Subject: [Fot] Spring Rates

From: "Kenneth Knight" <[email-masked]>
Date: Sun, 22 Nov 2015 08:49:07 -0800

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There have been a number of posts recently about front springs for TR3/4/6's
etc.  To have an idea what to change to you need to know what you have.
Below is a reference to a great book on car set up and handling.  There is a
specific section dedicated to understanding coil springs, leaf springs and
torsion/sway bars including formula's for calculating rates for what you
have.  I just checked and there are many copies available on-line in new and
used condition.  I have the 1976 edition but it looks like it was updated in
1987.  

"How to Make Your Car Handle" Fred Puhn, HP Books

While there is a picture of a Porsche on the cover of each edition we will
forgive Fred.  The Triumph he was racing has already flashed through the
frame and is well up the road.

Happy Thanksgiving and Cheers to All,  Ken

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</o:shapelayout></xml><![endif]--></head><body lang=3DEN-US link=3Dblue =
vlink=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal>There have =
been a number of posts recently about front springs for TR3/4/6&#8217;s =
etc.&nbsp; To have an idea what to change to you need to know what you =
have.&nbsp; Below is a reference to a great book on car set up and =
handling.&nbsp; There is a specific section dedicated to understanding =
coil springs, leaf springs and torsion/sway bars including =
formula&#8217;s for calculating rates for what you have.&nbsp; I just =
checked and there are many copies available on-line in new and used =
condition.&nbsp; I have the 1976 edition but it looks like it was =
updated in 1987.&nbsp; <o:p></o:p></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>&#8220;How =
to Make Your Car Handle&#8221; Fred Puhn, HP Books<o:p></o:p></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>While there =
is a picture of a Porsche on the cover of each edition we will forgive =
Fred.&nbsp; The Triumph he was racing has already flashed through the =
frame and is well up the road.<o:p></o:p></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>Happy =
Thanksgiving and Cheers to All,&nbsp; =
Ken<o:p></o:p></p></div></body></html>
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From: fubog1 <[email-masked]>
Date: Sun, 22 Nov 2015 12:21:57 -0500

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Excellent book on suspension setup...
Glen

=20

=20

=20

-----Original Message-----
From: Kenneth Knight <[email-masked]>
To: FOT <[email-masked]>
Sent: Sun, Nov 22, 2015 11:49 am
Subject: [Fot] Spring Rates

There have been a number of posts recently about front springs for TR3/4/6=
=E2=80=99s etc.  To have an idea what to change to you need to know what yo=
u have.  Below is a reference to a great book on car set up and handling.  =
There is a specific section dedicated to understanding coil springs, leaf s=
prings and torsion/sway bars including formula=E2=80=99s for calculating ra=
tes for what you have.  I just checked and there are many copies available =
on-line in new and used condition.  I have the 1976 edition but it looks li=
ke it was updated in 1987. =20
=20
=E2=80=9CHow to Make Your Car Handle=E2=80=9D Fred Puhn, HP Books
=20
While there is a picture of a Porsche on the cover of each edition we will =
forgive Fred.  The Triumph he was racing has already flashed through the fr=
ame and is well up the road.
=20
Happy Thanksgiving and Cheers to All,  Ken

m

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<font color=3D'black' size=3D'2' face=3D'Arial, Helvetica, sans-serif'>E<fo=
nt size=3D"2">xcellent book on suspension setup...<br>
Glen<br>
</font>

<div> <br>

</div>

<div> <br>

</div>

<div> <br>

</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black">-----=
Original Message-----<br>

From: Kenneth Knight &lt;[email-masked]&gt;<br>

To: FOT &lt;[email-masked]&gt;<br>

Sent: Sun, Nov 22, 2015 11:49 am<br>

Subject: [Fot] Spring Rates<br>

<br>

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<div class=3D"aolReplacedBody" lang=3D"EN-US">

<div class=3D"WordSection1">

<div class=3D"MsoNormal">There have been a number of posts recently about f=
ront springs for TR3/4/6=E2=80=99s etc.&nbsp; To have an idea what to chang=
e to you need to know what you have.&nbsp; Below is a reference to a great =
book on car set up and handling.&nbsp; There is a specific section dedicate=
d to understanding coil springs, leaf springs and torsion/sway bars includi=
ng formula=E2=80=99s for calculating rates for what you have.&nbsp; I just =
checked and there are many copies available on-line in new and used conditi=
on.&nbsp; I have the 1976 edition but it looks like it was updated in 1987.=
&nbsp; </div>

<div class=3D"MsoNormal">&nbsp;</div>

<div class=3D"MsoNormal">=E2=80=9CHow to Make Your Car Handle=E2=80=9D Fred=
 Puhn, HP Books</div>

<div class=3D"MsoNormal">&nbsp;</div>

<div class=3D"MsoNormal">While there is a picture of a Porsche on the cover=
 of each edition we will forgive Fred.&nbsp; The Triumph he was racing has =
already flashed through the frame and is well up the road.</div>

<div class=3D"MsoNormal">&nbsp;</div>

<div class=3D"MsoNormal">Happy Thanksgiving and Cheers to All,&nbsp; Ken</d=
iv>

</div>

</div>

</div>

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From: "Randall" <[email-masked]>
Date: Sun, 22 Nov 2015 11:11:05 -0800

> There is a specific 
> section dedicated to understanding coil springs, leaf springs 
> and torsion/sway bars including formula's for calculating 
> rates for what you have. 

Thanks, Ken, I'll have to pick up a copy.

Sometimes it's good to get independent confirmation of the calculations.  Here's a shot of the test bed I threw together to check
leaf spring rates.
<http://s258.photobucket.com/user/TR3driver/media/Tools/DSCF0008.jpg.html>

You could easily do something similar for coil springs.

The area of the piston in the air cylinder is known, so it's easy to calculate force from air pressure applied.  (There was also a
table supplied by the air cylinder manufacturer.)  The cylinder came from eBay, $30 IIRC; the rest came from Home Depot or MMC.
Hard to see is the second needle valve, to bleed pressure off.  Since leaf springs have a lot of internal friction, I measured
deflection at several points going both up and down, then used Excel to fit a line to the results.

The setup confirmed what I knew going in : The new leaf springs I got from TRF were way too stiff even for racing, let alone street
use.  But I was also able to check some original springs, and weed out the weak ones.

-- Randall