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Re: Springs

To: Theo Smit <theo.smit@dynastream.com>
Subject: Re: Springs
From: Larry Paulick <lpaulick@comcast.net>
Date: Thu, 11 Nov 2004 18:35:52 -0500
Theo, if my memory serves me right, the stock springs were something 
like 265 ppi.  I purchased a set of CAT 335 ppi and they were too soft 
for my purposes.  You could tell the differences between the stock 
springs and the CAT springs easily by the wire diameter, and like wise 
with the 425 springs.

I now have 425 or 450 ppi fronts and 190 ppi rears from Dale A.

I also designed a sway bar setup that mounts to the crossmember with 
poly bushings and spiracle bushings at the a arms, and it really un 
binds the front end.

I looked at the Koni site last night and they recommend against using 
shocks for dive or sway control, but use springs and sway bars for those 
functions.

I had Doug Jennings Sr. and Jr., who are very familiar with Tigers, and 
very fast east coast drivers, drive my car and they said it was neutral, 
and you could drive it anywhere as it was balanced.

I still feel like it dives too much and the sway is more than I like but 
I have nothing to compare it with, so I will mush on till  I feel 
comfortable or change the design.


Larry

Theo Smit wrote:

>Hi Rodney,
>The stock springs were closer to 300 pounds per inch. The CAT springs
>calculate out to 335 pounds per inch or so, and then there are springs that
>are for the seriously competition-inclined, at 450 pounds per inch and up.
>One of the problems with the CAT springs is that depending on exactly which
>set you have, they will coil-bind before they reach the bump stops. That
>condition, where the windings of the coil are compressed so they're touching
>each other, results in a very harsh ride and can lead to chassis damage.
>
>As Stephen Waybright noted, if you free up the swaybar action (by putting
>bearings on the crossmember instead of the A-arms) then you remove a
>significant source of extra stiffness and then you can run stiffer springs
>without actually incurring a ride harshness penalty. That may seem
>counterintuitive, but the way that the swaybar is constrained to move in the
>stock setup causes a significant parasitic load on the suspension and
>getting rid of it improves the compliance and lets the shocks, springs, and
>swaybar do the job they were each intended for.
>
>Best regards,
>Theo





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