Overton's rr

[ZERO25]

Its quite a bit lower in dynamic than the others. I talked to two other national LH drivers, they said they see it but cant figure it out!

[MasterSbilt_Racer]

If all you do is lower the rr, car gonna wheelie.

[95shaw]

The real needed information needed is the contact patch pressure at all 4 wheels at a specific dynamic point in question.

Travel needed to provide those weights can be achieved by any number of methods.

Is this actually better because of the method used to achieve this attitude?

[Austin34471]

The real needed information needed is the contact patch pressure at all 4 wheels at a specific dynamic point in question.

Travel needed to provide those weights can be achieved by any number of methods.

Is this actually better because of the method used to achieve this attitude?

This is very very much not how it works. With the tools we have, it impossible to calculate how much weight is on all 4 tires. Maybe Ghopper is getting close to simulating it, but linear shock positions tell you very little about how much weight is on said tire.

[95shaw]

This is very very much not how it works. With the tools we have, it impossible to calculate how much weight is on all 4 tires. Maybe Ghopper is getting close to simulating it, but linear shock positions tell you very little about how much weight is on said tire.

That was my point. There is no way of knowing the weights on the tires by simply looking at the attitude of the car.

Any mix of springs j bar settings, control arm positions, etc, can alter the actual dynamic weight seen by the contact patch.
Trying to equate attitude with some specific handling characteristics is fruitless.

[Austin34471]

That was my point. There is no way of knowing the weights on the tires by simply looking at the attitude of the car.

Any mix of springs j bar settings, control arm positions, etc, can alter the actual dynamic weight seen by the contact patch.
Trying to equate attitude with some specific handling characteristics is fruitless.

I see. I thought you were saying that spring loads at certain positions were representative of how much weight was on the tire. Your last paragraph is spot on.

[billetbirdcage]

This is very very much not how it works. With the tools we have, it impossible to calculate how much weight is on all 4 tires. Maybe Ghopper is getting close to simulating it, but linear shock positions tell you very little about how much weight is on said tire.

Blasphemy

You mean if I increase the droop load on my LR shock at full extention by 200#, I'm not adding 200# more to the LR tire while going around the track?

Hmmm, who would of thunk . . . next your gonna say that LR weight highly varies with the banking of the track too I suppose.

^all sarcasm^

[ZERO25]

Trying to equate attitude with some specific handling characteristics is fruitless.

So you dont agree that Overtons car has more rear aero downforce?

[95shaw]

Trying to equate attitude with some specific handling characteristics is fruitless.

So you dont agree that Overtons car has more rear aero downforce?

I'm saying I can set the rr bars and bury the right quarter panel of the body into the track.

Does that mean there is more aero downforce?
I'm not feeling it

[Ghopper]

Better description: "more body roll, less body pitch compared to other generally fast Longhorn cars."

This helps you look past the narrowly focused discussion about RR components and move on to system level response....that includes the resulting LF response and a few parts in between.

[95shaw]

Better description: "more body roll, less body pitch compared to other generally fast Longhorn cars."

This helps you look past the narrowly focused discussion about RR components and move on to system level response....that includes the resulting LF response and a few parts in between.

I think I understand what you are saying.

I know the RR tire is loaded by not only the RR spring and bars, but also the LR spring and bars, the j bar, and the lift arm. Any aero loads are applied to the contact patch through these routes.
Not knowing if the setup is exactly the same as the other cars, there is no way to know the contact patch pressure on any of the tires.

I realize that geometry changes loading as well, so travel at other corners has a bearing in relation to timing of weight transfer, making the LF important, especially at turn in, which sets up the whole corner.

I cannot see how blindly assessing visual cues can deliver useful data without knowing more of the picture.

[MasterSbilt_Racer]

I think I understand what you are saying.

I know the RR tire is loaded by not only the RR spring and bars, but also the LR spring and bars, the j bar, and the lift arm. Any aero loads are applied to the contact patch through these routes.
Not knowing if the setup is exactly the same as the other cars, there is no way to know the contact patch pressure on any of the tires.

I realize that geometry changes loading as well, so travel at other corners has a bearing in relation to timing of weight transfer, making the LF important, especially at turn in, which sets up the whole corner.

I cannot see how blindly assessing visual cues can deliver useful data without knowing more of the picture.

He's just better articulating what I said with my one sentence earlier in the thread (post2). Looking at the rr is like looking at an average height tree in the forest. It isn't half the story, nor do I think it's even much of the story. The pitch comment is the key to the whole analysis, IMO. I didn't want to go as far as to directly point that out.

[ZERO25]

He's just better articulating what I said with my one sentence earlier in the thread (post2). Looking at the rr is like looking at an average height tree in the forest. It isn't half the story, nor do I think it's even much of the story. The pitch comment is the key to the whole analysis, IMO. I didn't want to go as far as to directly point that out.

Rumley must not have a degree in forestry!

[95shaw]

Rumley's most notorious achievement came before the cars were on bump stops on the rf, and chain limiters on the lr.
As was indicated in a couple posts before, rr height is mostly dictated by chain length and stop rubber spring rate and height.
With both of these at their physical limits the car teeters toward lf or rr.
Lift arm and j bar can affect which of these car teeters toward. CG height and position as well as rr and lf spring rates also have an effect.
I guess we should throw tethers in there as well.

I'm not certain aero plays as much of a factor as some would let on

[MasterSbilt_Racer]

Rumley's most notorious achievement came before the cars were on bump stops on the rf, and chain limiters on the lr.
As was indicated in a couple posts before, rr height is mostly dictated by chain length and stop rubber spring rate and height.
With both of these at their physical limits the car teeters toward lf or rr.
Lift arm and j bar can affect which of these car teeters toward. CG height and position as well as rr and lf spring rates also have an effect.
I guess we should throw tethers in there as well.

I'm not certain aero plays as much of a factor as some would let on

Hold on. Guys been running bumps for like 15 to 20 years, depending on what percentage of the field makes it count.

The car doesn't have to teeter between any two points. Most do teeter lf to rr, however.