ludwig said:
Ok , I said that I would not react , but I guess I just can’t resist .
1.why a clamp , while you already have a perfect fixing point in the threaded cross tube of the original head steady ?
( I find RR's expanation about adjustability not convincing )
2.the max amplitude of the vibration is less than 2 mm .Using rose joints to control this is technological overkill .
3.an adjustable link to correct the vertical alignment of the rear wheel ??
if the rear wheel is not in the same plane as the front wheel , that is because of faults in the the frame , engine cradlle , or swing arm .
If you can’t live with that , correct it .
It seems silly to me to put a lot of torsional load on the isolastic system , in order to compensate for a warped swingarm ( and many are ) .
4. sidenote : by using an undamped system like a DT , even more stress is put on the exhaust system .
The way the mufflers are fixed to the frame is an engineering mistake .
The entire system should be bolted to the engine cradlle to prevent cracking .
5.The job of a headsteady is essentially to allow free movement in a vertical plane , and limit lateral movement to a preset value .
Damping , friction reduction or a compensating spring are optional .
This goal can easily be achieved by a simple strap of steel bolted to the head ; held in check by a U- shaped clamp on the frame , or something similar , using the existing fixing points .
Ok , maybe slightly more complicated , but anybody who can drill and weld , can make it in an afternoon for less than 5 dollars material cost .
Ludwig, I shall try to respond to each of your points:
1) The geometric orientation of the heim link doesn't lend itself to connecting to the existing threaded holes without having to fashion a more complicated connection. The clamp is very simple and very effective. With this approach, an adjustable armature is created which can be placed as necessary to properly align the plane of the heim link to the plane of the motor and frame; as the length of the link varies, so too must its connection point to the frame in order to retain proper alignment; thus the rotating armature is the simple approach.
2) That's a straw dog argument. The heim is designed to accommodate a small amount of movement, just as you've measured. Read the specifications of a heim joint and you will see that this is precisely the appropriate application for the devise.
3) You are grappling here with the essential facts of the isolastic system as applied to the Commando frame. This is precisely why an adjustable method for aligning the motor/frame/wheel assembly is necessary for precise vertical wheel alignment.
4) Damping occurs via the two lower isolastic units, quite obvious really. The head steady accommodates the resulting up and down movement - no stress, just simple motion.
5) The preset value for lateral movement with a heim joint is exactly zero (0.0000) That is why they are used in aviation applications, including helicopters, and other critical moving situations that require movement in a precisely controlled plane. I don't see any value or need for the MK 3 suspension spring and therefore don't use it or recommend it. It's basically complex and superfluous.
Your suggestion for using a simple strap of steel bolted to the head seems contrary to all the points you've raised, such as damping, stress, torsional load, and so on.
Sidenote - My bike uses the original 750 headers, and all the standard hanging brackets. There has never been a failure due to stress cracks, or any other type of failure. Suspending the headers/mufflers on rubber grommets is the logical extension of the isolastic system. Some wiser Triton and other custom bike makers have borrowed those parts for precisely the same reason - to isolate vibration and reduce failure due to stresses. Bolting the system to the engine makes no sense at all, but maybe I'm missing something there.??
The notion that a better system is one that is cheaper to make reminds me of the guys here in the USA who wear these little beany helmets. As some of us are prone to observe, Five dollar helmets for five dollar brains. Just my opinion.
Mark