Lmp2 gets unstable after 8 laps - advices?

Discussion in 'General Discussion' started by ThomasJohansen, Feb 8, 2020.

  1. ThomasJohansen

    ThomasJohansen Registered

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    I'm trying to build up some endurance pace, but...

    At lemans in LMP2 Oreca07,
    the first 6-8 laps it drives perfectly.
    After 8-10 laps I'm having trouble keeping up the pace due to the car becomes more unstable. The rear have a higher tendensy to loose grip in turns.


    After 8-10 laps it has 87% tirewear left.
    I'ts medium tires, about 60-70 degrees in temps, with 2.0 bars.
    Im driving with P3 on rearwing.
    Moving the brakebias during race to adress less fuel weight, have less than little effect.
    After pit refueling its keeps being unstable.


    Is it the rubber in the racing line thats gets slippery?
    Are the tires done after 10%?
    should I drive with a higher rear downforce to begin with to handle this later rear unstability?

    other suggestions?
     
  2. Christos Segkounas

    Christos Segkounas Registered

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    Welcome to the unique world of the LMP2.
    "Is it the rubber in the racing line thats gets slippery?"
    Nuh.
    Changes in humidity/track temp/air temp don't do anything in rf2 for grip.

    "Are the tires done after 10%?"
    Definitely not, but they will have overheated by that point and feeling slidey.

    "should I drive with a higher rear downforce to begin with to handle this later rear unstability?"
    You could.
    Don't expect that to fix much though and your questions/problems will remain.

    Also shifting the brake bias to the front will not fix the rears locking up at low speed, it will however introduce front lock ups on entry, so again, no definitive solution there, just find the best compromise.

    You can't tell the lmp2 what to do, it tells YOU what to do and you need to oblige imo.
    If it starts sliding then maybe you should start backing off.
    Complete a few stints and you will have a much better idea yourself.
     
  3. Remco Majoor

    Remco Majoor Registered

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    The rear tires are wearing faster compared to the fronts, definitely when you are pushing. This shifts balance to oversteer. What we do for VEC is start with a more understeery setup, so at the end of the stint its only a little bit oversteery. The rest we compensate with the right foot and not throwing it into the turn as hard.
     
  4. ThomasJohansen

    ThomasJohansen Registered

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    thx for your great feedback.

    i'll try to make it more understeery to see if its more stable in the end of a stint.
    I better turn down the AI to avoid forcing myself to push too hard, its proberly part of my problem.
     
  5. ThomasJohansen

    ThomasJohansen Registered

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    It was fantastic, did almost 16 laps without feeling the car was unstable.
    had a few driving errors but they even didnt ruin the tires.

    stiffened front arbs and changed rear df to P4.
    It made all the difference, its easier to drive so I didnt overdrive it.
    I even did a new personal record in this car.

    Will do 30 laps later today to test is some more.

    thx for your advises.
     
    pkelly likes this.
  6. AMillward

    AMillward Registered

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    It's a common thing for people to set a car up, think it handles amazing and will only drive very short distances. So when it starts to wear in it becomes 'undriveable' because you're not used to tyre wear being what it is.

    Don't worry, I do that too ;)
     
  7. Andregee

    Andregee Registered

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    Its mostly related to tire pressure. Over 180kpa, the tires loose grip and when the rear tires heat up faster, you have to start with more tire pressure at the front to compensate that.
     
  8. Remco Majoor

    Remco Majoor Registered

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    no, we do lowest tire pressure, because rf2 is just like that.
     
  9. Andregee

    Andregee Registered

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    And we don´t make it so yes. There is a reason why the standard LMP2 and GTE setups have more air pressure in the front than in the back. And exactly because everyone thinks that the minimum pressure is always better, these problems of balance shifting arise
     
  10. Lazza

    Lazza Registered

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    I'm intrigued to know where the long run consensus is on this, because this is exactly what gets disregarded by some people talking about lowest pressure = best setting in rF2 (they concentrate on raw single lap grip, and the fact the tyres don't suffer damage/fail with very low pressures [which in itself is limited by the available setup values and thus doesn't always qualify as "unrealistically low pressure", but I digress...]). The potential saving grace for rF2 in that argument is that lowest pressures aren't always best for long runs, so I'm curious where the truth sits in this case. Although I guess like anything setup related there's usually at least 14 ways to skin a cat, so one person's workable pressures are another person's undriveable pressures on a long stint... beginning to wonder if the question is worth asking now.

    Plus this is just one car, with its tyres and pressure range, so it's not the be-all and end-all. Anyway, consider this a polite request to continue discussing this topic in a friendly and thoughtful manner :D
     
  11. ThomasJohansen

    ThomasJohansen Registered

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    Well, I did 30 laps this evening and the car was way better but not perfect. I then stiffened the rear arbs and changed rear camber from 1.6 to 1.5 and changed from medium to hard tires. Lowered temps about 2 kpa on both front and rears. Then did another 30 laps, and the car was really comfortable, easy to drive, and small mistakes didnt had any effect on tires. At first my laps was 1-2 seconds slower but did a few laps which was really good. I did change tires when they reached below 75% wear (after 20 laps).
     
  12. davehenrie

    davehenrie Registered

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    I had almost the same experience as the original poster, Driving a GT3 Aston, I was forcing the pace to try and keep up with 100% AI at Sebring, with fairly good results, but after about 9 or 10 laps, little things escalated and I was recovering slides and tail happy handling. I have always used less tp in the rear, by about 5kpa, but I had not tried any of the other suggestions. Definitely a topic I'll want to see more advice for.
     
  13. Lgel

    Lgel Registered

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    My two cents.

    I test my setups with 3x tire wear and fuel usage. That means that in 20 mn I simulate approximately an hour stint, with some of the effects of heavy fuel load on ride height, lap fuel usage, tire wear and braking distances.

    While trying to use the lower cold tire pressures, I monitor tire pressures at the end of my run (in motec or in the setup screen), I try to reach even hot tire pressures on the same axle, and monitor evolution of tire pressures between rear and front axle, as Andregee remarked, the balance between tire pressures of the two axles may change as temp in the tires builds up (a lot on some cars with default setup after 7 to 8 laps), changing the car balance.

    On most tracks I end with a slightly asymmetrical setups for tire pressures and camber settings.

    Cheers.
     
  14. Remco Majoor

    Remco Majoor Registered

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    Yesterday I had an endurace race with the LMP2, core temps got so high that it didn't matter at all. Single stinting softs with lowest pressure, was way quicker than double stinting mediums as well, because its rF2. At the end of my soft stints, I could do the same lap times as at the beginning.
     
  15. Christos Segkounas

    Christos Segkounas Registered

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    Yes, the base mod pit stop timings in relation with tire performance make the "endurance" tag a joke.
    Most leagues will manipulate the timings to provide more strategic options and make these cars actually usable in their intended purpose.
     

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