Q: Who “Needs” a Steering Damper?

[Greg Field]

Just go look up the old service bulletin on the rake change in the triple clamps. Dave Richardson showed it to me in early 2002 or so. It listed the part numbers for new and old, and what do you know? They match the two series of part numbers shown in the current parts diagrams. That's good enough proof for me, but you doubters can go ahead and do your own research, or not. Facts are facts. The earlier ones are twitchier than the later ones. We offered the upgrade kit (with the "canted" triples) to our customers, but few opted to spend the money. Instead, they just kept their dampers cranked up. But keep believing in demons and haikus if you want.

[docc]

I really can't see the difference between the "fork tube angle" and the "rake." Isn't that the rake of the fork (tubes)?

 

Anyway, I am not not aghast that Guzzi may have tried some interim changes leading to a substantial frame change in 2002. And, yet, I am (aghast). In fact, it is quite surprising to try and catalog or otherwise comprehend the continual development in this series. I'm impressed with the factory's attempts to address "issues" with the product. Whether it is press, or customer feedback, or nasty crashes we, perhaps, will not know.

 

Nonetheless, Moto Guzzi has continually addressed and improved its product. I like my RedFrame and appreciate its "compromises."

 

Sag this, damp that . . . I still believe its greatest drawback "as delivered" was the Pirelli Dragon Corsa tires and soft springs. Weavy devil woman at 90 mph; like dancing with a really large, drunk woman on very high heel shoes; somebody's gonna get hurt and it could be you.

[GuzziMoto]

Just go look up the old service bulletin on the rake change in the triple clamps. Dave Richardson showed it to me in early 2002 or so. It listed the part numbers for new and old, and what do you know? They match the two series of part numbers shown in the current parts diagrams. That's good enough proof for me, but you doubters can go ahead and do your own research, or not. Facts are facts. The earlier ones are twitchier than the later ones. We offered the upgrade kit (with the "canted" triples) to our customers, but few opted to spend the money. Instead, they just kept their dampers cranked up. But keep believing in demons and haikus if you want.

Speaking only for my self, I consider it "proven" now. Thanks Greg for that info.

I'm not good with belief in things I can't see, taste, smell, or touch, anyway. I'm a non-believer kind of guy.

[GuzziMoto]

I really can't see the difference between the "fork tube angle" and the "rake." Isn't that the rake of the fork (tubes)?

The steering head angle is the axis on which the forks rotate on. If you change the angle of the fork tubes without changing the steering head angle you can accomplish a few things but if you do it without changing wheel base then you have not accomplished much. The biggest issue with changing the angle of the tubes is as you turn the forks the difference in the two angles (the steering axis and the forks) changes the front geometry. When the forks are pointed straight ahead the two numbers add directly together (or subtract). But as you turn the forks the steering axis is still inline with the bike but the angle that the fork tubes are at isn't. It is hard to say what Guzzi accomplished without knowing how it effected wheelbase and trail. It would have made more sense to me to just change the offset and add a little more trail while dropping the front to weight the front wheel better if there was a problem with stability. But what ever. Hope this made sense. I'm better at talking then typing.

[luhbo]

Speaking only for my self, I consider it "proven" now. Thanks Greg for that info.

I'm not good with belief in things I can't see, taste, smell, or touch, anyway. I'm a non-believer kind of guy.

 

Enlighten me, please (language barrier and so, you know ):

 

a) Greg is comparing part numbers and finds that some numbers match. Right so far?

b ) Now he says this, for him, is proof enough that later clamps were tilted, right?

c) You answer that you are very hard to convince if it comes to believer questions.

d) Anyway, this "Matching part numbers make tilted clamps" vodoo is exactly what you've been waiting for?

 

e) Are you serious?

 

Please don't take this as argumentative. I'm just puzzled. The more as still none has reported any difference in wheelbase within the KR series. Did they still build KRs in 2002 or was this meant just for spare parts?

Same wheelbase - same parallel clamps. It's that easy. Maybe that the bore diameter has changed for instance, or the way the handlebars were attached, things like that.

 

Again: how do matching part numbers (matching to what btw.) provide any evidence that these newer clamps were off-axis? What am I missing?

 

Hubert

[luhbo]

....The biggest issue with changing the angle of the tubes is as you turn the forks the difference in the two angles (the steering axis and the forks) changes the front geometry.....

 

This does not apply. In fact it makes no difference how or in which way you achieve a certain trail. Be it offset, tilting or just bending like on a bicycle. It's always the same and identical result.

You'll see very small differences as soon as you shorten the legs (on the brake for instance). In this case tilted, off-axis clamps provide a different changing of trail. That's all.

 

In case you don't have a drawing board available you might find helpfull this:

 

 

Hubert

[GuzziMoto]

Enlighten me, please (language barrier and so, you know ):

 

a) Greg is comparing part numbers and finds that some numbers match. Right so far?

b ) Now he says this, for him, is proof enough that later clamps were tilted, right?

c) You answer that you are very hard to convince if it comes to believer questions.

d) Anyway, this "Matching part numbers make tilted clamps" vodoo is exactly what you've been waiting for?

 

e) Are you serious?

 

Please don't take this as argumentative. I'm just puzzled. The more as still none has reported any difference in wheelbase within the KR series. Did they still build KRs in 2002 or was this meant just for spare parts?

Same wheelbase - same parallel clamps. It's that easy. Maybe that the bore diameter has changed for instance, or the way the handlebars were attached, things like that.

 

Again: how do matching part numbers (matching to what btw.) provide any evidence that these newer clamps were off-axis? What am I missing?

 

Hubert

Greg saying that he has seen the technical bulletin for a change to the triple clamps is enough evidence for me at the moment. If you need more that is fine, but him telling me he has seen it is enough for me. He has credibility in my book.

Now, I would still like to see actual measurements showing the differences between the bikes. Are there changes to trail and wheelbase? I don't know but would like to find out.

[GuzziMoto]

This does not apply. In fact it makes no difference how or in which way you achieve a certain trail. Be it offset, tilting or just bending like on a bicycle. It's always the same and identical result.

You'll see very small differences as soon as you shorten the legs (on the brake for instance). In this case tilted, off-axis clamps provide a different changing of trail. That's all.

 

In case you don't have a drawing board available you might find helpfull this:

 

 

Hubert

Sorry, your not getting it. You are correct, trail does not care where it came from. But if where it came from causes the amount of trail to change as forces act on the bike then that does matter. The problem is not with how you get the trail but how it changes as the suspension moves and the forks are turned.

If part of your rake and trail comes from the fork tubes being offset at a 1 degree angle from the steering head (less steep), then you turn the forks 45 degrees to the right, you have now lost about 1/2 a degree (yes it is slightly less then 1/2 a degree, but this is just to give you an idea of what I mean) of virtual rake and gained a corresponding amount of trail since the front axle is now closer to the steering axis (which did not change when you turned the forks). And as you your self pointed out, when the forks compress on a bike with the angled clamps the trail will increase or decrease at a rate that is different then it would on a bike with normal clamps. Now, you could possibly use this to your advantage and make the bike more stable under braking or something like that, but it could also work against you if you don't consider all the ramifications of it when designing it. Motorcycle geometry is not a static thing, it is changing all the time as forces act on the motorcycle. Angling the fork tubes in the clamps changes the way the geometry of the bike changes as the forces act on it. This is not automatically a bad thing, but it can be if it causes the geometry to change in the wrong way at the wrong time.

I am not saying you can't use offset clamps or that it won't work, only that I would prefer to make more common changes first to achieve the desired handling traits.

Best of luck to you.

[Guest ratchethack]

In case you don't have a drawing board available you might find helpfull this:

Hubert, this is interesting.

 

What is the source of this drawing, and would you mind identifying exactly what it says in the drawing legend by way of identifying 1, 2, and 3?

 

Many thanks in advance.

[luhbo]

Only a quick sketch. The distancies like 505 or 230 roughly measured at noon, 92 trail from the papers. 1 top is standard, below -100mm while braking for instance. 2 is with .5deg in one way to get the maximum of trail change (huge huge monster 7mm), 3 is he same in the other direction. To avoid language barriers I admit I don't know whether this means raked in or raked out

As I said, just a rough sketch for checking what could be achieved if you go to a maximum of trail change with this method.

 

Hubert

[Skeeve]

...As far as Gregs claims I simply have no reason to doubt him but I have repeatedly pointed out that if Guzzi did do that it would not be the first or last dumb thing Guzzi has done (hydro valves?). ...

 

Exsqueezeme?

 

Guzzi's idea of putting hydraulic lifters in their cruisers was brilliant; it was the implementation that was lacking!

 

Why do you think Harley's are so frickin' popular? Because motorcycle buyers would rather wrench than ride? Having your bike [car, transport appliance, whatever] do its own valve adjustments is a fantastic idea, provided you can live with the performance limits this technology may enforce. On an engine that rarely or never sees 7k rpm on its tach, it's a no-brainer; that's why H-D switched to hydraulic lifters back in what, 1949?

 

What was dumb was Guzzi giving up on the hydraulic lifters as soon as they'd gotten them sorted out...

[stormsedge]

Okay, I've read most of the nine pages posted here. I know my damper leaks, and I'm certain I have it dialed almost to or at minimum...that due to speed wobble when I first bought the bike used 6 years ago...so, I'm game to try another---is there a good replacement out there? Not a gold plated one, but the one that will do the job reliably for a reasonable period of time (like years)? k

[docc]

Okay, I've read most of the nine pages posted here. I know my damper leaks, and I'm certain I have it dialed almost to or at minimum...that due to speed wobble when I first bought the bike used 6 years ago...so, I'm game to try another---is there a good replacement out there? Not a gold plated one, but the one that will do the job reliably for a reasonable period of time (like years)? k

S'E:

 

Have a look at this thread on the leaky Bitubo:

 

Bitubo Steering Damper . . .

[stormsedge]

Thanks Docc. k

[luhbo]

Sorry, your not getting it. You are correct, trail does not care where it came from. But if where it came from causes the amount of trail to change as forces act on the bike then that does matter. The problem is not with how you get the trail but how it changes as the suspension moves and the forks are turned.....

.....

Best of luck to you.

 

No effect when turning the forks. Zero.

The effects while the suspension is moving are marginal. That's why I provided the sketch.

 

So far Greg only's made up dead riders killed by made up normal use wobbles. So far no stories of Red Frames that become or became unrideable and deadly as soon as you touch the brakes. It seems you two are a good team, though, so who knows what story comes next.

 

Hubert