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Author Topic: Bronze Swing Arm Bushings For C5?  (Read 4293 times)

Ducati Scotty

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Re: Bronze Swing Arm Bushings For C5?
« Reply #45 on: July 06, 2010, 12:09:47 AM »
Stability on a bike should increase with straight line speed, unless the geometry is way off, or there is another factor upsetting the straightness if you will. I don't think the geometry is that far off.

The geometry doesn't need to be off, just inadequate for the speed.  Long trail, better high speed, short trail, easier flickability into turns.  All the REs are short trail bikes.  This is also the reason choppers got long forks. The increased trail was much better for straight line stability at high speeds.

You would be surprised how little of a difference you need to make to notice.  It's common for some sport bikes to move the fork tubes up in the triple clamps a little bit.  1/4" can make a bike amazingly better at turning, sometimes even dangerously so since high speed stability suffers.

All that said, changing tires is a much cheaper way to go about things.  Again, tire sizes and profiles can make a huge difference.  And as mentioned, tires are cheaper than wheel swaps.

Again, I don't think you should necessarily stop moving forward with the bushings, just putting these options in too.

Scott

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #46 on: July 06, 2010, 12:55:56 AM »
The geometry doesn't need to be off, just inadequate for the speed.  Long trail, better high speed, short trail, easier flickability into turns.  All the REs are short trail bikes.  This is also the reason choppers got long forks. The increased trail was much better for straight line stability at high speeds.

You would be surprised how little of a difference you need to make to notice.  It's common for some sport bikes to move the fork tubes up in the triple clamps a little bit.  1/4" can make a bike amazingly better at turning, sometimes even dangerously so since high speed stability suffers.

All that said, changing tires is a much cheaper way to go about things.  Again, tire sizes and profiles can make a huge difference.  And as mentioned, tires are cheaper than wheel swaps.

Again, I don't think you should necessarily stop moving forward with the bushings, just putting these options in too.

Scott
All good points Scotty, and well taken.I do believe the answer is going to lye with a combination of all of these thoughts. I'm having an Engineer friend of mine over to have a look, who by the way has a sweet cb500t , that I work on, and get his opinion.
 will get it.  Dan.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #47 on: July 08, 2010, 03:42:25 AM »
OK,after consulting with my Engineer friend and he running some numbers,had the following suggestions, to be tried incrementally.
 The swing arm bushings are adequate, but pivot bolt/spacer need lubrication. No da Right?
  Gusseting of swing arm, in area of the intersection of pivot tube and side tubes, in an arch shape with 10 gauge steel, increasing swing arm rigidity by a factor of 2.This may make the swing are too stiff, and eliminates almost all of the flex. Also more labor for me.
  Option two is to cross brace swing arm, about 2 1/4" down from pivot tube, between side tubes with equal or greater size pipe.(1" Black Pipe).This works out to be about a 30% reduction in rigidity from above, which may be enough. Less work for me.
   He also had an interesting thought about the front wheel. Leave the stock 18" rim and low profile tire, but add 4 crimp on spoke weights, directly across from each other, spaced evenly around  rim.Weights of maybe 3/4 oz or 1 oz. Then balance wheel with a 5th,of what ever size needed. This will give the front wheel more mass, and more difficult to upset at higher speeds,but retaining most of the maneuverability of the smaller wheel. Pretty cool thought Huh?  Cheaper than a new tire/ rim.
 Sparks will be flying in the Garage tomorrow Boys, I'll let you know. Dan
        
« Last Edit: July 08, 2010, 01:55:47 PM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Ducati Scotty

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Re: Bronze Swing Arm Bushings For C5?
« Reply #48 on: July 08, 2010, 02:46:55 PM »
The weights?  I dunno.  The tire itself already weighs much more and is further out on the rim than weights would be providing for higher angular momentum.  And you think your problem is at the rear.  Will it really matter?  I've also never seen anyone make a motorcycle wheel heavier for better performance or handling.

All the other stuff sounds really good.

Scott

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #49 on: July 08, 2010, 04:59:14 PM »
The weights?  I dunno.  The tire itself already weighs much more and is further out on the rim than weights would be providing for higher angular momentum.  And you think your problem is at the rear.  Will it really matter?  I've also never seen anyone make a motorcycle wheel heavier for better performance or handling.

All the other stuff sounds really good.

Scott
Yea, I don't know either Scott, but as I said in my earlier post , it may be both. And it's all theory until tried.
 With the weights he went on about Inertia, gyro scopic forces, body's in motion with greater mass/ weight being harder to upset from that motion.Basically it's like simulating a larger wheel, with it's weight characteristics, not it's size. I know, a little "Rube Goldburgish" What the heck, its a couple of doller experiment.
 I guess with alloy wheels, what your trying to achieve is a power to weight reduction, at least in part. also with alloy you can have wider rim, for less weight then steel. Steel would off set any gains.
 I think adding a few ounces of weight in not a big deal to this very light Bike, and who knows? it may help. WOW !! it's getting deep Huh?
Dan.
« Last Edit: July 08, 2010, 05:28:43 PM by gashousegorilla »
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Ducati Scotty

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Re: Bronze Swing Arm Bushings For C5?
« Reply #50 on: July 08, 2010, 06:19:04 PM »
Certainly worth trying, but if I recall correctly, weight contributes to angular momentum and the gyroscopic vector in proportion to the square of it's distance from the center of rotation.  So just buying a heavier style of tire would be way more effective than weights since the outer heavy skin of the tire weighs more and is further from the center.  Also, making wheels lighter is generally done because while it takes a linear amount of force to accelerate the chassis in a straight line, accelerating the wheels in rotation up to the same speed takes roughly 4 times the amount of energy.  I think there's another formula with a squared factor in it but I don't recall if offhand.  Also, the gyroscopic force created by a wheel makes the force required to turn the bars grow exponentially with speed.  You can use the mildest counter steering inputs to great effect at slow speeds but racers really need to work to turn a bike that's moving at 150-200mph.

There have really been vast improvments in the understanding of how and why a motorcycles handle the way they do in the last 20 years.  Fork rake, wheel weight, wheel diameter, and so many other things play a part but trail is really one of the strongest factors.  In fact a bicycle or motorcyle stays upright on it's own mostly because of trail, not gyroscopics.  I believe there was an experimental rig built with counter rotating gyros to cancel the gryo force of the wheels, still totally ridable because of trail.  Without cutting and rewelding the frame or making big fork mods it's hard to modify trail.  The easiest thing to do is change tires or suspension heights which may have a smaller effect but still has some.

All that said, there are things to keep in mind.  Physics is often non-intuitve.  This is a theoretical discussion of a single element that may or may not be the cause of a real motor bike that is a complex collection of moving systems.  Sometimes something that makes no sense in theory fixes a problem.  You could probably get to the root of why but it's often not worth figuring out.

Wow!  And you thought it was deep before!

As you said, a few dollars to see what happens.  I just have an ingrained need to know why.  Ignore me at your leisure ;)

Scott

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #51 on: July 08, 2010, 06:34:55 PM »
Certainly worth trying, but if I recall correctly, weight contributes to angular momentum and the gyroscopic vector in proportion to the square of it's distance from the center of rotation.  So just buying a heavier style of tire would be way more effective than weights since the outer heavy skin of the tire weighs more and is further from the center.  Also, making wheels lighter is generally done because while it takes a linear amount of force to accelerate the chassis in a straight line, accelerating the wheels in rotation up to the same speed takes roughly 4 times the amount of energy.  I think there's another formula with a squared factor in it but I don't recall if offhand.  Also, the gyroscopic force created by a wheel makes the force required to turn the bars grow exponentially with speed.  You can use the mildest counter steering inputs to great effect at slow speeds but racers really need to work to turn a bike that's moving at 150-200mph.

There have really been vast improvments in the understanding of how and why a motorcycles handle the way they do in the last 20 years.  Fork rake, wheel weight, wheel diameter, and so many other things play a part but trail is really one of the strongest factors.  In fact a bicycle or motorcyle stays upright on it's own mostly because of trail, not gyroscopics.  I believe there was an experimental rig built with counter rotating gyros to cancel the gryo force of the wheels, still totally ridable because of trail.  Without cutting and rewelding the frame or making big fork mods it's hard to modify trail.  The easiest thing to do is change tires or suspension heights which may have a smaller effect but still has some.

All that said, there are things to keep in mind.  Physics is often non-intuitve.  This is a theoretical discussion of a single element that may or may not be the cause of a real motor bike that is a complex collection of moving systems.  Sometimes something that makes no sense in theory fixes a problem.  You could probably get to the root of why but it's often not worth figuring out.

Wow!  And you thought it was deep before!

As you said, a few dollars to see what happens.  I just have an ingrained need to know why.  Ignore me at your leisure ;)

Scott
WOW !!!!!! HEAVEY!!!!, I think from now on it's ProfessorScotty. LOL. It is very good indeed to have you involved in this complex conundrum. And yes the Why about it, is what's  Driving me to such extreme and complex platitudes. :D
 Thanks Scott, Dan.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #52 on: July 09, 2010, 03:29:45 AM »
OK, Had some positive results tonight. Cut and tac -welded in the 1" cross brace on the swing arm. I tac-welded because were just experimenting for now. Put everything back together and took her for a ride. Some slower speed stuff first for safety. Initial impressions were that the bike felt more solid and slower speed handling seemed unaffected.
 Pulled over to check the welds, and see that everything was in order. Then hopped on the closed course Highway. I got a 10-15 mph increase in stability :o. I found that I could cruise comfortably at 70mph. Not bad Huh?, but anything above that, the bike would start to get squirrely . So I think it's a decent improvement, but there's room for more. Time to try the Rube Goldburgish wheel weight test ;D. then onto a probable tire and or wheel size increase. I got pic's, but again, I can't get them to upload. Come on guy's any idea's.
 Dan.
« Last Edit: July 09, 2010, 03:34:17 AM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Ducati Scotty

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Re: Bronze Swing Arm Bushings For C5?
« Reply #53 on: July 09, 2010, 06:55:51 AM »
If you're running any current version of Windows then 'Paint' is a program that's probably already installed.  It's not much but it can shrink the size of files by just making them smaller, no fancy 'save at a lower resolution stuff, just fewer pixels.  Try that and see if you can get a smaller file that you can upload.

And nice job!  From what I've read all around here 70 is the highest comfortable speed well sorted stock bikes go.  And that's chassis stability comfy, engine vibes get grumbly at that speed. 

If this works out you might start getting swingarms mailed to you to improve :)

Scott

Ice

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Re: Bronze Swing Arm Bushings For C5?
« Reply #54 on: July 09, 2010, 07:12:52 AM »
WOW !!!!!! HEAVEY!!!!, I think from now on it's ProfessorScotty. LOL.

I second the motion  ;)

All in favor say aye  
 ;D



All kidding aside, my sincerest thanks for providing more useful education in that one post than four years of high school science class.
« Last Edit: July 09, 2010, 07:20:25 AM by Ice »
I can break it better,,,,at night, in the rain, on the trail,, 20 miles from nowhere.

REA #136

"TIMEX", the '06 Iron Barrel Military that takes me everywhere I want to go... and some places I shouldn't.

qgolden

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Re: Bronze Swing Arm Bushings For C5?
« Reply #55 on: July 09, 2010, 12:58:22 PM »
I have software that will reduce the pixle size of your image.  Paint gets a bit squirrely if you try to resize it much.  I can do it with no loss of quality.

Feel free to send me the files and I will do it an send them back to you.

-Q
Any other Enfields in New England?

Ducati Scotty

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Re: Bronze Swing Arm Bushings For C5?
« Reply #56 on: July 09, 2010, 04:21:20 PM »
Now that's community :)

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #57 on: July 09, 2010, 05:51:44 PM »
I second the motion  ;)

All in favor say aye  
 ;D



All kidding aside, my sincerest thanks for providing more useful education in that one post than four years of high school science class.

AYE!!!!!!!!!
 Thanks boy's but don't send them in just yet, I'm going to take it all back apart tonight and finish off the welds, grind and paint nicey nice, then put some miles on the bike to make sure everything is cool.Were stiffening something up, just want to make sure it does not show up somewere else in the form of a crack, I'll be the Guiney Pig. By the way, I do not believe bronze bushings are gonna work, due to the fact that the face of the plastic bushings ride flush up against the inside of the frame.Plastic to metal. Bronze would grind into the Frame. For lubrication, it's a simple matter of pulling out the pivot bolt and squeezing in some grease, support swing arm though. I will probably still add grease fitting by projects end.
  Scotty, vibs are really not that bad at 70 mph, especially for a single. By comparison I would say it's a little better than a 1200 Sporster.And what they say around here about the motor smoothing out with time, is true, it definitely does.
  For the pic's I have some before shots, gotta take some after shots.will due,then try paint, as the Professor suggests,  ;D. If not I'll email them to you Golden for your magic touch.
 OK? Now let me get out of here and get back to work. I'll get wit yooz  Guys latta. Sorry, "You Gentlemen Later", That was my Jersey slipping out.
Dan.  
« Last Edit: July 09, 2010, 05:56:04 PM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #58 on: July 10, 2010, 03:30:26 AM »
Some before pics. Cool, paint worked! Below you will see the comparison of the cb350 swing arm on the left and C-5 swing arm on the right along with pics of measurements of the C-5 swing arm.
« Last Edit: July 10, 2010, 03:36:40 AM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: Bronze Swing Arm Bushings For C5?
« Reply #59 on: July 10, 2010, 03:44:25 AM »
Here's some more. What the............. how did that last one get in there?  Oh well you got a preview of my next project. ::)
« Last Edit: July 10, 2010, 03:47:50 AM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.