Wayne,
Your reasoning is correct. I would prefer the better handling than the
milage.
>
>
> > You can lower th front and raise the rear
> >
> > On Thu, Sep 3, 2009 at 8:52 AM, Wayne Barratt
> >
> > >
> > >
> > > Legitamate ways to reduce drag on a GMC Motorhome.
> > >
> > > Install a front spoiler or air dam, the largest you can find that will
> > > still give you adequate ground clearance. This will reduce airflow
> under the
> > > vehicle which would otherwise swirl around on components that hang down
> > > under the vehicle causing drag. Some sort of undertray or belly pan may
> also
> > > help with this problem.
> > > Nascar race cars even haved smoothed and boxed lower A arms on there
> > > suspension to lower underbody drag.
> > >
> > > Reducing frontal area of the vehicle would also help, fitting the
> smallest
> > > mirrors you could comfortably see out of and removing all the ladder,
> A/C
> > > roof boxes would also help.
> > >
> > > Fitting flush wheel covers would work also.
> > >
> > > Doing all of the above would undoubtedly lower the Cd of the motorhome
> and
> > > give slightly better MPG,but at the expense of Comfort (no roof AC)
> > > Convenience (no roof pod) Safety (small mirrors) Ground clearance
> (spoiler)
> > > --
> > > 1976 23' GMCII By Explorer
> > > _______________________________________________
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> > >
> >
> >
> >
> > --
> > Jim Kanomata
> > Applied/GMC, Fremont,CA
> > jimk
> >
http://www.appliedgmc.com
> > 1-800-752-7502
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> >
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>
>
> Hi Jim,
> I know lowering the front and raising the rear of a sedan or hatch back has
> been proven to reduce drag on production based race cars (like mine), but I
> am unsure how it would pan out on a vehicle with a very long roof like the
> GMC motorhome.
>
> My own feeling is whilst lowering the front would obviously limit the
> amount of air passing under the vehicle (lessening drag) the subsiquent
> raising of the rear as a result would expose more of the roof section
> increasing the total frontal area increasing drag.
>
> Also I suppose lowering the front would screw up the ground clearance and
> geometry of the suspension , increasing castor angle (making the steering
> more resistant to turn when the vehicle is in motion) and increasing
> negative camber scrubbing the inner edge of the front tyres out prematurely.
>
> I have no idea whether GM actually put a full size GMC motorhome in a wind
> tunnel, but scale models may have been tested at various points in the
> vehicles design.
>
> The GMC certainaly has an aerodynamic look about it, so at least creating
> the impression it slips through the air with ease(compared to other
> motorhomes of the period) was on the designers minds.
>
> Wayne
> --
> 1976 23' GMCII By Explorer
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
>
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>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
