Analysis of shock force vs. velocity graph ?
Analysis of shock force vs. velocity graph ?
(OP)
This is a force vs. velocity graph for a performance OE front shock with only 10K miles on it so I do not believe it is worn our, but it does have unusual damping IMO. Testing was conducted by an experienced tech at Koni's facility. Any thoughts on why the relatively high bump at low velocity and the great lack there of damping for rebound?
Thanks for any input as I've not seen this profile before and the rear shock also has an odd profile.
Thanks for any input as I've not seen this profile before and the rear shock also has an odd profile.





RE: Analysis of shock force vs. velocity graph ?
Maybe that is an artefact of the number of datapoints.
Yes the rebound curve looks very odd. I don't remember seeing any production shock with a concave characteristic before.
There again the bump/rebound ratio is odd in itself, I'm used to seeing bump of roughly 50% of the rebound damping.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Analysis of shock force vs. velocity graph ?
Below is the rear shock graph which kinda makes me think they were trying to compensate or induce something specific but who knows what?
RE: Analysis of shock force vs. velocity graph ?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Analysis of shock force vs. velocity graph ?
RE: Analysis of shock force vs. velocity graph ?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Analysis of shock force vs. velocity graph ?
Everything kind of looks reversed from what I'd expect that is why I posted the graphs for feedback. As best I can tell at the moment the front and rear suspension natural frequencies are proportionate to the 58% front weight bias so that's why I don't know what to think. It may just remain an unsolved mystery? <LOL>
RE: Analysis of shock force vs. velocity graph ?
Is this how you pros would calibrate a performance shock for spirited street and occasional track use?
RE: Analysis of shock force vs. velocity graph ?
RE: Analysis of shock force vs. velocity graph ?
Goran
RE: Analysis of shock force vs. velocity graph ?
As far as the shock graphs are concerned, the vehicle weight is 3500 lbs. with a 58% front bias with a front MR^2= .92 and rear = .94. Front and rear natural suspension frequencies = 2.0 Hz.
RE: Analysis of shock force vs. velocity graph ?
RE: Analysis of shock force vs. velocity graph ?
Regards
Goran
RE: Analysis of shock force vs. velocity graph ?
RE: Analysis of shock force vs. velocity graph ?
I've also seen odd C/R ratios used as a bandaid to make up for springs that are too soft or other deficiencies in the system.
Based on the 3500lb and 58% front bias, this clearly isn't a pure sports car like an elise or even a Corvette. 2.0Hz seems to be on the high end, and I'd expect the rear to be higher than the front from the factory. Is this your modified setup?
If you are looking for recommendations on how to calibrate, we need quite a bit more information, starting with, but not limited to, what behavior you want to change.
RE: Analysis of shock force vs. velocity graph ?
The 2.0 Hz natural suspension frequency is a consideration for performance driver's education type events run on road course tracks. The OE set-up is around 1.32 Hz front and 1. 37 Hz rear. The goal is to reduce roll and pitching with the higher traction tires typically used for the HPDE events and still retain acceptable street ride comfort in a dual purpose vehicle.
It appears that some performance shock suppliers have had good success for both ride and handling improvement by using more low velocity bound damping, say below 2-3"/sec. This seems to allow for lower rebound damping to keep the tire planted over bumps and still support the car to limit roll and pitching. This approach is reported by some folks to improve the ride and handling over the traditional approach of increased rebound with minimal increase in bound as the Koni Sport shock uses for performance street and HPDE type activities.
RE: Analysis of shock force vs. velocity graph ?
Great forum folks, Thank you.
RE: Analysis of shock force vs. velocity graph ?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Analysis of shock force vs. velocity graph ?
Norm
RE: Analysis of shock force vs. velocity graph ?
RE: Analysis of shock force vs. velocity graph ?
With out the Absolute graph, it seems hard to tell if the low speed part of the force curve is influenced by bleed or residual pressure?
RE: Analysis of shock force vs. velocity graph ?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?