"Secret Photos" of the 68 Petty Road Runner at the Daytona 500

[Budnicks]

I believe body template inspections are said to be a result of the 1966 Ford "Banana" of Junior Johnson.

View attachment 1872556

If it wasn't then &/or the 66-67 7/8:1 scale Chevelle by Smokey Yunick

 

[j-c-c-62]

But Nascar is reactive, seldom proactive, meaning the templates only showed up AFTER someone racing pushed the rules too far and others finally noticed and complained.

 

[Geff McCarthy]

underbody stramlining reduces drag greatly. Hence all contemporary cars have a frangible air dam under the bumper. I have trashed one on my Olds, now my Lincoln, on the standard height parking buffers.

 

[odcics2]

Another example of using rake to get laminar airflow over the backlight.

 

[j-c-c-62]

Another example of using rake to get laminar airflow over the backlight.
View attachment 1872670

1. This is the problem, your first "example" of laminar air flow is flawed, and not based on any evidence, you obviously cannot accept that.
2. This second "example" here of a race car a few years later shows a car with an improved back window solution and a car with greater static rake that unfortunately negates by a small amount the better windshield rake, but any laminar flow is likely still only fleeting
3. Linked is a wind tunnel test with smoke trails of a relatively modern Viper, and it is clearly obvious that no laminar flow is present in the rear window trunk area.
4. A well accepted rule of thumb in Aero design to maintain laminar air flow is the surface cannot depart from the path of the ambient airflow by MORE than 7 degrees. I can offer plenty of reference books to support that thinking or you can do your own research if in doubt.
There are cases where that is pushed to ten degrees, but is seldom ever a goal
5. I am going to guess your first flawed example of laminar air flow had a rear window angled in the 35 Degree range
I am also going to guess your second flawed example of laminar air flow had a rear window angled in the 25 Degree range
I'm going to guess the Viper rear window has a 20? degree angle.
6. This link shows laminar flow at approx a 5? Degree rear window trunk angle
https://www.shutterstock.com/shutte...re-conceptual-prototype-inside-1592564221.jpg

I however cannot put too much stock in the last pic here, although it shows the concept well. It appears maybe rather doctored as the smoke lines are too crisp, there appears to be zero turbulence mere feet from the tunnel, fan, and there is zero turbulence in the wake of the car.

 

[odcics2]

1. This is the problem, your first "example" of laminar air flow is flawed, and not based on any evidence, you obviously cannot accept that.
2. This second "example" here of a race car a few years later shows a car with an improved back window solution and a car with greater static rake that unfortunately negates by a small amount the better windshield rake, but any laminar flow is likely still only fleeting
3. Linked is a wind tunnel test with smoke trails of a relatively modern Viper, and it is clearly obvious that no laminar flow is present in the rear window trunk area.
4. A well accepted rule of thumb in Aero design to maintain laminar air flow is the surface cannot depart from the path of the ambient airflow by MORE than 7 degrees. I can offer plenty of reference books to support that thinking or you can do your own research if in doubt.
There are cases where that is pushed to ten degrees, but is seldom ever a goal
5. I am going to guess your first flawed example of laminar air flow had a rear window angled in the 35 Degree range
I am also going to guess your second flawed example of laminar air flow had a rear window angled in the 25 Degree range
I'm going to guess the Viper rear window has a 20? degree angle.
6. This link shows laminar flow at approx a 5? Degree rear window trunk angle
https://www.shutterstock.com/shutte...re-conceptual-prototype-inside-1592564221.jpg

I however cannot put too much stock in the last pic here, although it shows the concept well. It appears maybe rather doctored as the smoke lines are too crisp, there appears to be zero turbulence mere feet from the tunnel, fan, and there is zero turbulence in the wake of the car.

I’m going by what Gary Romberg told me. I don’t see why he’d lie about it. My friend Larry Rathgeb concurred.

 

[64BEL]

Here's an interesting video about the car in the race. The King stomping and hammering on the roof is an entertaining part.

 

[Photon440]

Petty himself said that he lowered the front end to get less wind under the car. There are NASCAR rules about minimum front end height, measured before each race. Richard found a way to cheat; he put a little plastic cup filled with hard grease between the torsion bar adjustment screw and the bar, keeping the front end high enough. After a couple of laps, the grease all squeezed out and the front end lowered down to where he wanted it. It wasn't measured again after the race.

 

[odcics2]

That Petty 68 Runner was a work of art.

 

[j-c-c-62]

I’m going by what Gary Romberg told me. I don’t see why he’d lie about it. My friend Larry Rathgeb concurred.

Nobody has said anybody lied. Lying in my book requires intent to mislead, etc.
If they said it, they are either misinformed or felt the subject was beyond the knowledge of their audience gave the simplest answer.
I don't know, not sure I care much, but I prefer to not read in the near future how everyone's rear mopar windows are the cat's meow with laminar air flow, or whatever. Aerodynamics is a very deep complex subject, and nobody knows hardly anything for certain, and why only testing always has the final say.

 

[j-c-c-62]

Here's an interesting video about the car in the race. The King stomping and hammering on the roof is an entertaining part.

I attended that race. Not sure if I arrived morning of the race or for a support race the day before. As a spectator in the infield, it was thought to be a vinyl roof, not paint. Communication/radio broadcast/Pa at the track was either nonexistent or very primitive.
The video shows RP on the hood trying to resolve the roof gap problem, I have not had a lot of experience with roof skins, but the way that roof flexed multiple times with only minor contact as RP was working on the gap, makes me wonder how viable is the extreme acid dipping theory on the matter.

 

[j-c-c-62]

Petty himself said that he lowered the front end to get less wind under the car. There are NASCAR rules about minimum front end height, measured before each race. Richard found a way to cheat; he put a little plastic cup filled with hard grease between the torsion bar adjustment screw and the bar, keeping the front end high enough. After a couple of laps, the grease all squeezed out and the front end lowered down to where he wanted it. It wasn't measured again after the race.

Years later it was reported some would freeze the shocks slightly extended and install at the last minute for the same result

 

[Kern Dog]

I don't know how "hard grease" could survive a single second with the weight of the car on it. I call bullshit.
More likely is solid plastic pieces that deformed or split with a little run time.

 

[Scott 70 GTX]

Check out the details of the slicked up Plymouth!
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[Scott 70 GTX]

I noticed some interesting stuff.
Torsion sway bar up front.
Electric fuel pump or just a filter.
Sitting high in the back for a track car.
The 3 RR’s on the C pillar.

 

[Photon440]

I don't know how "hard grease" could survive a single second with the weight of the car on it. I call bullshit.
More likely is solid plastic pieces that deformed or split with a little run time.

I wondered too, but that's just what Richard claimed.

 

[odcics2]

I heard about using a small rock in the torsion bar pivot. It would get crushed out after a few laps...
One each side, of course.

 

[Rennkafer]

I noticed some interesting stuff.
Torsion sway bar up front.

That's how most all sway bars work. That one is just custom fabbed and no doubt adjustable to remove any preload (and possibly change the rate, can't really see the end of the arm).