Who knows how to read shock dynos?

I have some old Koni graphs laying from getting them rebuilt, they generally tell you damping rate vs piston velocity over its range of deflection. The test is pushing/pulling piston at .2 M/sec, then .3, .4, .5. and measuring compression and rebound. RPM says how rapidly its being pulled/pushed. As velocity goes up, damping force does too. There are four lines for compression, and four for rebound as a function of piston velocity over a range of deflection (50mm). If I'm reading the chart correctly the shock isn't all that linear over its travel, but I suspect most act this way.

Rebound is way higher than compression, which means shock will compress, then hold spring in compression. The damper setting seems to hardly effect compression, but does change rebound. The range of adjustment seems narrow, perhaps these are designed quite stiff and its just for fine tuning.

I don't know what those numbers mean in terms of how they'll ultimately feel on the car, but if I can find my old Koni charts I might have a clue.

No doubt a suspension engineer could look at those and tell you a lot more.

bostonaudi said:

...No doubt a suspension engineer could look at those and tell you a lot more.

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hehe... how can I be of service? :biggrin:

ask away.

I'll will a bit of info... this "report" is super shady.

The graphs are bogus, btw... the data may be good, but the labels and range are wrong.

.2 M/sec = 7.87 in/sec WAYYY to high of a velocity to start reporting data. From plotting the info, it would appear that they have a digressive valving. The nose/knee and blow-off data are not there.

If you just evaluate the lines... by just looking at it, crap-ton of compression, very little rebound. Of course as Boston said the inverse (and is correct) the graphs are reversed from what is common practice :bonk: and is reported incorrectly. Gas pressure seems to still be in there, so dampening is actually going to be lower (skewed) than what is indicated (real life application just feels like more spring rate and can shift the graph).

The graph is force vs displacement and not force vs velocity (which would have told you more about the damper). The adjusters are below average grade and have considerable cross-bleed (rebound adjustment affects compression), but tolerances have to be insane (Penske, Ohlins, Dynamics, etc) to be consistent. I'd love to see a force vs velocity chart. The waviness suggests that there is some hysteresis there, but instead of graphing velocity, they just give you some numbers. NO WAY do these have a balanced canister or head valve.


Overall, it really does not tell you crap due to it's lack of credibility stemming from sporadic data.

Thanks guys. I was kind of suspecting something like this. This is for Powered by Max coilovers. They have nice shiny aluminum like all the other Taiwanese coilovers (K sport ahem) but they only had one picture of the damper at the bottom:

Max said:

They are not as harsh with 8/10kg's as say a GP sport coilover with 9/7kg's because of our unique damper. Our damper has relatively little compression damping allowing the larger rate spring to compress more easily upon impact, yet they have an extraordinary amount of rebound damping to control the bounce you may expect with a conventional damper.

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After they posted the shock dyno on their forums a customer asked:

Customer said:

i dont understand this, anyone wanna explian

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Max said:

Dont worry too much about it, the only thing that matters is if you kile the way they feel when you drift.

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Customer said:

ok

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So then Simmsled, what do you think about these two? It's kind of old data from Road and Track in 1997 but it's comparing the kinds of shocks available when you get a Ground Control suspension kit.

GAB R




And Koni




They did release the raw numbers in a table too so here is the source if you want it:
http://www.fd3s.net/suspension.html#SHO

Why am I looking at all this junk? Well I'm just paranoid of what I am actually getting when I buy a suspension. So I'd like to learn what to look for. The Taiwanese ones sure are tempting for $1000, but from what you told me the damper sounds super crappy.

Ooh fun! Yeah, don't have time tonight... but I'll type up an analysis over lunch tomorrow (Friday).

Glad to see some proper graphs off of Roehrig software. :thumbsup:

GodSquadMandrake said:

...nice shiny aluminum like all the other Taiwanese coilovers (K sport ahem)

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lol. I almost went there. :wink:

GodSquadMandrake said:

So then Simmsled, what do you think about these two? It's kind of old data from Road and Track in 1997 but it's comparing the kinds of shocks available when you get a Ground Control suspension kit.

GAB R

And Koni

They did release the raw numbers in a table too so here is the source if you want it:
http://www.fd3s.net/suspension.html#SHO

Why am I looking at all this junk? Well I'm just paranoid of what I am actually getting when I buy a suspension. So I'd like to learn what to look for. The Taiwanese ones sure are tempting for $1000, but from what you told me the damper sounds super crappy.

Click to expand...

The GABs are old school technology. Progressive valvings ride like crap and are nervous at the limit. They require you to run excessive amounts of high speed dampening with very little low speed transitional control. [See how the GAB damper was only tested to 7in/sec? The person dynoing these was either being nice or only had a 500# load cell.] Yeah, you might have 4 nice clicks to adjust, but its all more or less of the same thing. You will have to run an excessively high spring rate with these that is not necessary with a damper with more finite control.
*I do not recommend these, there are better options.

The Konis have a more modern valving to them. You have a much wider control over the 'body roll' portion of the dampening curve. They start out somewhat progressive and then go more digressive/linear. That low speed adjustment is the Koni's bread and butter. The only minor downside is that the adjuster has a rather wide adjustment range and no precision detents. With some seat time, you can fine tune them to get em where you want (or dyno them). It depends on how serious you want to get.

Honestly, with the level you're getting to... I'd seriously consider investing in a set of Penskes. If you are going to have the car for a while, the enjoyment level will just keep on going up. Each time you rebuild them, they are essentially new again. I'm going to be stopping by Penske Racing Shocks this month to see some old friends, I'll see what my price on a set would be.

All in all, the Konis get my approval... the GABs just don't cut it these days.

I love having simmsled around!

Simmsled would these Koni shocks work for a high spring rate like 700-1000 lb/in? It's for Tsukuba circuit. The speeds won't exceed 100 MPH so downforce doesn't really come into play here, I gotta rely just on tires and suspension. So that's why I'm keeping the spring rates so low. But for the street that's still a really high rate that's why I'm wondering on what shocks to get because I don't want to get another set of street shocks and blow them out.

Angel@forge said:

I love having simmsled around!

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x2

Thanks guys!:biggrin:

GodSquadMandrake said:

Simmsled would these Koni shocks work for a high spring rate like 700-1000 lb/in? It's for Tsukuba circuit. The speeds won't exceed 100 MPH so downforce doesn't really come into play here, I gotta rely just on tires and suspension. So that's why I'm keeping the spring rates so low. But for the street that's still a really high rate that's why I'm wondering on what shocks to get because I don't want to get another set of street shocks and blow them out.

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Do you have a link to the kit?

Simmsled said:

Do you have a link to the kit?

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http://www.gtfactory.jp/cms/page.php?9

What kind of time frame do you have?
I ask because I don't think those Koni dampers will hold up and the MAX dampers have shady written all over them.

I'd call Koni or Bilstein to see if you could get some 'Race' dampers valved for those spring rates.

Bilstein doesn't have a kit for my car, only B6 shocks (46mm monotube non adjustable). So I could get shocks, but wouldn't be able to adjust the shocks myself and that's no bueno. Checking Koni now...

I looked up the Penske shocks, they have them but the 7500 series is almost $3,000 just for the shocks.

Ok Simmsled, more choices. Pick one?
http://rx7boutique.com/Suspension.html

I'm lost. Once you get past the Taiwanese brands with the in your face cheap marketing you get hit by these other brands from Italy, Germany and Japan advertising super performance and a hefty price tag but no shock dynos or data to back it up.

GodSquadMandrake said:

Ok Simmsled, more choices. Pick one?
http://rx7boutique.com/Suspension.html

I'm lost. Once you get past the Taiwanese brands with the in your face cheap marketing you get hit by these other brands from Italy, Germany and Japan advertising super performance and a hefty price tag but no shock dynos or data to back it up.

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Ohlins, hands down.

1.)Ohlins DFV (dual flow goodness!)

2.)Ohlins PCV


And if they end up needing service, let me know. I have Ohlins on my speed dial. :thumbsup:

GodSquadMandrake said:

Bilstein doesn't have a kit for my car, only B6 shocks (46mm monotube non adjustable). So I could get shocks, but wouldn't be able to adjust the shocks myself and that's no bueno. Checking Koni now...

I looked up the Penske shocks, they have them but the 7500 series is almost $3,000 just for the shocks.

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Let me see what I can get a set of them for. I'll let you know in a week or so.