Can shock-dynos tell you what the highest spring rate it can handle?

[mike156]

That's the sprung mass natural frequency and doesn't account for tire compliance. The equations work better when used proeprly, as I'm sure Andy knows.

As a rule of thumb using that number, 0.66*critical for compression, 1.5*critical for rebound. Anybody want to answer "why?"

[Racecomp Engineering]

Originally Posted by mike156

That's the sprung mass natural frequency and doesn't account for tire compliance. The equations work better when used proeprly, as I'm sure Andy knows.

As a rule of thumb using that number, 0.66*critical for compression, 1.5*critical for rebound. Anybody want to answer "why?"

And also why maybe .33* critical is good for high speed comp, .75* critical for high speed rebound.

I was going along with the basic Optimum G stuff to keep it simple. Or simple-ish.

- Andy

[mike156]

Yeah, it's all ball park stuff anyway.

A good indepth thread would be pretty awesome though.

[JDKane527]

Is there a standard velocity used for when calculating ideal damping? 2 in/s was mentioned in this thread, is that the standard or just an arbitrary number for the sake of computation?

[solidONE]

0-2"/sec velocities are considered low speed damping range, anything above is considered high speed damping. While the low speed damping is arguably more important and easier to tune, you need to consider the entire range of velocities. High speed damping is where you tune get compliance over sharp bumps, curbing, etc. to cover all the points of consideration when choosing and tuning dampers Andy will have to write an entire book on the subject.

[djliquidsteele]

Originally Posted by Racecomp Engineering

I kinda feel like doing a shock info sticky.


- andy

I kinda feel that when the time comes to upgrade my suspension further, I'll just call you up and ask you all what I need.

[fooddude]

I wonder what Ohlins R&T dynos look like..Especially since they mention/hark that they have a special one of a kind design where the valving loosens up considerably during high speed damping for bumps n shit. Must look like an ultra digressive graph plot. Maybe stiff damped low speed and soft for high speed? ..would be very interesting to see how much diff it is than (or if it really is different as they say) compared to conventional and already done designs/valving.

[JDKane527]

Originally Posted by fooddude

I wonder what Ohlins R&T dynos look like..Especially since they mention/hark that they have a special one of a kind design where the valving loosens up considerably during high speed damping for bumps n shit. Must look like an ultra digressive graph plot. Maybe stiff damped low speed and soft for high speed? ..would be very interesting to see how much diff it is than (or if it really is different as they say) compared to conventional and already done designs/valving.

Sorry can't figure out how to embed images that someone else uploaded to Flickr
Ohlins Front
http://www.flickr.com/photos/gtmotoring/8738910139/
Ohlins Rear
http://www.flickr.com/photos/gtmotoring/8738910099/

KW V3 Clubsports Front
http://www.flickr.com/photos/gtmotoring/8738899195/
KW V3 Clubsports Rear
http://www.flickr.com/photos/gtmotoring/8738899149/

Courtesy of @GTM_Challenge

So then if 0-2 in/s is considered low speed, would high speed be considered 2+ in/s? Low speed ideal compression damping would be 66% and ideal rebound damping would be 150%, and ideal high speed damping would be half that of the low speed. When plotting this, you end up with less "ideal" damping at 3 in/s due to the transition. What exactly occurs during the middle speed transition, and what is the best way of modeling this? I would like to learn more about this. Thanks in advance.

[solidONE]

Ohlins maintains a digressive curve throughout the adjustment range. Even though it is single adjustable both the compression and rebound is affected proportionately, it looks like. The curves looks very good to me. Sexy curves... mmm..

the KW looks to be very good as well. Huge range of adjustment, should accommodate a large range of spring rates, but damping turns progressive at the low range. Very nice as well.

[JDKane527]

Put together this spreadsheet to help in determining the maximum spring rate a given coilover can handle.

Created the spreadsheet around the KW V3 Clubsport to use for my purposes, and utilized GTMotoring's shock dyno plot to estimate the damping based on their posted photos.

17x9 +35 WedsSport TC105 and Hankook 225/45/17 RS3: 40.5 lb
Assume additional 19.5 (?) lb of unsprung mass
Unsprung mass per corner: 60 lb

I used the weights from my last corner balance to get the following:
Front sprung mass per corner: 335kg
Rear sprung mass per corner: 257kg

Plugged the 60N/m and 70N/m spring rates they come with to determine the ideal damping. It is on the softer end of the range that the KW Clubsport damper is capable of. While I have no data that at a given damping setting, the measured damping curve matches the ideal damping, it does look like it can intersect and get a few points, so there is a compromise.

Feel free to critique to help enhance accuracy of the spreadsheet.

https://drive.google.com/file/d/0B4k...it?usp=sharing

[solidONE]

If you want "ideal" you're gonna have to shell out some serious change.

I believe this compression curve is produced by Penske's patented regressive valve. You don't want to know how much this setup would cost... (I'm guessing they're about the same market value as one or maybe 2 fresh kidneys on ice. If you REALLY want it lol)

@JDKane527 Your spreadsheet looks pretty good man, but I'll let Andy and the others do the critiquing.

[CSG Mike]

Originally Posted by solidONE

If you want "ideal" you're gonna have to shell out some serious change.

I believe this compression curve is produced by Penske's patented regressive valve. You don't want to know how much this setup would cost... (I'm guessing they're about the same market value as one or maybe 2 fresh kidneys on ice. If you REALLY want it lol)

@JDKane527 Your spreadsheet looks pretty good man, but I'll let Andy and the others do the critiquing.

I'll tell you in person the next time I see you so that I can see your reaction

[DougW]

I should be able to create something similar with the Damptronic shocks by changing the control map during bump, I will be on the shock dyno next week and give it a try. Always remember the most important spring is the tire.
DougW

[fooddude]

Originally Posted by JDKane527

Sorry can't figure out how to embed images that someone else uploaded to Flickr
Ohlins Front
http://www.flickr.com/photos/gtmotoring/8738910139/
Ohlins Rear
http://www.flickr.com/photos/gtmotoring/8738910099/

KW V3 Clubsports Front
http://www.flickr.com/photos/gtmotoring/8738899195/
KW V3 Clubsports Rear
http://www.flickr.com/photos/gtmotoring/8738899149/

Courtesy of @GTM_Challenge

So then if 0-2 in/s is considered low speed, would high speed be considered 2+ in/s? Low speed ideal compression damping would be 66% and ideal rebound damping would be 150%, and ideal high speed damping would be half that of the low speed. When plotting this, you end up with less "ideal" damping at 3 in/s due to the transition. What exactly occurs during the middle speed transition, and what is the best way of modeling this? I would like to learn more about this. Thanks in advance.

Wow...didn't know dem KW Clubsports had much firmer valving then the Ohlins R&T (though the hysterisis looks much better on the ohlins..assuming the closer and less deviation is better).. make me more attracted to the T2's now hehe