Headshake / Wobble Issue with SW Motech Topcase

[seferdilovan]

Hi everyone;
 
I bought a topcase / sidecase set from SW-Motech Trax Adventure and also crash guars from SW Motech. I set them on my bike. After few week later a came across with a strage headshake problem.
 
You can watch it from this link;
 
[video src=https://www.youtube.com/watch?v=mnCiGG9WrGA" size="large]
 
 
 
My bike is like now with the equipment;
 

 

 

 

 

 

 
 
 
 
I was riding with;
 
-only "Topcase" and it was carry about 1.5 kg - 2 kg. Didn't installed sidecases.
-front 36psi
-rear 42psi
-original suspension settings
-original tires (Dunlop D222)
-seat position high
- I'm about 100 kg. /185 cm
 
 
After that problem I change the suspension setting as harder for preload and rebound for both front and rear suspension. However nothing changed!
 
 
 
 
Do you have any ideas? How can I fix this?
 
 

[thruster8999]

If you take the top box off does it still do it?

[seferdilovan]

If you take the top box off does it still do it?

Unfortunately yes, but not great as this shake. Lighter than this. 

[thruster8999]

Check to see if the weight is still on the rim. Tire might be out of balance. Also make sure the axle bolt is tight as well.
Mine would shake if I got on it real hard so I invested in a GPR steering dampner.

[desertfjr]

What I see is a big set of not very aero bags on the back of the bike. What you are fighting is an induced oscillation being imparted into the chassis by the air flowing over those bags. Imagine a flag flapping back and forth in the wind. The oscillation gets transferred into the pole. In this case those large square boxes are causing the air to behave the same over the back of the bike. The air collapses around you, then hits the boxes and you have a giant dirty pool of air at the back end...just like when you pull up little close to a semi and buffeting gets really bad.
 
You can try and make a few suspension adjustments. I doubt they will solve everything. Mostly it will mask the problem you have. The boxes are causing oscillation, imparting it to the chassis and it uses the rear wheel as the fulcrum. What you feel is the "head shake". I would encourage you to look into "vortex generators". Bing and Google are your friend. You may be able to apply them to the edges of your cases to help smooth the airflow and help reduce or eliminate the root cause of the tank slapper you have developing. Duct tape and cardboard will help you test the idea very cheaply.