BiWings Function ?

[Daytonatunnel]

Was it for appearance only, or does it do anything ?

[NOTACARLO]

I think it essentially acts as a diffuser, cutting the negative pressure behind the car so there's less drag from the rear. Not used for any type of down force.


I could be wrong, but it's entirely to flimsy even in perfect condition to push down on the rear of the car at speed.

[Daytonatunnel]

Just curious why it's there ? Thanks for some insight !!!

[gbeaird]

Probably for that 'Euro' look, as the Merkur of the era also had them. Additionally, it may have been to further distinguish the SVO from a standard Mustang.

I've seen no reports published on and aero the wing provides. As others have mentioned, it's probably minimal, but may actually cut the lift across the back of the hatch, which would make the car more stable at speed.

[86XR4Ti5SPD]

I can tell you with the XR4, the bi-wing did make it a little slipperier. When they went to the single deck lid piece in '88, the Cd went up some.

[svono50]

I think I remember reading something that stated the upper bi-wing gave ~50lbs of downforce to the rear at 100mph, but don't take my word for it. If it really does, I think you would see the wing sag quite drastically when you get up in speed. More than likely a marketing pitch to help sell the bi-wing's effectiveness.

[Horsewidower]

To hold your gas cap when you get gas, or your beer while you're waxing the paint.

[gbeaird]

It's what you tape the speeding tickets to. ;-)

[CP86SVO]

I think I remember reading something that stated the upper bi-wing gave ~50lbs of downforce to the rear at 100mph, but don't take my word for it. If it really does, I think you would see the wing sag quite drastically when you get up in speed.

It does...for me

At about 100 mph, that's exactly what I noticed. Up to that point, I remember
seeing the upper wing bouncing around at bit; over 100 mph, I can feel
the rear end getting a bit heavier in feeling and the rear wing bows in the middle and stops bouncing.

Much more noticeable with a stockish suspension too.

HTH

[4themasses]

To hold your gas cap when you get gas, or your beer while you're waxing the paint.

EXACTLY!! LOL

I was hoping someone would get all german engineering on this and make it like the Porsche and have it kick out at higher speeds.

Now THAT would be cool!

[Billibew]

According to the book Mustang Forty Years by Randy Leffingwell. "A feature exclusiveto the Mustang SVO was the bi-level rear wing assembly, which was effective in generating -0.011 lift versus +0.085 for a base Mustang. The top wing was designed to spill the airflow rearward, so that the air would tumble onto the rear lip of the lower wing and push the vehicle down, improve gas mileage." Page 294 side note of associated picture on that page.

Further interest on page 301. "Then there was the controversial bi-plane rear wing. A drag racer from the 1960's named Al Turner was involved in the grass-roots racing promotions that SVO was doing as part of Ford Motor Sports efforts. Turner had spent time in Europe and Australia for Ford, and he was familiar with Ford of Europe's Sierra XR-4i sports coupe series that wore a distinctive two-level rear spoiler. He recommendeded it and pushed hard for its adoption to the Mustang. Older staffers within SVO who had witnessed the distinctive grille of the Edsel warned Turner that high-visiblility features could hurt a car as much as help. After toning down the spoiler design from the Sierra (on which the top wing was aligned level with the roof line), everyone finally agreed that it probably did fit the GT image, even though it never would be appropriate for the tire-squealers."

I hope this helps. By the way this is a great book to have around for all Mustang enthusiasts.

[86XR4Ti5SPD]

After toning down the spoiler design from the Sierra (on which the top wing was aligned level with the roof line), everyone finally agreed that it probably did fit the GT image...

Good info, except for the incorrect description of the Sierra spoiler, which carried over to the XR4Ti here.

[Turbodog]

I had my upper wing off while repairing it from a crack. after re-install and bi-wing supports added, I could tell right away that the car was more stable at speed.