Isolastic Links

Dances with Shrapnel said:

So what's the problem with silicone grease? Isn't that what the factory recommended?

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The factory recommended wetting the rubbers with gasoline for installation because it evaporated quickly. No lube beyond that.

For safety reasons I would suggest tire mounting lube for installing the rubbers but leave the washers dry. Jim

Dances with Shrapnel said:

Hmmmm, ................I wonder.................., anyone out there providing this most valuable service?

:roll:

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Not 100% sure what you are implying. I've made no secret I offer a frame alignment service http://www.parallelengineering.co.uk/ though not expecting any work from outside of the U.K. Several enquiries but only one customer so far with a Featherbed, which was out due to probable accident damage. It had then been cut and welded near the top, rear frame bends. The owner reported on dry assembly of engine/gearbox/swingarm that everything lined up fine. I'm obviously not explaining myself well enough to laymen like yourself. I'll have to get some diagrams done to get my point across.

:lol: :lol: :lol: :lol: :lol: " Laymen " :lol: :lol: :lol: :lol: :lol: :lol: That will endear you to all us plebeians :lol: :lol: :lol: :lol:

Here fish, fish, fish, fish.

Love outing certain people.

olChris said:

:lol: :lol: :lol: :lol: :lol: " Laymen " :lol: :lol: :lol: :lol: :lol: :lol: That will endear you to all us plebeians :lol: :lol: :lol: :lol:

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So speaks THE Norton Commando expert, with, is it 10 miles riding? Let me know if that figure's incorrect. You appear to confuse the meaning of the two terms. Laymen refers to level of understanding. Plebeian refers to social class and is totally irrelevant in an engineering discussion.

Dances with Shrapnel said:

Here fish, fish, fish, fish.

Love outing certain people.

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Like I say, I need to make things clearer for the layman.

This thread seems to have gone off topic as per usual.
Just to recap,the original poster asked about devices that could limit the isolastics to work in vertical movement only and control any sideways movement mechanically.
The head steady has a major impact on even new and adjusted isolastics,any modification to aid these parts would take for granted they were in good to excellent condition to start with.

Nater_Potater said:

We all have most likely seen the aftermarket top mount that uses a Heim-end link rather than the muffler rubbers, but has the same thing ever been applied to the iso mounts? As many threads as I've seen (proper shimming, which washers to use, running the MkIII vernier adjusters), hasn't anyone built a Heim-end link for the lower isos that would completely eliminate having to shim the mounts? With this, the centering load would get carried by the Heim joints alone, completely removing any side-load from the isos themselves. It seems like H-D uses something similar on their rubber-mounted engines. Thoughts/ideas/links? I'm getting ready to perform a major R&R to my '74, and would like to see the options out there.

Nathan

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It had nothing to do with bent frames,wonky steering heads or wobbly wheels.
Although there is (obvious) merit in having the chassis components in harmony as far as alinement there is some conflict when they are mounted via rubber donuts or pucks at the cylinder head not to mention the swing arm does not pivot off the main frame.
I had wondered why Norton did not use/try a rear frame cross tube and panhard bar or watts linkage of some sort (below the cradle) to aid the isolastics as the head steady does or even a third lower isolastic of some sort.

Perhaps one interesting thread could be spared and stay on topic.

Time Warp said:

It had nothing to do with bent frames,wonky steering heads or wobbly wheels.

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Thank you Time Warp for bringing this around.

The Commando Isolastic solution with Teflon sliders is an eloquent solution and I say a bit ahead of the curve. Rod links offer much tighter conrol with essentilally 0.000 inch movement as opposed to the Commando specification of around 0.005 inch with the Teflon washers. In the ideal world you should be able to run the Commando Iso's down to near 0.000" but that would require greater tolerances with regards to frame assembly and engine balance (ie. eliminate any rocking couples). I see it as a design compromise.

As for durability and serviceability, I just don't know which would be better, rods versus Teflon washers. From a serviceability standpoint, rod links are simpler to get at and replace whereas standard isolastic systems (even vernier style) are a PITA to adjust, service and replace. From asthetics and symetery, the isolastics look better than a rod link in the front of the motor.

I do know that an Isolastic Commando when properly modified with additional Teflon sliders at the head steady and below the transmission as well as changing the mix of rubber doughnuts is confidence inspiring but no where near as precise as a Featherbed or Seeley Mk2.

Dances with Shrapnel said:

Thank you Time Warp for bringing this around.

The Commando Isolastic solution with Teflon sliders is an eloquent solution and I say a bit ahead of the curve. Rod links offer much tighter conrol with essentilally 0.000 inch movement as opposed to the Commando specification of around 0.005 inch with the Teflon washers. In the ideal world you should be able to run the Commando Iso's down to near 0.000" but that would require greater tolerances with regards to frame assembly and engine balance (ie. eliminate any rocking couples). I see it as a design compromise.

As for durability and serviceability, I just don't know which would be better, rods versus Teflon washers. From a serviceability standpoint, rod links are simpler to get at and replace whereas standard isolastic systems (even vernier style) are a PITA to adjust, service and replace. From asthetics and symetery, the isolastics look better than a rod link in the front of the motor.

I do know that an Isolastic Commando when properly modified with additional Teflon sliders at the head steady and below the transmission as well as changing the mix of rubber doughnuts is confidence inspiring but no where near as precise as a Featherbed or Seeley Mk2.

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You made more sense when you were talking about fish.

It was standard UK police practice to set gaps 1/2 factory but they had to be ordered and paid to tolerate the vibration, similar with C'do racers with competition motivation. Only a few c'do's have broken frames or pilot fillings with too tight of gaps, because the word got out and rather uncomfortable to do so anyways. If your C'do's don't deliver smooth flying carpet road orgasms better than human kinky sex, then no wonder no one understands my sick addiction to a tri-linked Ms Peel. Pure magic lurking with properly tamed isolastics how ever ya can get er done.

hobot said:

It was standard UK police practice to set gaps 1/2 factory but they had to be ordered and paid to tolerate the vibration, similar with C'do racers with competition motivation.

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The bit about UK police, where did you get this from?

As for stating "similar with C'do racers", that's not my experience.

I would agree there is a practical limit to which you can reduce clearance on the standard iso's due to things such as less than parallel and/or flimsy iso components. This is why properly designed and installed rod links ares so slick - zero clearance.

When UK-NOC was freely available and Brit Iron well populated before the end of last century, rest of the world was informed Bobbie's bikes gaps set .005-6 for more secure handling to chase other criminals on cycles and such. On sweetie pie Peel I ended up .008 front and .0012 rear as best compromise between early complete isolation onset yet not enough slack to slap the gaps enough even tri-links couldn't stifle the weave/wobble Hinging. Anywho I just can't imagine a better N handling cycle, that is tire slip/skip/drift/slides plus crossed up states didn't bother the lean angle nor the forks to compensate, need pilot skill at all, so just invites into rather faster smoother less effort ways around. The isolastic Commando may yet Rule The World again if I live long enough to demo it. Here's one reference from 1994 by Peter Azlan on Capt. Norton archives where I got much of my early lore.

The recommended clearance in the manual is 10 thou, the British Police were known to set their's to 6 thou, for improved handling. Some clearance is essential. When designed Norton were very keen to keep the weight of the frame down, it was therefore designed with isolastics in mind. If you remove all the clearance in the isolastics, you may improve the handling for a bit until the frame brakes.

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http://www.captain.norton.clara.net/cnn2sec33.html

ludwig said:

Dances with Shrapnel said:

..there is a practical limit to which you can reduce clearance on the standard iso's due to things such as less than parallel and/or flimsy iso components..

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Can you explain that ? .

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I have found that the torque placed on the through bolts of the iso's has a minor influence on clearance of the iso's - it should not but it does. Fair enough, use a torque wrench and the problem goes away but Norton could have used something a bit more substantial than the thin "flimsy" through tube that the rubbers mount to.

I have been frustrated with attempting to set isolastic clearances (even with vernier adjusters) due to out of parallel components, both factory installed and apparent OEM replacements. Maybe it was my luck of the draw that I ended up with less than ideal components on more than one occasion. I found that using a feeler gauge in the isolastic gap to measure clearance was also misleading as there were tight spots and loose spots (not parallel); so what do you measure to. There is one topic somewhere in this forum where the OP was showing how the steel iso cups over the iso tubes were dished and he was lapping them to get flat.

Now this forum has plenty of discussions on the various "best way" to set isolastics. I have settled on using a dial indicator to measure relative side movement between the frame and engine and that seems most reliable and reproducible for me. I can dial in the ride comfort and I also have been in the range of 0.1mm, but that is it. This is with multiple bikes. Again, luck of the draw?

But this whole discussion is in the context isolastic links (link rods with heim joint ends) which have zero clearance.

So again, the isolastics as supplied from the factory have a practical limit with respect to how close you can set them. I had thought about using different materials (sintered bronze) but not sure what, if anything would be gained by that other than less drag with tighter clearances. I attribute drag (friction) as to why the isolastic system starts to buzz the bike differently when clearances are reduced further than the practical limit.

For most road use, factory specs or down to 0.005" is plenty good.

ludwig said:

I set my isos front and top at 0.1 mm , about half factory value , and rear to almost zero .
It gives a mild vibration over the entire range , that doesn't bother me at all .
I find that with a good head steady , wear is very limited , in the order of 0.1 mm over 20 - 25000 km .
So adjusting isos should be for the majority of Commando owners a once in a lifetime event .
Like I said in another thread , I have no provision for adjusting my isos : no shims , no vernier .
When out of spec , I either remove a little material from the collars or replace the PTFE washers .
In fact , you don't even need PTFE washers if you make the tube caps out of teflon or something similar ..

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In my thinking, maintaining movement is the key here. If it was possible to set everything to .001" clearance and the movement it still there, and it doesn't wear too quickly then it should be fine...although as you say above with yours set tighter, there is more vibration. I am sure there will be comments that it's not possible to set the Iso's to .001" but my point is theroretic...if it was possible, then it should work.

Ludwig, could you explain how your head steady works? It looks like the washer is against the upper frame mount. How does it move? Is there clearance on the bolt that goes through the center? If so, how does this not create a wear situation? Even with the spring it would seem that under certain conditions the movement would be enough to cause the hole to become elongated. and damage to occur to the washer.

Dances with Shrapnel said:

Time Warp said:

It had nothing to do with bent frames,wonky steering heads or wobbly wheels.

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Thank you Time Warp for bringing this around.

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Thanks to the both of you. I tried to derail it earlier with my iso bushing grease comment, but the argument was already too ingrained. Ah, it's been a fun journey!
Nathan

Nater_Potater said:

Dances with Shrapnel said:

Time Warp said:

It had nothing to do with bent frames,wonky steering heads or wobbly wheels.

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Thank you Time Warp for bringing this around.

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Thanks to the both of you. I tried to derail it earlier with my iso bushing grease comment, but the argument was already too ingrained. Ah, it's been a fun journey!
Nathan

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You don't have to do anything to derail the discussion. Once it gets up to speed it acts just like a Norton with loose isos.

Al-otment said:

olChris said:

:lol: :lol: :lol: :lol: :lol: " Laymen " :lol: :lol: :lol: :lol: :lol: :lol: That will endear you to all us plebeians :lol: :lol: :lol: :lol:

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So speaks THE Norton Commando expert, with, is it 10 miles riding? Let me know if that figure's incorrect. You appear to confuse the meaning of the two terms. Laymen refers to level of understanding. Plebeian refers to social class and is totally irrelevant in an engineering discussion.

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I think comnoz is a patrician - there is royal blood there somewhere, as in the Count of Basie or the Duke of Ellington.

hobot said:

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Very cool Watts link diagram! Gee, another Scottish invention that helped define the modern world. http://en.wikipedia.org/wiki/James_Watt Begin disparaging comments here... :wink:

comnoz said:

You don't have to do anything to derail the discussion. Once it gets up to speed it acts just like a Norton with loose isos.

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I'm glad I wasn't drinking milk when I read your post; it would have come out my nose!

ITS OFFICIAL



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