RE: Changing the roll center of a suspension

["Steve Moresi" <smoresi@domain.elided>]

If you are just trying to reduce roll- I assume this is the purpose of the
mod - you need to find the height of the CG of the vehicle.  The closer the
roll center is to the CG the less roll you will have, because of the smaller
moment generated.  What is really interesting is to get the roll center
above the CG, and the car will lean _into_ the turn!

Steve
SLO, CA
74 Spi
64 Spi

%-----Original Message-----
%From: owner-alfa@domain.elided [mailto:owner-alfa@domain.elided]On Behalf Of
%George Schweikle
%Sent: Monday, November 19, 2001 6:26 PM
%To: Nizam Zambri; alfa@domain.elided
%Subject: Re: Changing the roll center of a suspension
%
%
%Nizam,
%
%I don't have my "How To Make Your Car Handle" book handy, but here's what I
%remember: the front and rear roll center points must be connected to
%establish the roll axis. Think of this as the longitudinal line that the
%entire car rotates around as it leans. This really establishes the basic
%handling characteristic, and to define this axis requires knowing both the
%front and rear roll centers. I'm not sure about the roll axis of a GTV-6,
%but the 105 Spider/GTV has the roll axis angled downward from rear
%to front.
%This why stock Spiders seem to want to corner on their outside front wheel
%as the rear of the car hikes up. The Panhard bar kits sold for 105-chassis
%cars move the rear roll center from the T-bar attachment at the top of the
%differential to the level of the Panhard bar under the diffential.
%A drastic
%change of 8-10 inches that improved the handling of my Autocross Spider. I
%believe the GTV-6 Watts link already provides a fairly low rear roll center
%at the center link pivot on the DeDion tube, but don't know how this
%compares to that of the front suspension. Calculating the roll center of
%independant front suspension is more complicated, but the Fred
%Puhn book has
%some excellent material on this topic.
%
%How about some comment from the racers out there?
%
%Regards,
%
%George Schweikle
%Lexington, KY
%76 Spider
%87 Milano
%
%----- Original Message -----
%From: Nizam Zambri <nizam@domain.elided>
%To: <alfa@domain.elided>
%Sent: Monday, November 19, 2001 8:35 PM
%Subject: Changing the roll center of a suspension
%
%
%> Hi guys,
%>
%> There has been lots of talk lately about shocks, and springs.  Zamani
%> also brought up drop spindles and upside-down balljoints.
%>
%> What we are really trying to do is to move the roll center further down
%> in a chassis.  >
%> I had a brief conversation with Larry at APE and he didn't think this
%> was a good idea.  However, I'll keep his reasoning for later because I'd
%> like to hear what the forum has to say on the subject.
%>
%>  ...some of you may think differently.  What
%> say you?
%>
%> Nizam
%
%--
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