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Spring tension

To: triumphs@autox.team.net, rjl6n@virginia.edu
Subject: Spring tension
From: TR6Massey@aol.com
Date: Sun, 22 Dec 1996 14:29:30 -0500
John and all

Reguarding the task of reducing the tension on the bonnet latch pawl - 
I am an engineer (albeit an electronics engineer) and cutting coils from the
spring will reduce the tension.  Yes you do make it stiffer (call increasing
the spring rate) but at the same time you reduce the pre-load on the spring
more and the net pressure at the same compressed length will be reduced.

The following is technical, be forwarned.

The spring rate is the amount of force required to compress or streach a
spring a unit of distance
Free length is the length of a spring when no force is acting upon it.

Example:  If we have a spring 4 inches long with 10 coils and a spring weight
of 10 lb/in and compress it to 3 inches than we have compressed the spring 1
inch and 10 lbs were required.  Since we have 10 coils each coil has
compressed 0.1 inch.  If we cut one coil off now we have a spring on 3.6
inches long.  To compress this new spring 1 inch each coil now must compress
.111 inch (approx).  Now the spring has a spring rate of 11.1 lbs.  However
if we compress the new spring to 3 inches the total compression is .6 inches
and .6 times 11.1 lbs/in is 6.667 lbs applied!  An extreme example is if we
remove 2.5 coils the free length of the spring is now 3 inches.  The force
required to compress it to 3 inches is zero.  We could shorten it more and
tension would be required to make 3 inches long.

However, it has been my experience that it is not the spring that causes the
binding but the bonnet snubbers (the rubber cones in the corners) may need
adjusting (IMHO)


But what do I know? I use AOL.

Best reguards

Dave, St. Louis, MO USA
TR6Massey@aol.com


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