Thanks to all for your comments this week.
Steve
1961 MGA
SSchultz@worldnet.att.net
----------
> From: Vince Bly <Vince.Bly@gsfc.nasa.gov>
> To: Steven R Schultz <SSchultz@worldnet.att.net>
> Cc: Team.Net <autox@autox.team.net>
> Subject: Re: Sway Bar Options
> Date: Wednesday, January 20, 1999 7:04 PM
>
> At 09:03 PM 1/19/99 -0500, you wrote:
> >
> >I am a rookie and would like some help is setting up my car for
> >vintage autocross . I have a 1961 MGA. The car will be primarely
> >driven on the road and occasionally raced in autox. The stock front
> >sway bar measures 5/8" Will replacing it with a 3/4" bar make much
> >of a difference? I have found a non-specific 3/4" bar and for $120
> >more can get an ADDCO sway bar. Is there any difference?
> >
> >The car does not have a rear sway bar but one is available. Will
> >it make a difference?
> >
> >Steve
> >1961 MGA
> >SSchultz@worldnet.att.net
> >
> >---------------------------------------------
>
> Steve,
>
> Replacing your 5/8" sway bar with a 3/4" bar will make a big
> difference. The stiffness of a round member (in both torsion and
> bending) is proportional to the 4th power of the diameter. So, in
> this case, the 3/4" bar is a little more than twice as stiff as the
> 5/8" bar.
>
> Although the total weight transfer in cornering is determined
> by the height of the center of gravity (CG) and the track width,
> sway bar(s) determine how much of the weight transfer takes place
> at the front versus the back. A stiffer front sway bar means a
> larger fraction of the total weight transfer will occur at the
> front. Of course, stiffer bars also decrease body roll during
> cornering.
>
> _Usually_, installing a stiffer sway bar at one end of the car
> will make that end drift more when cornering and the other end drift
> less. For example, installing a stiffer front bar will _usually_
> make the car understeer more or oversteer less. A stiffer rear bar
> will _usually_ have the opposite effect.
>
> Under most circumstances, the cornering force a tire can
> generate is proportional to the force pushing the tire against the
> pavement and THE PROPORTIONALITY CONSTANT IS LESS THAN ONE. In
> other words, if you increase the force between the tire and the road
> by 50%, the available cornering force will be increased by some
> amount less than 50%. For this reason, weight transfer during
> cornering is a bad thing; unavoidable, but bad never the less. It
> is for this reason that road racing cars have as low a CG as the
> rules allow. It is also for this reason that installing a stiffer
> bar at one end will cause that end to grip less and the other to
> grip more (think about it).
>
> I hope this helps a little.
>
> Vince Bly
>
>
|