mx5cartalk.com

Been looking at the FCM calculator. Most of it makes sense in terms of bounce frequencies, roll stiffness, front roll couple.

A little confused about what "ideal" bounce frequency ratio (expressed rear to front on FCM web site) should be. FCM says stock 1990 is 0.97. Have read in some places it is better to have rear bounce frequency higher than front (something to do with stopping oscillation when going over bumps). Is this correct? So why is this not the case stock from factory? Should this ratio be as close to 1 as possible? Does it really matter?

you generally have the rear ride frequency high so it catches the front frequency after the excitation.

I thought the NA6 was 89%, i.e. 1.11/1.05 F/R. My own experience with FRC and bounce ratios has led me to stick pretty close to Mazda's original ratios. When I've gone too stiff at the back then I've found the ride got choppier and a bit uncomfortable. At the moment I'm running 10/7 springs. That gives me a 87.5% bounce ratio which is surprisingly comfortable. It also sticks like StaB on corrugated bitumen and dirt and that makes me think that the rule about the rear catching the front is myth.

We've got a race suspension tuning shop down the road from us. Their recommendation for me was also to go for around 90% for comfort and balanced grip. This is a bit different from their own standard rec though in http://www.racing-car-technology.com.au/What%20you%20will%20know.htm

hmmmm - just checked FatCat's online calculator. They've changed all their bounce values from what they had a few years ago, no idea why. They now have an error in the column titles too, it should say F/R not R/F under Bounce Freq Ratio. You can see it yourself just by looking at the individual front and rear bounce values.