An Educated Discussion on Shock Dynometers

[Gnnr]

I came across an article someone posted on another 240 board, discussing the different types of road surfaces (highway, street, mountain roads, and track) and their relation to the car's suspension. I googled the article and found the original source, here's the link (sorry that its on drifting.com).

Anyways, this got me to thinking about the performance of shocks and I was off into researching shock dynos and such. Now what I'm having a hard time understanding is, what would be the ideal setting for each of these different conditions. Which is hard to figure out, as a lot has to do with preference. The information I've found on shock dyno's is a bit overwhelming, very technical, and more from an engineer's standpoint. If someone could help break it down some, in lamen's terms, that'd help me out a lot. I want to understand how to properly read a shock dyno, and what are the most important things I should look for. I'm really trying to grasp the whole compression/rebound relation. I know that if either is at an extreme its usually not ideal, and its about finding the balance between the two. So if anyone could help me in understanding the concepts, please post.

[BOROSUN]

i think its rebound. too slow rebound, harsh ride. too fast rebound, bouncy.

[GSXRJJordan]

I read the article on drifting.com, and it seems like they started with fairly accurate information, and had some moron write the article.

First off, the basics are true, that stiffer suspensions do not necessarily function better on bumpy surfaces than softer suspensions. The reality is that most coilovers are fine on the street, and as long as you dont set them too stiff, they won't bounce you through a stop or anything that serious. As far as mountain roads, you need the stiff springs to maintain speed through the sweepers and change direction faster, but ultra-stiff damping will bounce you into a rail if you're not careful.

About settings - 90% of car suspensions have compression adjustment, that also effects the rebound. Basically you're closing the valve that allows fluid to move out of the pistons way - the smaller the opening, the more force it takes to move the piston a certain amount, up (compression) or down (rebound). Really expensive suspensions (Ohlins 4 way adjustable) have not only ride height (1), preload (2), and compression (3) adjustment, but a seperate rebound (4) adjustment, basically so you can run really high compression adjustment without running unnecessarily high rebound - get stiff suspension without sacrificing traction.

Shock dynos are informational to a point, but I'll take the race tested suspension over the one that looks great on paper but doesnt have the good words from those who know - hence my Tanabe Sustec Pro Super Sevens =D

[Gnnr]

Ahh, I see. So what thing should I look for on a shock dyno graph? What things would be indicative of a bad damper or a suspension that is too stiff? Also, is rebound the amount of time it takes the for it to return to its normal state?

[EchoOfSilence]

I've been wondering about this myself. It isn't exactly an easy thing to understand...

The capstone course for Berkeley's BS in M.E. is shock dyno use.

but yeah... if someone could explain shit that'd be great

[NemeGuero]

Ted & Nancy have a shock dyno.. I'll give them a holler.
(T&N Enterprise)

[Wiisass]

Go and buy the past two issues of Drift and RWD sport and read the damper articles. The first article is on my site, it's on my forum somewhere. I haven't uploaded the second one yet. But you'll find most answers to your questions on there. There's also another article I wrote about the shock dyno I was using last year and how it works and what it does and how it allowed me to make progress on some dampers. It's on there too.

And JeffMilano is wrong. When you talk about dampers and you say 4-way, that means that they are high and low speed rebound and compression adjustable. Preload and ride height adjustability have nothing to do with the damper. And most of the other stuff he said is off.

Just go read the articles and if you have any good questions I'll answer them later.

[Gnnr]

Ahhh, Wiisass! It was actually one of your PDFs I found on ZT through a google search. Didn't know you where on here. Yes, I'll go look for those other articles and see if I can come to a better understanding.

[Wiisass]

I uploaded the second article last night. So it's there as well. But you should still go and subscribe to drift and rwd sport because I will have more suspension tech articles in the coming issues.