Just to put my two penn'orth in, i have as my primary car a Dutton Phaeton S1 much like an extreme but with less clever engineering, it has a 2.0 Pinto so it's not the lightest car in the world coming across the weigh bridge at 770 kg with me in the seat, or about 680-690 kg kerb weight. my fronts are 225lb/in (10" free length...too stiff, they will be down rated to 180-200lb/in) and my rears are at 150lb/in X 12" free length. The rears are about right for the "two up" driving i and my wife do a lot of. Although if i were to drive the car solo more often i would go for 120lb/in. there is in the kit car world a widely held belief that stiffer springs improve handling, It almost never does. my car originally had 275lb/in fronts and 190lb/in rears it was a little to liable to breaking away on corners and roundabouts, softening the springs made a huge difference and the car now holds the road very well (you have to own quite an expensive car to keep up with me in the bends) Here is a link to a site which, whilst it is a Dutton site has a very interesting article on calculating spring rates, it might help point you in the right direction.
http://www.godspeed.me/forums/viewtopic.php?f=14&t=84 hope it is of interest, Dave. -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To post to this group, send email to quantumowners@googlegroups.com To unsubscribe from this group, send email to quantumowners-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/quantumowners?hl=en IMPORTANT NOTE: All information presented herewith is provided on an "As Is" basis, without warranty or the implication thereof. Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s).