Rotary Junkie
Premium
- 9,810
- Canton, MI
- RJs_RX-7
LSD Guide Summaries
- Thread starter Motor City Hami
- 105 comments
- 72,625 views
nomis3613
Premium
- 831
Bread82, thanks for sharing the links.
I believe that in real life preload means the diff is locked until a torque difference is achieved between the left and right wheels (link, link, link, link).
If I may throw in my own take on how diffs work in real life (please correct me if I'm wrong, also here is a great page)
- An open diff (0 / 0 / 0 in GT5) sends torque down the "path of least resistance" (increased grip = more "resistance" for that wheel). If both wheels have enough grip, it's all cool, but when the one wheel starts to spin, its grip decreases so the open diff sends all the torque to that wheel. So the gripless wheel is spinning furiously and you end up going nowhere.
- A locked diff (60 / 0 / 0) means that both wheels must always travel the same speed. But as you go around a corner, the outside wheel needs to travel further (therefore faster) than the inside. So, instead, a tyre must skid so that you can turn- this often makes the car harder to turn.
- The best of both worlds is a diff which is locked when it needs to be (full throttle) and open the rest of the time. But then this can cause harsh handing effects, so we need to add a few more things and we end up with an LSD (which contains complicated things like lockup %, coasting lockup and preload)
- pre-load "smooths out" the LSD's behavior. By keeping some diff lock even when the diff is unloaded, it reduces nasty transitions as you go from throttle to brake. To understand how it works, imagine you need to change a flat tyre on your car: with an open diff, the wheel in the air will spin freely; with preload the wheel will not turn until you push it with enough force to "unlock" the diff. So while you're cornering, initially the diff will be locked, but once the difference in speeds (outside wheel needs to travel faster) causes enough torque difference across the axle, the diff unlocks and the car will turn as if it has an open diff (assuming you are not accelerating or braking).
As for the differences between real life and GT5, IMHO
- GT5 does not include the understeer caused by too much diff lock (when you have enough traction, the locked diff pushes the inside wheel faster than it needs to go, which causes understeer)
- it is not possible IRL for a mechanical LSD to spin the outside wheel faster than the inside. However, this happens in GT5, which is why the "GT5 super Diff" can drown out the effect of suspension settings.
Hope this helps.
I believe that in real life preload means the diff is locked until a torque difference is achieved between the left and right wheels (link, link, link, link).
If I may throw in my own take on how diffs work in real life (please correct me if I'm wrong, also here is a great page)
- An open diff (0 / 0 / 0 in GT5) sends torque down the "path of least resistance" (increased grip = more "resistance" for that wheel). If both wheels have enough grip, it's all cool, but when the one wheel starts to spin, its grip decreases so the open diff sends all the torque to that wheel. So the gripless wheel is spinning furiously and you end up going nowhere.
- A locked diff (60 / 0 / 0) means that both wheels must always travel the same speed. But as you go around a corner, the outside wheel needs to travel further (therefore faster) than the inside. So, instead, a tyre must skid so that you can turn- this often makes the car harder to turn.
- The best of both worlds is a diff which is locked when it needs to be (full throttle) and open the rest of the time. But then this can cause harsh handing effects, so we need to add a few more things and we end up with an LSD (which contains complicated things like lockup %, coasting lockup and preload)
- pre-load "smooths out" the LSD's behavior. By keeping some diff lock even when the diff is unloaded, it reduces nasty transitions as you go from throttle to brake. To understand how it works, imagine you need to change a flat tyre on your car: with an open diff, the wheel in the air will spin freely; with preload the wheel will not turn until you push it with enough force to "unlock" the diff. So while you're cornering, initially the diff will be locked, but once the difference in speeds (outside wheel needs to travel faster) causes enough torque difference across the axle, the diff unlocks and the car will turn as if it has an open diff (assuming you are not accelerating or braking).
As for the differences between real life and GT5, IMHO
- GT5 does not include the understeer caused by too much diff lock (when you have enough traction, the locked diff pushes the inside wheel faster than it needs to go, which causes understeer)
- it is not possible IRL for a mechanical LSD to spin the outside wheel faster than the inside. However, this happens in GT5, which is why the "GT5 super Diff" can drown out the effect of suspension settings.
Hope this helps.
- 904
- York Virginia
- chilybee
That LSD Guide is almost exactly what was available in GT games before Prologue.
And that is the way it shoud be now. And I am speaking of the types of LSD offored, and how they effected the car.
And that is the way it shoud be now. And I am speaking of the types of LSD offored, and how they effected the car.
Hello
I have been working with the LSD for the first time, and I must say all the tips 'n tricks from this forum have really helped me, working with the LSD made the car a lot more save and fast around the track. I just came up with a question while testing my car on Laguna today which colour of the tyre indicator should show up in the corner while exiting the corner blue or white?
Cbastjan
I have been working with the LSD for the first time, and I must say all the tips 'n tricks from this forum have really helped me, working with the LSD made the car a lot more save and fast around the track. I just came up with a question while testing my car on Laguna today which colour of the tyre indicator should show up in the corner while exiting the corner blue or white?
Cbastjan
- 1,847
- London
- Ziz528
Irrelevant so long as its not turning red. Blue is cold tyres, white is warmed up tires. 
- 4,803
- Dearborn, MI
- MotorCtyHamilton
Update post 2.09 game patch. See opening post.
- 3,359
- California
- PumpinNumbies
Hami will you update my explanation to the following: Thanks.
Initial: Effects the cars stability throughout the entire turning process.
High Initial, usually means more understeer, better forward bite.
Lower Initial, usually means more agility, less acceleration.
*Use the highest Initial Setting possible, without experiencing understeer.
Acceleration: Effects the car under acceleration while exiting a corner and distributes the power between the inside and outside tires.
High Accel, usually means more outside tire spin.
Lower Accel, usually means more inside tire spin.
*Use the highest Accel Setting possible, without experiencing excessive outside wheel spin.
For longer races with tire wear, I recommend using lower numbers to prevent exaggerated wheel spin under low grip conditions experienced when tire life is lower.
Braking: Effects the car while braking, coasting and entering turns.
Higher DeAccel, usually means more understeer on corner entry & coasting through the center.
Lower DeAccel, usually means better agility, but less stability, potential oversteer on entry.
*Use the lowest number possible, where you can safely drive-in as hard as you like, without losing control, or experiencing oversteer.
Initial: Effects the cars stability throughout the entire turning process.
High Initial, usually means more understeer, better forward bite.
Lower Initial, usually means more agility, less acceleration.
*Use the highest Initial Setting possible, without experiencing understeer.
Acceleration: Effects the car under acceleration while exiting a corner and distributes the power between the inside and outside tires.
High Accel, usually means more outside tire spin.
Lower Accel, usually means more inside tire spin.
*Use the highest Accel Setting possible, without experiencing excessive outside wheel spin.
For longer races with tire wear, I recommend using lower numbers to prevent exaggerated wheel spin under low grip conditions experienced when tire life is lower.
Braking: Effects the car while braking, coasting and entering turns.
Higher DeAccel, usually means more understeer on corner entry & coasting through the center.
Lower DeAccel, usually means better agility, but less stability, potential oversteer on entry.
*Use the lowest number possible, where you can safely drive-in as hard as you like, without losing control, or experiencing oversteer.
- 4,803
- Dearborn, MI
- MotorCtyHamilton
Done
- 4,803
- Dearborn, MI
- MotorCtyHamilton
After all of this time, I think the community is still trying to really figure out 4wd LSDs. https://www.gtplanet.net/forum/showthread.php?p=8151229#post8151229
The good news is that there is a 4wd Wagon/SUV tuning challenge coming this week. I will pay special attention to LSD tuning during this competition and report back my theory.
- 697
- glyfada
- bellitsa
Ty for prompt reply, yea seem to remember those words of yours "The 4wd drive train just isn't my favorite" good luck, will re read ur link, btw ur stuff has been tremendouly helpful for understanding tuning.
- 904
- York Virginia
- chilybee
Hami, thank you for your work. It helps a lot because working out what actually happens on the track takes a lot of trial and error. I am starting to publish tunes and without your work and the other senior tuners here I would be toast. I might still be toast. LOL But I want you and the others to know what you do is pretty damn cool.
- 2,529
- Alton, Illinois
- big_noobowski924
What ever you do DO NOT stick it on your tongue!!!
Good explanation though, very informative.
Good explanation though, very informative.
- 291
- Oxfordshire
- Bread_45
I just read through this thread again for the first time in several months, and think I remember a test I did shortly after this post:
You're right, IRL an LSD should not be able to spin the outside wheel faster than the inside, the outside has more downwards load on it and thus will generate more grip. However as many people have seen, setting the GT5 diff extremely locked turns the outside wheel red whilst the inside wheel stays white.
This is going from memory, but I seem to remember I used the replay mode to take camera shots of the inside and outside driven wheels, using a long exposure time. With a decent choice of alloys (fewer spokes makes it easier to see), you can see the amount of motion blur you get from the wheel rotating during camera exposure. If your exposure is too long then both wheels will look very blurred and you won't be able to discriminate between them. If you dial down the exposure you can get to the point where one wheel looks pretty much "stationary" i.e. the image has no motion blur, and the other is showing some amount of blur, when using an open LSD.
An easy test for this is to get an open diff, stick one wheel on grass, and another on track, and pull away at full throttle - the grass wheel spins faster.
I seem to remember that with a 60/60/60 locked diff, when the outside wheel was red and the inside white, that there was no noticeable difference between the inside and outside wheels' speed (as you'd expect from a locked diff). I think the reason that only the outside goes red is because it is spinning at the same speed as the inside, but has more friction (due to the greater downward load on it). More friction = more heat = red outside wheel. They're rotating the same, but the tyre temp gauge shows the outside as hotter.
Cheers,
Bread
- 1,973
- Florida - USA
- Flsurffisher
Thanks Hammy!
