Skorpion with Scotts steering damper

[hb7]

My latest Skorpion with Scotts steering damper because I got into a
bad tank slapper on the freeway and broke my ankle.
Took me 10 years to find that freeway defect to provoke the
force 10 tank slapper at 65 mph. A damper would have saved me...
We underestimate the danger when we ride....I think it is human nature.
Can't happen to me...etc.

Get a steering damper. You don't need it
until you need it. No bike is immune from a tank slapper.
Ok, maybe a goldwing is immune. Btw, I'm looking for a stock traveller/tour exhaust.
If you need help getting the damper installation mounts : I have it figured out.
hb7@ca.rr.com






Now here is the inspiration for you....

[DAVID THOMPSON]

full details yes please
and may i note that the roads all over the usa
are getting worse as the years go by
i have had 2 tank slappers over the last 50 years
but managed to recover from both
but it was just raw terror mixed with luck
both were caused by pavement problem
one was a pot hole and it busted the front wheel bearings in my 74 r90 s

dave

[hb7]

Interstate 10 W/B in El Monte CA.... I hit this expansion slot + pot hole at about 8pm at night at about 65mph.
I got maybe 3 slaps before the bike slams into the road. Changing lanes did me in, if I had hit it straight on
probably nothing serious. Fortunately, I slid off the freeway and didn't get run over.

[Linegeist]

I'm impressed with the damper .... but is it me, or is that steel fulcrum pin, welded to the front tank bracket, a fracture point waiting to happen? I can't help thinking that the flexing taking place there during normal use is going to lead to stress fractures in fairly short order .....



Sorry to be a jonah - but that arrangement makes my tiny engineer's mind itch somewhere I can't scratch.

[Norman Wade]

There's one on British Ebay at the moment. http://cgi.ebay.co.uk/SUZUKI-DRZ400-SCOTTS-STEERING-DAMPER_W0QQitemZ300417713190QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item45f24a8426
You'll have to make your own brackets, though.

Norman

[hb7]

I don't think the weld is suspect. Is there something you see ?
This the method Scotts suggested.

[Anders]

Depending on how you dialled in the damping there will be some load and flexing of the tank bracket that may or may not result in metal fatigue.

Normally there should be minimal low speed damping so during everyday riding very little stress would be put on the tank bracket.

These Scotts dampers are at least in part designed by Ohlins, they are a marvel of precision jets/orifices to get equal damping in both directions. If the jet inside are off by a 1/100:th of a milimeter the left/right balance of the damping will be upset.

How do I know this you migth wonder, back in 1997 I was employed as a lab engineer in the development lab of Ohlins. One of my assignment was to pinpoint the manufacturing tolerances needed to achieve consistant performance from theese dampers.

[DAVID THOMPSON]

to hb7
i have a 97traveller
which bike should i order mine for so i get the hardware
so i have to make the least amount of home made stuff
and where in the usa do i order from
dave

and of course if i have to ask the price. i probably can not afford it

[hb7]

I paid 375 for a mild scratched damper with the mount. I will happy to pick up or order the same MZ Skorp mounts for you.
They have not done a Skorpion before.
Nothing was home made. I had to drill the top triple for 2 -6mm bolts and weld the locating pin.
The Scotts Damper manufacturing is near me.Call me if you want me to help. henri 323-933-1366

[hb7]

Greetings Anders,
The locating pin is very strong with the weld. I had it done by a certified welder.
I will put a pipe on it and stress it to see.

What would you set the sweep at ? 34-44-54-78º
Very impressed with the damper.

My thoughts are, it's a matter of time before every street rider finds a tank slapper.
Should be mandatory...on bikes.

Depending on how you dialled in the damping there will be some load and flexing of the tank bracket that may or may not result in metal fatigue.

Normally there should be minimal low speed damping so during everyday riding very little stress would be put on the tank bracket.

These Scotts dampers are at least in part designed by Ohlins, they are a marvel of precision jets/orifices to get equal damping in both directions. If the jet inside are off by a 1/100:th of a milimeter the left/right balance of the damping will be upset.

How do I know this you migth wonder, back in 1997 I was employed as a lab engineer in the development lab of Ohlins. One of my assignment was to pinpoint the manufacturing tolerances needed to achieve consistant performance from theese dampers.

[Anders]

Greetings Anders,
The locating pin is very strong with the weld. I had it done by a certified welder.
I will put a pipe on it and stress it to see.

What would you set the sweep at ? 34-44-54-78º
Very impressed with the damper.

My thoughts are, it's a matter of time before every street rider finds a tank slapper.
Should be mandatory...on bikes.

The weld itsef is probably no concern, however the tank bracket would be flexing under load which may cause metal fatigue over time.

I would start with 78º and reduce if handling/maneouvering in low speed corners (i.e. full lock) is negatively affected. Theese dampers are designed for MX use originally, in your typical on-road steering damper application there is no option to adjust the sweep since it is really not needed.

[Linegeist]

My point exactly Anders. The welds on that installation look excellent, as does the reaction pin - but I can see that thin steel tank bracket flexing laterally and, over a period of time, developing cracks at its base and then fracturing and shearing off the frame. That this might well happen at a time it's neede most - at highest loading (ie a tankslapper) I'd be a bit wary of this, to say the least.

To my tiny mind, the bracket ought to be replaced by a heavier guage item to deal with the stresses involved.

How do I know this? I'm a retired Mechanical Engineer with a fair amount of (military) experience in metal fatigue analysis (bridging) which makes bridges fall down (suddenly) which makes people like me wary of small stressed parts (sleeplessly)

[djsbriscoe]

Hi,
Maybe boxing in the rubber damper on both sides would add to ridgidity. I agree the weld looks strong enough but the top of the bracket at the bend will work harden with continuous flexing. If the bracket is turned into a box the twisting will be reduced.

Just my humble opinion.

David

[hb7]

My observation is that the weld and the front tank bracket does flex.
I will have a 19mm support plate welded inside the tank bracket to stiffen this up.
I'll cut the rubber to make room.

best,
henri