Slightly O/T NASCAR question

[jaybee]

I wasn't quite sure where to go with this one. The NASCAR fan board I frequent has virtually NO interest in technical topics (very frustrating) and this is a little too technical for the other Street Rod and specialty car boards I frequent. My subject pertains to the new "Car of Tomorrow", which Hendrick Motor Sports is using to dominate this year's points battle. I won't bash them for spending up to 10 times what the other major teams spent on early development, if you can get your hands on the cash that's what you do to win races. Obviously that money bought them something that no one else has figured out, but what? I now have a theory and want to see if it makes sense. On Sundays telecast the broadcast team were talking about how the new car has a much higher center of gravity and rolls much faster in turn in than the old car. Observationally, it seems like the teams are having trouble with losing control just as they start the turn in or just as they get on the throttle, not through the center when the suspension is normally in coil bind on oval tracks. My guess is that there's something about the camber curve, bump steer, or similar that causes instability as the car goes in and out of coil bind. That's rather long winded, but does it sound plausible?

[Project69]

Yea this belongs in Advance tech. section.

What you want is beyond mere average joe shmoe tech. knowledge.

[derekf]

I don't have the answer, but I'll be subscribing to this thread. Thanks for asking.

[High Plains Mopars]

Well, going into coil bind eliminates your suspension and makes your sprring rate go to infinifty which quickley makes you loose control. These cars are not going into coil bind now and haven't anytime in the modern area. That would be becoup bad engineering if they did.

I think it simply is driver familiarity. These guys have spent most their competitive life piloting vehicles that were not radically disimilar in roll center height, CGH, roll axis, weight, aero, or most other factors. Now they are. They are adjusting to the new feel. Kinda like open wheel drivers in IROC.

No mention of tires here either. Has NASCAR mandated a new compound for the COT?

[jaybee]

Actually HPM, they are using coil bind on the front end during cornering and have been for the last several years. The front valance or splitter is positioned to be just clear of the track at full compression in order to get maximum downforce. Then under acceleration the front end comes up several inches. I suppose they get away with it because they have tires with a lot of sidewall, very smooth tracks, and not a lot of variety in corners. Consider how little suspension travel is in a top-tier open wheel car like IRL or Champ Car, their suspension is very close to solid.

[Norm Peterson]

I thought the COT had got them AWAY from a coil-bind situation on the front end. The big-bar/soft-spring approach had been all the rage lately, along with whatever shock technology they could get away with. All for aerodynamic reasons, BTW, let the car ride as low (at the front in particular) as you can get it to after passing tech and the templates - and make up the necessary roll resistance with a huge sta-bar.

And that brings up the aero part of the problem. Seems the change from an air dam plus a spoiler to a splitter and a wing did not affect the two ends equally or proportionately. Tuning the wing angle for aero balance appears to have removed too much rear downforce for the available braking. I'll have to point to the Watkins Glen race and all the commotion that happened on the entry to Turn 1, though I think there was a bit of brake hop involved there as well.


Norm

[jaybee]

Norm, I dunno but they still talk about coil-bind setups on the broadcasts. I think you're right about the aero balance being off. Could be part of the plan is to NOT give them enough rear downforce to use all the front downforce that's achievable. If that's the case but the mindset is still to maximize front downforce and work all the other variables around that it could be a problem. The "aero push" problem that has been the bane of good racing for the past 2-3 years seems to have almost completely disappeared with the COT. To me that says the car isn't so aero-dependent (one of the stated goals of the new car), the car manages air in such a way that it's less affected by dirty air, or there's enough downforce that it just isn't an issue. I have no idea which.

[RaceMan]

There's alot to it !! The high center of gravity plus the aero balance ,. The higher you hold something up in the air(taller car) the harder it is to balance. Trying to get it all to work together with new starting points is not easy!!! Henderick just spent alittle more $$$ and time on it !!

[terryr]

They're using soft springs in the front but still have stiff ones in the rear, for whatever reason. This makes the rear stay up at speed.
I just read an article on this but can't remember where.

This type of wing/splitter aero was used for years in other types of racing. Perhaps Henderick just has some more experienced people.

[68fusion]

coil bind with the tire acting as your spring?...1lb equals 50 or 25 lbs of rate.
Most teams use the 7post to "test" setups under track conditions. Nascar is an "information" game,(like most $sports) the more you have the better you'll run.Put the right people and information together and you win championships. Big dollar amounts do not mean automatic success.