For what it’s worth, I thought I’d add my thoughts on the whole isolastic / featherlastic thing and describe what I’m proposing to do with my Featherbed Commando.
After quite a bit of reading and also talking to Murray here at Cyclecraft in Perth, it would seem that isolastic mounting is required unless you enjoy being shaken to pieces. The various ‘fixes’ at best seem to make it bearable and personally, I think my 850 shakes quite enough. Call me Mr Wuss, if you will. Murray suggested using the Commando cradle and, as I had a spare one, this suited, so I started there.
The Norton isolastics allow for vibration in all directions in the vertical plane and hold the engine, etc in alignment across that plane. That is a compromise that Buell didn’t make and I’m also planning to separate these components. My plan, however, is to use four Norton isolastic mounts for vibration control (one on the head, one front, one above and one below the swingarm mount) with a cross link alongside each mount. These will be the rose jointed head steady type. The intent is that the isolastic mounts will ‘float’ on the mounting bolts with, say, 10mm(?) clearance either side. The rubber boots will be seals only and the whole arrangement will be held in alignment by the cross links. Theoretically, these should be Watts linkages but, over the small distances the engine moves, a simple link will be adequate. The wideline frame has enough room to make these a decent length too. They have to be oriented across the frame. Anything aligned along the frame must, at some time, have vibration pushing on to it and transfer that directly to the frame.
I’d also read some references to doubt about the rigidity of the standard cradle. It does only consist of two plates with no real diagonal bracing, so this may be correct. It also occurred to me that you have this great long swingarm lever out the back and the only thing trying to keep it in alignment is broken into three parts (front mount, engine, cradle). My plan now is to fabricate a stiff alloy cradle that joins the front isolastic to the two rear isolastics creating a rigid lever to resist the forces from the swingarm. My initial review indicates it should be viable, although I’ll need to consider getting it all in the frame.
IMG_0087Large.jpg
The drawing is a concept only, so don’t look too closely, and doesn’t show various mounts that will be required for the cross links, rear suspension, exhaust, blower, etc.
IMG_0086Large.jpg
These are just my thoughts but, as there’s nothing new under the sun, I assume someone has already done this and I’d be interested to be pointed in their direction or see some photos of what’s been done. Any advice gratefully received.
Regards,
Lance
After quite a bit of reading and also talking to Murray here at Cyclecraft in Perth, it would seem that isolastic mounting is required unless you enjoy being shaken to pieces. The various ‘fixes’ at best seem to make it bearable and personally, I think my 850 shakes quite enough. Call me Mr Wuss, if you will. Murray suggested using the Commando cradle and, as I had a spare one, this suited, so I started there.
The Norton isolastics allow for vibration in all directions in the vertical plane and hold the engine, etc in alignment across that plane. That is a compromise that Buell didn’t make and I’m also planning to separate these components. My plan, however, is to use four Norton isolastic mounts for vibration control (one on the head, one front, one above and one below the swingarm mount) with a cross link alongside each mount. These will be the rose jointed head steady type. The intent is that the isolastic mounts will ‘float’ on the mounting bolts with, say, 10mm(?) clearance either side. The rubber boots will be seals only and the whole arrangement will be held in alignment by the cross links. Theoretically, these should be Watts linkages but, over the small distances the engine moves, a simple link will be adequate. The wideline frame has enough room to make these a decent length too. They have to be oriented across the frame. Anything aligned along the frame must, at some time, have vibration pushing on to it and transfer that directly to the frame.
I’d also read some references to doubt about the rigidity of the standard cradle. It does only consist of two plates with no real diagonal bracing, so this may be correct. It also occurred to me that you have this great long swingarm lever out the back and the only thing trying to keep it in alignment is broken into three parts (front mount, engine, cradle). My plan now is to fabricate a stiff alloy cradle that joins the front isolastic to the two rear isolastics creating a rigid lever to resist the forces from the swingarm. My initial review indicates it should be viable, although I’ll need to consider getting it all in the frame.
IMG_0087Large.jpg
The drawing is a concept only, so don’t look too closely, and doesn’t show various mounts that will be required for the cross links, rear suspension, exhaust, blower, etc.
IMG_0086Large.jpg
These are just my thoughts but, as there’s nothing new under the sun, I assume someone has already done this and I’d be interested to be pointed in their direction or see some photos of what’s been done. Any advice gratefully received.
Regards,
Lance
:wink:
