Friction Steering Damper

[BMCMOTO]

Yes the originals like this are friction.  https://www.mgcycle.com/index.php?main_page=product_info&products_id=556   They may not look like it but they are. I put a new one on my MILLE GT and it squeaked all the time. I gave the shaft a tiny squirt of brake clean and it loosened up till the brake clean evaporated, works silently now.

Brian

[moto]

Crusty calls its seemingly identical unit non-adjustable hydraulic.

A hydraulic damper gives more resistance as the rate increases.
A friction damper should be the opposite. My vague recollection
is that the Crusty item acts like it is hydraulic.

Whatever the original was, it seems hydraulic is better here.

Thanks for your answer, though.

[BMCMOTO]

Simple to test per my post!

Brian

[Gusable]

Anyone put an aftermarket damper on a Guzzi that did NOT come with one?  I’d like one on my cal2. Didn’t come with one and I don’t see any tabs or brackets on frame. Need to fab something up I guess.

[moto]

Simple to test per my post!

Brian

What test do you propose, exactly?

[BMCMOTO]

A simple squirt of brake clean on the shaft. If it then moves more easily, it indicates that it is a mechanical device and not hydraulic. Usually, friction dampers of this type are actually packed with rubber rings around the shaft and then compressed into the tube for resistance. A drop of fluid will make the rubber slide along the shaft easier. I suggest brake clean because it evaporates quickly and leaves no lubricant behind, unlike WD40 or carb cleaner. I believe Crusty's description is mistaken, just my opinion, and I am willing to be proven wrong. In fact, I would welcome it as I would like to have one if it really is hydraulic!!

Brian

[BMCMOTO]

So Moto, what is the verdict, is the damper hydraulic, or friction, enquiring minds want to know???

Brian

[moto]

So Moto, what is the verdict, is the damper hydraulic, or friction, enquiring minds want to know???

Brian

It's friction. I'd already decided I had been wrong about this, which seemed to de-motivated me to look.
But on removing one end of the damper it is completely obvious that is friction because it resists movement
constantly at any speed of movement. By the way, your suggested test was excellent, though I didn't need to use it.

While I was procrastinating I thought more about the issue of friction vs. hydraulic, and wondered whether
Guzzi had a reason to choose friction. After all it could easily have whipped up a hydraulic unit since it
was making its own fork hydraulics on site.

I decided that friction might be better sometimes. When I was being hammered by that tremendous side wind
I think bike would have been better off not yielding at all to the blows rather than deflecting and then
damping the resulting weave.

I opened my copy of the engineering text, Motorcycle Dynamics, 2nd English ed., by V. Cossalter.
It turns out that he analyzed the effect of a hydraulic steering damper among
many other factors in a complex mathematical model describing both wobble and weave.
Weave is the more dangerous mode in which both the fork and the body of the bike rotate
around the steering head. In wobble it's just the fork.

The equation he used to describe the damper's force is Nm = c (Radians/Sec). Radians/sec is a rate of
movement like mph, where a radian is about 57 degrees of rotation around the steering head,
and c is the damping constant. The formula says the force of resistance in Newton meters
is a linear function of the speed of rotation. This describes a hydraulic, not a friction, damper.

The author concludes that "increasing the the damping constant ot the steering damper
is a very easy way to increase the damping ratio for the wobble mode, although it has the
undesired effect of slightly reducing the weave mode damping" (p.272). This is in a
complex mathematical model being run through many simulations changing parameter
values.

I'm left wondering what is best: no damper, a friction damper, or a hydrualic damper. But the
one I bought from Crusty is clearly friction, not the advertised hydraulic type.

[BMCMOTO]

Thank you for checking it out! If it had been hydraulic I really did want one! They mount very easily that's for sure, most of the hydraulics are harder to mount and if mounted on the right like many Guzzi's harder to adjust on the fly. A non adjustable hydraulic would be perfect in that location.

Brian

[wirespokes]

The hydraulic damper resists motion in both directions. So in that respect it's the same as the stock friction unit.

I can adjust mine on the fly by reaching over the tank with my left hand. It's not clumsy or at all difficult.

I can't help thinking the friction damper was the cheapest solution and the reason Guzzis came with them.