Contour Enthusiasts Group Archives Forums Modifications Suspension Spring Rates on Stock SVT Contour

Searched on this, and am trying to determine my steer bias % versus my Mazda 6 to see where I am positioned.

What is the kg/mm spring rate for the SVT stock springs f/r?

http://www.contour.org/FAQ/FAQ.php?s=specs

The SVT springs are darn close to the others. IIRC, they're just a hair softer than the early SE springs (or maybe the same?)

Remeber that the 6 has a dramatically different motion ratio than the SVT. Also, it's quite possible that the 6 and the SVT have a significant difference in the motion ratio... well, ratios, between front and rear. Thus these numbers might not really mean anything.

FWIW, I'm running 525/425 with a stock 200m front bar and Aussie bar in the rear. It's very balanced in low-speed corners, and works great for autocross, but gets hairy at higher speeds. Lifting at the limit at 60 mph will get the back end very loose, very fast. I've spun it trailbraking or lifting in a slalom several times on the autocross course.

James,

The spec sheet I have shows the 99 CSVT and the 99 SE had the same spring rates of 20 N/mm (same as kN/m) front and 18 N/mm rear. If you need the wheel rates (ie spring rates multiplyed by the respective motion ratios), let me know.

Brian, do you have the motion ratios for the Contour? They look to be high, but the longer arms in the rear should make them even higher in the back. I have been guessing something like .90 f and .95 r, but I've never actually gotten good enough measurements to make meaningful calculations. Anything you have would be helpuful.

Well, I've got the wheel rates listed in the spec sheet I have, so it should be simple to calc the motion ratios.

Front Spring rate = 20 N/mm
Front Wheel rate = 18.8 N/mm

Front motion ratio = FWR/FSR = 0.94


Rear Spring rate = 16 N/mm
Rear Wheel rate = 15 N/mm

Rear motion ratio = RWR/RSR = 0.9375

Thanks for the data!

How different would a 98.0 likely be?

I looked at the MVSS spec sheet on the 98, and it indicates the same spring rates, but the wheel rates look all messed up, so I'm not even going to bother quoting them; they should be the same as the 99.

I have no clue what you mean by wheel rates, but I am pasting them into the calculation request, and hopefully he knows what to do with them.

Thank you so much for all the info!

Keep in mind, I'm comparing to what is now a 23mm front and a 27 mm rear on the Mazda6 as set up, but at least the rear has a shorter span than on the Contour. Spring rates: 8kg/mm front 5.5kg/mm rear. I like it, but the guy doing the calculations thinks it's dangerously tail happy by the numbers.

Think of wheel rate as the effective spring rate as viewed by the wheel. Remember that the control arm acts as a lever and multiplies the spring rate as seen at the wheel. Of course, in almost all cases it is a value between 0 and 1 . . .

Brian, the way you did that results in the squared version of the MR, right? I've seen both the acutal lever arm ratio and the square used as Motion Ratio before, but of course the squared version is the only one that matters.

So, that would mean srqt(.94) = .97, which is the lever ratio of the suspension, correct? For instance, double-wishbone Hondas are around .7, which squared is .49, so a 500lb spring for me gets a similar wheel rate that a 1000lb spring would get on the Honda, ignoring the progressive effects of the suspension.