Isolastic Links
- Thread starter Nater_Potater
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I don't dispute Watt's linkage theory, but what's it got to do with a rod-end fixed at one end. The other end moves up and down with the engine and there fore it's motion is not linear - the moving end describes an arc. With a rod-end on the head steady this will effectively rock the top end of the iso assembly and therefore the angle between the front and rear iso thrust faces will be constantly changing - albeit small but never the less the movement is not linear.
hobot said:Back on track, "Watt's Parallel Motion" in 1784. His linkage of rods and joints was linear to within 0.0008" per inch of motion.
I get what your saying Hobot... within the context of front and rear "iso" assistance, a Watts linkage will help stabilise movement. Seems that nobody challenges the use of heim ended head steadys, and nor would I... But IMO "Control Puck" as ludwik describes at the below rear (cradle) will contribute enourmously to the wanderings of the swingarm.....
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ludwig said:
Yes, agree, that is where I see the folly of spending money on getting a decent Commando frame/bike aligned to the nth degree, pure folly as there are other areas that reap much more benefits. I like the tight sliding pucks as that is what Herb Becker has used on his Commando road racers and from first hand experience, it is smooth operating yet tight handling.
ludwig said:
Agree, and I never stated nor suggested such, but the reality is that - frame flex + iso sideways movement = more, and flame flex + zero tie rod movement = less.
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Dances with Shrapnel said:
Dances with Shrapnel said:
Dances with Shrapnel said:
So do you think that precision frame alignment might be a solution to the "out of" and "not parallel" instances you mention, or would that be "pure folly". You obviously don't think that using a dial indicator (I had to read this twice) to set isolastic clearance, possibly to the "nth degree", "pure folly", also.
Dances with Shrapnel said:
You'll get more friction, not less, using sintered bronze on steel instead of the standard PTFE/steel combination, later ones are sintered bronze PTFE, but I guess you know this. I haven't heard so much bollocks since the last time I visited Norvil and had the misfortune of listening to Les Emery.
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Al-otment said:
Please elaborate?
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I am sure it had something to do with the.....angle between the front and rear iso thrust faces constantly changing - albeit small but never the less the movement was not linear! :lol: :lol: :lol:
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First off study history of isolastic development for the smooth sailing reason there's only so much rubber area/mass supporting engine hopping. Rubber is strange filtering stuff to put compression and shear vibrations through it.
Another fella wanted it so sent off now. You could see its witness marks to show a sight arc 1/16" long, slightly raised towards front, from engine upward kick backs on the rear pivot when given throttle.
Dances jumps in...
Yes, agree, that is where I see the folly of spending money on getting a decent Commando frame/bike aligned to the nth degree, pure folly as there are other areas that reap much more benefits. I like the tight sliding pucks as that is what Herb Becker has used on his Commando road racers and from first hand experience, it is smooth operating yet tight handling.
Yeah man we've had Kenny and Doug trade rides for both to say they liked theirs better which implies just different feel/compensation to control but same capacity to put power down in turns.
Every 'hard' point of a C'do can be deflected by human pressure with rather shorter levers than distance of tire patches to frame attachments. i discovered this on 2 Combat bend from crashes and engine siezures, prying and beating back to decent assembly and chain alignments. There is a 'lot' more torsion issues in C'do frames than long arm bowing/flexing, though that's going on too. Peel is so flabbergastlingly fine I could actually feel the difference in these conflicting vectors nuances I had no idea about even after corner school excesses that got me banned, I learned what i came for. I really believe Peel has solved the tire conflict issues that's the bane of all other motorcycles. Peel is like Chinese Junk or a palm tree in a hurricane- gives with the punches but springs right back to neutral ready for more. No one believes the deeper funner power handling a compliant silent dampening frame set up I'm "hooked" on but to get a sense of the low pilot skill-effort loads Peel allowed, go 15ish mph and turn forks sharply, say L w/o leaning off upright. That is the sense of the forces acting to twist frame up, so too rigid cycles can only do counter steering, which increases tire vector conflicts, yet its only one phase out of 5 for Peel, sort of like rest of the world is trying to race around on two gears against a cycle with 5. I tell ya what, a logical people to me would want what I'm on and hope ya get it as its better than drugs or sex that fades over time.
Ah so Grasshopper correctomundo so Peel has long enough, 5+ inches, rump "radius" rod as the lower half of a linear Watts link and a raised-lifted breast support as top link with the cradle being the center plate and since the iso cushions limit the u/d motion from both engine throttle snaps and rear suspension + chain drive thrusts to a maximum of 1/16" in any direction, my opposing and oppositely pivoted two main links prevent the iso gaps getting into a bind when the frame flexes. Further these two main links help tie together the sort of tongue in groove or plate in a fork- overlapping power unit and frame/front, each too weak by itself but sharing the loads, uHHH La LA! With just the above a head steady is not needed for handling. Head steady in Peel only took out the wind eddies on forks, which prior felt for all the world as road texture, nope.
Ah so my dear feather weight refined Ludwig, for purest sense of handling joy I want nothing but the tire patch sense getting through. When I fitted the 3rd link Ms Peel literally disappeared by 2000 rpm so only road texture wind gusts and turbo fan smooth thrust sense got through. Main over all sense of riding Ms Peel was of a over loaded huge inertial dampened Goldwing. Peel was so uncanny smooth I had to fight back psychedelic flashbacks when sensations merged w/o regard to the reality around me, witnessing world whizzing by and G's forces of brain blood slosh but no sense of a machine under me. It definitely does take away a good bit of the sense of how fast I was going which sort of forced me learn turns quicker than expected.
Hehe olChris you're getting into my camp now. Head steady and other center of frame stabilizers can only stifle side tipping or twisting on axis through the two iso mounts. Its absolutely vital in otherwise un-tamed isolastics but its just a minor wind eddie eliminator with 2 Watt's [like] links far enough away from the pivot points its got adequate leverage on the spaghetti like frame and swing arm and down tubes and fork stanchions. Swash plates may work as well but a late mentor Gerry Bristow [in Italy that'd catch air sideways on cresting turns too] made one the 1st if not the 1st teflon puck top steady but didn't like the buzz sense in cycles so sent it to me to play with. I was so happy with the rods I never got too before Peel stuck throttle event.
Another fella wanted it so sent off now. You could see its witness marks to show a sight arc 1/16" long, slightly raised towards front, from engine upward kick backs on the rear pivot when given throttle.
Dances jumps in...
Yes, agree, that is where I see the folly of spending money on getting a decent Commando frame/bike aligned to the nth degree, pure folly as there are other areas that reap much more benefits. I like the tight sliding pucks as that is what Herb Becker has used on his Commando road racers and from first hand experience, it is smooth operating yet tight handling.
Yeah man we've had Kenny and Doug trade rides for both to say they liked theirs better which implies just different feel/compensation to control but same capacity to put power down in turns.
Every 'hard' point of a C'do can be deflected by human pressure with rather shorter levers than distance of tire patches to frame attachments. i discovered this on 2 Combat bend from crashes and engine siezures, prying and beating back to decent assembly and chain alignments. There is a 'lot' more torsion issues in C'do frames than long arm bowing/flexing, though that's going on too. Peel is so flabbergastlingly fine I could actually feel the difference in these conflicting vectors nuances I had no idea about even after corner school excesses that got me banned, I learned what i came for. I really believe Peel has solved the tire conflict issues that's the bane of all other motorcycles. Peel is like Chinese Junk or a palm tree in a hurricane- gives with the punches but springs right back to neutral ready for more. No one believes the deeper funner power handling a compliant silent dampening frame set up I'm "hooked" on but to get a sense of the low pilot skill-effort loads Peel allowed, go 15ish mph and turn forks sharply, say L w/o leaning off upright. That is the sense of the forces acting to twist frame up, so too rigid cycles can only do counter steering, which increases tire vector conflicts, yet its only one phase out of 5 for Peel, sort of like rest of the world is trying to race around on two gears against a cycle with 5. I tell ya what, a logical people to me would want what I'm on and hope ya get it as its better than drugs or sex that fades over time.
Nater_Potater
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'Can't remember where we were talking about it, but there was discussion about an easier way to measure iso side play by using a dial indicator. Well, after replacing mine with a MkIII adjustable unit, here's what it looks like:
The magnetic mount rides nicely on the end of the kick start shaft with the dial's anvil against the foot peg stem, hands are applied to the back of the rear tire and frame loop, then opposite pressure is applied back and forth. Note how the dial indicator is almost directly in the vertical plane with the rear mount, giving a very close approximation of true side movement. On a side note, each adjustment hole on the right mount equates to 0.006" of side play. Lest you believe slop in the kick start shaft could induce an erroneous reading, my "assistant" tried holding her thumb against the lever. No difference in the reading anti-thumb to post-thumb. I also noted the most reliable readings were obtained with the bike on its wheels (no stands) and held vertical by said assistant. Isn't she beautiful? Give her a big round of applause!
The magnetic mount rides nicely on the end of the kick start shaft with the dial's anvil against the foot peg stem, hands are applied to the back of the rear tire and frame loop, then opposite pressure is applied back and forth. Note how the dial indicator is almost directly in the vertical plane with the rear mount, giving a very close approximation of true side movement. On a side note, each adjustment hole on the right mount equates to 0.006" of side play. Lest you believe slop in the kick start shaft could induce an erroneous reading, my "assistant" tried holding her thumb against the lever. No difference in the reading anti-thumb to post-thumb. I also noted the most reliable readings were obtained with the bike on its wheels (no stands) and held vertical by said assistant. Isn't she beautiful? Give her a big round of applause!
Nater_Potater
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Well, new vernier MkIII rear iso set to .008", front and top iso untouched (as in 10K miles/40 years old), new Avon Roadmaster 100/90 on the rear, and, after more than two-hundred miles, there's been absolutely no sign of the Hinge, even at speeds well past the pre-upgrade onset (75 mph). So, my quandary is now, what stopped the fierce wobble? Was it:
a) The loose rear iso? I tried loosening the new unit to .025", and it still doesn't wobble;
b) Replacing the thirty-year-old somewhat square-profiled Dunlop Sport Elite, or;
c) Balancing the rather violently out-of-balance rear wheel assembly?
I'm inclined to believe the wobble was driven by a combination of the square and out-of-balance tire, rather than a loose iso. Suffice it to say, the wonderful handling characteristics and smooth, almost lack of perceived vibration at speed are back. It's the bike I remember from forty years ago! For that, it was worth it to change out the rear iso.
I'm putting this one to bed. Maybe I'll put a link on the head stay, but probably not.
Next, The Single Mikuni! I'll start another thread for that one...
Nathan
a) The loose rear iso? I tried loosening the new unit to .025", and it still doesn't wobble;
b) Replacing the thirty-year-old somewhat square-profiled Dunlop Sport Elite, or;
c) Balancing the rather violently out-of-balance rear wheel assembly?
I'm inclined to believe the wobble was driven by a combination of the square and out-of-balance tire, rather than a loose iso. Suffice it to say, the wonderful handling characteristics and smooth, almost lack of perceived vibration at speed are back. It's the bike I remember from forty years ago!
For that, it was worth it to change out the rear iso. I'm putting this one to bed. Maybe I'll put a link on the head stay, but probably not.
Next, The Single Mikuni! I'll start another thread for that one...
Nathan
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There's been long decades of reports from those working in vintage shops of bad handling being solved by new tires till they wore out again so most likely only thing that improved your handling pleasure had little to do with anything else. Cdo's isolation threshold and deepness has ALOT to do with tire condition and tire pressure. The harder the tires the smoother the isolastics function. I would run near 60 PSI for the sheer smoothness if I didn't have the miles of rough road jarring they transmit over 40 PSI. If the road is smooth and the turn banked right I"ve skipped out rear on purpose by lean an power and fork turn half dozen times w/o hinge onset but had weave/wobble set in horrifically on same ride on slightly lumpy road and gusty conditions on long easy mild leaning sweeper I had to run into far lane to recover only going 70 when surprise freak out hit. i do not believe any of you are really pressing your un-tamed Cdo's, wisely like me too, to really know what is doing what so close to unable to recover states. I promise myself each ride not to press into danger zone but everything seems so fine right up till it suddenly ain't. Last ride on my race tire shod super motortard modified suspension SV650 had its front shudder a few inches of groin fear spikes slippage working up zig zags seeking some of Peel's G levels but just ain't up to it so merely a low maintenance appliance to run errands on rather than fast handling thrills only my Ms Peel could fix.
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