Tuning a LSD

Discussion in 'CCC' started by THE_KART96, Mar 17, 2011.

  1. THE_KART96

    THE_KART96 TPRA Staff

    The LSD is one of the most unknown part of the tuning arsenal. When we read about them, some get scared by the thought that it can cause the car to push and make it harder to turn. So most will turn every thing down to the low end and run it there. By doing this, they are leaving a lot on the table. So I hope to shed some light on this part.

    A common setting that people use seem to be 5 20 5. This setting lets the car feel like a 1 way diff. It helps a little, but not a lot. The standard setting is 10 40 20. To some, this means nothing. So let's break it down for you.
    The "10" is in the initall torque. This shows you how fast the LSD will lock up when you hit the gas. Lower the # the slower it will lock up, but with a lower # the chance of a push is reduced.
    The "40" is the acceleration torque. This is the speed that the LSD locks up. So a higher # the harder it will pull out of the turns. The lower # will not pull as hard but will reduce the push factor.
    The "20" is how long the LSD stays locked under braking. The longer it stays locked, the better the stability under braking, but it can make it harder to turn in. So from what you have just read, you might think, "Great. Something eles to make this piece of crap handle like....." And if you take it too far, it will make your life h___.
    So how can you use this? Well here are a few tests you can do. Take the car out with the settings that you have now. As you exit the turns, listen to the engine and feel how the car pulls out of the corner. Dose it sound and feel like the tranny is slipping? If so, this means that you are over powering the LSD and you are losing time and speed. Using the 5 20 5 as a example, adjust the first two by 10 clicks. now it should read 15 30 5. Take the car back out onto the track. Now what is happening? You should feel a better responce out of the turn and a higher speed. Have the lap times come down? There should be a difference here also. If the car pushes too much, try taking the 15 down a few clicks. Now try again. If you are happy with the turn in, leave it.
    Now do you find that the back tries to break loose under hard breaking? If so, move the last setting up to 15. Run it again. Better? Good. Now you can try a stronger setting to see if you like it. If not, put it back to 15 and run it there.
    Each type of car will react differently. A AWD has 2 LSD's. Make sure the front one is set lower than the rear one. So if the rear is set to 15 35 15, set the front to 10 30 10. FWD cars is a different animal and can give you head aches. So try 5 30 15. 5 to keep the push down, 30 to pull out of the turns and 15 to keep it stable under braking. Good luck and have fun.:sHa_thumb2:
     
  2. HyperKat

    HyperKat Licensed Racer

  3. THE_KART96

    THE_KART96 TPRA Staff

    Tell me about it.
     
  4. clacksman

    clacksman Licensed Racer

    Indeed. I try running the diffs up, but so far it always slows me down and/or makes the car drive 'worse'. So until I learn something new it'll be 5/20/5 or thereabouts.
     
  5. timneyb

    timneyb Licensed Racer

    Try running 5/30/5 in your RX-8 at Indy Road. I got out of the tight hairpins without the little acceleration hang I was having with the diff turned down.
     
  6. hey6541

    hey6541 Licensed Racer

    yeah i really gotta play around with this thing and learn it.
     
  7. NBA336

    NBA336 Licensed Racer

    Thanks Kart. That is really good information on a subject I'm sure a lot of us ignore. I'm going out now to fool around with it for tonight!!! Thanks again. Cheers,
     
  8. The_Revengel

    The_Revengel Licensed Racer

    I want to thank you too! I'm beginning a new project (Blitzfraulein) and this may help. I seem to be a fan of tuning my cars for understeer - and maybe that's my driving style talking.

    Update: After adjusting the settings on both Blitzfraulein & Maleficent I discoverd my lap times dropped about a second on ThunderCloud. I went the route of 5/10/5 and instantly felt more stable & quicker around the track.

    Apeesheeateit!
     
    Last edited: Mar 24, 2011
  9. STVM_TurboTuna

    STVM_TurboTuna Licensed Racer

    Kartracer, is this at all a summary of some of your post? (rear wheel drive car)

    Acceleration Setting...
    higher setting makes car more stable, but can cause it to push/understeer.
    lower setting lets the car turn easily, but it can cause it to turn too much/oversteer.

    Braking Setting...
    higher setting makes car more stable, but can cause it to not turn in
    lower setting can allow a 'wild ride'

    Also, Initial and Acceleration sound like they have basically the same effect on a car?
     
    Last edited: Mar 24, 2011
  10. The_Revengel

    The_Revengel Licensed Racer

    I'm interested in this answer as well. I've discovered (both through trial & error as well as other drivers using my cars) that I tend to tune for understeer. After I adjusted my LSD (*shakes head at sixties joke*) I found that both cars improved their performance in the corners - somewhat correcting understeer. Now that could have been my adjusting to the car but I'm curious to see what "Jedi Master Kart" has to say on the matter.

    Or anyone for that matter.

    I've got about as much 'Force' as Michael 'Jar-Jar' Spinx.
     
  11. larrys4227

    larrys4227 Licensed Racer

    Hey ..... I get that joke ... :)
     
  12. DPTurbo29

    DPTurbo29 Licensed Racer

    My take on the "Initial" and "Acceleration" settings has always been this. I think the initial setting controls how much torque (power, think throttle position) it takes to activate the LSD, and the Acceleration setting controls the strength of the clutch pack lock-up. I could be wrong. Just my guess.
     
  13. THE_KART96

    THE_KART96 TPRA Staff

    Ok, let's see. For a RWD let say your setting is stock at 10 40 20. Now adjust it to 20 40 20. You should feel that a push has started. If you try 15 40 20, the push has reduced some but is still there. Now try 15 35 20. The push is reduced even more and the responce out of the turn is faster than stock. Reason for this? Well, the way I see it is that the first setting is the speed that the LSD (he he) will lock up. The second setting is how hard it locks up. So by lowering setting 2, you reduce the harshness of the lock up. So it will feel smoother. this will give the feeling that they both are doing the same thing, but what it's doing is working together to make the car run better.
     
  14. DigitalWolf333

    DigitalWolf333 Licensed Racer

    Ok I have several mustangs. Mustangs have some SERIOUS rear wheel spin when tuned up, and often has a hard time making it out of turns. Lowering my settings to 10 15 15 solved this problem with stability, I don't have problems with wheel spin during turn. But my lap times deffnitely took a hit.

    Reading this I think I might need to change some things, any suggestions?
     
  15. THE_KART96

    THE_KART96 TPRA Staff

    From what you have posted, I would move the 2nd setting up by 5. Test and, if needed, 5 again. Once things get loose, adjust down by 1 and test. Do this untill your happy.
     
  16. SiLeNtMuRK14

    SiLeNtMuRK14 Licensed Racer

    After reading the OP, I have a question.

    I'll use suspension for an example to help explain my question more accurately.

    I usually have a different suspension setup for each track (when racing competitively), which can seriously reduce lap times.

    Do you think that, when switching between tracks, changing the LSD settings would be beneficial regarding lap times?

    OR...

    Do you think that, once you tune a car's LSD, you've pretty much got it dialed in?
     
  17. THE_KART96

    THE_KART96 TPRA Staff

    I play with the LSD at every track. Some tracks are lacking tight turns so you can adjust the LSD to lock up faster with little effect.
     
  18. RackAttack

    RackAttack Licensed Racer

    Just rediscovered this video from the 30s that does an excellent job of showing how a differential works, definitely worth a watch.

    A limited slip differential basically just adds to that idea of a differential by giving you control over what percentage of the power is given to each wheel under different circumstances.

    [video=youtube;K4JhruinbWc]http://www.youtube.com/watch?v=K4JhruinbWc&NR=1[/video]
     
  19. NBA336

    NBA336 Licensed Racer

    Thanks Rack. That was pretty cool.
     
  20. Wallhugger60

    Wallhugger60 Licensed Racer

    Ain't much simpler than that. Thanks Rack
     

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