Nose Vibrating at Speed

[ed1948]

Under the front bumper where the nose clips on I can see that the plastic tabs have worn shiny areas from movement. I'll be taking it off and reassembling the front end. Do the plastic push through clips hold the plastic tightly because if I move the lower lip there is lots of movement? Wonder if screws should have been used?

Is there a purpose of the small deflector under the rad support because the nose lip is already doing the same function?

 

[axisg]

I was advised that those tabs are specifically there to allow the movement and if you were to bolt them down it could contribute to the nose warping. He also said they would tear on light impact with say a concrete parking block. Same with the tabs on the rear bumper. I will have to crawl under my car to check but I don't recall an air deflector under there.

 

[ck80]

Is there a purpose of the small deflector under the rad support because the nose lip is already doing the same function?

It is there to help force the air to pass through the condenser and radiator fins instead of passing underneath the car as a path of less resistance

 

[UNGN]

The core support air dam is the single best passive cooling aid on the car. When we first finished our 2+2 we were having cooling issues - we were using a viscous clutch fan and they would stop working from racing abuse and the car would overheat, even at speed. We extended the radiator support air dam with a piece of conveyer belt supported by spring steel brackets and all of the cooling problems disappeared.

This allowed us to cover the upper grills completely for aero.

 

[pontiacgp]

The core support air dam is the single best passive cooling aid on the car. When we first finished our 2+2 we were having cooling issues - we were using a viscous clutch fan and they would stop working from racing abuse and the car would overheat, even at speed. We extended the radiator support air dam with a piece of conveyer belt supported by spring steel brackets and all of the cooling problems disappeared.

This allowed us to cover the upper grills completely for aero.

just wondering why you cover the upper grills, we would cover the grills on our circle track sportsman and pro late model for qualification to increase the down force to help with planting the nose during corning.

 

[kalidromos13]

I'm guessing he covered the grill since the air dam provides a high?(correct me if I'm wrong) pressure point, so basically the fan just sucks up/ and or air is directed from the opening near the air dam, to the radiator. Since there is plenty of airflow through the air dam opening, you can cover the grill to help with aerodynamics. I had the same problem, the engine wouldn't overheat but it would go over 220 pretty easily and it would do it at speed. Ever since i put an air dam under it never goes past 220 on the gauge.

 

[UNGN]

Front end lift is a huge issue with most street cars designed before 2000 or so. Auto makers didn't think anyone needed to go 150 mph. Overdrive gears were weak and would break if you ran a car that fast for any length of time. 1990's/early 2000's C5 Corvettes, Mustangs, Trans ams, etc.... you name it, take them up to 165 mph and they will top out the springs.

Covering the upper grills on the 2+2 makes a bunch of downforce and makes the nose slghty lower at 165 than it is at rest, while the radiator support air dam keeps the motor @ 180 degrees.

I'm going about 165mph in these pictures:

You can tell how fast I'm going by how far the windows are blown out. They don't come off the seals until 140.

Here is a typical Mustang at the same speed trap going only 150mph:

and late 1990's Cobra:

And 4th gen F-body with a taped up nose:

None of these cars are accelerating, This is towards the end of a long straight and if anything, they are decelerating.


C5 corvette noses are higher than any of these above 160 mph.

Here is a Tom Whalen's C5-Z06:

Tom set the Overall Record at the Big Bend Open Road race in 2015, but when I originally showed him this picture back in 2008, he freaked out. He had no idea he was topping out the suspension @ 160 mph (at rest, the car is SLAMMED). He blocked off the grills and added an extractor hood and now it goes over 210 mph.

 

[kalidromos13]

Excellent description!! But damn that GP looks like it was meant to go fast!! I'm sure the OP has his answers now haha

 

[ed1948]

Thanks, I have the answer...no need for a speedo - just watch the side window gap: 1/4" = 100mph. 1/3" = 110. 1" = 140