Rod Linkage Head Steadies and Vibration

Ok, so to the question of IF a rod head steady transmits more vibration than the stocker.....

The "theory" suggests that it does, doesn't it?

1) the stock heady steady, because it is rubber snubber mounted, therefore has to absorb "some" vibration, or at least isolate that vibration from the main backbone tube, and so from the rider's perception.

2) a rod linkage head steady's "advantage" is that it virtually eliminates by design side to side head movement while allowing up and down and fore and aft movement.

anyone dispute the above facts?

novice conclusion on my part: therefore because the rod linkage "has" to transmit more vibration to the backbone than the stocker, only because any tendency of the head to "want" to move side to side is eliminated and that force is directed to the backbone.

yes or no? and this has nothing to do with whether the rider feels any more vibration or not, all "in theory"

1up3down said:

Ok, so to the question of IF a rod head steady transmits more vibration than the stocker.....

The "theory" suggests that it does, doesn't it?

1) the stock heady steady, because it is rubber snubber mounted, therefore has to absorb "some" vibration, or at least isolate that vibration from the main backbone tube, and so from the rider's perception.

2) a rod linkage head steady's "advantage" is that it virtually eliminates by design side to side head movement while allowing up and down and fore and aft movement.

anyone dispute the above facts?

novice conclusion on my part: therefore because the rod linkage "has" to transmit more vibration to the backbone than the stocker, only because any tendency of the head to "want" to move side to side is eliminated and that force is directed to the backbone.

yes or no? and this has nothing to do with whether the rider feels any more vibration or not, all "in theory"

Click to expand...

It will transmit more vibration it the vibration is happening on a sideways plane.
A properly set up and balanced 360 degree twin will produce no sideways vibration so "theoretically" no more vibration should be transmitted to the chassis. Jim

Amazingly enough if you hunt up the many top rod links reports world wide you will find by and large there is less vibration transmitted, much to my own pleasant surprise after installing the 1st top link to find out it didn't. If anyone's does, its not an innate fault of the rod link. If I set adjustment any thing but most slack I got buzzes in waves as side loads put a slight binds in the nil ball slack. When ya put 3 links together - at least with the cradle 2 in opposition of Watt's like linkage and leave the top and front links slightly compliant - a Cdo can feel like it flat disappears but for its turbofan smooth thrust and ease of direction change G's blasting grin back to your ears. Be inventive and improve the breed as ya can.

david-taylor-history-t12317.html#p143797

1up3down said:

Ok, so to the question of IF a rod head steady transmits more vibration than the stocker.....

The "theory" suggests that it does, doesn't it?

1) the stock heady steady, because it is rubber snubber mounted, therefore has to absorb "some" vibration, or at least isolate that vibration from the main backbone tube, and so from the rider's perception.

2) a rod linkage head steady's "advantage" is that it virtually eliminates by design side to side head movement while allowing up and down and fore and aft movement.

anyone dispute the above facts?

novice conclusion on my part: therefore because the rod linkage "has" to transmit more vibration to the backbone than the stocker, only because any tendency of the head to "want" to move side to side is eliminated and that force is directed to the backbone.

yes or no? and this has nothing to do with whether the rider feels any more vibration or not, all "in theory"

Click to expand...

I think you need to be more specific when you talk about vibration. If you are talking about the vibration at around 2700rpm, all Commandos do it to one degree regardless of the headsteady. Look up harmonic resonance and excitatory frequency. It's either the natural frequency of the rubber iso's or the frame itself. I lean toward the iso's because when I put in extra rubber buffers in the rear iso it diminished the vibration at that point in the RPM's at where it goes ape $hit by quite a bit. The proof for me was when I noticed the the engine itself didn't vibrate any more when it passed through the RPM zone of the worst vibration. So, it's not a question of a particular HS transmitting vibration to the backbone of the frame. The frame is the source of the vibration at it's worst point.

If you are talking about the vibration above that range then I've found no difference between the stock HS and a rod type. And I found no difference between the CNW and the DT headsteadies. That is until the DT headsteady wore out, which was at about 7000mi. I think it was a problem of dirt getting into the bearings and that they might be a little too small. It's not a question of load capacity so much as it is simple wear.

Most of the vibration above "The Zone" is due to the fact that the loads on the iso's originate at the contact patch of the rear tire which is two feet back and one foot down from the closest iso. The rear iso becomes a fucrum that loads the iso's at a rate that is a multiple of the load at the tire. The engine might be vibrating in a single up and down plane but the engine is tilted in the frame to the extent that's allowed by the iso's clearances, which isn't much. So the vibration is negligible, most other bikes don't even come close.

P.S. I meant to say bush, not buffer.

I use DT head steady on my 850 and I would say the vibrations are at approximately the same level as with original parts.
The version I use is with the MK3 spring and tuning this you change the vibration level and at what rpm you get vibrations.
For me vibrations is a non-issue with this mod and the handling improvement is significant.

Regards,
Per

rpatton said:

Bill, who wrote the article?

Click to expand...

It's in Roadholder 301 page 35ff by a Peter Charlton.
Fritz

bad_friday said:

rpatton said:

Bill, who wrote the article?

Click to expand...

It's in Roadholder 301 page 35ff by a Peter Charlton.
Fritz

Click to expand...

Yeah, I just found it, December Issue with the Christmas ornaments around a '50s International. I thought it was a full-blown article - its just over a page with a couple of illustrations, called 'Get Your Isolastics in Line'.

Anyway, very informative short piece, and Mr. Charlton lists his email if anybody needs clarification.

I alerted Peter if his ears were burning to lookie in here for a a nod of recognition.

Its very educational to scary dangerous out of the blue to feel what its like on an ordinary Commando w/o a head steady installed. Not much noticed till crossing paint lines or a bit gusty or lumpy section, woohooie I'd rather ride out a blow out, if head steady installed or otherwise no way could I even keep on the road or upright. THE Hinge HITS like you can't believe bucking bronco action.

hobot said:

I alerted Peter if his ears were burning to lookie in here for a a nod of recognition.

Click to expand...

Too bad you didn't ask him to consider the possibility of posting the article here. There might be a problem with copy-write issues with the Roadholder though.

rpatton said:

hobot said:

I alerted Peter if his ears were burning to lookie in here for a a nod of recognition.

Click to expand...

Too bad you didn't ask him to consider the possibility of posting the article here. There might be a problem with copy-write issues with the Roadholder though.

Click to expand...

I doubt there's any info there that hasn't been known for the last 30 years. Plus there is Fair Use to consider.

Peter Charlton has been almost daily contact via private or public BI list for over 2 decades now so can ping him to post the article here but as stated, the isolastic adjusting-correcting info has been available for well over 3+ decades. Main trick is to use images in bar mirror to guide where to do what.

By far the smoothest most secure craft I've ever ridden was Ms Peel with Patton's robust rump rod, Brain Tryee breast link and hobot head link, with last 2 made to give some silly mm or so deflection and isolastics set pretty close to normal wide gaps, but not too much more or the Hinge sets in again, [at rather faster higher loads than unlinked] but if tightened into police or racer narrow gap Peel transmitted some buzz in waves. Once all adjusted Peel became better than a falpping in the breeze flying carpet and not trapped like on RR track rails limited best path though turns. When I hear a bike feels like on rails it makes me grin as that's how limited others image is on what it can be like on a real neutral handling cycle, based on the ingenious Unapproachable Norton Isolastic Commando. Catch up as ya can, it ain't me I'm bragging about, so if not mature enough to realize that and look past me me me d/t a reflection of you own ego state of mind, you may see what I'm so besides myself to put some real power on and more mass off in public and on race tracks to prove the time savings that a Ms Peel set up can deliver. Does help to grind some meat off the front doughnuts and add a few more doughnuts to the rear like Bob Patton directed me.