I've never seen a shock dyno like this and don't know how to read it or plot it? How does this look. Is this well dampened?



JET

 

i have no idea either. guessing that ext = Extended and comp = Compressed

Ext 305 = Extended length is 305mm
Comp 127 = Compressed Length is 127mm

I'm probably WAY off, but its a guess to see if i am close at all.

it appears to be a 12way adjustable system and each reading is a Ext/Comp reading in that particular valve setting. IDK!!



or could be pounds as well?? see, i have no idea!

 

If I read it correctly:

Top row is N * 0.3 m/s = speed of movement (1 * 0.3, 2 * 0.3, 3 * 0.3, ...)
Middle row is the force (Newtons?) exerted by the shock during extension
Bottom row is the force (Newtons?) exerted by the shock during compression

 

It's like being asked to review a youtube clip and all you get to see is a screen shot. Not even close to enough information to form any opinion, IMO it's that way on purpose.

You need to see a graph or plot the show's the entire range of dampning, low, mid and high speed. Talking about 0 to 15 or 20 in/sec on velocity or 0 to 35 cm/sec on velocity (Bilstein uses yet another distance measurement that I don't recall).

 

i would plot it like how PDX_racer suggests and compare it to a known shock dyno for your car.

 

You cannot determine a dampners worth by only seeing one single velocity, you have to see a graph that charts the entire speed range. Only showing one speed is done to hide from you the things you need to see to make an informed decision.

In a few weeks I'll have plots for Koni SA's and hopefully oem 2005 shocks done on a roehrig engineering dyno.

 

Any shaft speed beyond .3 m/s is meaningless as far as handling is concerned. Shaft speeds above about .3 m/s are into the blowoffs on the shock and dyno readings at that speed just show how well the shock handles curb hopping.

It appears the shocks above are digressive but only at shaft speeds above .3 m/s (if I'm reading the chart correctly). That's a common way for a cheap shock manufacturer with progressive shock valving to make it appear as if the shock is digressive. In reality, the shock is progressive until the valving blows off.

Always be suspect of shock dynos that show shaft speeds above .3 m/s and be really suspicious of the dyno graphs that show the knee point at .3 m/s or above. If I've misread the chart, I apologize. Its not the way shock dynos are normally presented, which makes be doubly suspicious.

 

the way PDX suggested is not only one velocity. it's

.3 m/s
.6 m/s
.9 m/s
1.2 m/s
etc

the shock dyno's i've seen are force vs. shaft velocity

remember we're just taking a guess at the data the OP posted. so i assume the top row is shaft velocity, and the bottom two rows are force. convert the dimensions, plot, then compare to another dyno to see if it comes anywhere close to a shock dyno. if it doesn't then we're guessing wrong.

i googled a bit to make sure i understood how they measure force on a shock and found this pdf... coincidentally from roehrig. heh

data from the OP would make a peak velocity plot

http://www.roehrigengineering.com/ca...ome%20from.pdf

 

John, I think your seeing things in the chart that aren't their, though we both agree that how the chart was done is highly suspecious. I'm not used to the math they have used, but all the dyno plots that I have seen that are in m/s, show forces past .3 m/s and these are charts that are NOT from a company pushing a agenda. The chart posted above is only showing .3 m/s shaft speeds and what the damper does in each of it's 12 dampning settings at that one speed, where in the data coming from that would make it possible to form a opinion on if they are degressive, linear or progressive without clear knowledge of what is going on at all the other shaft speeds? With out that we also don't know how they handle the blowoff point and where they go from that point. What are they doing at .05 m/s, .1 m/s, 1.5 m/s? You see what is claimed at those 12 settings at that one piston shaft speed.

 

I read his reply, he's not saying their are more then one shaft speed. All the graph show's in one piston speed and what the damper gives out in each of it's 12 settings.

 

OK, that makes more sense regarding the chart. I did misread it.

*digression*

IMHO, from a performance/aftermarket standpoint, showing how the shock valving handles a shaft speed beyond .3 m/s feet per second is meaningless. There's no driver or track input (other then hitting a FIA curb) that reaches that speed - at least for people racing production based vehices (there are some closed and open wheel cars running big aero that will see those kinds of shaft speeds from pitch changes). I might be old school in my thinking about shock damping and my knowledge might be outdated. I'm willing to be educated.

I have been told by shock engineers that they have to design the shocks to handle ALL situations and they need to understand the shock's behavior at shaft speeds way above .3 m/s. I completely agree with that, but posting that information as being of some performance/handling benefit is misleading. For us, IMHO, anything over .3 m/s is noise and tends to distort the data.

*/disgression*