The Staff of Motorsport Marketing
The Staff of Motorsport Marketing Writer
1/29/21 11:17 a.m.

[Editor's Note: This article originally ran in the May/June 1997 issue of Grassroots Motorsports]

Story by John Hagerman

For the last four decades, serious race cars have sported fully independent suspensions. Street cars, including some of the most notorious sports models, have traditio…

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noddaz GRM+ Memberand UltraDork
1/29/21 11:33 a.m.


I will have to read this several more times to get it.  lol


David S. Wallens
David S. Wallens Editorial Director
2/5/21 12:59 p.m.
noddaz said:


I will have to read this several more times to get it.  lol


Cool. We recently posted a few other suspension fundamental articles from the same series:

Understanding anti-roll bars

Understanding alignments

slantsix Reader
4/3/21 7:42 p.m.

Love it Good stuff from GRM.... back from the historical times when I was young, dumb and did not know about GRM.



Thanks for (re)sharing!



fearlesfil New Reader
7/19/21 3:38 p.m.

Back in '88 I put all this in Excel. I added fields for current and desired ride heights, length of control arm, where the shock/ strut mount intersected that arm (so it could calculate the lever arm length), and spring compressed and free heights. From these plus the items in the article, the current spring's stiffness and the weight on that corner are calculated.

Then I use Excel's "goal seek" Tool for a "number of coils to cut" field, which calculates to 1/10th of a coil to get to the desired ride height. As it iteratively cuts 1/10th of a coil at a time, it recalculates the increase in spring rate (due to fewer free coils/ reduced free height) and the resulting drop in ride height. When the difference between the desired and calculated ride heights goes negative, it stops and reports the most recent iteration.

The "incremental steps for reference" are just there as a sanity check that the calculated number of coils to cut are reasonable. 

I've used it successfully on several Mustangs (street and track), a Toyota AE86, a Mitsubishi Mighty Max (Dodge D-50) oval track truck, and a Formula Ford. 

8valve Reader
7/21/21 1:52 p.m.

Interesting "spring steel" and regular steel act the same way.  Had no idea.

" increase of as little as 0.200 of an inch in spring wire diameter can stiffen a spring by over 20 percent (based on a 0.333-inch wire diameter spring)."

Does not compute! *smoke from ears* 

Also steal vs steel is peeving my pet off.

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