[BiscuitMan]

Jeff Gordon, Denny Hamlin, Kurt Busch and Kyle Bush all are questioning the way Roush is adjusting the rear housing on Carl Edwards' #99 Ford to create a competitive advantage. Many in the garage said during testing at Lowe's earlier this week that the yaw created. Edwards' car appears to be going sideways on the straightaway, creating more side force heading into the turns by turning the rear housing to the right gives Edwards a competitive advantage.

Drivers noticed something different in the way Edwards' car traveled early in the season. Denny Hamlin said it was "yawed" out and could go places he couldn't.

NASCAR already has a rule restricting more than a quarter-inch change plus or minus to adjust the housing. Friday, the announcers on the Darlington practice show commented about the way a lot of the cars looked like they were going sideways down the straightaway. To me it looks like more than a quarter inch adjustment. However, the people at Roush may have figured out a way to build the “yaw” effect into the chassis.

I’ve used this adjustment on quarter mile short tracks to make the car turn. It’s like a “rear steer” effect. But at high speeds, evidently aerodynamic allows the side force to help turn the car. Now all the other competitors are trying to use this adjustment.

NASCAR said there are no plans to further police the rear housing adjustment

[Phils20]

You know, I thought it was just a trick of the light, but I was thinking the cars were "crabbing" a bit as they were showing them head on taking the flag.

I hope they don't allow the teams to start twisting these cars up.

If we can see it on TV, NASCAR has to see it.

If true, write the rule and stop it now, or we'll have more tweaks found.

[Racer Duck]

If the rear end is over the maximum yaw adjustment, it's a rule violation. But I don't think that's what's going on.

Consider this: what if the the rear end has been "offset" to the right and the body "adjusted" to match the rear end offset. That would provide additional performance advantages: not much, but then in the Cup series a little bit can be the difference between 1st and 10th!!! It would also cause the car to appear to "crab"...

[Quality88]

Originally Posted by Racer Duck

If the rear end is over the maximum yaw adjustment, it's a rule violation. But I don't think that's what's going on.

Consider this: what if the the rear end has been "offset" to the right and the body "adjusted" to match the rear end offset. That would provide additional performance advantages: not much, but then in the Cup series a little bit can be the difference between 1st and 10th!!! It would also cause the car to appear to "crab"...

Oh boy... here we go again, I feel another gray area infringment comin on.

[Mudbug]

Originally Posted by Racer Duck

If the rear end is over the maximum yaw adjustment, it's a rule violation. But I don't think that's what's going on.

Consider this: what if the the rear end has been "offset" to the right and the body "adjusted" to match the rear end offset. That would provide additional performance advantages: not much, but then in the Cup series a little bit can be the difference between 1st and 10th!!! It would also cause the car to appear to "crab"...

That a great piont an may be whats going on. Like you said a few tenths means a few spots. I guess we will have to wait & see.

[Bob Tanner]

Originally Posted by Racer Duck

If the rear end is over the maximum yaw adjustment, it's a rule violation. But I don't think that's what's going on.

Consider this: what if the the rear end has been "offset" to the right and the body "adjusted" to match the rear end offset. That would provide additional performance advantages: not much, but then in the Cup series a little bit can be the difference between 1st and 10th!!! It would also cause the car to appear to "crab"...

A question: I see what you're saying and understand but... IF the off set was so much that it could be visually seen then how would the car meet all the templates. The templates are part of a stationary machine and from what I understand the car is pushed under the machine the then the templates are dropped on the car and it either matches or doesn't. Unless there is a lot of flexibility in the template movement i seems to me that this trick would be caught quickly.

[Racer Duck]

Originally Posted by Bob Tanner

A question: I see what you're saying and understand but... IF the off set was so much that it could be visually seen then how would the car meet all the templates. The templates are part of a stationary machine and from what I understand the car is pushed under the machine the then the templates are dropped on the car and it either matches or doesn't. Unless there is a lot of flexibility in the template movement i seems to me that this trick would be caught quickly.

Bob. I'm surprised you let a detail slip past you so easily: how perfectly do you think 43 different teams could push 43 different cars under a stationary template? Of course the template needs to be able to move around .. otherwise tech would take an extremely long time just because of the difficulty in lining up the car perfectly with the template.

The template checks the body and wheels from reference point to reference point.

The only way to statically check yaw is to identify a set of frame reference points and measure from there. And since each chassis manufacturer is free to "adjust" their frame within certain tolerances, it's darn near impossible to detect which adjustment produces yaw.

Conventional wisdom dictates the smallest head-on profile is the most aerodynamic. However, I did notice in tonight's race several cars that seemed to "crab" down the straights - mostly Roush cars - who seemed to be handling the aero problems well. It may be that ole Jack discovered some aero quirk on a level with say, propeller anti-cavitation on submarines, that is giving his cars an aero advantage over the 'Yota's power.

And, as a former racer, you should know all to well that racers are quick to spot "inconsistencies" in their world and to copy them if the inconsistency seems to have some sort of performance advantage .. whether real or imagined.



A quick story about racers and copying: back in '69 my brother started using white silicone sealant in place of the rubber gaskets under the intake manifold that never seemed to seal right on the chevy engine. One night a fellow racer was peering into our engine compartment while my brother was checking the spark plugs and saw the white "stuff". When he asked what it was, my brother looked at him and said "Speed secret." Then he made him promise not to tell anyone. The racer quickly agreed, and my brother leaned over and whispered "Tooth paste". The next week the racer showed up at the track with tooth paste sealing his intake to the block .. and it melted as soon as the engine got warm... We all had a big laugh over that one. Then my brother pulled out the white silicone and fixed the guy's oil leak! He still hung around our car a lot after that, but was a lot more cautious about believing anything we said.

[Bob Tanner]

Originally Posted by Racer Duck

Bob. I'm surprised you let a detail slip past you so easily: how perfectly do you think 43 different teams could push 43 different cars under a stationary template? Of course the template needs to be able to move around .. otherwise tech would take an extremely long time just because of the difficulty in lining up the car perfectly with the template.

The template checks the body and wheels from reference point to reference point.

<slap!> Thanks. I needed that.

Your point is well taken. I just plain blew that one.

[DOF_power]

So another case of the "unfair advantage" that breaks "the spirit of rule" but not the letter of the rule.
That's what every self respecting bunch of engineers/mechanics/designers have done since ... the beginning of motor-racing.

[clutch]

Originally Posted by Racer Duck

The template checks the body and wheels from reference point to reference point.

I'd like to know where are all these reference points ...how many, how far apart etc..
obviously he is within Nascar rules as they are quite aware of the situation and the crying from some of the stars...

I'm still not convinced you can manipulate the body too much

[Quality88]

Originally Posted by Racer Duck

A quick story about racers and copying: back in '69 my brother started using white silicone sealant in place of the rubber gaskets under the intake manifold that never seemed to seal right on the chevy engine.

Hmmm, we use the black gasket silicone at work on alot of sealed chevy engines we put out at work.

[Bob Tanner]

After reading this thread prior to the race I couldn't help but look closely to see if the cars were "crabbing" down the straight. Maybe it was just the camera angle but it sure looked like the Hendrick cars and the Roush cars were at a slight angle?

[BiscuitMan]

Originally Posted by Bob Tanner

After reading this thread prior to the race I couldn't help but look closely to see if the cars were "crabbing" down the straight. Maybe it was just the camera angle but it sure looked like the Hendrick cars and the Roush cars were at a slight angle?

I think the secret is out in the open and nearly every team has incorporated some form of rear housing adjustment and/or positioning to take advantage of this phenomenon.

[Racer Duck]

Originally Posted by Quality88

Hmmm, we use the black gasket silicone at work on alot of sealed chevy engines we put out at work.

back in '69 there weren't a lot of color choices...

today we use black or red "RTV", depending on anticipated heating.

Originally Posted by BiscuitMan

I think the secret is out in the open and nearly every team has incorporated some form of rear housing adjustment and/or positioning to take advantage of this phenomenon.

like I said, racers are very quick to copy something they think is an advantage. the "engineers" are, most likely, studying this and will report the "technical" ramifications in due time...

Originally Posted by clutch

I'd like to know where are all these reference points ...how many, how far apart etc..
obviously he is within Nascar rules as they are quite aware of the situation and the crying from some of the stars...

I'm still not convinced you can manipulate the body too much

If you had your 2008 NASCAR Rulebook, you'd have all the information. You did get yours this year, didn't you?

If you shift the front to the left, say, half an inch to an inch and the rear the same amount to the right, you will have moved the body very little, but the aero effects could be tremendous and the "yaw" would be visible when in motion.