[Turninconcepts.com]

Had a busy day today.

First some notes on the test. The test equipment was a really nice electromagnetic Roehrig setup.

We only tested to 50mm of travel. Why? Because really that's all that we felt was necessary overall to get the results we needed.

The velocities tested at were this:
0.05 m/s
0.13 m/s
0.22 m/s
0.33 m/s

Why these rates? These are just the general all around rates they have pre-programmed into the system that give a good idea of what's happening across a range of low and high speeds.

Settings for testing (all down from full firm):
Front:
5 down
6 down
7 down (race setting we use)
14 down (street setting we use)
21 down

Rear:
3 down
6 down
9 down (race setting we use)
18 down (street setting we use)

A few notes before the pics:
As you go softer the settings have less of an affect. It was explained that this is normal for needle valve setups. As you open the valve more the needle becomes less and less of an obstruction until you get to a point of diminishing returns and the only resistance is the actual size of the orifice itself (keep this in mind as the oil thins when it heats up). In other words, there is a point where the only thing slowing the flow through the needle valve is the size of the opening for the valve.

It seems that while they are primarily rebound adjustable the adjustment does have a small affect on compression. Albeit pretty small to a point.

Compression is on the top half. Rebound is on the bottom half.

Units are Newtons and meters/second.

EDIT!! Stroke used was actually 50mm. My mistake!

I scanned these so if you can't see things I can rescan.

[Turninconcepts.com]

Next trip will be for the AST setup, and while we're at it we'll have some stock struts dyno'd.

As for the big question - stiffer springs. Yes, you can. Hell you could run really stiff springs on them, but you're going to hate it and they most likely won't last long.

Mild increase and still have it a) livable and b) properly handling. Sure. Up 1K would be no problem for them.

[fullerton]

Great to see that the adjustments are true and actually have the desired effect!

How similar are these dampers to the flags?

[4banger]

Thanks for the nerd candy.

[Turninconcepts.com]

Originally Posted by fullerton

Great to see that the adjustments are true and actually have the desired effect!

How similar are these dampers to the flags?

Different. those would have to be dyno'd separate.

[evilSTi7]

So do you think the settings you run are the best for each situation (road and track) or would you change your recommended settings? I'm not the greatest at reading the dyno graphs, but it looks like from the graphs maybe running 5 clicks front and 6 clicks rear would be the best on the track?


Also, thank you so much for doing this!

[Turninconcepts.com]

Originally Posted by evilSTi7

So do you think the settings you run are the best for each situation (road and track) or would you change your recommended settings? I'm not the greatest at reading the dyno graphs, but it looks like from the graphs maybe running 5 clicks front and 6 clicks rear would be the best on the track?


Also, thank you so much for doing this!

in consideration to spring rates vs dyno looking at pure numbers you could, but our feel for the car says otherwise.

Now, keep in mind that with the new springs those settings may not be the same for the track once we get them dialed in.

[BigSky]

did you meausre the total travel by chance when you had them off? 80mm is probably not too terribly far off the total travel for the Ohlins???

a quick comparo to the Koni 8610's the front rebound is actually pretty similar, the front compression the Ohlins are firmer damped. the rears the 8610's appear to have more rebound on tap- the Ohlins figures are bracketed on either side by the Koni's- the Koni's from full soft to full firm run almost consistently a full 1000 NM between the two. the Koni's are slightly more firmly damped in compression in the rear

what do the 2nd set of graphs (force vs displacement) tell us?

[DuncanG]

Did Koni say why they gave you peak velocity plots rather than the more detailed continuous velocity plots? Seems a waste to use a modern linear servo dyno to do the same job as an old crank dyno. Maybe there's a practical advantage.

Some more resolution at lower velocities would be nice. Eg vel of 0.04, 0.08, 0.16, 0.32, perhaps an additional run at 0.02m/s.

Do these Ohlins have the PCV or DFV valving? There's not enough resolution in those plots to tell.

[stretch]

I revised my suspension calculator just for this. (4banger, I hope you like the changes... I'll upload them shortly.)

Those fronts look way overdamped to me, even at the soft settings. I'm not even accounting for friction in the suspension in my analysis (which would raise the total resistance), a new feature in the calculator.

First is TiC's street setting. This is for 392/280 spring rates, 3500lb vehicle weight, 58% on the front axle. (This is all stuff you'd see on the upper half of this spreadsheet.)




TiC's track setting is about 15% firmer mostly in low piston rebound speeds.



In comparison, the stock struts calculate to 70% critically damped front, 65% rear (peak, both on rebound, and accounting for some suspension friction). This is exactly what we'd want to see. So, the front Ohlins are much stiffer at low wheel speeds and still slightly stiffer at high wheel speeds. The rears look better matched to the springs than the fronts but still much too stiff.

The fronts going over 100% damped is just absurd- do these things ride well or are they closer to JDM stuff? They're not quite as overdamped as some Teins but at a cursory look, they're much stiffer than anything else for the STI (relative to the spring rate). I don't understand how these could ride well. The front struts look better matched to a 700-750lb/in spring.

Overall, I'm just surprised. Either these calculations don't mean a damn thing, they're totally wrong, or there is lots of room for improvement here. Something isn't right... and yet I'm pretty sure my calculations are accurate. (I keep looking for the error.)

[Saabaru STI]

Was this done with Ohlins Sportslines with the factory springs (Eibach) or the replaced Swift Springs?

[stretch]

Originally Posted by Saabaru STI

Was this done with Ohlins Sportslines with the factory springs (Eibach) or the replaced Swift Springs?

Shock dynos are done without springs. For my calculations above, however, I assumed the listed spring rates were accurate and linear.

[fullerton]

for us noobs, could someone give a quick explanation of how to read the plots?

[Turninconcepts.com]

Originally Posted by BigSky

did you meausre the total travel by chance when you had them off? 80mm is probably not too terribly far off the total travel for the Ohlins???

a quick comparo to the Koni 8610's the front rebound is actually pretty similar, the front compression the Ohlins are firmer damped. the rears the 8610's appear to have more rebound on tap- the Ohlins figures are bracketed on either side by the Koni's- the Koni's from full soft to full firm run almost consistently a full 1000 NM between the two. the Koni's are slightly more firmly damped in compression in the rear

what do the 2nd set of graphs (force vs displacement) tell us?

No we didn't measure total travel. He set it at 80mm to try to keep off the bumpstops and get a better measure of the valving alone. It was his decision.

force v. displacement is simply that the force generated vs a certain displacement. Follow X-axis first and then go on y-axis to read it.

Originally Posted by DuncanG

Did Koni say why they gave you peak velocity plots rather than the more detailed continuous velocity plots? Seems a waste to use a modern linear servo dyno to do the same job as an old crank dyno. Maybe there's a practical advantage.

Some more resolution at lower velocities would be nice. Eg vel of 0.04, 0.08, 0.16, 0.32, perhaps an additional run at 0.02m/s.

Do these Ohlins have the PCV or DFV valving? There's not enough resolution in those plots to tell.

No they did not say, and I did not think to ask.

Take a look at the velocities run. They are pretty close to what you're asking for.

Good question on the valving. I don't know. If I had to guess I'd say PCV based on how they behave when you soften them, but don't quote me on that.

[stretch]

Originally Posted by fullerton

for us noobs, could someone give a quick explanation of how to read the plots?

Here's an excellent article from Grassroots Motorsports that explains what to look for in a damper:

Shock tech

Here are some other good reads, in no particular order:

http://www.circletrack.com/techartic...er_shock_dyno/ (really basic article for newbie's)
http://www.circletrack.com/techartic...ech/index.html (bigger article)
Shock Absorber Tuning (getting more technical)
What's junk and what's not. (opinion piece, states the 65-70% critically damped rule)
How the machine works. (Really good article from a shock dyno manufacturer.)

Some stuff on Ohlins PCV/DFV valving (since it was just mentioned)

Lastly, here are other shock dynos for STI/WRX products (I need to update this thread!):
http://www.iwsti.com/forums/suspensi...iscussion.html