Longer lasting cush drive material available

[Admin Jaap]

I just don't believe it... people getting upset and start insulting each other over f***ing cush drives!

[dlaing]

Oh-oh. I reckon this means you'll be pulling your cush drive apart again to fill in the holes you drilled, Dave.

 

Since it'd be quite a chore to match the original rubber-based compound that was no doubt swept up off the floor after you drilled your blocks, and stuff the drill shavings back in (let alone get it to say stuffed in there), you could fill in the holes with something with less hysteresis than the rubber blocks themselves for a truly composite solution! Steel rods would be convenient to cut to shape and drive in. No hysteresis a-tall there. Wooden dowels would be easier to cut. Not much hysteresis there either. You could even pour a 2-part urethane compound of known lower hysteresis in the holes! Now this would seem to satisfy that burning, seething obsession you've had with urethane, and at the same time fulfill the seemingly still unfulfilled desire you've had to pursue "better", more "advanced" materials science on your cush drive for -- how long's it been now? A year? 2 years?

 

Please do keep us apprised.

 

"Better living" through Junk Science

In an earlier post I described how I drilled only one drill hole through the radius of the deceleration cush pies in such a way that it formed an air cushion. While only slightly adding to the quantity of hysteresis over an undrilled bushing, the air cushion should have an excellent quality of hysteresis.

I only did this in the direction of deceleration as I did not want to risk creating a bottoming out condition during acceleration.

Thanks to Troy and Ryland, we have a better idea of what forces the bushings might face.

[Skeeve]

Now that you've mentioned it, I'm truly sincere in asking this question now. Can you either quantify or qualify wot "superior performance [in terms of providing the "proper" level of cush w/o having to modify it]" would mean to you, and explain how this would improve your life, and/or that of your Guzzi?

 

Enquiring minds. . . (well, you know)

 

Well Ratch', I'll try:

We know that neoprene [general use "rubber"] compounds tend to alter their attributes significantly over time as they age and oxidize, so a material generally known to exhibit less of this trait [as in urethanes] would be nice.

 

As far as "proper" level of cush goes, since it has been established by those more expert than I that by drilling the stock rubber wedges, the drivetrain will last longer and provide a more agreeable ride, then something approaching this level of pliability without the necessity of providing extra aeration would seem to be ideal.

 

Thirdly, a compound that exhibits less hysteresis, ie, more perfect elasticity, would mean that the energy absorbed during the power pulse would be more completely recaptured during periods of [for lack of better phrase] "slack" time, ergo, better [altho' probably immeasurable] efficiency. [but let's not forget that the lower heat levels generated would likely beneficially affect the consistency & longevity, even if the efficiency delta is too small to measure!]

 

And let's not ignore longevity: all these attributes combined into a product that has to be changed every time you have the rear tire off still wouldn't interest me: I just don't want to have to shell out for it more than once every 100,000 miles!

 

Now, this is a LOT of cake to both "have" & "eat" it too! But since in the case of some "ideal cush drive" having it is eating it, in the sense that it is something used in the having thereof, yet is not used up in the process [unlike cake! ]

 

Does any of that make sense? Probably not, & for that I'm truly sorry!

[Guest ratchethack]

. . .[sigh]. . . I try so very very very very hard to understand -- yet understanding itself often seems so mercurial hereabouts. So rare. So fleeting. Etherial, even. . . Sorta like trying to capture butterfly farts and stuff 'em in a bottle. . .

 

Hm. Now let me see if I've got this straight:

. . .I'll assume [that] we ideally should pursue less, not more hysteresis.

I drilled only one drill hole. . .While only slightly adding to the quantity of hysteresis over an undrilled bushing, the air cushion should have an excellent quality of hysteresis.

So less is clearly good. And yet, wot you did was go for more, because more was actually less in the decelleration blocks? Does this mean that for the acceleration blocks, the thing to do is go for less, because less is actually more ??

 

Doesn't this mean that instead of drilling them, we should actually be stiffening up our drive blocks by inserting steel or wood rods??

 

Or is it possible that by drilling only one hole, as you did, that since the air cushion "should have" such "an excellent quality of hysteresis", that you actually decreased the hysteresis of your blocks by providing an air cushion, and the air cushion provides less hysteresis than the undrilled block -- much as adding steel or wood rod would do?!

 

Is this Advanced Engineering Logic 568? I never studied Logic at Doctorate level. Sounds like this must've come out o' a graduate course f'er sure.

[Guest ratchethack]

We know that neoprene [general use "rubber"] compounds tend to alter their attributes significantly over time as they age and oxidize, so a material generally known to exhibit less of this trait [as in urethanes] would be nice.

Thanks for takin' a whack, Skeeve.

 

I won't repeat my well-supported and oft-repeated observation again that "rubber" is not a monolithic material, but as in the case of cush drives and tires, rather a highly complex, highly engineered material, which can exhibit a wide spectrum of properties, including exceptional longevity and resistance to oxidation and resistance to changing properties over time. -- Oops. Too late. I did it anyway.

 

If there were one example -- anywhere -- of a Guzzi cush drive known to have suffered loss of original properties over time, I'd be interested in studying it! Upon consistent, multiple findings of such evidence, I'd hasten to concede your point. But I b'lieve the fact is that we have no such evidence (not one known example) in the wide wide world o' Guzzi's -- and that wide wide world o' Guzzi's includes the multi-decade experience of many Pro's who've chimed in on this -- at least some were inclined to do so, until the needle on the silly meter started bouncin' off the max peg a long ways back.

 

I reckon wot most o' this boils down to is "go with wot's proven to work -- especially when there ain't any known shortcomings" vs. wot so many o' those without any experience or knowledge in such an esoteric, and highly engineered environment wotsoever figure "should be better".

 

But so much to do about waaaaaaaaaaaaaay too little has been soooooooooooo much fun here, why stop now?

 

Frickin' amazin', ain't it?

[Admin Jaap]

I reckon wot most o' this boils down to is "go with wot's proven to work -- especially when there ain't any known shortcomings" vs. wot so many o' those without any experience or knowledge in such an esoteric, and highly engineered environment wotsoever figure "should be better".

You're soooooooooo right here.

But so much to do about waaaaaaaaaaaaaay too little has been soooooooooooo much fun here, why stop now?

Plenty reasons; boring others to death and wasting bandwidth are just two

Frickin' amazin', ain't it?

No

 

The funny thing is, you all now where this discussion is going to end and yet you persist in going on. FWIW, when this thread gets closed, and you don't have to be a psychic to figure out why, I can't even be bothered putting it in the archive...

[dlaing]

. . .[sigh]. . . I try so very very very very hard to understand -- yet understanding itself often seems so mercurial hereabouts. So rare. So fleeting. Etherial, even. . . Sorta like trying to capture butterfly farts and stuff 'em in a bottle. . .

 

Hm. Now let me see if I've got this straight:

 

 

So less is clearly good. And yet, wot you did was go for more, because more was actually less in the decelleration blocks? Does this mean that for the acceleration blocks, the thing to do is go for less, because less is actually more ??

Less hysteresis appears that it could improve things for the reasons Skeeve mentioned.

Drilling the deceleration bushings was a compromise to soften the cush, and not much was lost, because I traded quantity of hysteresis for quality, via an air cushion/dampener.

 

Doesn't this mean that instead of drilling them, we should actually be stiffening up our drive blocks by inserting steel or wood rods??

No. Something like superballs or springs, but not so much that you get pogo'ing.

 

Or is it possible that by drilling only one hole, as you did, that since the air cushion "should have" such "an excellent quality of hysteresis", that you actually decreased the hysteresis of your blocks by providing an air cushion, and the air cushion provides less hysteresis than the undrilled block -- much as adding steel or wood rod would do?!

 

Is this Advanced Engineering Logic 568? I never studied Logic at Doctorate level. Sounds like this must've come out o' a graduate course f'er sure.

No, it would not be like adding steel or wood.

I suppose it is possibly lessening hysteresis by creating an air cushion, but overall it is making it softer, and I presume the air will leak out creating a dampening effect and thus more hysteresis.

Are we all on the same page when it comes to defining hysteresis?

To my mind, in over-simplified terms it similar to dampening.

Things with high hysteresis are things that absorb energy, but return little of it, like a Tempurpedic mattress, sorbothane shoe inserts, a gel saddle insert, a polyester fill stuffed pillow.

Thinks with lower hysteresis would comparatively be a Spring mattress, Nike Air running shoes, a spring saddle, an inflatable pillow.

Perhaps we ideally need a two stage bushing, with the first stage soft and high hysteresis and the second stage with low hysteresis, but firm.

Sorbothane and progressive springs???

Nike air bubbles and Dr. Scholl's Gel inserts?

Ideally springs and hydraulic dampers, but that is getting too elaborate.

H8Chains had some ideas.

[dlaing]

If there were one example -- anywhere -- of a Guzzi cush drive known to have suffered loss of original properties over time, I'd be interested in studying it!

As I mentioned in the other thread, my V65 cush suffered a loss of original properties.

But it is not available for studying.