Limited Slip Differential (LSD) theory

[OdeFinn]

My most noted results while driving were when I swapped the current setup around from 12/36/5 to 36/12/5, once I did that, I was clearly able to turn the inside wheel red first.
It should be noted it's quite easy to tell when the inside wheel spins first, and it happens a while before it turns red. That's the reason for the very high lsd setting, with lower it spins the inside wheel the whole way around the track.

Try same setups with, CH, CS, SS and RS tires, you get different red tire.

 

[CSLACR]

Try same setups with, CH, CS, SS and RS tires, you get different red tire.

I am aware. You seem to be under the impression that you're the only one who has ever tried this?
Generally speaking the lsd needs raised with stickier tires, but this isn't privileged information.
12/36/5 and 36/12/5 are not the same while accelerating, the lsd initial is not as powerful as the accel or decel functions. I found 12/36/5 and 36/24/5 about the same. Or roughly 2-1 accel/decel strength over initial.

 

[OdeFinn]

I am aware. You seem to be under the impression that you're the only one who has ever tried this?
Generally speaking the lsd needs raised with stickier tires, but this isn't privileged information.
12/36/5 and 36/12/5 are not the same while accelerating, the lsd initial is not as powerful as the accel or decel functions. I found 12/36/5 and 36/24/5 about the same. Or roughly 2-1 accel/decel strength over initial.

Do you use LSD for gaining more grip or less? Now you make me confused, really backward thinking.

 

[CSLACR]

Do you use LSD for gaining more grip or less? Now you make me confused, really backward thinking.

Cornering grip, or straight line grip?

 

[DaBomm4]

I just did a test and used the Data Logger to examine my test.

Ford Mustang Boss 302 '13
ride height - min
springs-dampeners-arb - max
camber-toe 0.0

Circle test on SH tires
5/5/5 - inside wheel faster
60/5/5 - wheel speed equal
5/60/5 - wheel speed equal
5/5/60 - inside wheel faster

Question, if the 60 represents 60%, then shouldn't one wheel still be faster than the other during this test?

Edit: I tested again on RS tires and observed something, without Data Logger.

Circle test on RS tires
5/5/5 - inside wheel turns red, outside stays white
60/5/5 - inside wheel turns red, outside turns orange at most
5/15/5 - both wheels turn red and about the same time

 

[CSLACR]

I just did a test and used the Data Logger to examine my test.

Ford Mustang Boss 302 '13
ride height - min
springs-dampeners-arb - max
camber-toe 0.0

Circle test on SH tires
5/5/5 - inside wheel faster
60/5/5 - wheel speed equal
5/60/5 - wheel speed equal
5/5/60 - inside wheel faster

Question, if the 60 represents 60%, then shouldn't one wheel still be faster than the other during this test?

Edit: I tested again on RS tires and observed something, without Data Logger.

Circle test on RS tires
5/5/5 - inside wheel turns red, outside stays white
60/5/5 - inside wheel turns red, outside turns orange at most
5/15/5 - both wheels turn red and about the same time

^ I found that using 60/5 and 5/60 made it more difficult to figure out. The high setting made them all want to spin the outside wheel more easily than lower setups, which are more likely to be neutral or spin the inside wheel.
Something closer to a usable setting reversed seemed to work significantly better. (which is why I grabbed an existing car setup and reversed the lsd 12/36/5 - 36/12/5)

 

[DaBomm4]

^ I found that using 60/5 and 5/60 made it more difficult to figure out. The high setting made them all want to spin the outside wheel more easily than lower setups, which are more likely to be neutral or spin the inside wheel.
Something closer to a usable setting reversed seemed to work significantly better. (which is why I grabbed an existing car setup and reversed the lsd 12/36/5 - 36/12/5)

With the first part of my test, I did your circle test in first gear and then finished the lap to watch the wheel speeds in the Data Logger, I had exactly equal speeds with 60/5 and 5/60. Then I changed tires and tested again to see, I couldn't do a complete circle with either 5/5/5 or 60/5/5 within the space of the track.

 

[OdeFinn]

Double, on phone...

 

[OdeFinn]

Question, if the 60 represents 60%, then shouldn't one wheel still be faster than the other during this test?

Yes, and it's, 65% is actual locking rate, init+accel.
It's so stiff lock at it's not easy to see differences, but using F40 and waving it you get 1-3kmh differences visible pretty easy.

 

[DaBomm4]

Yes, and it's, 65% is actual locking rate, init+accel.
It's so stiff lock at it's not easy to see differences, but using F40 and waving it you get 1-3kmh differences visible pretty easy.

Well, I ran full laps to go with each test and except for off throttle, I was getting full lock around the whole track with both settings. I am assuming that the F40 was max/min for the suspension also to try and account for body roll?

 

[OdeFinn]

@DaBomm4 you need good grip to get differences visible, so for that test maybe RS tires, stiff but not maybe maxed.
During body roll you'll see it too.
.
.

 

[DaBomm4]

stiff but not maybe maxed.
During body roll you'll see it too.
.
.

yes maxed out everything,

But here you said maxed, so now you mean well balanced/stiff?

@DaBomm4 you need good grip to get differences visible

I had very little wheel spin through the course, but I was close most of the time, pushing hard around the track.

 

[OdeFinn]

But here you said maxed, so now you mean well balanced/stiff?

To see how LSD is locking(what tire skis and what not, altering this by adding better going tires and lower grip tires) you have to eliminate other suspension parts= stiff body/suspension.
To see how much LSD locking is slipping between tires on that particular case you need maximum grip= balanced/good suspension.(stiff body/suspension might work when using good grip tires)

 

[CSLACR]

With the first part of my test, I did your circle test in first gear and then finished the lap to watch the wheel speeds in the Data Logger, I had exactly equal speeds with 60/5 and 5/60. Then I changed tires and tested again to see, I couldn't do a complete circle with either 5/5/5 or 60/5/5 within the space of the track.

My circle test? I don't have a circle test.
In any case, I would bet, (and it seems) the data logger either isn't accurate, or doesn't factor in cornering for wheel speed differences without wheelspin. Neither would surprise me.

 

[OdeFinn]

My circle test? I don't have a circle test.
In any case, I would bet, (and it seems) the data logger either isn't accurate, or doesn't factor in cornering for wheel speed differences without wheelspin. Neither would surprise me.

You did or not did reverse spinning test?
Next time you start proofing something, PLEASE include video of it, then we know at you have done some tests, and maybe see some results too.

@CSLACR could you make your mind, first you're praising data logger and Motec, and suddenly when it supports something else than your point of view you're starting to accuse it as inaccurate.

So what's your mind? Or should you just change your system to metrics and double accuracy of logging?

 

[OdeFinn]

Example by quick calculating:
Car with 2m wide wheel rail.
90 degree turn where inner tire travels 10m then outer wheel travels 13.14m, difference is 31.4%, and if travel speed of inner tire is 50kmh then outer goes 65.7 kmh, difference is 15.7kmh.
From this we see at numbers are not so big what were hunting here.

45 degree turn, same 2m rail, lenght of turn 50m(inner wheel), traveled distance on outer tire is 51.57m, speed difference 3.14%, So if speed is 100kmh on inner wheel then outer travels 103.14kmh..

 

[CSLACR]

You did or not did reverse spinning test?
Next time you start proofing something, PLEASE include video of it, then we know at you have done some tests, and maybe see some results too.

@CSLACR could you make your mind, first you're praising data logger and Motec, and suddenly when it supports something else than your point of view you're starting to accuse it as inaccurate.

So what's your mind? Or should you just change your system to metrics and double accuracy of logging?

It's not a circle test, I put a FWD car in reverse and did donuts with multiple lsd settings. It's far from a "method", it just quickly and easily showed me differing results on different lsd settings. The fact that you expect GT's lsd function exactly like a real one was unexpected, but really after driving the car around a bit, I could clearly see one setup was burning the inside tire up, and another wasn't. IMO this isn't something that "needs video". Everyone with a copy of GT6 can do this.
Should I make a video like your video?
Quote me "praising" data logger or Motec. 10,000$ prize.

I may have "suggested" someone else use it, but the secret premise for that, would likely be that I trust data logger more than their ability to drive.

 

[OdeFinn]

@CSLACR, Okey just suggested..

If you lay 5kg sledgehammer on your feet gently it won't hurt, but if you drop it from 10cm altitude it hurts. After drop force of 5kg is stationary and same on both cases, why other hurts?
Gently getting full gas, or full on park against brake and release.

Your test wasn't doing much. Too many aspects left out, or not diagnosed.
Or in another words, it wasn't diagnosed properly.

 

[CSLACR]

@CSLACR, Okey just suggested..

If you lay 5kg sledgehammer on your feet gently out won't hurt, but if you drop it from 10cm altitude it hurts.
Gently getting full gas, or full on park against brake and release.

Your test wasn't doing much. Too many aspects left out, or not diagnosed.

But it did astronomically more than your testing.

In any case, I was never in this to do data logging or Motec, as I'm not a fan of the practice. (or more specifically, how much easier for me personally it is to just drive)

Ok, thanks.
After my current testing obligation is fulfilled, I'll grab some of the cars and go nuts with them, and see what I find. I already have plans to test a couple things then, so this will fit in nicely.

I still plan to grab a rwd and 4wd car and goof around with them a bit, but for me, my opinion is good enough, and I'm not in it to "prove" anything to anyone. I offer my help/opinion/expertise(when applicable) and if it's taken, great. 👍 If not, that's cool too.

Once I'm done I'll give my opinion on all drivetrains, and that will be the end of my tenure here in this thread, not out of anger, but because that's simply the limits of my effort. Nothing personal, call it laziness.

 

[OdeFinn]

In any case, I was never in this to do data logging or Motec, as I'm not a fan of the practice. (or more specifically, how much easier for me personally it is to just drive)

If this LSD thread was based on feelings then there would be only locked thread after OP.

 

[DaBomm4]

In any case, I was never in this to do data logging or Motec, as I'm not a fan of the practice. (or more specifically, how much easier for me personally it is to just drive)

I typically go by feel and the tire temp icons for setting up my cars too. Too much effort to: get a good lap, save lap, exit the time trial, read the data, adjust according to the data and repeat.

To clarify, what I meant with the circle test is the donuts that you did, just I was in first gear instead of reverse. My second test with RS tires shows something interesting like your 12/36/5 vs 36/12/5 test. I could not get the outside wheel to turn red during my donuts attempt at 60/5/5 but the outside wheel easily goes at 5/15/5. This shows me that the initial's value is not that important compared to the acceleration's value.

 

[CSLACR]

If this LSD thread was based on feelings then there would be only locked thread after OP.

No, it wouldn't. It's the bickering and insulting that gets them locked, not driving or tuning by feel.
Secondly, this thread contains exactly zero documentation, recordings, or anything of the sort in it currently, and it's been open a few weeks. I'm contributing to your subject exactly as much as one other person, (not yourself) and other than that it's a dead thread. I'm not sure chasing away the only existing people is the fastest way to what you want in this case.

I typically go by feel and the tire temp icons for setting up my cars too. Too much effort to: get a good lap, save lap, exit the time trial, read the data, adjust according to the data and repeat.

To clarify, what I meant with the circle test is the donuts that you did, just I was in first gear instead of reverse. My second test with RS tires shows something interesting like your 12/36/5 vs 36/12/5 test. I could not get the outside wheel to turn red during my donuts attempt at 60/5/5 but the outside wheel easily goes at 5/15/5. This shows me that the initial's value is not that important compared to the acceleration's value.

Exactly. 👍 I am curious as to what the ratio is between them, like a power-to-power ratio, for example maybe 4 initial is equal to 1 accel/decel? Or is it even the same from car to car?

This is something everyone can test and see for themselves, it's far less work to just try out yourself, then to ask other people to make videos, take data logging's, and jump through all kinds of hoops for.

@OdeFinn - Basically, the point is if you want to prove your theory, you'll probably be required to prove your theory.
I guess technically you've made a thread asking others to prove your theory for you, and for now I wish you good luck on that, I'll share what I find after further testing anyways, but it won't be video or data logging's that you could make yourself.

 

[OdeFinn]

Exactly. 👍 I am curious as to what the ratio is between them, like a power-to-power ratio, for example maybe 4 initial is equal to 1 accel/decel? Or is it even the same from car to car?

Maybe figuring out how big difference is on traction when banging lock from 5% to 20%, or from 60% to 65%, that's the clue over here, other rips tires out from ground and there you go. Sledgehammer again..

 

[CSLACR]

Maybe figuring out how big difference is on traction when banging lock from 5% to 20%, or from 60% to 65%, that's the clue over here, other rips tires out from ground and there you go. Sledgehammer again..

That's actually incoherent in English as posted.
I genuinely have no idea what you're trying to say here sorry.

I think the easiest way would be to try more medium numbers, for example, 8/15/5 is a pretty common rwd setting for me, which I can almost guarantee 15/8/5 will allow the inside tire to spin wildly in almost all cases, but 8/15/5 actually limits the excessive wheel spin and the outside tire will certainly break loose if pushed hard enough.
Running 60/5/5 and 5/60/5 is running enough lock to cause outside wheelspin on either, so it (can) make it harder to distinguish.

 

[DaBomm4]

Running 60/5/5 and 5/60/5 is running enough lock to cause outside wheelspin on either, so it (can) make it harder to distinguish.

To add to this with an actual test result.

Donut test on RS tires
5/5/5 - inside wheel turns red, outside stays white
60/5/5 - inside wheel turns red, outside turns orange at most
5/15/5 - both wheels turn red and about the same time

By bumping up the tire grip level to RS tires it was easier to distinguish that 60 on the initial does not even equal 15 on the acceleration adjustment, it is closer to about 10 (for the given test vehicle and settings).

 

[CSLACR]

To add to this with an actual test result.

By bumping up the tire grip level to RS tires it was easier to distinguish that 60 on the initial does not even equal 15 on the acceleration adjustment, it is closer to about 10 (for the given test vehicle and settings).

Yes, I think the key is having enough grip that they don't both turn red immediately from gobs of power and/or lack of grip. I had that issue on SS on the VW with it's 377HP. That's actually what prompted reverse, that and my knowing GT doesn't use decel for reverse anyway.

 

[OdeFinn]

So now we have enough "data" from non biased testing and I may also contribute this.
I will try to grab some time on Sunday/Monday and make some tests from those already used/tested values.

@CSLACR I feel sorry for you if you really don't understand what I ment on my earlier post.

 

[CSLACR]

So now we have enough "data" from non biased testing and I may also contribute this.
I will try to grab some time on Sunday/Monday and make some tests from those already used/tested values.

@CSLACR I feel sorry for you if you really don't understand what I ment on my earlier post.

It's fragmented English at best, nobody understands it.
I was cutting you a break and being nice because you're not native to English, but if you're so dense that you can't grasp the idea that you're terrible, terrible, pathetic English isn't always perfect, let me be the bearer of bad news: Your English sucks.

Now, I'd like to cut you a break, because it's not your first language, whaddya say?

 

[OdeFinn]

@CSLACR great, nice to hear that, anyhow I'm trying to focus my interest on information itself, not formation. But thanks for your opinion.

 

[Ridox2JZGTE]

@OdeFinn : Here is an old thread that discusses the LSD with 60/60/60, it was in drifting forum and locked, but the first page has wealth of information and another drifter suggested to use clutch in order to test LSD setting accurately.

https://www.gtplanet.net/forum/thre...ence-inside-also-full-lsd-explanation.307085/

Read the OP and till the end of page 1. Before running tests, be sure to understand what is initial torque/preload in LSD ( particularly clutch plate LSD )