[fredmeister]

Originally Posted by 911st

Colin,

I was referring to torsion bar 911's. The 964 + after have different geometry, tend to run at higher weights, and are full race cars on different tires.

Also referring to DOT R type tyres that most DE/TT drivers are using.

For a 2200 lb early 911 I have heard 400/600 is a starting point for cars converted to coil overs. As a point of reference, 23/33 torsion bars are about 250/400 lbs per inch. Not drought many run higher rates than this.

As to my estimates being way off, Ed's car is a good data point for the type of car I was referring to and fits my thinking.

However, I am surely not an expert on this, just trying to help and learn.

Thank you for the info.

you have to remember too that torsion bars are acting at different points on the control arms so what you really should be quoting are wheel rates to compare apples to apples.
Thus a 31mm torsion bar may be equivalent to a 600in-lb coil spring for example once the actual wheel rate is calculated. unfortunately getting the dimensions from the suspension to run the numbers is the hard and tedious part, and most of us are relying on the previous experience of others to recommend specific spring/bar sizes that have hopefully already done the math.
FWIW, I had met Ed at the track this summer and seen his car. wow, it is nice and he is fast. i thank him for the info.