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Revised Spring Rates
DavidM - 11/11/07 at 02:14 PM

The springs I'm currently running are 275 front and 185 rear and although the handing is very well balanced, the ride is a bit "firm".

I'm going to change to softer springs as part of my winter mods, but what increment would people suggest, where I would feel the difference.

I'm thinking 250 front and 165 rear. The car weighs 550kgs wet.

Any suggestions?

David


britishtrident - 11/11/07 at 03:39 PM

Is the car handling neutral or understeering or over steering ?

Also what tyre pressures are you running ?


Volvorsport - 11/11/07 at 04:14 PM

live axle ?


DavidM - 11/11/07 at 09:31 PM

Live axle with very neutral handling easily controlled on the throttle. 18psi tyre pressures.

I'm happy with the handling, I just want a more compliant ride, without going too soft.

David


procomp - 12/11/07 at 08:02 AM

Hi In short you would want to go softer on the rear so you had more grip.

After that if you are serious about trying to play with the handeling then the first step will be to have the dampers looked at as they will almost certinally be way out of balance if just off the shelf units. Plus to get the best out of a live axle you will need dampers with the right valving to work due to the unsprung weight issues.

HTH cheers Matt


britishtrident - 12/11/07 at 07:37 PM

Sounds fine --
165 lb/in might be as soft as as you can go on the rear without having to use a lot of pre-load which raise the danger getting coil bound on bump.

Lotus Sevens used much softer spring rates (I have seen 70 lb/in quoted for the rear) but on all models Lotus always used very long springs with loads of pre-load. The original Lotus Seven was also lighter and had the engine futher forward than a most Locosts.


On the front if you find you have chosen to soft a spring rate you could consider making up a thin (soft) anti-roll bar for the front as this will have less effect on ride quality than raising the spring rate.


paulf - 12/11/07 at 10:55 PM

Hi David.
I have 250 on the front and 160 on the back of mine and its seems ok as you have seen when following it does seem to take up most of the bumps, I have got longer dampers on the back at13.5 inch and did find that when i had shorter rear dampers they would occasionally bottom out but the present combination seems about right.
I do get some understeer on long fast corners but think that is more of a tyre issue but maybe softer front springs and an antiroll bar may help but dont have time to experiment at present.
Paul.