noob question about ride height

[rk]

So it would appear that downforce is merely a function of the two controllable front and back values. So while rake does have an undeniable indirect effect on grip (in relation to how the physics models bottoming out), it doesn't have anything to do with downforce. Thanks for testing it Zardoz.

Do yourself a favor. Take a smaller car, say a 1968 Nissan Fairlady, a '69 Jaguar E-Type or a Lotus Elan, give it some power and bump the auto to 10 or 12. Then take it to a fast, narrow road, I recommend The Nurburgring, and try to drive it past 120mph. Do anything you want to keep it from "wandering " off the high speed section, except for reducing speed. Then go back to the tune screen and rake the suspension so the front is 30mm lower than the rear, then come back here and post your theory why the wandering has stopped. Oh, and please explain why the programmers raked the Pescorolo while you are at it.

 

[Ezz777]

Do yourself a favor. Take a smaller car, say a 1968 Nissan Fairlady, a '69 Jaguar E-Type or a Lotus Elan, give it some power and bump the auto to 10 or 12. Then take it to a fast, narrow road, I recommend The Nurburgring, and try to drive it past 120mph. Do anything you want to keep it from "wandering " off the high speed section, except for reducing speed. Then go back to the tune screen and rake the suspension so the front is 30mm lower than the rear, then come back here and post your theory why the wandering has stopped. Oh, and please explain why the programmers raked the Pescorolo while you are at it.

Why complicate the issue with an innumerable amount of uncontrollable factors ie the 'ring. The 'ring is bumpy, if your rear ride height is too low you will bottom out, lose rear traction and hence struggle on the fast bits. Raising your rear ride heights helps.

The super speedway on the other hand is not bumpy. Raising your rear ride height does NOT help.

Both high speed, one bumpy. One rear ride height helps - one where it doesn't.

In terms of the pescalaro - perhaps they realised how crap their physics engine is at high speeds on bumpy roads (just have a look at your car down the mulsanne when you are doing the sarthe II enduro) and so raised the rear to make it drivable. Why wouldn't they raise every other cars bum then?

 

[djaft3rb3ats]

Why complicate the issue with an innumerable amount of uncontrollable factors ie the 'ring. The 'ring is bumpy, if your rear ride height is too low you will bottom out, lose rear traction and hence struggle on the fast bits. Raising your rear ride heights helps.

The super speedway on the other hand is not bumpy. Raising your rear ride height does NOT help.

Both high speed, one bumpy. One rear ride height helps - one where it doesn't.

In terms of the pescalaro - perhaps they realised how crap their physics engine is at high speeds on bumpy roads (just have a look at your car down the mulsanne when you are doing the sarthe II enduro) and so raised the rear to make it drivable. Why wouldn't they raise every other cars bum then?

i see and understand you point, what what i think rks point is that you're not always going to be on a flat race track, a overall good tune is better than tuning for each track each time you race.


djaft3rb3ats

 

[Dr_Watson]

a overall good tune is better than tuning for each track each time you race.

personally i feel the opposite is true.
if you want the most out of every track, make changes not comprimises.

 

[djaft3rb3ats]

well, they both have their ups and downs. the individual tuning per track per car is very tedious and time consuming, but the outcomes would be much better than the general one.

the general tune is good that its easier to make and less time consuming. you could still win, but now it depends on the driver more, imo



djaft3rb3ats

 

[Ezz777]

personally i feel the opposite is true.
if you want the most out of every track, make changes not comprimises.

Precisely my dear watson ( sorry couldn't help).

On a nice clean flat track there really isn't much need to have massive rakes on your chosen vehicle. I usually run between 5mm and 10mm rake on flat tracks, and 15 - 20 mm of rake on bumpier one (obviously depending on the car).

So i guess if you are afraid of entering the dreaded settings section for each track - run 12.5mm ( 👍 👍 ) rake and deal.

DJwhateveryournameis - I doubt very much that a general 'compromise' tune was anything related to what RK was getting at. We have been discussing the varying effects of ride height in this thread.

 

[djaft3rb3ats]

wow, get off my crack?
so we got a little sidetracked, sheesh.

besides, it has something to do with rake because im for it like rk is and i was explaining an issue with ride height and where/when/why it would be appropriate. you were speaking of a little or no rake for ur speedway as a test course where as rk use nurb and i was commenting that using rake would help and that using no rake for the super speed way would not help you in nurb.


djaft3rb3ats

 

[Ezz777]

sidetracked indeed!

the whole testing was to ascertain the effect of rake on downforce. the super speedway - where downforce will be a huge contributor to good lap times was an ideal testing location for RK's hypothesis. The 'ring, due to its bumpy nature, will NOT prove that rake increases DF, but only that rake can improve lap times on a bumpy track.

Wasn't trying to get on your crack, just wishing people would read a thread from start to finish rather than jumping in the middle and ignoring much of what's been said earlier.

 

[djaft3rb3ats]

sidetracked indeed!

the whole testing was to ascertain the effect of rake on downforce. the super speedway - where downforce will be a huge contributor to good lap times was an ideal testing location for RK's hypothesis. The 'ring, due to its bumpy nature, will NOT prove that rake increases DF, but only that rake can improve lap times on a bumpy track.

Wasn't trying to get on your crack, just wishing people would read a thread from start to finish rather than jumping in the middle and ignoring much of what's been said earlier.

i noe, i was just commenting on it...sheesh



djaft3rb3ats

 

[Zardoz]

...the individual tuning per track per car is very tedious and time consuming, but the outcomes would be much better than the general one.

the general tune is good that its easier to make and less time consuming. you could still win, but now it depends on the driver more...

Yep.

The operative phrase here is "time consuming". Multiply the number of cars you want to work with times the number of tracks you want to run them on, and the time required gets totally out of hand.

That's why GT Vault has always had a setup category called "Road Setup". Its the "general tune" you refer to. Having an ideal setup for each car on each track is just impractical.

 

[doormeister]

Having an ideal setup for each car on each track is just impractical.

my wife is already complaining about how much time I spend on this game...

 

[Ezz777]

i know we are getting into general setup now, but my per track setting changes are usually restricted to an adjustment of ride height and corresponding spring rate correction - depending on bumpyness of track. Then a final gear ratio correction. If you want to get generalise - have a bumpy and non-bumpy setup in A and B, and then all you have to do is set the final.

 

[Zardoz]

...have a bumpy and non-bumpy setup in A and B, and then all you have to do is set the final...

That's what I've started doing, with "C" completely stock except for driving aids, gears, and maybe brake balance.

 

[Zardoz]

Okay, now I'm really confused.

I'm trying some setups on the LMP cars, putting a lot of laps on them with stock suspension to get an accurate picture of whether or not my modded setups are actually better, or whether "improvements" I perceive are just wishful thinking on my part.

Using Midfield as my primary test track, I was surprised that the stock '03 Pescarolo was consistently a little faster than the stock '04 Pesky, even though it is down on HP to the Playstation car. The reason was obvious: The '04 understeered more.

There is only one difference in their stock suspension settings: The front ride height. The '03 Courage car is flat at 80/80. The '04 Playstation car is raked at 50/80. I figured what the hell, and set the '04 car at 80/80.

Bang: Over seven-tenths of a second faster, just like that, with the same near-neutral, near-perfect handling of the '03 car. The '04 is now faster than the '03.

I don't get it. What is going on here? The 80/80 setting is definitely better than 50/80, so why did PD drop the nose on the Playstation car?

 

[Ezz777]

possibly a mistake - i wouldn't put it past those PD guys to have missed a little detail here and there...

i reckon it may be because the 04's front may have been bottoming out on some of the high speed corners on midfield (i love midfield - wish there were more races there. ever since the mad midfield minute quest grabbed me in gt2 i can't get enough of the place).

theoretically the main benefit of lowering your car would be to increase your mid corner speed (edit: sorry given the amount of physics under the bridge in this topic i shouldn't have simplified it this much, but oh well couldn't be arsed thinking much (friday night here)). i personally find that all the LMPs handle so well that there's almost no point in dropping them much and that on high speed course (and courses with big ripple strips) it is often better to raise them up a ways to cope with the bottoming out-loss of grip phenomenon. I run most with rear at max height and front 15mm below. Seems to work ok.

 

[Duke]

OK! my engineer/racer friends have finally gotten a break in their season and had a chance to answer my question. The first quote is what I asked them; the second is the answer from a guy who is a chassis/suspension engineer in the specialty group for a major car manufacturer. He's also an SCCA club racer.

Assume that we don't have coilovers, so we can only adjust the ride height for BOTH wheels at a given end of a car together (ie with matched spring lengths).

Can relative ride height affect static weight distribution?
Theoretically or realistically?

My stance is NO. Corner jacking works because the diagonal wheels that you AREN'T adjusting form a fulcrum across which you can tip the load of the car's static weight. But if you're raising both the rear wheels (or, for the sake of argument, both wheels on one side) there is no geometrical fulcrum generated and the car simply rotates without changing the weight distribution.

Theoretically, if the CG is high enough above the axis of pitch, a small amount of weight shift might occur, but I maintain that this is negligible under any real circumstances and is in fact probably smaller than the margin of error of the scales themselves.

Am I correct?

Here's the answer I got:

I agree with [Duke's] comments. The effect of raising one whole end on net weight distribution is theoretically there, but minimal. Handling balance changes that occur due to altering the ride height at one end of the car are much more due to the ride height effects on roll center height. I'm not so sure GT4 simulates roll center movement.

 

[MADTJ]

OK! my engineer/racer friends have finally gotten a break in their season and had a chance to answer my question. The first quote is what I asked them; the second is the answer from a guy who is a chassis/suspension engineer in the specialty group for a major car manufacturer. He's also an SCCA club racer.

Here's the answer I got:

ok, thank you, i understand

 

[Ezz777]

seems that while "agreeing with Duke's comments" he is in fact saying that Duke's "stance" is wrong. interesting though. Perhaps if Duke hadn't put in both sides of the same argument it would have been a tad clearer.

So we now all agree that there will be a change in weight distribution when you change ride height!?!

 

[rk]

Bang: Over seven-tenths of a second faster, just like that, with the same near-neutral, near-perfect handling of the '03 car. The '04 is now faster than the '03.

I don't get it. What is going on here? The 80/80 setting is definitely better than 50/80, so why did PD drop the nose on the Playstation car?

The answer seems obvious to me, it is a "clue".
It is apparent that with all other settings at default, the 80/80 ride height works best. the setting of 50/80 seems more consistent with current real-world practice, so I doubt it is a ruse or oversight. It is my guess that it is there to indicate an ideal, or at least a direction toward which to apply settings. Again, rake is reflective of current racing practice, but, just as we tweak gears and dampers, the vehicle must be tuned or focused to apply the, if any, advantages of rake.

OK! my engineer/racer friends have finally gotten a break in their season and had a chance to answer my question. The first quote is what I asked them; the second is the answer from a guy who is a chassis/suspension engineer in the specialty group for a major car manufacturer. He's also an SCCA club racer.

Having considered myself quite versed in matters of geometry and objects physical properties, I was fully confident in my agreement with your position on static ride height as applies to weight distribution. When I performed my "famous" experiment, it was to soundly quell other posters' expressions to the contrary. I would observe that your racing friends meant "yes" when they said "very little", because they were considering the relative small angle changes assosciated with adjustments on cars they race. However, after spending almost $20 on postal scales and hanging an elaborate jig from the ceiling of my warehouse, I observed significant weight transfer when I took my "stick-as-car-chassis" and supported it from the "jacking stick" which had been attached to it throughout the experement. Because of the extreme length of the jack stick, the weight transfer appeared to be in the order of 50%, or half the value on the scale that was supporting the end to which the jack was attached. The original post that described my experement is #43
But please, Duke, my offer still stands, I would love it if you, or anyone else, proved my experement flawed.
Actually, the true question, I suppose, is: "How negligible is negligible?"

 

[Ezz777]

The answer seems obvious to me, it is a "clue".
It is apparent that with all other settings at default, the 80/80 ride height works best. the setting of 50/80 seems more consistent with current real-world practice, so I doubt it is a ruse or oversight. It is my guess that it is there to indicate an ideal, or at least a direction toward which to apply settings. Again, rake is reflective of current racing practice, but, just as we tweak gears and dampers, the vehicle must be tuned or focused to apply the, if any, advantages of rake.

It may well be a clue.

Lets just say that i definitely fit into the "'ye of little faith" category when it comes to consistency checking in the GT series.

Why then is this the only car (sorry probably not the only one - but i am not about to go and check every single one) that comes with a rake as its default susp setup? I guess i would love to believe that the PD guys would have actually done some testing on some of their default susp setups - but i can't help but feel that they don't do any. I don't claim to be a tuning expert, but the number of times i drive their default setups and can improve them straight away implies to me that they simply have a generic setup that they give to all similar cars regardless of their individual handling characteristics.

 

[Pink_the_Floyd]

Keep in mind, if you put the rear height to high, more weight will be transferd to the front wheels when braking which can result in more understeer.

 

[Duke]

seems that while "agreeing with Duke's comments" he is in fact saying that Duke's "stance" is wrong. interesting though. Perhaps if Duke hadn't put in both sides of the same argument it would have been a tad clearer.

So we now all agree that there will be a change in weight distribution when you change ride height!?!

What he's saying is what I said: while there is a theoretical change in weight distribution, in real terms it is a negligible amount.

 

[Zardoz]

The answer seems obvious to me, it is a "clue".

Might be just that. PD works in strange and mysterious ways, especially in GT4. Maybe they're dropping hints in lieu of providing documentation about how the game actually works...

 

[Ezz777]

What he's saying is what I said: while there is a theoretical change in weight distribution, in real terms it is a negligible amount.

Exactly - i was just clarifying for all those who may not have been following the thread. i guess the main cause for confusion was the fact that the 'expert dude' was responding to a message from you that mentioned both sides of the discussion. One side being your 'stance' whereby you stated that there wouldn't be a change in weight dist - which he disagreed with - and the other being your theoretical view (opposite to your stance) - which he agreed with.

I just hope its just a tad less muddy for anyone perusing the thread and trying to figure out what was going on...

 

[rk]

It may well be a clue.

Lets just say that i definitely fit into the "'ye of little faith" category when it comes to consistency checking in the GT series.

Why then is this the only car (sorry probably not the only one - but i am not about to go and check every single one) that comes with a rake as its default susp setup? I guess i would love to believe that the PD guys would have actually done some testing on some of their default susp setups - but i can't help but feel that they don't do any. I don't claim to be a tuning expert, but the number of times i drive their default setups and can improve them straight away implies to me that they simply have a generic setup that they give to all similar cars regardless of their individual handling characteristics.

There are other cars with default rake, granted, not many. the fact that all default suspensions can be improved upon is, to me, another facet of the clue. While I don't believe there is a generic set-up, I believe there is a function or formula with which they "de-tune" a car, which they do not apply to the arcade version. Not all arcade cars are superior either, while I prefer most, some definately defer to my own tune, among them the Pescarolo's and the Poly F1. If we had the values of the arcade cars tunes, it would help greatly to discover the reversable "de-tuning" formula.