Making a Cushier Cush Drive

[Guest ratchethack]

Innovation often involves taking an idea that others huff at and making it sucessful.

Greg Field is good at that. I am surprised he is not on board with urethane

Dave, with all due respect, you will no doubt continue to be surprised by that of which you have no knowledge, or even the faintest comprehension. . .

 

Wot kind of R&D effort in terms of expertise, time and money d'you suppose is represented by the development of the correct urethane formula in the BST CF wheels? D'you have any idea if the BST wheels have been proven long term, in terms of cush drive effectiveness relative to wot works in the V11 as proven by years of use (such as drilled rubber blocks have been in my own case, for one example)? D'you imagine that the same formula -- even if you could manage to duplicate it in your garage -- would be the correct one for the design of the Guzzi cush drive?? Wot d'you suppose the probabilities would be of BETTERING the characteristics of a drilled set of cush drive blocks that Greg was wise enough to rely upon by decades of experience based on his own knowledge and that of all the Pro's he knows of who've also done it previously??!!

 

Why do you suppose that if YOU could whip up the "perfect urethane solution" here with "6 hours of shopping and 2 hours of work" as you've so naïvely imagined and proposed, IT HASN'T BEEN DONE BEFORE?!

 

Better question yet -- if it's so easily done, WHY HAVEN'T YOU ALREADY DONE IT?!

[Guest drknow]

Well, to throw additional gasoline on this fire, the OEM cush drive in my last race bike's wheels (06 ZX-10R for sale) were urethane. The company used to sell wheels with rubber, but they switched a few years ago. In fact, between 04 and 06 the urethane changed durometer, color, etc, even though the cush insert mold stayed the same, the wheel remained the same, and the bike's weight remained the same.

 

Seems to me that what most people here agree on is that the longevity and durometer of the rubber is in question on the stock cush drive inserts. Drilling seems to be a viable solution for many folks. However, this doesn't mean other answers wouldn't be superior. Am I going to find the proper urethane compound, make a mold, test it, and then sell it? Hell no! I'll drill mine should the need arise. However, I applaud someone deciding they could engineer a better mouse-trap. If Dlaing made these, I'd sure be up for buying a set to try. More effort has certainly gone into less for our beloved bikes than this.

 

Meanwhile, pass me that drill bit...

 

dk

[dlaing]

 

Better question yet -- if it's so easily done, WHY HAVEN'T YOU ALREADY DONE IT?!

Because of the bolts, and Greg's story of how difficult it was to get them out, along with other people's stories and my own brief attempt.

I mentioned this before, but you must have lost your recollection for my brilliant words.

Besides if I get there and find that my batch of pucks is softer than Greg's chrome-alloy-rubber, and in fine condition, I might just lube it up and or drill them.

Right now the plan is to buy the right tool for the screw removal, and come the next tire change I'll do an exploration.

One possible plan is to pull some of the rubbers so I can match it up against some known durometers, probably at a skateboard shop where they sell wheels and truck bushings in various assorted durometers.

I might have to spend $20 on R&D, but it could be worth it.

I already asked San Diego Plastics if they have a durometer, but they don't.

I figure if I can roughly determine what the durometer should be.

My target will be about 5-10 durometers softer than the Chrome-Alloy hard pucks.

How hard are they really? You probably have much better idea having handled them.

From wikipedia some general durometers are :

Ebonite Rubber 100 A

Hard skateboard wheel 98 A

Solid truck tires 50 D

Soft skateboard wheel 75 A

Automotive tire tread 70 A

Door seal 55 A

Rubber band 25 A

Sorbothane 0 A

So, I am guessing that Chrome-Alloy hard was an exaggeration and that Ebonite hard rubber 100A might be about what Guzzi put in there, but probably a little softer, as I find it hard to believe Guzzi made them 100A or harder.

Skeeve suggested 50A is too soft, and over 70A would be better, maybe around an 87A.

I am inclined to agree, but need to pull the cushes to make sure.

 

The other option is to send one of the wedges to the experts that Pierre recommended and get an estimate to have it done at about 5 less durometers.

 

If I do that, it is a simple upgrade, and hopefully inexpensive.

Unproven? Sure, but I have more faith in going with 5 less durometers and maybe a few small drill holes than making swiss cheese with a drill bit, or intestinal gas, like BFG'a wife did.

 

I am sure I can sell atleast 48 wedges, if the price is right...

 

[pete roper]

Blibble, blibble, nark, nark, whiffle, whiffle, bark, bark, LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_ALA.............AAAAARRRRRRGHHHHH!!!!!!!!!

 

Pete

[g.forrest]

[docc]

I wasn't really saying that I wouldn't modify the cushies without space age material. If I were to drill them I would like to make some cleaner holes and space them more consistently and uniformly. Not that it would make a hair's worth of difference in how they work and I realize no one sees them but me. It's just how I like to do things.

 

No offense to Greg nor to others, but the only rendition I've seen of these modification looks a bit raggedy. I don't think that takes anything away from its functionality, yet I'm surprised no one offered up a bodge point.

 

My pucks felt as soft as tire rubber. Of course it's mighty hard to gauge durometer with a fingernail while the Wikapedia results are thought provoking. It looks like they're saying the rubber from a solid truck tire (is that like for a tow motor or child's wagon?) is softer than an automotive tire?

[Dan M]

Blibble, blibble, nark, nark, whiffle, whiffle, bark, bark, LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_LA_ALA.............AAAAARRRRRRGHHHHH!!!!!!!!!

 

Pete

 

 

DITTO

[Guest ratchethack]

Better question yet -- if it's so easily done, WHY HAVEN'T YOU ALREADY DONE IT?!

Because of the bolts, and Greg's story of how difficult it was to get them out, along with other people's stories and my own brief attempt.

I mentioned this before, but you must have lost your recollection for my brilliant words.

Hm. Well, certainly the "brilliance", as well as all the logic and most of the reason have all escaped me, since the "bolts" you mention have to come out regardless of anything you do, and my recollection of wot you mentioned before is quite good.

 

Dave, I've been fabricating my own parts from just about every kind of material imaginable since I made a go-cart out of a neighbor's lawnmower when I was 11 -- and fabricating parts of greater and greater sophistication ever since. Following the go-cart, there was the "first" motorbike, which I made out of a heavy frame bicycle with balloon tires and another lawnmower engine. My home workshop today usually has at least a half-dozen projects running concurrently, along with 2 motorcycles. At age 11, when my paper route was my only source of development funds, I think I spent a total of $25 on materials on the go-cart, having scrounged a few things, and fabricated the rest of the parts I needed from scratch, including a quite effective set of fully adjustable foot-pedal-operated brakes with wooden brake shoes that worked by applying equal braking force on both rear tires. As I recall, this was a hard requirement put on me by the ol' man, who (rightfully and thankfully!) demanded a successful demonstration of their effectiveness, straight-line stopping performance, and dependability before allowing me to run the infernal thing. . . but I digress. . .

 

I've mixed up 2-part polymer compounds by the hundreds for lots of different projects -- not to mention making my own replacement parts (by numbers far too numerous to recall -- certainly many many hundreds) for motorcycle restorations out of 2-part epoxies, plastics, rubber, aluminum alloy, steel, brass, fiberglass, etc., etc. -- and of various combinations thereof on moto's, cars, trucks, boats, etc etc.

 

Not all the parts I fabricate from scratch are successful. Many have failed for a variety of reasons. Many have succeeded only after second, third, or more attempts. Many never succeeded at all.

 

My point is that despite my complete lack of professional training in the trades, and at least middling-capable, but possibly sub-par professional level workshop capabilities, I at least possess a deep-level appreciation for mechanical and materials engineering borne of my own hands-on experience. I reckon Greg, Dan, and Pete (as well as many more "non-Pro's" such as myself on this thread) have far superior kinds of professional background experience, possibly hundreds or even thousands of times beyond mine in terms of both sophistication and volume -- for which they have no doubt received qualified professional training to start with. That's why I respect their read on this. I reckon your lack of experience also explains your lack of respect for their opinions as they've expressed them here. You don't seem to have any appreciation whatsoever for wot it is that you have no knowledge of. . . and how could you?? It would be one thing if you had some humility about this, but I continue to find your "no problem" naïveté not only preposterous, but incredibly presumptuous.

 

In the spirit of helpful suggestion to you, with sincere intent to assist you in your apparent upcoming junk science project, let me suggest for openers that if you found the 6 threadlocked "pie plate" retaining screws "too difficult" for you, that frankly, you more'n likely lack the resourcefullness, experience, skill, and determination required to design and fabricate such a highly engineered thing (in the materials engineering sense of the term) as a cush drive for the Guzzi -- not to mention one that works better than drilling the blocks.

 

I have to admire your intent, Dave, but I believe that your naïveté here seriously trumps wot's lacking in the ---err, rather empty bag of experience and knowledge that you bring to this consideration. HINT: I submit to you that the school art project you mentioned, where you made molds and mixed up some colorful stuff to pour into the molds -- for decorative purposes, I presume? -- will be of no value to you wotsoever in this kind of a project.

 

I suggest to you that getting a target durometer reading for a starting formula is only a tiny fraction of the great many more important considerations involved, of which I have mentioned only a few previously.

 

Now just because I find the cost/benefit and requisite R&D effort here far beyond my own shade-tree fabrication inclinations is no reason YOU shouldn't go for it, after all. . .

 

I do wish you the most sincere good luck, Dave. Really.

 

POSITIVE NEW IDEA AND OFFER!

 

Look -- this thread has gone way past tedious, Dave. Can't we just get on with it and get SOMETHING done?!?!

 

Now just to show you how sincere I am after throwing all the cold water , I will make you this offer: If you're actually as sincere in your intent to do this as your posts indicate you are, and you can get your rear wheel off, (and assuming you'd be interested in my assistance ) I will gladly come over with tools and have those threadlocked button-head screws out for you within 15 minutes, and I will guarantee my work 100% -- free of charge. After that, y'er on y'er own, my friend. . .

 

You can PM me with your response to my offer.

[belfastguzzi]

ObCushDrive content: How about a hydraulic baggie that smooshes the fluid one way or the other under thru a calibrated hole? Maybe w/ a "spike load" relief valve in the mix?

 

Nuts!

 

This dang BBS software keeps appending my posts to the last one, so I can't push it over the top to 12 pages!

 

Someone, give me a hand here! We can't disappoint Pete!

I reckon that the invisible power of magnetism could have a use here. Opposing magnetic forces should provide some nice tuneable cush? Go for belt and braces and still use the rubber wedges – but impregnated with magnetic filings?

 

Mind you, talk of gerbils, er, was that off topic? Not necessarily: what about ditching the rubbers and stuffing the drive with fattened gerbils? Self-lubricating.

 

Dave, I've been fabricating my own parts from just about every kind of material imaginable

Gerbils?

[dlaing]

My pucks felt as soft as tire rubber. Of course it's mighty hard to gauge durometer with a fingernail while the Wikapedia results are thought provoking. It looks like they're saying the rubber from a solid truck tire (is that like for a tow motor or child's wagon?) is softer than an automotive tire?

Yah, I thought that one was a little odd to.

On that wiki page they have another entry that puts automotive tire at 50-70A

http://en.wikipedia.org/wiki/Durometer#Dur...ommon_materials

In any case, if the stock pucks are as soft as automotive tire, placing them below a 70A, then I doubt I'd bother with urethane. The whole point of the urethane would be to get away from the 95A or harder rubber.

While urethane is availble below a 70A it is less common and at 70A some mild drilling will do the trick for the stock rubber, but at 95A it seemed to need extreme drilling as shown in Greg's photos. Maybe Guzzi ships various densities of rubber and Ratchet and Greg got rocks and Docc and maybe others got compliant rubber.

I guess we have wasted a few pages on my otherwise bright idea.

But just to keep it going...

I recalled a better word than driveline lash, slack or freeplay that represents slack plus cush, and that word is slop.

Drilling holes or using softer rubbers will increase slop, maybe lash, not slack and not freeplay.

[dlaing]

 

POSITIVE NEW IDEA AND OFFER!

 

Look -- this thread has gone way past tedious, Dave. Can't we just get on with it and get SOMETHING done?!?!

 

Now just to show you how sincere I am after throwing all the cold water , I will make you this offer: If you're actually as sincere in your intent to do this as your posts indicate you are, and you can get your rear wheel off, (and assuming you'd be interested in my assistance ) I will gladly come over with tools and get those threadlocked button-head screws out for you within 15 minutes, and I will guarantee my work 100% -- free of charge. After that, y'er on y'er own, my friend. . .

 

You can PM me with your response to my offer.

Thank You!

I will consider the generous offer.

Your experience and skills are certainly appreciated.

I don't mean any disrespect when I question authority.

The experienced should just learn not to call 70A durometer material Chrome-Moly hard and should learn that a challenge can be be made to asserting that drilling holes won't increase lash.

I certainly learned that slack is different from lash. Thank you.

But I still have doubts about this friction plate.

For now, I have to respect authority that it is ok to get greas on, but I do suspect it might be to provide friction damping.

[docc]

I agree it had to be making friction in order to wear into the metal like that, even if it is intended only as a 'gasket.'

 

Mine now has a thin coat of moly, so very little friction if any.

[Guest ratchethack]

OMG no. . .

 

First it was this:

Driveline slack is NOT the amount of free movement of the driveline with NO LOAD on the driveline!!!

Driveline slack is the amount of free movement of the driveline going from maximum hard decceleration to maximum hard accelleration!!!

Next we were graced with this:

It is difficult to see from here and I like to play within my ability.

Yes indeed. Well within y'er ability in this thread -- stem to stern.

 

And now this:

I certainly learned that slack is different from lash. Thank you.

Now Dave, lest we get too overly chummy over my offer above -- I must tell you that if you insist on making this too painful for me, I will rapidly lose interest -- though I will continue to stand by my offer regardless, pending your acceptance, of course. . .

 

I mean Painful , Dave. With a capital "P". PAINFUL . Now please:

 

May we kindly dispense with the falsely fabricated concepts and false terminology -- I'm BEGGING YOU!!!!

 

Where have you "learned" that driveline slack is different from driveline lash??! Not in this thread! This is clearly another of your beloved "inventions of convenience" which I've noticed you routinely create out of thin air, without any foundation in reality wotsoever, apparently in attempt to support the frivilous and fanciful whimsy that seems to gush forth uncontrollably from somewhere deep within your imagination. No Pro in the business of drivelines -- motorcycle, car, truck, boat, YOU NAME IT! -- would EVER EVER EVER agree with this! Your repetition of falsehoods here, left temporarily without immediate, well due, vigorous refutation, doesn't magically transform them into truths , Dave! Many of us (myself included) simply tire of having to make corrections and explanations every time you lay out another whopping delusion -- as if you were spouting established fact, and as if you possessed well-established credibility on the subject at hand. . .

 

You keep bringing back the image of the wildebeest with the croc clamped on its head. It's not a good look, Dave. . .

 

D'you find it comfortable?

But I still have doubts about this friction plate.

For now, I have to respect authority that it is ok to get greas on, but I do suspect it might be to provide friction damping.

Next, please drop the idea of a "friction plate", for cryin' out loud!

 

Can we at least nip this next potential demonic monstrosity in the bud and avoid running down yet another silly rabbit trail?? This term was merely an unintentionally poor choice of words by Docc, who was (understandably) a bit baffled by wot he found when he encountered wot Guzzi refers to as a "gasket". I repeat -- this thing has NO friction damping function whatsoever!!! Yes, friction from dust and grit causes surface wear on the drive plate and the retaining ring. But I REPEAT -- the thing provides NO FUNCTIONAL DAMPING to the action of the cush drive! It's merely a bit of a barrier against road grit, as previously explained, and as I b'lieve you would clearly see if you'd actually ever had your cush drive apart!

 

Please may we kindly dispense with any more folly and confusion than absolutely necessary?!?!

 

Please, please, PLEASE try to stay focused and not spin off on wild tangents in all directions, Dave.

 

Now you have a COMPELLING proposal in front of you that finally allows you to actually DO wot you've been so stubbornly -- nay -- so tenaciously -- insisting on doing here, advising others, and making false statements as if your authority on cush drives were on a par with -- even superior to! -- the Pro's who've contributed to this thread. It would appear that there's next to nothing left to impede your progress now! This would allow you to actually post with some actual EXPERIENCE with a V11 cush drive under your belt!

 

No excuses left, Dave. You have an immediate ACTION PLAN!

 

Time to stand and deliver!

 

Can you? Will you?

 

In the immortal words of "The Iron Lady", Maggie Thatcher (who had huevos ), who was famously quoted having said to our hapless and very nearly hopeless ex-President G.H.W. "Read My Lips" Bush (who had alubias ):

 

"Now don't go wobbly on me, George!"

[Skeeve]

But just to keep it going...

I recalled a better word than driveline lash, slack or freeplay that represents slack plus cush, and that word is slop.

Drilling holes or using softer rubbers will increase slop, maybe lash, not slack and not freeplay.

 

No.

 

"Slop" aka "lash" is the accumulated free play from stacked tolerances, ie: each part has a range of acceptable sizes to facilitate assembly. If all parts were press fits, then there would (could) be no slop. If the wheel was assembled, the open space within filled w/ raw rubber goo & the whole assembly autoclaved to vulcanize the rubber, then there would be no slop whatever within the cush drive assembly. Later disassembly of the hub to drill the cush drive rubber would in no measurable way compromise this methodically manufactured "zero tolerance" fit, and the rubber bumpers (now w/ holes added, or should I say, material taken away?) would be more compliant, but there would be no increase in slop, lash, or whatever the heck you want to call it.

 

Of course, if all the parts in the driveline from the splines back were a press fit, we wouldn't need the cush drive in the first place, so this exercise is beyond academic, but whatever. I just wanted to correct the notion that drilling the cush drive rubbers somehow changes manufactured tolerances anywhere in the Guzzi driveline.

 

[belfastguzzi]

QUOTE(dlaing @ Aug 8 2007, 08:45 AM)

 

But just to keep it going...

I recalled a better word... that represents slack plus cush, and that word is slop.

 

 

No.

 

"Slop" aka "lash" is the accumulated free play from stacked tolerances, ie: each part has a range of acceptable sizes to facilitate assembly. If all parts were press fits, then there would (could) be no slop...

 

No and also.

 

In a way, in another thread elsewhere, Ralphy kinda suggests that this could also be viewed as "cleavage". Seems like a more poetic description, so I suggest that it has merit.