AnswerID: 78830 Submitted: Monday, Oct 04, 2004 at 21:44
Ian from Thermoguard Instruments
replied:
Hi Voxson,
It's because a coil spring is really a 'rolled-up' torsion bar - a length of spring steel bar that is twisted as the
suspension compresses. An 8 coil spring of the same diameter and grade of spring steel as a 7 coil one is a longer length of 'torsion bar'. So, the same twisting force (vehicle weight) twists the longer bar to a greater degree.
I'm no spring guru but I believe the critical factors are the free length of the coil and it's 'rate' - the force needed to to compress it each unit of length - lbf/inch or N/m?? The rate is a function of the overall length of the steel bar (no. of coils and spring diameter) and the thickness of the spring steel (bar diameter) - and presumably some combinations of bar dia. and no. of coils work better than others. That's what we pay the 'spring gurus (gurii?)' to work out.
 | Thermoguard Instruments |
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FollowupID: 338352 Submitted:
Tuesday, Oct 05, 2004 at 14:03
Voxson (Adelaide) posted:
Yes.. But it craps me no end when a 4x4
shop raves about a certain spring and you put it in and then find it to be saggy... I was almost thinking about poly airs when i decided to use the newer remade spring which hardly even feels the weight of 220kgs of fuel and a trailer full of garden pebbles..
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