Tein Active EDFC?? Yes please :)

[Lauren]

Dan you might not want it, but how do you know until you've tried it?

Yes there are stepper motors atop each damper to adjust them. That bit is fairly low tech, though the motors are said to be very accurate. The clever bit is in the programming of everything individually. Having ten steps for areas of adjustment, so, G0, G1, G2 etc and then be able to adjust the parameters front and rear relative to G-Force, laterally, longitudinally and also for speed is an interesting concept. Also you can match all these different settings for each axis independently.

In some respects you can fine tune it so much that it's a little daunting and obviously you've got to know about handling in order to set it up in any way that is going to be good. But, there must be a potential for variances in damping force to be advantageous to having a static setup for at least a proportion of the time. Effectively if you knew what you were doing on track you could set the right compromise that would suit a variety of corners by having different settings for different speeds and g-force. You'd need to be clever though, I admit!

The manner by which damping force is changed is in small increments in g-force or speed so the manner in which it feels isn't like suddenly going from soft to hard, it's a transition and you feel as say the lateral g-force increases. It does feel different and then some acclimatisation, but not much because it simply changes to a stiffer suspension settings the fast you go in speed and lateral and longitudinal G, which is generally what you want. This gives the potential to have a good setup for both slow and high speed corners as you can set it up through defined speed ranges for each step.

[ZDan]

Originally Posted by Lauren

The thing is in practice it works extraordinarily well. But this all depends upon what you want out of a suspension setup. I drive 30K miles a year, I compete in a sprint series and also do a few trackdays.

For me, I can have my cake and eat it. The ride is better than stock but when I up my game so does the damping and it firms up when you need it to.

For my FD, I find my "street settings" on the Ohlins DFV to be totally up to the most spirited street driving. And one or two clicks all around and I have my preferred track settings.

The speed variation is useful and important. Mine doesn't increase in stiffness until I go over 60 km/h. Then it increases in stiffness right up to 200km/h which is just as far as I set it to. The lateral G increases are stepped and you can make these small or large and obviously independent at the front and the rear.

I wouldn't *want* any devices to be changing my preferred settings based solely on vehicle speed and g's! Seems to me a very poor approach! There are times when you are driving fast and cornering hard when you *want* the damping to be more supple, not stiffer.
Every corner is different, and you would want a system that could adjust based on that fact. Whether it went by GPS and could be preprogrammed, or whether it monitored more than just speed and g's.

The reality is, you're cruising down an A road, you increase your speed the dampers firm up so you don't get that floaty feeling you otherwise would have were they on a softer setting of lower speeds and then when you being to corner the dampers increase stiffness from 0.15g onwards. You can custom set what happens at what G-force levels or you can select a linear mode which may be better for track work. Obviously you can just set them at any level manually so they are static on a scale of 0-64, so plenty of adjustment.

I think the way to go would be to have damping adjust for RATE OF CHANGE in g's, not strictly on g's. I would want stiffer damping to arrest roll rate while I'm turning in, NOT while I'm at maximum-g cornering.

I also kinda think that in many cases you'd want *softer* damping at high speeds and *stiffer* damping at lower speeds. But my impression is that I wouldn't want it to vary based on vehicle speed at all.

I think it's hard to conceptualise how it might work and there are always those that just won't believe something like this can be any good, but for my needs it serves the purpose very well indeed.

Not a hard concept to grasp. It can adjust low-speed damping of traditional manual-knob adjustable dampers on the fly, with vehicle speed inputs and longitudinal and lateral g inputs. IMO, those inputs are not enough.

Of course the beauty is, you can simply set it up to do exactly what you want.

Can you have it adjust damping based on rate-of-change in g's? That's what I'd want to try.

[Lauren]

Originally Posted by ZDan

I think the way to go would be to have damping adjust for RATE OF CHANGE in g's, not strictly on g's. I would want stiffer damping to arrest roll rate while I'm turning in, NOT while I'm at maximum-g cornering.

I also kinda think that in many cases you'd want *softer* damping at high speeds and *stiffer* damping at lower speeds. But my impression is that I wouldn't want it to vary based on vehicle speed at all.

Not a hard concept to grasp. It can adjust low-speed damping of traditional manual-knob adjustable dampers on the fly, with vehicle speed inputs and longitudinal and lateral g inputs. IMO, those inputs are not enough.

Can you have it adjust damping based on rate-of-change in g's? That's what I'd want to try.

You can adjust the RATE OF CHANGE in G-force, that is the point. The changes make a noticable difference I find.

As I tried to explain before, you don't notice the dampers go from soft to hard in an instant, it is proportional to the g-force levels you have set it to change and each change is a step which can be fairly subtle if you want it to be. The faster you turn in the quicker the damping force will increase of course. How you load the G is obviously a factor.

[ZDan]

Originally Posted by Lauren

You can adjust the RATE OF CHANGE in G-force, that is the point. The changes make a noticable difference I find.

As I tried to explain before, you don't notice the dampers go from soft to hard in an instant, it is proportional to the g-force levels you have set it to change and each change is a step which can be fairly subtle if you want it to be. The faster you turn in the quicker the damping force will increase of course. How you load the G is obviously a factor.

Changing damping based on G's is NOT the same as changing it based on the *rate of change* in g's.

It sounds to me like you might be able to specify a damping setting based on the level of g's, but I want *different* damping settings at the same cornering g's depending on whether the lateral g's are *changing* rapidly or not.

[Lauren]

You can set the rate of change in g-force. You have ten steps in which to vary the rate of g force and the level of change you want.

Though for the second part you can up the rate of change around a g-force level if you wanted to. So the steps can be quite big if you so choose. It will just vary as it loads and unloads.

[ZDan]

Originally Posted by Lauren

You can set the rate of change in g-force. You have ten steps in which to vary the rate of g force and the level of change you want.

Though for the second part you can up the rate of change around a g-force level if you wanted to. So the steps can be quite big if you so choose. It will just vary as it loads and unloads.

Can you set it such that it will give *different* damping at 0.5g depending on whether g's are changing or not? I.e., soft damping at 0.5g constant cornering, and stiff damping at 0.5g with g's rapidly rising?

[Lauren]

Well, it will vary to the rate you set it at. So you could have a given setting at 0.5g that is constant (of course), it won't change if the g-force isn't varying. Then you could set the damper settings to ramp up with whatever increase in g-force you select when it exceeds 0.5g.

[Lauren]

I should add you can also set it in linear mode so it increases at a set rate. Or the other setting lets you 'arrange' what settings you want with a chosen g force level.

[ZDan]

Then it does not allow you to vary damping level based on the rate of change in g's. They should develop that...

[Lauren]

I'm not sure if I'm following you here. But you can set the rate of change in G's. So you could have a varied level of adjustment and say have the damper stiffness vary only a little around a given rate of G, then make it increase the further you go away from that setting, so you could ramp up the change in damping more aggressively at a set a G level.

[Racecomp Engineering]

What he means is that you'd want one damper setting if the car is at a sustained 0.5g, and another if its quickly going from say 0.2g to 0.7g. You'd want different things at that 0.5g point.

Just like you'd want different damping at 100 mph depending on the road surface. And maybe I'd like firm damping in a slow corner but maybe not if it's a bumpy one.

- Andy

[Lauren]

Ahh okay. Well, then no you can't do that. Changing settings at a given speed for G though is not a problem.

[Shankenstein]

Originally Posted by Racecomp Engineering

What he means is that you'd want one damper setting if the car is at a sustained 0.5g, and another if its quickly going from say 0.2g to 0.7g. You'd want different things at that 0.5g point.

Just like you'd want different damping at 100 mph depending on the road surface. And maybe I'd like firm damping in a slow corner but maybe not if it's a bumpy one.

- Andy

Probably a stupid question, but has anyone attempted to mount a linear displacement sensor IN or ON a shock/strut for this type of control?


I know they're regularly used to tune real racecars, but only for data acquisition purposes.

I'm sure we could use accelerometers, but the data would be sketchy at best. One on an unsprung component and one on a sprung component. Subtract to get the differential movement. Lots of noise in the data, mounting issues, etc.

If you wanted to go full-retard (and don't we all?!), take that data and stream it into a recursive least squares algorithm using a basic suspension model. Snag the coefficient related to damping, and input that to a controller. As with most tracking applications, you'd try to minimize the observed error (between critical damping and the estimated coefficient). Even a simple "proportional + dead zone" controller would get the job done.

*scratches my chin stubble* That kind of a solution would "auto-tune" your suspension. Seems like a very marketable product for one-time passive tuning or always-on active tuning.

[Lauren]

I wonder what research and development Tein have done on this to get the preset values that are available (4 presets)?

I'm hopefully going to get a factory tour of Tein in Japan when I go in August. I will hopefully have some discussion when I'm there.