Just a guess but here goes - spring rate is dependant on OD, wire diameter,
and the number of active coils. Two springs with the same OD and length can
have the same rate even though one has fewer coils at a smaller diameter
wire, and the other more coils at a larger wdire diameter. The main
difference is the torsional stress seen by the spring wire ( and the solid
height with the spring fully compressed). If the sorsional stress value for
the material is exceeded, the spring can take a "set", or in worse case,
fracture and fail.
My guess is that over the years it was found that the springs with fewer
coils were being overstressed so they changed the design to compensate.
Mark Sedlack
OROC
Cuyahoga Falls OH
66 1600 http://home.neo.rr.com/mark2000/images/datsun1600/
77 280Z http://home.neo.rr.com/mark2000/images/datsun1600/Z.htm
----- Original Message -----
From: "RWM" <RWM@rwmann.com>
To: "chriscoker@mail.comcast.net" <chriscoker@pop3.comcast.net>
Cc: <datsun-roadsters@autox.team.net>
Sent: Friday, February 14, 2003 1:51 PM
Subject: Re: NISMO comp springs - how many coils should they have???
> Interesting. Which ones are lighter, and by how much?
>
> - RWM
>
> "chriscoker@mail.comcast.net" wrote:
> >
> > I've had two types of NISMO comp springs side by side, the number of
coils was different, as was the wire diamter. I worked through the math,
and the spring rate was essentially the same. The spring with the larger
number of coils will have a slightly larger wire diamter. I think the
spring with the larger number of coils is a later design, as I recently
bought a couple of sets of these from NISMO. I compared them with the
'older style,' which has been on my race car for around 20 years.
> >
> > Either style of spring should work fine.
> >
> > Chris Coker
> > www.risensonracing.com
> >
> > Original Message:
> > -----------------
> > From: Adam Bradley ambradley@attbi.com
> > Date: Fri, 14 Feb 2003 09:17:17 -0800
> > Subject: NISMO comp springs - how many coils should they have???
> >
> > I have seen a bunch of pictures recently of comp front springs that have
a
> > large number of coils, such as the auction at
> >
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=34200&item
=2403085015.
> > The springs I bought a couple of years ago from my Nissan dealer
> > (supposedly NISMO comp springs) didn't have this many coils and were
> > noticeably shorter than my stock springs that I took out of the car.
Then
> > today I saw the pic at http://www.datsun.org/fairlady/June2001.htm that
> > shows fewer coils more widely spaced, like my springs.
> >
> > So which is right???
> >
> > Adam Bradley
> > '70 Datsun 1600 Roadster SPL311-28181
> > '67 Datsun RL411 SSS sedan RL411-11321
> > '66 Datsun PL411 sedan PL411-022447
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