[Engenia]

I need an adjustable steering damper for track only use, and before I ditch the oem unit the thought occurred that if I modulated the solenoid it might just give some finer control over the damping. Of course, it would have to be disconnected from the ECU and a bespoke controller installed instead. I'd make it myself.

Aprillia did something very similar on the RXV550 for idle air control.

Before I launch into this project, has anyone heard of this being done already, or at least discussed?
(A search has revealed nada.)

 

[BillV]

I'm inclined to say that you haven't searched enough. Here's what I think I know about it. So you could change the damping by flashing the ECM. I remain curious about the modulation frequency. I found the modulation table here many years ago.

I guess you could disconnect the ECM (actually you'd have to connect it to a bypass resistor) and control the damper via an Arduino and a variable resistor. In that way you could change it on the fly while riding. But that sounds like a bit much.

P.S. A step beyond that would be to mimic what Suzuki did by having the Arduino also connected to the speed sensor signal. You could then have your own table and speed sensitive damping values. The variable resistor could then change the damping based on speed and it's resistance.

 

[TwistedMister]

isn't it electronically controlled? no manual adjustments

 

[Engenia]

I'm inclined to say that you haven't searched enough.

You're dead right! The search I did took half an hour before I gave up. There are hundreds of hits. So I thought a long term inmate might speed things up - and you have. Thanks heaps BillV. Your links have helped immensely.

... you could disconnect the ECM (actually you'd have to connect it to a bypass resistor) and control the damper via an Arduino and a variable resistor. In that way you could change it on the fly while riding.

That is precisely what I was hoping to do, using an MSP430 based circuit of my own design, and modifying the ECU to disable this function.
I suspect the damping will not be progressive though, like the Matris SD-R for example, where the damping rises dependant on the force being applied. Any standard, or linear damper will do this, but Matris has supposedly arranged the damping to be non-linear.

isn't it electronically controlled?

Yes it (the ECU) does have solenoid control over the degree of damping, but I don't. I want to be able to set it manually, dependant on the track conditions, not speed. Besides, the speed sensor has already been removed as an unnecessary distraction on a track bike, so the ECU has no speed information to work with.
I could have simply disconnected the speed signal from the dash and let the ECU continue doing it's thing, but in my experience, head shakes are the result of the front wheel lifting off the deck and coming back in contact when pointed in the wrong direction. That can happen when crossing a pothole in a corner, or leaving smooth pavement and entering rough, but that is rare on a track. Headshakes on the track on my K2 750 are caused by acceleration out of a corner in lower gears, not at high speed. It doesn't have the power to lift the front wheel above 4th gear.

 

[BillV]

The Hyperpro RSC damper also has non-linear damping. At one time, 15+ years ago, their dampers had a problem with leaking seals. But I think they've sorted that out some time ago.

Stiffer steering head bearings, i.e. roller bearings, might help with headshake. A lighter front wheel, i.e. BST, will have less rotational inertia and may also help, if you can afford it.

Years ago I briefly played with a Cypress Semiconductor PSOC. The biggest drawback back then seemed to be the lack of free development software. Since then I think they've significantly enhanced that. There's a PWM demo project here. I'm unfamiliar with the MSP430. However my general impression is that the Arduino has a huge following that other microprocessors don't have, even though the others may have better specs.

A speed display may be a distraction but the speed rotor and its sensor are small parts and it doesn't have to be connected to the cluster. I personally like the idea of speed dependent damping but suit yourself. The idea of having a base speed dependent profile that can be made stronger or weaker by adjusting a potentiometer sounds attractive. That ought to be well within the abilities of a microprocessor.

 

[TwistedMister]

you can also put heavier weight in em for a more stiffer slower feel..

 

[Engenia]

Years ago I briefly played with a Cypress Semiconductor PSOC.

I used that PSOC uC once. It's the only one that you can decide after fab which port will be used for what, and if you get it wrong, you can change it without hardware changes. It's got something like a PAL between the ports and the pins. The drawback, for what I generally do, is that they aren't that frugal on power. Unlike the MSP430 that runs on moonlight, when configured right.
The Arduino is great for people that don't want to build their own hardware. It's not particularly powerful, or frugal, but it has a following.

One of the first things I did when I got the gixxer, was remove all of the wires and mechanisms that were unnecessary for the track. No sense in having them there to increase unreliability. My K2 track bike has a race loom. There is nothing there that isn't needed. Not even superfluous connectors. The ignition switch is a toggle switch!

 

[BillV]

The damper solenoid resistance is around 12 Ω so it's going to draw as much as 1 amp. I haven't checked but would expect that to be significantly larger than any of the microprocessor draws.

 

[Engenia]

Absolutely, but a simple MOSFET will solve that problem. Their on resistance is now in the milliOhms, so it won't even need any kind of heatsink. Besides, the solenoid will need 12V and the MSP430 will run on 3.5, so a level shift is needed regardless.
Actually, thinking about it, it will need to be pulsed on and off, which will require a bit more sophistication than a simple MOSFET, but not much.
Before I start down this track I'm going to try the Chinese 'Matris' damper used with success by craigfer63, but I think it has promise.