CSG Mike's observations on dampers/coilovers

[CSG Mike]

Originally Posted by 2point0

Aww what happened to that list? I was hoping to see them separated out into what you'd consider "well" or "badly" damped.

Someone(s) will get offended, so I just deleted the list. It was incomplete anyways, since I don't remember everything I've driven on...

[Racecomp Engineering]

Crap, I missed it!

- andy

[schtebie]

Originally Posted by Racecomp Engineering

Crap, I missed it!

- andy

x2

Repost please! :happy0180:

[OrbitalEllipses]

Originally Posted by schtebie

x2

Repost please! :happy0180:

The customers demand it!

[naikaidriver]

Originally Posted by post_break

So what do you thinking about springs that have higher rates? RCE for example matched with stock dampers.

I would like to hear your opinions on this as well.

Scott

[ATL BRZ]

Would like to see the list as well.

OEM Struts plus RCE Yellows = 65% critically damped on a shock dyno... 250lbs/in and 22mm drop front and rear is plenty for me with my DD that sees the track frequently. The complete lack of body roll and oversteery goodness with the RCE sways and some decent negative camber front and rear just finish off the "OEM+" setup I've been tracking with for many months now.

Good guy @Moto-P 's words should be etched in stone and carried to the top of Mount Olympus,

Originally Posted by Moto-P

Summary, if you are not very versed in dynamic tuning of a sports car like the FRS.
I can elaborate on definition of soft as "compliant, well damped, and allowing enough stroke at low loads" OF course that can be had in different combinations of factors but generally, the suspension on this car needs to MOVE.

Stock Tires + Stock Tires = pretty darn good.

Low+ Stiff+ Stock tire = bad, hard to rotate, easy to understeer (plow)

Soft + mid-height -20~30mm (or plenty of stroke built into coilver) + medium grip street tire = FUN, Fairly quick, easy to handle, and close to original setup.

Low+Stiff+Race tires = proper race car setup, but requires a lot of driving skills to make it go fast.

From this thread: http://www.ft86club.com/forums/showthread.php?t=10643

[mit_peid]

Did you get an opportunity to test drive anything with the Koni yellow dampers? I have those along with Eibach Pro-Kits waiting to be installed. Wondering if there's a correct damper setting to best match the spring-rates of the Pro-Kits with the Yellows. My goal (not sure if I can achieve it) is to not make things worst than stock, but willing to give up a little comfort to maintain the performance of the stock car.

[Calum]

How do you calculate the damping as being critically, under, or over damped when the springs compression curve is linear and the damper has a force vs. speed curve, and that curve is different for both compression and rebound? This is an honest question, and something that has been bugging me for a long time.

[shu5892001]

Exact reason why I am saving up for Ohlins/KW/JRZ instead of going with HSD/BC/Stance, do it right or don't do it.

[CSG Mike]

Originally Posted by Calum

How do you calculate the damping as being critically, under, or over damped when the springs compression curve is linear and the damper has a force vs. speed curve, and that curve is different for both compression and rebound? This is an honest question, and something that has been bugging me for a long time.

I judge dampers via butt dyno. It's not perfect, but it's served me pretty darn well when it comes to dialing in dampers.

I'd like to learn how to do it mathematically as well, but there's so many factors involved...

Per wikipedia... (this only applies to idealized spring damping; there's so much more to damping a car going over a road....)

Originally Posted by wikipedia

The value of the damping ratio ζ determines the behavior of the system. A damped harmonic oscillator can be:
Overdamped (ζ > 1): The system returns (exponentially decays) to equilibrium without oscillating. Larger values of the damping ratio ζ return to equilibrium more slowly.
Critically damped (ζ = 1): The system returns to equilibrium as quickly as possible without oscillating. This is often desired for the damping of systems such as doors.
Underdamped (0 < ζ < 1): The system oscillates (at reduced frequency compared to the undamped case) with the amplitude gradually decreasing to zero.
Undamped (ζ = 0): The system oscillates at its natural resonant frequency (ωo).


Critical damping (ζ = 1) [edit]
When ζ = 1, there is a double root γ (defined above), which is real. The system is said to be critically damped. A critically damped system converges to zero as fast as possible without oscillating. An example of critical damping is the door closer seen on many hinged doors in public buildings. The recoil mechanisms in most guns are also critically damped so that they return to their original position, after the recoil due to firing, in the least possible time.
In this case, with only one root γ, there is in addition to the solution x(t) = eγt a solution x(t) = teγt:[4]

where and are determined by the initial conditions of the system (usually the initial position and velocity of the mass):

[Racecomp Engineering]

Originally Posted by Calum

How do you calculate the damping as being critically, under, or over damped when the springs compression curve is linear and the damper has a force vs. speed curve, and that curve is different for both compression and rebound? This is an honest question, and something that has been bugging me for a long time.

When people say 65% critically damped...generally this means it is 65% critically damped in the low speed range (0-2 inch per second or so) for rebound and compression. It may be higher or lower in the high speed range. It isn't necessarily the same throughout (it rarely is honestly).

Some like a little higher than 65% for low speed piston velocity and then closer to 65% in the higher speed range. Some like 65% for low speed and 50% for high speed piston velocities.

I'm all about theory as a starting point but to me it is a starting point. Not a hard and fast rule. Calibrated butt dynos are excellent tools. Feel, driver preference, and driver confidence can be very important too...and sometimes drivers adapt and end up faster. But I do really like having a starting point over a wild-ass guess.

Bottom line and this is what I think CSG Mike was getting at: sometimes we see numbers way beyond or way below what they should be and that's a problem. Get near 65% in the low speed range and you're at least close.

- Andy

Disclaimer: I am not a shock engineer and I defer to others often. I just try really really hard to learn from them. It hurts my brain too sometimes.

[euroshowoff]

Whose hosting the next AMA lol....


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[shu5892001]

Originally Posted by CSG Mike

Someone(s) will get offended, so I just deleted the list. It was incomplete anyways, since I don't remember everything I've driven on...

Can you PM the list please?

[CSG Mike]

Originally Posted by euroshowoff

Whose hosting the next AMA lol....


Sent from my iPhone using Tapatalk 2

Reddit style AMA? Is this thread secretly for karma?