and will make attempts to make it all more simple.

There seam to be a few who can do more than just repeat the in game menu description in their own words (people wonder why the "theories" are so alike should realize that)

o_O

Error duo post

So when I save your document what do I view it with? I'm going to have to figure out how to work your 'calculator', but I get the idea you're putting in. You go into great detail, but you could make it simpler in terms to help others understand. All you have to do is give an example of one car- say a SuperGT car, or even a LeMans style car, as those have decent power but are hard to control, especially in mid corner or corner exit.

Surely the weight, downforce, camber, toe, ride height, dampers etc. settings affect things?

phil_75

Surely the weight, downforce, camber, toe, ride height, dampers etc. settings affect things?

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Yes they manage vehicle weight. Goal being reduce WT as much as possible and balance the weight as much as possible.

The LSD manages the power given.

More weight = more weight pushing down converting into weight transfer, weight transfer puts sideways force on the tire instead of downward force. This means less weight pushing the wheel down and more pushing it sideways.

For every action there is always an equal and opposite reaction.

Any of the weight transferred into sideways force pushing the outside wheels, an equal amount of force is pulling sideways on the inside tires. With an equal amount of sideways force applied to the inside and outside wheels, the lighter side will have a lower ability to effectively apply power, and so the lighter side is always more likely to break traction due to the LSD.

Simply put
Weight transfer = the weight pushing the car down is converted into force pushing the tires to the outside. That sideways force and equal and simultaneous weight loss reduces the tires ability to grip, and therefore also reduces the tired ability to effectively apply power.

You can't do anything to the weight with the LSD all you can do is use it to manage the power given with the weight your already working with.

So yes they effect the LSD, but the LSD doesn't effect them. So your weigh transfer should all be minimized and balanced already when you dial in the LSD.

No_OBsT33R

Your on the right track thumbs-up

It's just a little bit reversed.

In a turn the wheels spin at a different speed to make the corner at a given speed.

It takes 10 percent difference in wheel speed before the LSD slips, if your int is set to 10.. Until then it acts locked and gives all available power.

<snip>

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I'm trying to understand your approach one step at a time, so bear with me on this one...

My understanding of a limited slip differential is that - until the threshold 'slippage' is reached - it acts like an open diff, and then gradually locks itself. Am I wrong?

kilttraeger

I'm trying to understand your approach one step at a time, so bear with me on this one...

My understanding of a limited slip differential is that - until the threshold 'slippage' is reached - it acts like an open diff, and then gradually locks itself. Am I wrong?

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My understanding is a bit of the same...

More that an LSD will act open until enough force is applied on it to force the clutches together and cause it to try to lock.

In most factory differentials (usually 1-way) this occurs only under acceleration. 2-way, 1.5 way, etc, do it when a decelerative force is applied to the diff input (engine braking) and are only "open" when under little to no load.

Now, because of all this, I'm a bit partial to setting my diffs to be as close to one-way as possible with as much decel lock as necessary... Braking oversteer can be cured by left-foot braking (applying throttle under braking applies torque to the diff, causing it to try and lock) and lift-off oversteer can generally be tweaked to be useful rather than murderous.