ISOs or rose joints to control side to side movement?

So what works? or better still what would work better?

I know Jim has rose joints on the front and on the head but regular ISO on the back, someone else also has the same setup and I "think" Hobot has rose joints at all 3 (or is it 4 ??) places Norton placed ISOs or rubber biscuits.

Without going deep in calculations or paper analysis, it seems to me that the standard rubbers in the tubes on stock Nortons could be used to allow up and down shaking while removing the adjustable or not steel and teflon washers and replace all three with rose joints all having the same lenght, this way the motor could shake like a paint mixer in the up and down plane without any side to side play, the rear wheel would be better aligned with the front and thus handling would be just as good as a Featherbed, am I right in my thinking?

Jean

I like a high quality top steady that retains or implements the Mark III type spring preloader, although some poo-poo the entire top steady as redundant.

Windy Eads makes the best front steady I've seen, I've used 4 of them now.

I like Hobot's rear steady to round out the trinagulation of steadies, a very logical end. However, it conflicts with oil filter access and/or centerstand access, unless an improved variant has been determined... (moot point if you don't use a centerstand and/or you can properly locate the oil filter head)

In an ideal re-engineering of the Commando chassis I too like the three link configuration. But I'm not out to make a 40+ yr old design compete with a modern bike. Call me crazy. Someone else can do the rework and more power to them but it's not for me.

Jeandr said:

So what works? or better still what would work better?....

Click to expand...

a) Have a look at http://www.freepatentsonline.com/4776423.pdf which is the Buell patent on the Isoplanar system (and count the links...)

b) I'll try to explain the kinematics behind the linkage for some of the stuff floating around in this discussion:

- With just the iso rubbers and no shims etc. the cradle can move relative to the frame with six degrees of freedom (longitudinally in X, laterally in Y and vertically in Z plus one rotation around each of the same axes).

- The first iso shim already acts as a planar slide bearing in theory and takes away three of these DoF: It doesn't permit lateral movement, no rotation around X and Z but it still allows X and Z movement and rotation around Y. The second iso doesn't change this situation but helps the first one and so on. As long as these planar guides are parallel they only help each other - actually you could add infinite amounts of these guides without changing the kinematics at all. The problem is that the real world isn't infinitely stiff and the Commando frame is especially "real" in this sense. The third iso at the head steady makes sense with respect to spreading the load - the actual planar surface of a single iso is very small, adding a second one theoretically makes this guide surface longer but still close to a line in terms of kinematics - so the third iso pretty far away from this line expands a triangle of (theoretically!) parallel guides. Why three isos? Actually it's a tripod and as the type of jpoint itself doesn't change anything in terms of kinematics three is sufficient.

- Replacing the top rubbers by a link is theoretically not a good idea: The isos need parallelism and the link counteracts this obviously. However because the movement is pretty small and the frame pretty flexible it still works...

- Replacing the isos (the shims etc., not the rubbers) with links: I'll try to explain this again in a mechanically correct way by adding links to the structure one by one and explaining what this means (Note: The links are parallel and of similar length in this description to simplify it and because this is how the linkage would be build):

First link: The link itself can only rotate relative to the frame and the cradle can only rotate relative to this link (The link can also rotate around it's longitudinal axis - called an identical DoF here in Germany, no idea what the rest of the world calls this - but that has no influence on the kinematics so I'll ignore this.....) The first link forces the cradle to move on a sphere with the link's length as its radius. The cradle itself can then rotate around the fixation point.

Second link: The second link also moves on a sphere but the cradle can now only rotate around the axis through the two link-to-cradle fixation points. Furthermore these two points obviously are now on a set distance. However one link can go up and one can go down so the cradle can be forced into a rotation.

The third link: This takes away the last rotational DoF of the cradle. However the forced rotation is still there - the three links can tilt in a non-parallel motion and thus the cradle rotates and - because the links follow their spheres - moves laterally. This is a similar situation to the isos...so it would already work, it would only load the rubbers and the suspension units with forces which don't come from the engine vibrations or the road shocks but from the torsional moment between front fork and rear s/arm.

The fourth link would block the tilting of the links forcing them to move in parallelism and therefore block this "forced rotation". The cradle moves on a very large sphere (the larger the longer the rods are) relative to the frame - a very similar situation to a planar guide with the added benefit of decoupling the suspension and iso rubbers.

One final remark to this Watt linkage thing: A Watt linkage is a device to control the motion of a specific point on a rod connecting two links. A point! Given the possible length of the links a Watt linkage in a Commando would force the cradle to tilt so much it would either lock the whole system or tear the rubbers apart. Okay, four Watt linkages providing mounting points for the cradle would theoretically work but ....well....how should I put that politely? :mrgreen:

My vote is three isos and use a Commando as a tourer. For racing I'd prefer reducing the engine vibration....

Tim

I'm all for practical mods, but I am with Dave, I have a 2002 and 2006 triumph to ride like a madman and I treat my 40 year old bikes like they are 40 year old bikes. ISO's, the vernier type work great for normal riding on average roads. If I had a second commando I may try more mods just for fun.

Here's quotes from the rod linkage mentor Bob Patton from spring 2001 emails
to various questions. I testify only the rear link transforms
handling security, the top and front links just make for less
nuance jostles and vibration reaching pilot through chassis.
What was found by the isolastic inventors, was any more rubber
area added just moves the isolation range upward. BUT
the rear isolastic is mostly a mass bearing pivot, so Bob and me
put in 2 or more additional large diameter cushions for less sag
yet no vibration transmitted. RGM fork brace and hobot
6" progressive spring and dampening mods make forks
disappear to pilot attention or notice. So there are at least
two Commando riders that don't think forks front tire have
much to do with real handling thrills.
hobot >>> hhehe, other bikes are no Competition, no comparison >>>
http://www.brockeng.com/mechanism/Watt.htm
http://www.brockeng.com/mechanism/Watt.htm

2nd ever proof of principle that led me over the edge.
http://rides.webshots.com/photo/1040309 ... 1179NBoCCa

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


The modification isn't really very complex, in fact it's easier than
setting up another iso. I'll send you a pic if you want.
The sag that concerned me wasn't uneven left to right so much as finding
the final relationship between two points on the cradle and frame after
the bike is assembled and sitting on its wheels. The linkage has to be
dead nuts level.

Putting an isolastic under the trans is a nice idea for the obvious
reasons, but it also handles some forces being sent to the cradle by the
swingarm. One of them is tension, or pulling the cradle backwards due to
the angled shocks. If you do a vector analysis you get something like
300lbs, static. The cradle rotates around the rear iso and pushes down
on the front iso and headsteady, adding to the weight of the engine.
That spring thingy helps somewhat. Ever notice how the quality of
vibration changes when the rear wheel is unweighted or nearly bottomed?
So having an iso under there is good, but linkages are better for
locating the cradle/swingarm in the frame. there's no such thing a
"parallel lines of force" on a Commando.

Mick Hemmings said in an magazine someplace that he uses five rubbers
in the rear iso. Skip Schloss was taking about using a urethane bushing
in there. I put six rubbers in there on the theory that the primary
vibration in the engine makes it go up and down; let it, around the rear
iso. Alot of bikes have been made with rubber bushings in the front and
one solid mount in the back.

You'er right, 6088K23 is the female 270lb one.
http://www.mcmaster.com/catalog/107/html/0968.html
That other number is the same one but male, the catalog doesn't give
much of a description.

5/16" is way too heavy for the flanges you need for the double shear
we'er talking about 1/8" is probably more like it.

Yeah, seems to be that the tilting motion is more significant. The
force originates at the tire contact patch, right? Everybody grabs the
swingarm and tries to recreate what's going on. Try grabbing the wheel at
6:00, or try pushing it sideways with your foot at the lowest point. The
effective lever arm originates at the contact patch.

The idea is to let the cradle move up and down or front to back but
not side to side. The arm has to be lined up on that axis. Any deviation
tilting it up or canting it anything from perpendicular to the
centerline is going to transmit vibration. Maybe you have seen some of
the Buells. They had at one time an outrigger anchor for their linkage.
The reason is the longer the arm the less acute the arc that the
movable end is going to travel thru. This arm is about 5" long. I
figured that the cradle moves maybe 1/8" in each direction from rest.

So, imagine a sphere with a radius of 5" Take a slice out that has a
surface area of 1/4" The surface of the old sphere still shows as a
convex surface. If you connect the two corners of the arc from the
surface and make a line perpendicular to it to the surface in the middle
that will tell you how much lateral motion you get translated from that
1/8" of motion. I had to compromise between mounting the Lords right in
the centerline and having too short an articulating arm. Theoretically,
you don't need to use a rubber mounted ball end and you should have that
much tighter alignment with negligible vibration. I was told that
regular rod ends wear to the tune of 10thou in no time. Because of the
location, it seemed this is a better way to go, I don't think it's
possible to tell the difference, but I haven't checked yet.


I can really tell the difference when riding at the limit on bad
roads. Last spring I was riding with Frank Forester and I was just about
at the edge. 40-50mph on 20mph roads that were shot as far as surface
goes. I could hang off the inside and ride it out, mainly steering with
my outside leg, pulling the bike over deeper or letting it go upright,
no handlebar input at all after the initial counter steer to get the bike
leaned over. This bike wouldn't do this before. The crappy forks really
showed themselves. they would windup and let go but always the sum total
of their deviations ended up ok. Not that much fun.

3/7/2001
You gotta mean folding pegs, right? I have rearsets and I like them,
but it is very unsettling to have you foot knocked off. I'm making up a
new swingarm with a disc so the left sides going to have to be all new.
Going to raise them a bit. Actually, when I think about the way I
described cornering it's really what most people are doing anyway. You
don't really steer thru a corner with your handlebars. Some people make
those weight transfers with their feet on the pegs, some people don't
even have their outside foot even touching the peg. It was the most
fantastic discovery I ever made about fast riding when it came to me that
the handlebars are just a convenient place to put the controls. The
second biggest deal was when I started putting a small backpack on the
seat behind me so that I wouldn't slide backwards due to wind blast.
When I stopped using the handlebars to keep from getting blown off the
bike a _lot_ of high speed handling problems went away. That reminds me,
I have to send my Interstate pianobench seat to Sargents to get it
modified.

The first ever of its kind that proved the concept works.
http://rides.webshots.com/photo/2674295 ... 1179zjlnOC


Bob Patton.

Tintin said:

Jeandr said:

So what works? or better still what would work better?....

Click to expand...

a) Have a look at http://www.freepatentsonline.com/4776423.pdf which is the Buell patent on the Isoplanar system (and count the links...)
Tim

Click to expand...

Luckily Buell didn't have to worry about Norton challenging their patent. They were very "unfavorable" in the description of the Isolastic. Makes it sound like it was just a rubber mounted engine with no side play control at all. Shame on them. Norton had shims for chrissake! :mrgreen:

Ah the Harley dudes wouldn't listen to the Commando isolastic designer's,
so used a diaphragm rubber isolator with many axli of freedom,
instead of the tubular doughnut and shaft one plane oscillation isolator.
Lord's Mounts are the one to bring rubber cushioning the world at large.
Maybe the Americans were ashamed to depend on British supply.
Alas Norton bean counters and management suckers nixed vernier adjustment
and any Helm's link experiments.

Regardless of how much further refined various forks and isolastic
linkages my occur, the whole package and every issue known
and a few un-experiencable by lessor NOT-Neutral handling motorcycles,
has been so solved its unbelievable but by two Commando surfers -
so far. If any leaning is involved at all, a rear linked Commando is
simply Unapproachable! A tri-linked Commando simply disappears
to pilot perception but the shove through brain stem to sacrum
into the compressed suspension and tensed chassis and out
the quauntum interface of tire/tarmac patch.

Ms Peel will just need a notch/crook in RH centerstand leg to have
it all.

hobot

Well, back in 1969 they still managed 99MPH laps of the Isle of Man and the NorVil Proddies did well on many short circuits. All pretty much using standard Isos front and rear with the top being Iso as well. Also on Dunlop K81 tyres. So what's the gripe with Commando handling?

All I know is if you try to stiff this up, the stresses get transferred into the frame and that's not to strong. Probably better off adding a couple of braces tubes to that before messing with rod joints all over it.

Mick

ML said:

Well, back in 1969 they still managed 99MPH laps of the Isle of Man and the NorVil Proddies did well on many short circuits. All pretty much using standard Isos front and rear with the top being Iso as well. Also on Dunlop K81 tyres. So what's the gripe with Commando handling?

All I know is if you try to stiff this up, the stresses get transferred into the frame and that's not to strong. Probably better off adding a couple of braces tubes to that before messing with rod joints all over it.

Mick

Click to expand...

My guess is that they cranked down the isos to almost no clearance, knowing that if the frame broke after the race they would just replace it.

With rod ends they would have had more control and it would have been a lot better on the frame.

I think the misconception is that the rod joints cause more stress on the frame, when what they are doing is just providing more control of the cradle and hence the rear wheel.

Mike, that's part of what's so unbelievable, that there is no stress
vibration transmitted into frame, Nay, the rear link and its helpers
relieve the frame strain for unbelievable tolerance to loads,
both held long and steady or spiked into controlled low and hi sides.
All the while feeling like Goldwing on auto pilot.
Flabbergastingly Fabulous!

Beware, weak upper body riders can loose grip in hard corner pulls.
Not a steering issue but can back flip over the tail lens.

hobot

Excuse me Mick eyes mis read at first glance and wrote Mike.
Was flashing back on the cornering thrills on this subject,>>
tunnel vision develops and lens muscles can't react fast enough
to focus on scenery zooming up rates.

Its so good its so good its so good...

hobot

Tim,

I understand what you are saying now and I agree with everything. As you said, the deflection introduced by linkages is related to their length but one has to draw the line somewhere. In practice they seem to work ok. I hedged my bets by using an elastomeric rod end that's rated at 20thou delfection at 270lbs. The main reason was to avoid breaking the frame because there really is no visible means of support down there, even with a cross-brace.
All of these linkages we're talking about are actually Panhard Rods not Watt's Linkages.
So far, I like Ludwig's headsteady the best. It has the 'set and forget" convenience of rods and is compatible with the other iso's. The Norvil headsteady makes sense on paper but it's a nightmare in practice. The DT is just the opposite.

THIS is the one I like for the rear.

http://rides.webshots.com/photo/2674295 ... 1179zjlnOC

(it's the last little photo in hobot's long post)

Without a six-page thesis, (my belief is) limiting the range of the isolastic units to coordinated longitudinal travel described by the three isolastic points results in a logically better solution than letting them move in any direction allowed by the mechanical limits of the hardware.

Even solid race framed 'Commandos' break their frame if BF is too low.
Kenny Cumminings has his break at least twice now.

Rod end links are just pivoting connectors, what ever name you call them.
What makes a Watt's linear linkage is the geometry of
the rod links. Ms Peel has Watt's like arrangement by rods placed
above and below the plane of isolastic mounts as well as beyond
the front and rear ends of the power unit. Ends of each rod oriented
180' to other rod. Each arc that one rod tends to swing the cradle on,
is opposed by the other rod.
Within the up down range of front and rear isolastics, 4.5-5"
radius limits cradle to vertical orbital w/o binding on links
to transmit vibration.

On Peel if I did not set radius adjusters to most neutral slack setting
vibration would get though.
If I set isolastics much below factory gap, vibration would get through.
If I set isolastics too far over factory gap, load handling would decay
with weave-wobble-jostles and tendency to amplify if not
letting off.
Best handling and ride, was with isolastics a bit looser than factory.

Once dialed in, uncanny huge monolithic inertial sense
of solid steady smoothness. Wind and nuance road
texture dampened out yet bigger lumps and lows are
felt but as if chassis was transparent to them just passing through.

But Peel's Watt's like arrangement is not needed to transform
into wondrous neutral handling bike that holds any angle
on its own, till pilot's light forces change as desired.
Only real need is Pattons rear link. The other two are more pilot
comfort and effort reducing features. The rear link is tough
to do, the other 2, not so much.
My tests reveal rear rod is worth ~80% improvement,
Front ~15% and top 5%.

On THE Gravel I can load and drift my SV650 wider holding some
straight steer so its also pivoting on CoG to help align into
next turn. When I try this on SV on pavement all hell
breaks loose so bad so fast I stopped trying on SV.Vtwin.
Same thing with in line 4 Ninja. My conclusion is fully rigid
bikes shoot themselves in their cornering foot. Side give is
also miss directed concept. Chassis twist with dampened
articulation to take tire conflict out is where the action is.

In real neutral handling bike only loads are about the same
axis as sitting still with feet down.

Only time Ms Peel really needs some firm pilot holding
of forks at set angle is when she is drifting both tires on
tarmac with slight straight steer, not crossed up to relieve loads
like flat trackers, but twisting chassis up like a torsion bar.
Chassis releases on let ups after apex, but just flings
bike the way you want it to go - no rebounding resonance.

hobot

ML said:

Well, back in 1969 they still managed 99MPH laps of the Isle of Man and the NorVil Proddies did well on many short circuits. All pretty much using standard Isos front and rear with the top being Iso as well. Also on Dunlop K81 tyres. So what's the gripe with Commando handling?

All I know is if you try to stiff this up, the stresses get transferred into the frame and that's not to strong. Probably better off adding a couple of braces tubes to that before messing with rod joints all over it.

Mick

Click to expand...

I'm with Mick a little bit here. When I was racing my Commando PR in Club races and AMA Battle of the Twins races, I made a lot of changes to the bike, but the isolastics weren't among them. I had the stock PR isolastics, including the "Norvil" top mount, that came from the factory. Even with 18" slicks, the hot technology at the time, it handled superbly. I set the isos at .005" - .010", and it tamed the vibration from the 920 at 7200 rpm and still handled great. A lot of Commando racers at the time (but not the factory bikes) decided that they had to run the isos at full tight, and all they managed was to wear them out fast. I'm convinced that most of the evil handling Commando stories are the result of worn swingarm shafts, improperly adjusted isos, worn steering head bearings, poorly set up front ends, etc. Just my humble opinion, of course.

I raced Commandos and featherbed Nortons pretty extensively in my younger days, and they do have totally different feels. Maybe some riders just aren't comfortable with the Commando for that reason, but that doesn't mean they don't handle well.

Having said all that, I plan to try a linkage system on my street Commando, just to find out how well it works. I'm not saying it might not be better. What I'm saying is that the original design was plenty good enough in the day.

Ken

Some form of compromise must have been done on the original design because let's face it, teflon and steel washers cost a lot less than rose joints and cheap shims provide some form of adjustment that is probably easier to obtain than fiddling with screws. While the original setup enhanced with adjustable ISOs is good, are rose joints better? Hobot seems to think so, at least that is what I understood. Anyone else gone full rose joints? And if so what is better, 3 or 4? The patent paper by Eric Buell, as far as I understand, say that 3 is OK, but 4 is better. On a Norton with a 3 point attachment, 3 would seen to be enough, the HD looks more like a box and prbably works well with 4, is that what they ultimately did?

Jean

hobot said:

Rod end links are just pivoting connectors, what ever name you call them.
What makes a Watt's linear linkage is the geometry of
the rod links. Ms Peel has Watt's like arrangement ....

Click to expand...

I would be a Watt linkage if you would use the cradle to control the movement of a point on the cradle to force a body attached to it onto a certain (almost linear) path. You are not doing this, are you? The aim is to control the cradle.

Take a look at this animation, maybe it's clearer then why a Watt linkage is one step further than what is happening on a rodded Commando:



Do you see the rotation of the cradle when the point is still on its (almost) linear path?

Could you please finally stop this name-dropping b*llsh*t as it is only adding to the confusion?


Tim

Jean,

The Harley touring bikes use three links along with pedestal rubber mounts for the engine. Their handling gets a little squirrely, though I can't see how anyone could tell. There is an aftermarket part for a fourth link under the trans.
http://www.progressivesuspension.com/to ... index.html

To answer your question about anyone replacing all the iso's with links, Dave Winship did it and put together a nice write up in the INOA links section.

For me, four iso's, four links, or a mix probably doesn't matter. The range of motion just isn't that much. I think adding a fourth mount under the rear iso with the swingarm in the middle does affect the handling and vibration because it helps stabilize the cradle in the vertical plane. The other iso's and the cradle itself then only have to deal with side to side push, not the twist from the swingarm. I left the front iso because I can't see that frame has much lateral strength or stiffness in that area anyway, but it does do a good job of holding up the motor.

Tim, that's me banging head on what you all are missing out on.
I sent that URL of the full figure 8 motion of a classic Watt's geometry.
But also sent this one that animates the small but essentially linear
zone. http://www.brockeng.com/mechanism/Watt.htm

I took your instruction years ago that Peel is only a Watt's "like" geometry.
I did not mount to center line of central linear plate. To fudge
and gain sufficient-excess radius arc, Peel's radius rods extend
from one side of frame to far side of cradle. Also rods are attached
above and below the isolastic mounts and beyond them front and back.
In the maximum extreme ranges of isolastic motion from engine
and road trust loads, it stays in essentially linear non tipping zone with
isolastic gaps of ~0.01+" [top steady is ignorable with or w/o it ]

I measured front and rear and top mount motion to see cradle
just bounces up/dn at front on rear pivot. On tires and just
engine blipping the front jumps up/dn ~1/8" of rest position
for ~1/4" oval orbital in a slightly bent- backwards arc.
With road loads added it jumps 3/16" either side of rest position
and fro/aft 1/8" for total of 3/8" x 1/4" vertical bent back oval.
http://thumb19.webshots.net/t/50/50/1/2 ... pYV_th.jpg

i was given the experimental sliding plate-puck head steady of late
Gerry Bristow - it has witness marks of the slight 1/16" long arc one
would expect with it mounted between rear pivot front bouncer.
Gerry retired in Greece and had a cresting chicane turn he'd catch
air on his 850 - pivoting in air enough to touch down
lined up to hook up into next line. He said his puck steady
transmitted vibes and did not improve handling in sustained wavy loads
in sweepers. Gerry died in a heart beat by aneurysm at family BBQ in UK
after a day of play on vintage bikes with his brother.
Gerry was a week away from installing Peel's lacy cut out front
brake rotor made my Ken Armand to lose 1.5+ lb mass.

On tires rear iso moves in mostly circular range of 1/16" around
its rest position. With road loads added its circle expands to 1/8"
rim around resting marks but slightly elongated in line of tire drive.

Until I hear of other non race 750 Commando's embarrassing
elite hi HP, fat tired rigid-solid chassis-engine elites, vintage to
electronic GP bikes, I don't think you'all know what you are missing
out on. All those bikes still get upset in sweepers and go rather
slow through chicanes and all emphasize braking to enter turns
and even continuing braking while leaned!!!!!! They brag how
quick and hard AFTER APEX they can get it on, Not Ms Peel...
HAHAHAHA-
Peel is testing tire spin traction for max acceleration where they
are hard on brakes, so I've no surprises staying on max power
into and out of any turn at any lean - and no fight or much pilot
effort or skill needed, thank goodness. Bob knows a rear
linked Commando seems to steer itself once you tell it
where to go by one little fork motion, might as well let
got of bars except to keep carb springs strained opened.

BEYOND the Extreme handling loads and greatly increased
safety for surprise hazards, broken axle, blow out, tree
falls, fallen deer, dump truck grills in your face around blinds...
and controllable riding on front locked up slides for dozen yards
The lulling comfort refreshment of
Huge Monolithic Massive Inertial Solidness
sense is beyond compare even just lugging along like a Harley.

hobot