74ok
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8 years and ~50,000 miles
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New use for a Kibblewhite Performance valve spring (2013)
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8 years and ~50,000 miles
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I am kicking myself for not adding this mod when it was easy to do access wise.
My (titanium) spindle head steady might be fine now but over time if the (new) Isolastics were to sag that could risk contact in the spindle bore frame mount. (Maybe only at certain RPM's, who knows)
That JC is a smart dude, a simple but effective modification over trying to hang the engine off the top frame tubes with a 'bed spring.
My (titanium) spindle head steady might be fine now but over time if the (new) Isolastics were to sag that could risk contact in the spindle bore frame mount. (Maybe only at certain RPM's, who knows)
That JC is a smart dude, a simple but effective modification over trying to hang the engine off the top frame tubes with a 'bed spring.
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I thought it might be possible but was wrong.
What I will do is have a hole in the JC frame mount for a bolt that threads into a stepped spring seat. (New AN inner and outer valve spring to keep it British)
Jacking on the bolt will lift the spring seat so a circular shim ( with slot to the central hole) can be slid under to alter the preload then the bolt tightened.
cliffa
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I did have an idea to get a piece of strong pipe welded to the bottom of the front ISO tube. The pipe would be large enough to contain the springs and would have a screw cap at the bottom so the pre-load could be adjusted. Then the top of the spring would sit directly under the ISO cross tube which has had the rubbers removed. ( maybe the smaller ones could be left for the occasional pot-hole) Obviously it wouldn't be in the same position as Jim's, but it would mean it could easily be reverted or transferred to another bike.
74ok
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I forget what all the spring is about, i guess take some weight of the iso's also allowing movement. Improvement with what? The iso's wearing out quick?
Wondered what this was about also
a linkage I made using one of my headsteady tie rods. I have removed the isolastic washers from the front mount and use the tie rod to eliminate the sideways play. That has been on there for several years. Jim
As far as the spring mounting goes, dunno about the upper bracket, whether just held in place by spring pressure along with the described 'nub'
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Previous post content removed being confusing to the specific thread topic.
The parts are machined now, the cup needs welding to the frame cross tube. I have a new AN valve spring set but as per a JC comment in the earlier part of the thread its rating might be to low.
The parts are machined now, the cup needs welding to the frame cross tube. I have a new AN valve spring set but as per a JC comment in the earlier part of the thread its rating might be to low.
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74ok
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New use for a Kibblewhite Performance valve spring (2013)
Getting ready for my upcoming 4-5000 mile road trip and thought I would play with reducing vibration on the road. The iso rubbers were replace a couple years ago but with heavy 880 pistons and steel rods the bike has never been as smooth as it was originally. Now after a couple years the...
www.accessnorton.com
I suppose with all the individuality out there, This KW spring is a one bike result but this part speaks volumes
comnoz:
A couple brackets and a little welding and a Kibblewhite valve spring. It supports the motor enough that when the front iso bolt is removed the holes stay lined up.I was shocked at the difference. The mirrors are clear and no tingling hands after a couple hours. I guess I will find out if it lasts over the next three weeks. Jim
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cliffa
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One thing to note : I'm pretty certain that Jim removed the rubbers from the front ISO completely and just uses the Panhard rod to control the side to side of the engine.
Edit : Found Jim's post. No rubbers in the front ISO tube. He also says KW springs were better than standard....
www.accessnorton.com
Edit : Found Jim's post. No rubbers in the front ISO tube. He also says KW springs were better than standard....
New use for a Kibblewhite Performance valve spring (2013)
Getting ready for my upcoming 4-5000 mile road trip and thought I would play with reducing vibration on the road. The iso rubbers were replace a couple years ago but with heavy 880 pistons and steel rods the bike has never been as smooth as it was originally. Now after a couple years the...
www.accessnorton.com
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74ok
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74ok
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comnoz said:One thing to note : I'm pretty certain that Jim removed the rubbers from the front ISO completely and just uses the Panhard rod to control the side to side of the engine.
Edit : Found Jim's post. No rubbers in the front ISO tube. He also says KW springs were better than standard....
New use for a Kibblewhite Performance valve spring (2013)
Getting ready for my upcoming 4-5000 mile road trip and thought I would play with reducing vibration on the road. The iso rubbers were replace a couple years ago but with heavy 880 pistons and steel rods the bike has never been as smooth as it was originally. Now after a couple years the...
"There is no rubbers or iso shims in the front mount. Just a spacer and a couple plastic caps to keep the dirt out.
The spring is easily removed by removing the long front mount bolt, this allows the motor to be raised just far enough to remove the spring.
The tie rod link keeps the front of the engine from moving side to side [like the original iso shims did -except the rod ends don't wear out quickly"
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I will post this here for anyone interested who might not venture out of the main forum.
I found even with new RGM Isolastics the front sagged around 3 mm with the weight of the engine and no form of head steady pull spring, observed with the end caps removed.
I made this bracket that attaches via the bottom bolt of the Isolastic engine mount, a longer 3/8 inch and two 1/4 inch UNF bolts together lock it in place.
Unlike the JC version this has Isolastics in place.
The inner and outer valve springs are standard new AN parts, the inner spring is preloaded via a OEM stepped valve retainer inside the top brackets bore.
The compressed length of the springs ended up at 31.5mm (42mm free length) to have the front 1/2 inch bolt slide in with no resistance.
I might cover it with a length of rubber inner tube and grease the springs.
I can only assume any Commando with no assist spring and old Isolatics will have more than 3mm sag compression of the outer rubber discs, maybe the inner rubbers close to contacting the tube bore which might account for varying vibration bike to bike.
A big thanks to JC for posting this mod.
I found even with new RGM Isolastics the front sagged around 3 mm with the weight of the engine and no form of head steady pull spring, observed with the end caps removed.
I made this bracket that attaches via the bottom bolt of the Isolastic engine mount, a longer 3/8 inch and two 1/4 inch UNF bolts together lock it in place.
Unlike the JC version this has Isolastics in place.
The inner and outer valve springs are standard new AN parts, the inner spring is preloaded via a OEM stepped valve retainer inside the top brackets bore.
The compressed length of the springs ended up at 31.5mm (42mm free length) to have the front 1/2 inch bolt slide in with no resistance.
I might cover it with a length of rubber inner tube and grease the springs.
I can only assume any Commando with no assist spring and old Isolatics will have more than 3mm sag compression of the outer rubber discs, maybe the inner rubbers close to contacting the tube bore which might account for varying vibration bike to bike.
A big thanks to JC for posting this mod.
74ok
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Thank you for the five signs of appreciation.
Its not like there are not more important things to do (but it is the hot for old air cooled bikes time of the year anyway) but wonder about the rear Isolastic.
In theory with the wheels on the ground, sitting on the bike would compress the lower part of the rubbers via the load applied to the 1/2" across the frame stud.
Maybe that means a push coil spring / springs above the Isolastic tube from a frame mounted base (space limitations) or maybe a Mk3 type spring that pulls the cradle from the lower frame rails. ?
#
Edit.
After some non technical testing there was no movement in the rear Isolastic.
If there was a worthwhile mod to be done there JC would have done it and most likely said so in this thread.
Its not like there are not more important things to do (but it is the hot for old air cooled bikes time of the year anyway) but wonder about the rear Isolastic.
In theory with the wheels on the ground, sitting on the bike would compress the lower part of the rubbers via the load applied to the 1/2" across the frame stud.
Maybe that means a push coil spring / springs above the Isolastic tube from a frame mounted base (space limitations) or maybe a Mk3 type spring that pulls the cradle from the lower frame rails. ?
#
Edit.
After some non technical testing there was no movement in the rear Isolastic.
If there was a worthwhile mod to be done there JC would have done it and most likely said so in this thread.
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Compression and sagging of the front rubbers is due to the short leverage from powerplant's CoG (gravity load) as well as torque reactions.
Rear isolastics are subjected to partial gravity load and torque reactions also, but due to the much larger leverage these loads are manageable.
Torque reactions are by far the largest loads encountered, including dynamic loads from riding the bike.
-Knut
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Will someone be making these for sale , considering the need to weld the lower step piece to the frame ?
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