Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2.fluke 9/24/84; site vax1.fluke.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!fluke!tron
From: tron@fluke.UUCP (Peter Barbee)
Newsgroups: net.auto
Subject: Re: springs?
Message-ID: <984@vax1.fluke.UUCP>
Date: Mon, 22-Apr-85 15:41:57 EST
Article-I.D.: vax1.984
Posted: Mon Apr 22 15:41:57 1985
Date-Received: Tue, 23-Apr-85 07:23:38 EST
References: <6386@ucbvax.ARPA>
Reply-To: tron@fluke.UUCP (Peter Barbee)
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 42

>particular, what are the pros and cons of constant rate springs (where
>F = kx and k is a constant) versus progressive rate springs (where k is not
>a constant and instead increases with x)?  

With a progressive rate spring the incremental displacement decreases assuming
a constant incremental force.  The advantage is you can load the car with more
weight (all other factors being equal).  Progressive rate springs may improve
handling also, the car should lean less in the extremes.  The best part is that
in most instances you don't realize you have stiffer springs.  The tradeoff is
that progressive rate springs cost more and will not necessarily behave
predictably as they wear.  Assuming the same length spring (linear vs.
progressive) the progressive will flex more within a shorter section thus
stressing (and wearing) that section of the spring faster than with a linear
spring.

I might ask the question, why note include the benefits of the stiffer rate
spring over the entire range?

>Also what are the tradeoffs
>involved in higher/lower rate springs (re: potholes and ride) and how does
>this translate for progressive rate springs?  

Higher rate springs impart a rougher ride (all other factors being equal),
for progressive rate springs you would need to know what the displacement
if to know how stiff they are, and therefore have a means of comparison.

>Since my car has excessive
>nose dive upon hard stopping, I assume the correct solution is higher rate
>springs.  

I don't agree with your assumption.  Stiffer springs will reduce nosedive
but a more elegant solution would be to regulate brake line pressure front
to back.

>Finally how do springs rates interact with shocks?

Shocks slow down the velocity of springs.  A damper is a device where force
is proportional to velocity ( F=bv ), generally the force and velocity vectors
are opposite in direction.  Thus the shock slows down and evens out the effects
of the springs.

Peter B