Damper setting

[slomove]

I got my new ProTech shocks installed and set them to the baseline recommendation of the manufacturer, i.e. 1-3 clicks for a lightweight car like a Se7en. I ended up using 1 click for the rears and 3 clicks for the front. Driving feels pretty good, I think much better than with my tired old Spax shocks.

 

 

 

Is there a "scientific" way of fine tuning the settings? I know I could experiment and tweak it on the road and on the track until it feels right. But I was wondering if there is a more straightforward method of optimization.

 

 

 

Thanks,

 

 

 

Gert

[slngsht]

I have often asked the same question, and never gotten a decent answer.

[Birkin42]

I have a fair amount of experience tuning shocks/forks on 2 wheels (motorcycles & mountain bikes) but not a much with 4 wheels since most cars don't offer a lot of adjustments on the shocks. I plan to fix that on my Birkin with a nice set of Ohlin's shocks though. I have read up on a lot of shock technologies and tuning methods over the years as well, though I don't claim to be an expert. Just here to offer an opinion.

 

 

 

Anyway, I believe there aren't many procedures offered for a few reasons.

 

One, settings are largely based on personal preference on what characteristics you put higher priority on as all shock setups are a compromise.

 

Two, most adjustment on shocks with multi-way adjustment have overlap so there is interplay between the adjusters.

 

Three, different car setups, suspension geometry's and tires can produced different results with a given change in the shock settings in some cases.

 

Four, there are many types of adjustments available on shocks these days, from rebound only, to 5 way dampening adjustment. I've even seen shocks which attempt to adjust both rebound and compression with 1 adjuster.

 

Five, there always seems to be the latest trend in tuning shocks, particularly for racing where you need to work around rules and there are aero considerations as well as mechanical grip. One day you should have fast rebound for good grip and the it should be high rebound to such the car down for less aero drag.

 

Six, a lot of people don't understand the setup of dampers and are afraid to make adjustments so they only run the factory recommended setting. I was amazed at how many motorcycle racers I came across how did this after spending a pile of money on a shock with a bunch of adjustments.

 

A lot of excuses for a situation that like you seems to be a lack of information on.

 

 

 

In terms of adjusting your shocks, this somewhat depends on what adjustments you have. Assuming you have low speed adjustment of rebound and compression, it is best to start with rebound.

 

Adjust it a click at a time until the rebound is to your liking. If it is too fast, the car will feel bouncy as you drive and you won't feel connected to the road. If it is too stiff, you will lose traction, the ride can become harsh, and the car can start to pack down or ride low in its travel (not always a bad thing if you talk to the NASCAR guys). You final adjustment will come down to feel versus traction.

 

Then move on to compression. The compression adjust mostly affect low speed motion of the car like brake dive, squat and roll. It also affects ride harshness, though this is mostly the high speed compression dampening which usually isn't offered on shocks unless you are paying big bucks. You can use the compression to set up things like turn in over/under steer and other transistion situations. Depending on the shock technology will determine how useful the compression adjuster is in tuning the handling characteristics of the car without making it ride harsh.

 

 

 

Hope this proves somewhat helpful, or at least interesting.

[slomove]

Thanks, yes that makes sense....Although it comes down to the trial and error method after all. Maybe that gives me just a good excuse for some test drives   http://www.usa7s.com/aspnetforum/images/emoticons/wink5.gif

 

 

 

 

 

Gert

[slngsht]

Thanks, yes that makes sense....Although it comes down to the trial and error method after all. Maybe that gives me just a good excuse for some test drives   http://www.usa7s.com/aspnetforum/images/emoticons/wink5.gif

 

 

 

 

 

Gert

 

 

 

http://www.usa7s.com/aspnetforum/images/emoticons/iagree.gif

[road warrior]

Info here from Koni.

 

 

 

http://www.koniracing.com/roadsetup.html

 

 

 

It may be of some help?

[slngsht]

Info here from Koni.

 

 

 

http://www.koniracing.com/roadsetup.html

 

 

 

It may be of some help?

 

 

 

Thanks, that was very helpful

[slomove]

The problem with these test drive based methods is that you really can not do it well on the road, except you find a nice choppy/curvy piece that you can run fast without police attention. On the other hand at regular track days the track time is too valuable to leave the track after every round, unstrap, get out, adjust, bundle up again and try one more time. Also, the traffic und just having fun distracts somewhat from the observation task. But I suspect this is just the way to go.

 

 

 

I had already wondered to build a mini shock dyno wich a spinning roller (maybe 4" dia, 1" off center) driven by a variable speed drill under the wheel and a cheap accelerometer chip stuck onto the car at this corner. The acceleration amplitude plot vs. frequency should give some good hints for the shock setting, e.g. overdamping or bouncing at resonance frequency. While such a gadget may not really be worth the effort it should be a fun project. On the other hand, being an instrumentation EE without much experience in suspension setup maybe I just don't see the complexity of the problem. Did anybody try this before?

 

 

 

Oh well, there are still 2 other projects in the pipeline to tackle first.

 

 

 

Gert

[Birkin42]

I would think mounting the accelerometer to the car is good for compression but maybe attached the axle may be better for rebound. Ultimately you should be able so see the effects of both in either location, but how readable will the data be?

[JohnK]

I've read in a number of texts that the procedure that Koni publishes on their website is the approach to sorting out shocks. And it is an approach, not a formula - and probably takes no small amount of practice before you figure out how to tell what's going on.

 

Cheers,

 

John K

 

Cincinnati

[mel kuipers]

John...Mel here....I bought Jerry Ebben's WMC Ultralite 2004, and will be Auto Xing it....I am looking for ideas for adjustable dampers to keep the front stiff and the rear less so...where would you start to look?....thanks