[MKTURBO]

could someone from tic pm me thier phone # so i can discuss a suspention setup with them so i can purchase it.......

[BigSky]

With both the Sportline and Flag being fully spec'd and assembled in Japan- I would guess that has a lot to do with the choice of damping and the choice in overall travel. It has been my experience that the Japanese tend to choose relatively short travel and very firm damping, this probably is at least in part to their road system.

If the Sportline or Flags were spec'd in the US or even the EU, they most likely would look different.

[fullerton]

Originally Posted by stretch

http://www.circletrack.com/techartic...er_shock_dyno/ (really basic article for newbie's)
http://www.circletrack.com/techartic...ech/index.html (bigger article)

do you have the correct urls of these?

[fullerton]

oh... thanks for the reading stretch.

found your post, and here are the two links:

Shock Absorber - Shock Dyno - Reading Shocks - Circle Track Magazine

Shock Absorber Tech - Overview - Suspension Tech - Circle Track Magazine

[evilSTi7]

Originally Posted by BigSky

With both the Sportline and Flag being fully spec'd and assembled in Japan- I would guess that has a lot to do with the choice of damping and the choice in overall travel. It has been my experience that the Japanese tend to choose relatively short travel and very firm damping, this probably is at least in part to their road system.

If the Sportline or Flags were spec'd in the US or even the EU, they most likely would look different.

I was under the impression they were spec'd in europe (are they from holland? i dont remember), and then just assembled in japan.

[DuncanG]

Originally Posted by stretch

Those fronts look way overdamped to me, even at the soft settings.

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 for the STI. 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.)

I don't have full dyno plots for my Ohlins-PCVs (early design struts for GC8) but the advertised 0.3m/s damping force figures are very close to what's in these plots. My old Legacy is quite a bit lighter in the front than the new Stis and I'm running 300/275 lb/in springs. I have to say that they don't feel over-damped - if anything the rears are a little underdamped in the fast range. Its hard to fault their performance as a fast-road setup - firm as you like (depending on clicks) in the corners, smooth and reasonably comfortable when pootling, compliant and controlled on the fast lumpy stuff.

My understanding is that it is common with digressive shocks to have the damping factor around 1 (or even much higher) at low speed. Remember that the shocks are also damping the sway-bar in cornering. I've recently acquired a set of the acclaimed Exe-tc track coilovers and they follow the philosophy of softish springs with highly digressive damping and on first impressions they are much more heavily damped in the low-speed than the Ohlins. Unfortunately I don't have a dyno chart for them.

I'll dust-off my own suspension calculator and see what damping factor it gives for these Ohlins. It calculates df by integrating force from 0 to 1m/s which is somewhat arbitrary but suits my needs. That produced a df of around 0.28 for my ASTs which I found to be under-damped. Millican advises a df of 0.25 for comfort up to 0.6 for performance but that seems to be based on linear damping (constant over all velocities).

[stretch]

Originally Posted by DuncanG

My understanding is that it is common with digressive shocks to have the damping factor around 1 (or even much higher) at low speed. Remember that the shocks are also damping the sway-bar in cornering. I've recently acquired a set of the acclaimed Exe-tc track coilovers and they follow the philosophy of softish springs with highly digressive damping and on first impressions they are much more heavily damped in the low-speed than the Ohlins. Unfortunately I don't have a dyno chart for them.

That can make sense for a track coilover. I don't think it makes sense for a street coilover. Huge initial forces with strong digression is exactly what a Tein Flex does.

I expected to see ~70% critically damped initially tapering to 50% or so at "street" settings. My "track" expectations were a little more relaxed but I still expected them to at least taper back to ~65%. Only the rears do that, but they also show much less digression.

I wonder if there's something the dyno isn't showing, such as hysteresis or an attenuation on very small strokes, that could be playing a large role.

I'll dust-off my own suspension calculator and see what damping factor it gives for these Ohlins. It calculates df by integrating force from 0 to 1m/s which is somewhat arbitrary but suits my needs. That produced a df of around 0.28 for my ASTs which I found to be under-damped. Millican advises a df of 0.25 for comfort up to 0.6 for performance but that seems to be based on linear damping (constant over all velocities).

I'm not familiar with this approach. So all the resistance from 0 to 1 m/s is essentially averaged? That approach doesn't make much sense to me (right now), but I'd love to read more about it. I've been looking for a cheaper copy of Milliken on ebay for three months now.

[BigSky]

my understading is that Ohlins Japan spec'd the setups, Ohlins "home" provides all the bits they need to achieve it- for the longest time the only market the Sportsline and Flags were offered was Japan

irregardless it appears these coilovers at least roughly follow much the general Japanese line of thinking of firmly damped, relatively short stroke

However- Arnie brought up a good point at the other fourm ( ) that not everything is revealed in a dynograph, Duncan alludes to this as well

[stretch]

...but most things are revealed on a dyno, and everything should be measurable with the right test.

Speaking of, here are the Ohlins Flags. A user here rbahr sent these to me back in May and I totally forgot about them. TiC had me digging for stuff to compare, and I found them again!







Overall they are still quite stiff. At a glance compared to the Sportlines (doing unit conversions in my head), they look softer and rebound with more adjustment, but a little stiffer in bump. So, they're less overdamped than the Sportlines, though I don't think it's enough to fall into the 65-70% critically damped range. The Flags come with slightly stiffer springs. I'll have to plot these to see the critically damped percentages.

[twiSTies]

the Flags there look like they have lots of overlap?

[DuncanG]

Originally Posted by stretch

I'm not familiar with this approach. So all the resistance from 0 to 1 m/s is essentially averaged? That approach doesn't make much sense to me (right now), but I'd love to read more about it. I've been looking for a cheaper copy of Milliken on ebay for three months now.

Thats just what I did in my program to get a single damping factor figure, like I said its arbitrary. Millikan says nothing about velocity sensitive dampers - its pretty old-school academic stuff.


I don't think you can say these Ohlins are way overdamped without actually driving on them. At least until you have your methodology calibrated against real-life. As I said the valving on these seems similar to whats on mine and the ride is civilised. I haven't experienced the Tein Flex so can't comment.

I tried running my program but its broke on XP Its a toy quarter-car time-domain simulator I knocked up to try and get a handle on the dynamics of non-linear dampers.

[Turninconcepts.com]

here's the thing that bothers me on this. Do we know that 65-70% is ideal for this car, and under what conditions?

What gets me thinking this is the math vs. the real world feel. While the numbers (and, Stretch, I do believe you have them correct unless we're both missing something major) show that these should be rather overdamped I have to argue that they feel fantastic when put on the car and driven.

So, where are we seeing the disconnect, and why?

[SOLUTION]

Originally Posted by Turninconcepts.com

here's the thing that bothers me on this. Do we know that 65-70% is ideal for this car, and under what conditions?

What gets me thinking this is the math vs. the real world feel. While the numbers (and, Stretch, I do believe you have them correct unless we're both missing something major) show that these should be rather overdamped I have to argue that they feel fantastic when put on the car and driven.

So, where are we seeing the disconnect, and why?

Can you talk to Ohlins and ask them? Or is that data considered private.

[Turninconcepts.com]

Originally Posted by SOLUTION

Can you talk to Ohlins and ask them? Or is that data considered private.

I'll shoot them an email, and see if they will share.

Now, I have many many books on suspensions, but the best all around book is the Milliken.

In it they have a forumula for critical damping which is

Ccritical =2* sq root of k*m (sorry don't know the ascii code for square root)

k is spring rate
m is mass

The relationship of damping coefficient C at Ccritical is C/Ccritical

[Turninconcepts.com]

Ok. I may have found something. I've got to run to my kids halloween party at daycare, but I'll post up more when I get a chance.