The World's Straightest Commando

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John,

I totally agree that just about any structure you can think of will flex. But from an engineering/common sense perspective what would be the best starting point for a motorcycle chassis - everything as intended, or wheels, steering head, swinging arm etc all mis-aligned to each other? Permanent distortion is one thing but a frame which momentarily flexes and then returns to it's original (straight) state is another. I find it difficult to believe anybody wallowing and weaving through curves on a motorcycle and so limiting it's performance is not going to care - especially after spending several thousand $'s, £'s or whatever on that motorcycle. This isn't joy, IMHO it is a badly engineered motorcycle and an accident waiting to happen. I'm curious, what would be the point of someone fitting a set of improved fork dampers to a motorcycle with a "distorted" frame?

yours, incredulously, Jose.
 
Jose Refit said:
John,



Well....back in 1970 my work mate had a commando, must admit i was amazed on the back one day,how the "thing" pitched ..but Derek only knew full bore, infact went on the blow it to bits, he was 19 and weaving was never a consideration..."Just give it hell"

Badly engineered? As we all know to well,it was down to time and money...with a ready world market . Watch Jay Leno Garage on his Norton JPN [you tube] not one mention of weaving...but i didnt see him down on his knee :lol: " quote" two fishermen, one turns to the other and says " this rod you borrowed me is crap, just had a 60lb fish and it bent double!" reply was" i only catch bait with it"! if you dont want a rod that bends,get another!



I totally agree that just about any structure you can think of will flex. But from an engineering/common sense perspective what would be the best starting point for a motorcycle chassis - everything as intended, or wheels, steering head, swinging arm etc all mis-aligned to each other? Permanent distortion is one thing but a frame which momentarily flexes and then returns to it's original (straight) state is another. I find it difficult to believe anybody wallowing and weaving through curves on a motorcycle and so limiting it's performance is not going to care - especially after spending several thousand $'s, £'s or whatever on that motorcycle. This isn't joy, IMHO it is a badly engineered motorcycle and an accident waiting to happen. I'm curious, what would be the point of someone fitting a set of improved fork dampers to a motorcycle with a "distorted" frame?

yours, incredulously, Jose.
Click to expand...
 
john robert bould said:
Jose Refit said:
John,



Well....back in 1970 my work mate had a commando, must admit i was amazed on the back one day,how the "thing" pitched ..but Derek only knew full bore, infact went on the blow it to bits, he was 19 and weaving was never a consideration..."Just give it hell"

Badly engineered? As we all know to well,it was down to time and money...with a ready world market . Watch Jay Leno Garage on his Norton JPN [you tube] not one mention of weaving...but i didnt see him down on his knee :lol: " quote" two fishermen, one turns to the other and says " this rod you borrowed me is crap, just had a 60lb fish and it bent double!" reply was" i only catch bait with it"! if you dont want a rod that bends,get another!



I totally agree that just about any structure you can think of will flex. But from an engineering/common sense perspective what would be the best starting point for a motorcycle chassis - everything as intended, or wheels, steering head, swinging arm etc all mis-aligned to each other? Permanent distortion is one thing but a frame which momentarily flexes and then returns to it's original (straight) state is another. I find it difficult to believe anybody wallowing and weaving through curves on a motorcycle and so limiting it's performance is not going to care - especially after spending several thousand $'s, £'s or whatever on that motorcycle. This isn't joy, IMHO it is a badly engineered motorcycle and an accident waiting to happen. I'm curious, what would be the point of someone fitting a set of improved fork dampers to a motorcycle with a "distorted" frame?

yours, incredulously, Jose.
Click to expand...
Click to expand...

John,

what the f*** you talking about???? Fishing rods are meant to bend. Commando's are not meant to weave - there are reason's why some do, but there are engineering solutions to these reasons,

Yours, still waiting for a reply to my fork damper question, Jose.
 
ARRRR! the fishermen story. in other words if you dont want a motorcycle frame]rod] to bend..get another that wont...simple.
 
John,

So to repeat, what's the point fitting upgraded fork dampers on a frame that you claim is bending in use and causing weaving???

yours inquisitively, Jose.
 
OK, OK, OK,
I GIVE!!
I THOUGHT SOMETHING CONSTRUCTIVE WAS GOING TO COME OUT OF THIS THREAD, THAT'S WHAT I GET FOR THINKING.

I'm out.

Vince
 
I communicated directly with Stevan Thomas the author of the link posted in this thread "The Worlds Straightest Commando" and the owner of the Norton in question.

The issues related to the fabrication positional errors outlined are real and could and likely will effect the alignment front to rear. The most important assumption to "The Worlds Straightest Commando" are properly functioning isolastics and an aftermarket head steady that controls side to side movement of the engine.

The argument about hinged feeling, etc. relates to poorly functioning isolastics and really does not answer the question of whether blueprinting the frame improves a Commando or not.

Since no one on this board has ever ridden the bike in question, not sure anyone can really comment on the question of improvement.

Since the design of the Norton isolatics includes some level of "flex" built in, it results in a solution to vibration but is not necessarily the best design in terms of maintaining perfect tracking which is the main argument against "The Worlds Straightest Commando".

In discussing this with Stevan, the conclusion was that the positional issues were significant enough to consider them contributors to potential alignment issues front to back so correction might improve the "tightness" and "feel" of the bike and this was the basis of blueprinting the frame in the first place.

I still intend to try to make the measurements on my Commando to see for myself what the variance is. I have access to the equipment so why not? Is it a waste of time? Who know's. I really question whether Kenny Augustine ever said it was a waste of time...more than likely he said there wasn't any way to verify if it was worth the effort because the handling, tightness and feel of the bike is really the personal judgment of the rider, so not a measurable result.
 
I certainly have not put the time into making all parts of my bike as perfect as the "Worlds Straightest Norton" but here are
some of the things I did to my injected bike several years ago when I upgraded the front forks.

I checked the steering head in comparison to a rod placed through the rear isolastic mounts. That was where I found the biggest problem with my bike. It took quite a bit of force to twist the steering head until it was perpendicular to the rod through the rear iso mounts but it moved into line without any kinks or signs of stress.

Second was installing a dummy axle with spacers torqued in place and making sure it was parallel to a tube through the center of the rear iso tube in the cradle. It took a bit of tweeking to get it right. The axle bolt and spacer must bee in place when applying pressure or it will move right back where it was when you tighten the axle.

I centered the rear rim in the swingarm with the sprocket parallel to the side of the cradle.

I centered the front rim in between the front fork tubes.

I centered the swingarm between the two rear down tubes with the rear rim aligned with the front rim using spacers on the rear isolastic.

I adjusted the front of the engine using the tie rod link to keep the rear wheel pointed at the front wheel.

I adjusted the head steady link till the front and rear wheels were on the same vertical plane.

I experimented with front and rear ride heights until I found the place where little push was needed to hold the bike in a turn yet it does not fall into the turn.

Now after installing the rear link I have a bike that feels like a solid mount engine and will coast from 100 down to a walking speed with no hands on the bars and have no shake or pull. Jim
 
Postby mikegray660 » Wed Oct 22, 2014 5:31 am
i think many of us wish ho'but would hold his breath - for an indefinite period
Click to expand...
Moderator above poster needs to be dealt with very soon and seriously or apologize for the malice. hobot.
====================================================================

Now after installing the rear link I have a bike that feels like a solid mount engine and will coast from 100 down to a walking speed with no hands on the bars and have no shake or pull. Jim
Click to expand...

Gee how about that Jim, who'd of thot. What you are feeling is the lack of rear patch swishing through rear iso to slap the front iso gap slack which starts forks oscillation escalating when wheel gyro's spin not enough to dampen. Sorry to read though that your's feels like a solid mount but that's prolly because you have statically pre-tensioned the top and front links to correct wheel alignment, that may not matter. If I tensioned Peel's links she vibed and got too unpredictable in resonances splashing-spiking > similar to my robustly rigid modern. Great up to instant its out of control. Ms Peel had uncanny huge massive inertial feel yet not solid mount rigid sense. Try your links set at neutral slackness with wheels sprung out of perfect and see if anything noticed.
 
hobot said:
Gee how about that Jim, who'd of thot. What you are feeling is the lack of rear patch swishing through rear iso to slap the front iso gap slack which starts forks oscillation escalating when wheel gyro's spin not enough to dampen. Sorry to read though that your's feels like a solid mount but that's prolly because you have statically pre-tensioned the top and front links to correct wheel alignment, that may not matter. If I tensioned Peel's links she vibed and got too unpredictable in resonances splashing-spiking > similar to my robustly rigid modern. Great up to instant its out of control. Ms Peel had uncanny huge massive inertial feel yet not solid mount rigid sense. Try your links set at neutral slackness with wheels sprung out of perfect and see if anything noticed.
Click to expand...

When I say it feels like a solid mount I am referring to the lack of slack in the handling. The engine vibration is as smooth as they get. Jim
 
Reminder- if you don't wish to see a users post you can set that up in your control panel. I like reading Hobot's posts. I know a lot of others do. The forum is designed so you can block someones posts if you, personally don't want to see them. Not sure if you know that, but Mike please use that function if you need to.
Control Panel > Friends & Foes > Foes (add username)

I am keeping this topic open for now, but will lock if it gets out of control
 
Appreciate the moderating Jerry.
===========================================

When I say it feels like a solid mount I am referring to the lack of slack in the handling. The engine vibration is as smooth as they get. Jim
Click to expand...

Ok that kind of lack of solid sense. To me more like lack of slack in a tensioned sling shot rubber rather than solid like bolted solid. I did not for an instant take you statement as engine vibes knowing your annoyance with any of that nuance. Try all links slack then one at a time adjusted w/o slack both tensioned then expanded for sense of what each link is doing. Peel's front link is 8-ish inches above iso so does not influence the iso gap width function directly and is on a long bolt-stalk [expedient scab on test] so did not stop front patch from twisting frame in relation to rear patch but only felt twist when maxing out traction trying to keeping both tires in effective contact, front pointing to outside of turn while rear lean and thrust trying to shove into the turn. This is point cycles require fork damper as tends to snatch front tire into direct road following which puts a horrendous flick through the frame. Trixie flops like a fish off deck approaching this, SuVee skips rear in frame take down judder or front tire slides and would hi side us if I didn't let off with some space allowed for time for frame and tire to settle down back in control and sensing any mess in pants. Freaking Peel makes me live for such orgasmic spikes from groin up.

I adjust tire air balance for easiest sense of steering, which is different than just higher pressures making tires easier to roll on smaller stiffer patches. Peel only took inputs to change direction downward or upward but unless sliding did not need further pilot effort to stay at set lean and radius. When sliding on Gravel or pavement I did not have to change anything but keep forks dampened to keep same angle till slide stopped by a pop up and better aligned to get out of there more upright. I did not have to cross up Peel doing this, so is different than a flat tracker slide that is still counter steering, ie: tire pointing to out side of turn not inward. Twists hit right before tire let goes and on re-grips so hands and feet felt like an inch of motion. Release a stiff spring and it rebounds, release a rubber band and it just goes slack to neutral.
 
hobot said:
Ok that kind of lack of solid sense. To me more like lack of slack in a tensioned sling shot rubber rather than solid like bolted solid. I did not for an instant take you statement as engine vibes knowing your annoyance with any of that nuance. Try all links slack then one at a time adjusted w/o slack both tensioned then expanded for sense of what each link is doing. Peel's front link is 8-ish inches above iso so does not influence the iso gap width function directly and is on a long bolt-stalk [expedient scab on test] so did not stop front patch from twisting frame in relation to rear patch but only felt twist when maxing out traction trying to keeping both tires in effective contact, front pointing to outside of turn while rear lean and thrust trying to shove into the turn. This is point cycles require fork damper as tends to snatch front tire into direct road following which puts a horrendous flick through the frame. Trixie flops like a fish off deck approaching this, SuVee skips rear in frame take down judder or front tire slides and would hi side us if I didn't let off with some space allowed for time for frame and tire to settle down back in control and sensing any mess in pants. Freaking Peel makes me live for such orgasmic spikes from groin up.

I adjust tire air balance for easiest sense of steering, which is different than just higher pressures making tires easier to roll on smaller stiffer patches. Peel only took inputs to change direction downward or upward but unless sliding did not need further pilot effort to stay at set lean and radius. When sliding on Gravel or pavement I did not have to change anything but keep forks dampened to keep same angle till slide stopped by a pop up and better aligned to get out of there more upright. I did not have to cross up Peel doing this, so is different than a flat tracker slide that is still counter steering, ie: tire pointing to out side of turn not inward. Twists hit right before tire let goes and on re-grips so hands and feet felt like an inch of motion. Release a stiff spring and it rebounds, release a rubber band and it just goes slack to neutral.
Click to expand...


I don't push this bike anywhere near the ragged edge. I save that for the track or the dirt. I do enjoy a spirited ride in the twisties but the only times I have pushed it is when a decreasing radius corner caught me by surprise. I have done several track days with it some years back. It surprised a lot of people but I was not pushing my luck.
The bike has only been down twice in the last 32 years, once when the layshaft bearing seized and a couple years ago when the trucks blew it off the highway shoulder.

The only complaints I have about the suspension is the fact that the fork seals don't last very long in the USD KYB's. Some day I am going to snag a pair of Ohlins for the front. Until then I replace fork seals about once a year. This year I ended up just under 10,000 miles and they are only weeping slightly, so I guess that's really not too bad. Jim
 
The reason why "parts" are replaced is down to the owners . Regarding my dampers and proberly less than 1/2 percent of total commandos.
When some [not all] have spent thousands on the available goodies..brakes, heads, carbs ,belt drives ,engine internals etc ..then go out on the road and hear that Fork clonk ..that starts to get annoying ...thats why they fit the damper kit. On the other hand some like the general feel ,mayby the 400 road users and 15 racers are just happy :?:



Jose Refit said:
John,

I totally agree that just about any structure you can think of will flex. But from an engineering/common sense perspective what would be the best starting point for a motorcycle chassis - everything as intended, or wheels, steering head, swinging arm etc all mis-aligned to each other? Permanent distortion is one thing but a frame which momentarily flexes and then returns to it's original (straight) state is another. I find it difficult to believe anybody wallowing and weaving through curves on a motorcycle and so limiting it's performance is not going to care - especially after spending several thousand $'s, £'s or whatever on that motorcycle. This isn't joy, IMHO it is a badly engineered motorcycle and an accident waiting to happen. I'm curious, what would be the point of someone fitting a set of improved fork dampers to a motorcycle with a "distorted" frame?

yours, incredulously, Jose.
Click to expand...
 
comnoz said:
I
I checked the steering head in comparison to a rod placed through the rear isolastic mounts. That was where I found the biggest problem with my bike. It took quite a bit of force to twist the steering head until it was perpendicular to the rod through the rear iso mounts but it moved into line without any kinks or signs of stress.

Jim
Click to expand...

Yep same meat different gravy..

The World's Straightest Commando


.
 
john robert bould said:
The reason why "parts" are replaced is down to the owners . Regarding my dampers and proberly less than 1/2 percent of total commandos.
When some [not all] have spent thousands on the available goodies..brakes, heads, carbs ,belt drives ,engine internals etc ..then go out on the road and hear that Fork clonk ..that starts to get annoying ...thats why they fit the damper kit. On the other hand some like the general feel ,mayby the 400 road users and 15 racers are just happy :?:



Jose Refit said:
John,

I totally agree that just about any structure you can think of will flex. But from an engineering/common sense perspective what would be the best starting point for a motorcycle chassis - everything as intended, or wheels, steering head, swinging arm etc all mis-aligned to each other? Permanent distortion is one thing but a frame which momentarily flexes and then returns to it's original (straight) state is another. I find it difficult to believe anybody wallowing and weaving through curves on a motorcycle and so limiting it's performance is not going to care - especially after spending several thousand $'s, £'s or whatever on that motorcycle. This isn't joy, IMHO it is a badly engineered motorcycle and an accident waiting to happen. I'm curious, what would be the point of someone fitting a set of improved fork dampers to a motorcycle with a "distorted" frame?

yours, incredulously, Jose.
Click to expand...
Click to expand...

John,

Extended top bushes and repositioned hole in the damper tube gets rid of bottoming and topping out problems. Don't see how your kit addresses these design problems unless it includes extended bushes and a replacement damper tube,

Yours, over and out and thanks for all the fish, Jose.
 
Jose Refit said:
Extended top bushes and repositioned hole in the damper tube gets rid of bottoming and topping out problems. Don't see how your kit addresses these design problems unless it includes extended bushes and a replacement damper tube,
Click to expand...

Whilst those mods do go some way to alleviating the topping and bottoming problem (neither does it particularly successfully, in my opinion and yes, I've tried both) they do not address the problem of lack of proper controlled damping, which the Lansdowne kit does because it is a complete damper system which doesn't rely on the fork bushes acting as the extension stop.
The Lansdowne kit is a considerable improvement over the aforementioned mods in my, and I'm sure may others' opinion who have fitted the kit.

http://www.lansdowne-engineering.com/
 
L.A.B. said:
Jose Refit said:
Extended top bushes and repositioned hole in the damper tube gets rid of bottoming and topping out problems. Don't see how your kit addresses these design problems unless it includes extended bushes and a replacement damper tube,
Click to expand...

Whilst those mods do go some way to alleviating the topping and bottoming problem (neither does it particularly successfully, in my opinion and yes, I've tried both) they do not address the problem of lack of proper controlled damping, which the Lansdowne kit does because it is a complete damper system which doesn't rely on the fork bushes acting as the extension stop.
The Lansdowne kit is a considerable improvement over the aforementioned mods in my, and I'm sure may others' opinion who have fitted the kit.

http://www.lansdowne-engineering.com/
Click to expand...

Maybe so, but is there any cheap DIY method a home mechanic can employ to prevent the shortfalls of the standard Norton forks :!:
Beginning able to adjust both the damping and the rebound damping as with the Lansdowne kit is not up everybody’s street :(
 
Bernhard said:
Beginning able to adjust both the damping and the rebound damping as with the Lansdowne kit is not up everybody’s street :(
Click to expand...

I fail to see why, as it couldn't be easier? :?
 
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