spring rates

[Dave Adams]

found this on my surfing trips, useful i think so here is a bit of what i found.

before you rush out and buy new springs, you will need to work out the "Effective Spring Rate". This will depend on what angle your Coil Over's are mounted at. When I mount my Shock's, I put mine back into the original top holes making the Shocks nearly upright.

My coils over are mounted at 20 degs, which if I was aiming for a Spring poundage of 150 lbs, I had to fit Springs rated @ 170 lbs to aim for an effective spring rate of 150 lbs. Take a look at the Chart if your brain has gone into overload.

Spring Angle	10 Deg	15 Deg	20 Deg	25 Deg	30 Deg	35 Deg	40 Deg	45 Deg
Effective rate	0.96	0.93	0.88	0.82	0.75	0.66	0.59	0.50

 You can see from the chart that if your Coil over is at 45 deg, your 150 lb string is only 50% effective, in other words it is only about 75 lbs.

I wanted 150 lbs effective.>150 divided by 0.88 ( my 20 deg angle ) equals 170 lbs spring.

 

 

 

[Adrian Southgate]

Thats a good find Dave.

I have a pallet truck at work which fits either side of the wheel quite snugly, maybe I should 'weigh' each corner.

Dave, could you add this info to the tech data for the Legerra on mr G's?

I can weigh the full car, each end and each corner individually which would give the approximate weight of a legerra with a pinto and 5 speed. Maybe a good starting point for other people to try and calculate theirs?

[Dave Adams]

Posted with a little more detail on MrG's forum, in the General Technical section.

I have weighed my Phaeton S1 with the 2.0 Pinto in it and it came out at 770 kg with me in it or at about 650 kg kerb wt. from memory it was 330kg front axle, 440kg rear axle, if you take me out of the car it's weight distribution would be some thing close to 50-50.

 

As i have said before, i have 225 lb/in springs up front and 150lb/in rears. this is about right except the fronts are a little hard and i think 180's or 200's at most would be perfect.