You ever pay attention to them?

They really are very interesting. To a race car driver. Yes.

Watch them going down the highway unloaded. That's easy to spot because they're bouncing up and down on their tires.

Watch the loaded ones too. Looks a little different eh?

And how'zit relate?

What's the limit on our spring rates? It's the tires own spring rate. And the rigidity of our chassis.

Ok, so where's the limit? How does one "calculate it"?

You don't. Tire spring rates are not fixed things - they vary with pressure, load, and speed.

All you can do is test.

I'm hoping to test my new setup next week. It's 1400F/1600R, no front bar, 32mm rear bar. I used my ICP chassis worksheet to model the relative front/rear roll stiffness and it's within a percent or two of my old setup.

I have no idea if I will be too close to the unloaded dump truck end of the spectrum - but it should be real interesting.

For what it's worth, alot of racing ITR's have run the LS front bar. The wheel rate contribution of this bar in roll is 32 lbs/in. You can appreciate why I considered it reasonable to delete it.

Scott, who's second biggest fear (after it simply not working out at all) is that it will work at Portland, but not at Seattle...

 

Actually, the tire spring rate is DIRECTLY related to tire pressure. That's it. Think of it as an air spring in series with the regular spring.

 

A dump truck?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MightyMouseTech &raquo;</TD></TR><TR><TD CLASS="quote">Actually, the tire spring rate is DIRECTLY related to tire pressure. That's it. Think of it as an air spring in series with the regular spring.</TD></TR></TABLE>

Sorry - the tire company engineers that share data with Real "Real Racers" tell them what I told you.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">

Sorry - the tire company engineers that share data with Real "Real Racers" tell them what I told you.

</TD></TR></TABLE>

Hmm, interesting, will have to investigate more..........

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">

Sorry - the tire company engineers that share data with Real "Real Racers" tell them what I told you.

</TD></TR></TABLE>

They behave more like a spring/absorber combo than just an undamped spring, no?

 

They've got some inherent damping - friction in the carcass, etc - so yeah.

But, as to the tire rate itself, it's so continuously variable in operation that one can only find an overall compromise of the rest of the setup around whatever the tire envelope happens to be.

I was thinking about it this way this morning: Our tires are hot and very sticky. We are taught to think about tire force variation (undesirable preventable excessive amounts of it) as an enemy to be combatted. But within the range of "stick", how far can we push tire force variation before our lap times start going the other way?

When you start splitting these little hairs for the last of the diminishing returns, you're deep into the seat of the pants and the stopwatch.

Scott, who fortunately knows little of such things...I just want my kaa slammed the most so it looks badass....

 

How much will the rear bar be contributing with such high rear spring rates?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">
I'm hoping to test my new setup next week. It's 1400F/1600R, no front bar, 32mm rear bar. </TD></TR></TABLE>

1400F/1600R Are switching to a the thicker, rubber diaper to help absorb those rates?

When are you testing Scott?

 

The rear wheel rate from the springs is 880, and the rear wheel rate from the bar is 540.

The ICP spreadsheet doesn't do the full dynamic model, so I don't have a value for the amount of load transferred by the bar itself.

But, crudely, the load transfer proportion should match the wheel rate proportion, so maybe the bar transfers 300lbs.

My old setup 1100R with Mugen 26mm bar had wheel rate from spring of 600, and wheel rate from bar of 411 - with the bar then transferring 340lbs.

*Disclaimer: These values are crude approximations! Why, there may even be errors in thinking represented here too! Don't try this at home. And if you do don't do it in drag and get caught by your wife!

Scott, who doesn't want to be too numeric..."Math is Hard!"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">
... 32mm rear bar.
</TD></TR></TABLE>

Holy swaybar girth, Batman. Got any pics of your subframe mounts? I'd be interested to see what you've got going on down there, if it doesn't reveal too many of your go phast secrets.

Casey, never knew they made 'em "that big" for our kaas

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bulldog_RS20 &raquo;</TD></TR><TR><TD CLASS="quote">

1400F/1600R Are switching to a the thicker, rubber diaper to help absorb those rates?

When are you testing Scott?</TD></TR></TABLE>

Since I quit eating those new PotatoE Chips cooked in that miracle oil those problems are "behind me".

Next Friday - Lotus Club.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Neo &raquo;</TD></TR><TR><TD CLASS="quote">
I'd be interested to see what you've got going on down there...</TD></TR></TABLE>

How can I say no to THAT!

I'll post some pics next week - when it's all done.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">
How can I say no to THAT!
</TD></TR></TABLE>

You've already mentioned your relatively big unit, so that won't surprise us.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">
I'll post some pics next week - when it's all done.</TD></TR></TABLE>

T'would be great. Good luck w/ the big 'speriment.

 

Any worries in bending stuff if j00 go offroading with such rates?

 

"What? Me go off?"

Really don't know.

But it's kinda like going from 10 to 11 anyway.

Scott, who's "really looking forward" to running over the curbing in Portlands old T7 with the new setup. Gawd I hope it doesn't just skate.

 

cool

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">

I'm hoping to test my new setup next week. It's 1400F/1600R, no front bar, 32mm rear bar. I used my ICP chassis worksheet to model the relative front/rear roll stiffness and it's within a percent or two of my old setup.

</TD></TR></TABLE>

Is a 32mm bar a hollow nascar type bar? Can you post pictures?

Are you still running the mugens with those rates?

 

Yeah, Speedway 1.25 with .125 wall, 40.5 long.

Yeah, still using the Mugen N1's.

We'll see.

Scott, who asked the other Scott...I NEVER take his advice first time...I like to come around to taking it in my own sweet time...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">Yeah, Speedway 1.25 with .125 wall, 40.5 long.
</TD></TR></TABLE>

Cool

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">
Yeah, still using the Mugen N1's.
</TD></TR></TABLE>

Man those shocks have had a long life You must treat them nice with a rebuild here and there

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote"> Gawd I hope it doesn't just skate.</TD></TR></TABLE>

You could try taking it at a few ticks under light speed the first few times through there.... just to get a feel.

John, who kept thinking about my wife and mortality as I was riding with Scott one day not so long ago.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by johng &raquo;</TD></TR><TR><TD CLASS="quote">John, who kept thinking about my wife and mortality as I was riding with Scott one day not so long ago.</TD></TR></TABLE>

you obviously haven't been married long enough... Last time I rode fast with a fast driver was with Corey in his father's WRX. Sliding through 10 at Summit. As I recall, my wife was not on my brain, or anywhere near it. As best as I can remember that was the thought:

"YEEEEEHAAAAAAA!"

more or less.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">A dump truck?

</TD></TR></TABLE>


lol, that dump truck has NAWS y0!! (NOS)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr. Teal &raquo;</TD></TR><TR><TD CLASS="quote">


lol, that dump truck has NAWS y0!! (NOS)</TD></TR></TABLE>

Thanks Captain Obvious!

Is the sky blue in that picture? huhu

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr. Teal &raquo;</TD></TR><TR><TD CLASS="quote">


lol, that dump truck has NAWS y0!! (NOS)</TD></TR></TABLE>

OMG, y'all are killing me. Did we all wake up this morning and take a stupid pill instead of our vitamins?

That is not a dump truck. That is a garbage truck/trash hauler.

This, for the record, is a dump truck.



Casey, who knows the difference between dump and trash