Anyone notice this soft top "bulge"?

[DeathbyPatience]

Hey all,

I had recently gone wheelin with some buddies and a photographer and I got some pictures of my truck driving on the freeway. I was driving at about 70 mph when these were taken and couldnt help but notice the bulge on the front portion of the soft top. When im stationary, theres some decent play in the soft top along the front portion which sits right behind the main support that connects to the frame. I've noticed that at speeds probably over 50mph, the top has some sort of air pocket wich makes it taught in a position similar to a bubble.

I just wanted to know if thats normal or if there is supposed to be some type of support which resricts the front end of the top from creating this extra drag.

Thanks in advance.

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[TantoIndian]

Wonder if that's a thing with soft tops?
I have a soft top as well, but I guess since I am driving , I never noticed from the inside

 

[chancewm]

Just spitballing here, but from an aerodynamics standpoint, that windshield would create a fair amount of turbulence in that area, so I'm guessing it's just the slack of the soft top being pulled up by that turbulence.

Or I'm full of it. Both are possible, and not mutually exclusive.

 

[1970AMCAMX]

Just spitballing here, but from an aerodynamics standpoint, that windshield would create a fair amount of turbulence in that area, so I'm guessing it's just the slack of the soft top being pulled up by that turbulence.

Or I'm full of it. Both are possible, and not mutually exclusive.

Pretty good spitball there, the combination of the windshield angle and the transition of the windshield to the top results in a low-pressure area over the front portion of the top resulting in the top lifting.

 

[BrentC]

The bulge is inevitable due to lift being generated on that trailing edge of the windscreen. The bulge doesn’t flap, meaning there’s no buffeting in this area, which is good.

I have been in severe winds with my soft top and not had any buffeting issues. I think it’s very well designed.

 

[66GT]

Hey all,

I had recently gone wheelin with some buddies and a photographer and I got some pictures of my truck driving on the freeway. I was driving at about 70 mph when these were taken and couldnt help but notice the bulge on the front portion of the soft top. When im stationary, theres some decent play in the soft top along the front portion which sits right behind the main support that connects to the frame. I've noticed that at speeds probably over 50mph, the top has some sort of air pocket wich makes it taught in a position similar to a bubble.

I just wanted to know if thats normal or if there is supposed to be some type of support which resricts the front end of the top from creating this extra drag.

Thanks in advance.

Aerodynamic lift. It's what makes planes fly.

 

[JT58Bronc]

I see most convertible tops bulge outwards on the highway. The bigger the top, usually the more the bulge.

 

[Adumb]

Its just what happens when your Bronco gets excited. I know it can be embarrassing, but its completely natural and you shouldn't worry about it.

 

[Shenanigans]

Had the same thing on my Jeep running with AC. Just crack a window and your outie will become an innie. I always worried the bulge would stretch out the top making it a little flaccid.

 

[AK SNO RIDER]

The bulge is inevitable due to lift being generated on that trailing edge of the windscreen. The bulge doesn’t flap, meaning there’s no buffeting in this area, which is good.

I have been in severe winds with my soft top and not had any buffeting issues. I think it’s very well designed.

There's actually severe buffeting in that area on the hard top with just the front seat panels removed.

To the point that I rarely run the highway with only the fronts off. I'll pull the mid section too so it's more pleasant.

 

[ou812545]

Mine has a dip. Anyone else's top have this same dip?

 

[BrentC]

There's actually severe buffeting in that area on the hard top with just the front seat panels removed.

To the point that I rarely run the highway with only the fronts off. I'll pull the mid section too so it's more pleasant.

Interesting characteristics. I have been running around town lately with the soft top in the fully retracted position, and have noticed I get an annoying exhaust resonance inside the cab with the side windows up. I can get it from my Bronco in a parkade, and have noticed it when behind a bus or big V8 at a light.

On the other hand, I can get bad buffeting inside my F150 cab with various openings of the windows and sunroof, and find I can cancel it all out by adding small openings on the rear windows and/or back window.

I love fluid dynamics - it was my best class in mechanical engineering back in the Jurassic when I was in school…

 

[hkbooner]

If something you can't see bothers you then you may have to seek some therapy or just just sell your Bronco.

Pretty sure OP was NOT going this direction in his post...

 

[palley6]

Mine has a dip. Anyone else's top have this same dip?

Definitely have this on mine

 

[66GT]

Had the same thing on my Jeep running with AC. Just crack a window and your outie will become an innie. I always worried the bulge would stretch out the top making it a little flaccid.

Stretching the fabric won't make it go flaccid in the long run. You're good.

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