[949 Racing]

Originally Posted by Clutch Dog

I always assumed good on street manners come at the sake of being too soft for the track and a good track set up (tires and suspension) would be too knar to drive on the road.

That's more a function of spring rates than damping. Good shocks will absorb bumps better than bad shocks.

Here is a cut/paste of something I wrote for a Miata forum a few weeks ago.


Common misconception is that good body control means a harsh ride. It's actually the exact opposite. A lower quality shock will tend to have internal friction, linear valving, poor or no pressure balancing with results in hysteresis at low piston speeds, low quality oil that breaks down early in the shocks lifespan, small piston with limited peak oil flow so poor blowoff at high piston speeds..

All of which contribute to poor ride quality and poor body control. The best shocks on the market for any platform, be it your 3/4T pickup, your UTV, your mini-van, your motorcycle and yes, your Miata will generally have better ride quality and handle better than cheap shocks. Some vehicles come OEM with really high quality shocks. The NA/NB are not among that group. While the Bilstein are very high quality for an OEM shock of that era, modern shock tech allows far greater performance. (86 no different)

The message there is not to think that you need to sacrifice ride quality for good handling. The variable here is RM (Roll Moment) and to a lesser degree, PM (Pitching Moment). In rough terms, this is how much force is trying roll the car at the limit of traction. OEM 185/60/14 NA6 tires would allow around .84g. Modern "super" 200 tw tires in a 225/45/15 will easily generate 1.35g on the same NA6. This is a lot more force trying to roll the car, thus stiffer springs are required to resist that additional Roll Moment.

These stiffer springs raise the bounce frequency, which you all would say makes the ride "busy". I liken it to the difference between being able to have that latte full, and not have it bounce out of the lid, to maybe asking them to leave a fair amount of room for slosh. Those higher rates make the car follow the road. So if the road moves around, so will you. This does not mean crash-bang over every little bump though. Not if they are good shocks.

Primary factors we look at when deciding on spring rates for a customer are tire choice and intended usage. The luxury of having shocks with a wide damping adjustment range and double digressive valving is that you can choose one spring rate that will support the driving you do then simply adjust the damping settings for highway trips, canyons or donning a helmet and getting serious.

This versatility assumes the same tires for all uses. If you swap between a fairly low grip tire that never reaches the limit of traction to a very high grip tire that lives at the limit, you will have a huge spread of peak RM/PM. You'll have to pick one RM to optimize and be perfect for and merely be good at the other. Street or competition basically. If your aggressive driving is all done on your medium grip daily driver tires, then one spring rate can often be perfect for everything.