Ballast position's effect on car handling.

Discussion in 'GT4 Tuning' started by shotamagee, Aug 11, 2012.

  1. shotamagee

    shotamagee

    Messages:
    624
    Location:
    Australia
    Adding ballast weight generally slows your speed / lap times, so there's not as much discussion on it in the forum.
    However if you have to add ballast, you might as well try to use the positioning available to you to improve the handling.

    Until recently I'd assumed that adding ballast weight over the front wheels of a car was a way to give the front tyres more traction, and consequently make the rear lighter and more likely to break traction,
    which should therfore reduce understeer.

    I have done this many times when chasing A-spec points, as using a harder grade front tyre compared to the rear gives you more points, but you inevitably have to battle understeer when you do it.
    I'm now doing the Hyundai Coupe FX manufacturer races and have been looking at some of the posts related to that race, some suggest having the ballast over the front and some suggest having it over the rear, which caused me to reconsider my initial assumption.

    So I went to the 400m test track with a FWD Yaris, a RWD Lexus IS200 and a MR Lotus Elise 190. Sure enough (after adding 200kg's of ballast) moving the balance over driving wheels helped traction and allowed me to record quicker times for all the cars, as I expected.

    But on the track it proved to be a different story;
    I drove the Lotus Elise 190 first, due to its low weight, I hoped the changes would be easiest to notice. They certainly were; with ballast settings of 200,50 the car oversteers everywhere, and had very little stability. When I changed that to 200,-50 it made a big difference, the car handling was way more neutral. So that was a pretty big indicator that maybe rear weight balance is the best way to cure understeer.
    The other cars were less conclusive. With the weight over the nose, it felt like it helped get the nose into the corner, but you'd get more understeer once on the power again, and the times with each setting (for both the Lexus & The Yaris) were pretty even as well. So the weight balance seems to works a little like the LSD, front weight balance gives you better drive, but rear weight balance allows the car to turn more easily.

    These results show that rear weight balance reduces understeer, but I'm still trying to completely understand the theory as to why this is, if other members have any input on the topic I'd appreciate hearing it.

    Apologies for lengthy post.
     
    Last edited: Aug 11, 2012
  2. JohnyPiston

    JohnyPiston

    Messages:
    246
    Interesting. I never use ballast weight but I have considered it for the Shelby Cobra. I will try it tonight and will let you know my thoughts.
     
  3. Ignignoc N Err

    Ignignoc N Err

    Messages:
    379
    Location:
    United States
    This makes me question whether or not they got the ballast balance backwards. I've seen cases where (like you originally surmised) getting ballast over the front wheels would increase turn-in response by shifting weight onto the steering wheels, which is logical and natural. However, if you put the ballast weight on the tail of the Elise 190 and it became more neutral, that seems to be exactly backwards from scientific theory.

    Perhaps we should put a little more time into investigating this...
     
    hEDpH81 likes this.
  4. shotamagee

    shotamagee

    Messages:
    624
    Location:
    Australia
    Note: This is all from memory,
    I find the Elise 190 to be pretty nervous even with stock settings, with the ballast over the rear it's even worse, but with it over the front, it now drives pretty much how I like.
    Its also worth noting I'm a DS2 user, as that affects my ability to drive cars with natural oversteer tendencies. (With the DS2 I'm effectively sawing at the wheel, which with a pointy short wheelbase car like the Elise is probably not the best way to drive).

    If someone had posed this question when GT4 was new I'm sure we'd probably have a more definitive answer.
     
  5. sammy neuman

    sammy neuman

    Messages:
    126
    Location:
    United States
    Too much weight (or downforce) on the front tires will cause the tire to deform and twist. Small steering inputs disappear in the friction. The result is understeer.

    The reason for the Elises problem is not a short explanation, but it also occurs in rl, and drivers of RR cars know it well.
     
    Last edited: Nov 24, 2012
  6. Infini 8

    Infini 8

    Messages:
    3
    Location:
    Dominican Republic
    For most MR/RR vehicles, I set the weight ballast's positions to the front (-50) and the weight will range from 50-200. That solves the nervous handing on quite a few MR/RR cars. I still cannot get the hang of driving a modified Ford GT... the ballast did almost nothing to correct it's behavior. :ouch:
     
  7. Ignignoc N Err

    Ignignoc N Err

    Messages:
    379
    Location:
    United States
    Okay, that makes a lot more sense, Shota. Having the ballast counter-balance the car's weight distribution should lead to a more neutral feel. I was misunderstanding you and thinking you were saying it was backwards.
     
  8. sammy neuman

    sammy neuman

    Messages:
    126
    Location:
    United States
    Forum search 'Taming the Beast', much work has been done on the Ford GT.
     
  9. Ignignoc N Err

    Ignignoc N Err

    Messages:
    379
    Location:
    United States
    Has anyone taken a specific interest in the Protomotors Spirra? That car had a more extreme handling dynamic than the Ford GT, IMHO. It lives up to the old addage, "At the last it biteth like an adder." I tried using that car to run the El Cap 200, but with all the altitude changes mid corner, this car was unusable. I never played around too much with ballast with this particular beast.
     
  10. sammy neuman

    sammy neuman

    Messages:
    126
    Location:
    United States
    Just tried it. Absolute stock from the showroom floor. At the first it biteth like an Adder also. First thought was "way to much load on the front end", and moved the weight-distribution slider to +7 without adding ballast. My game has some peculiarities, so I don't know if this works for others, but it made a huge difference in stability (and confidence). I tried 50lb of ballast here and there, but it did not improve on the bare +7. Mind you, it is still touchy, but didn't wallow like a pig. This is with a wheel, I'll have to try a controller and see if I even notice.
    Did try with controller. There was a notable difference (15sec with wheel, 5sec with cont. at El Capitan), but even with the wheel I couldn't get below 2 minutes.
     
    Last edited: Dec 31, 2012