Making a Cushier Cush Drive

[Pierre]

Please, Jaap?? You gave the old codger icon on my last request. Perhaps you would be so good as to follow-up with GJ's hint?

BFG, I think a "tougue in cheek" emoticon after one of your twisted posts would be redundant to all here, save one.

[dlaing]

Just for clarification, this is what I think Greg said about where he has found the wear. I can't visualize this interface as I've only had my clutch exposed once. I suspect this is an area that will tolerate zero lubrication.

I hope Greg or someone who has seen more than a couple of Guzzi splines could confirm your clarification.

Greg said,"Only in extreem circumstances. Bad wheel bearings or continual cycles of rusting and scraping off of rust are what most often takes out the wheel splines."

So, does that mean that in less extreme circumstances that the clutch splines going would be more common?

Why do they use springs instead of rubber at the clutch?

I would guess greater impact absorbtion within the space available, heat resistance, and a greater desire for durability out-weighed the natural damping of rubber.

 

I hope Greg or someone who has seen more than a couple of Guzzi splines could confirm your clarification.

Greg said,"Only in extreem circumstances. Bad wheel bearings or continual cycles of rusting and scraping off of rust are what most often takes out the wheel splines."

So, does that mean that in less extreme circumstances that the clutch splines going would be more common?

Why do they use springs instead of rubber at the clutch?

I would guess greater impact absorbtion within the space available, heat resistance, and a greater desire for durability out-weighed the natural damping of rubber.

Who cares!?! Just ride the thing!!!

[Guest ratchethack]

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!!!

Dave. There've been at least 3 Pro's on this thread who've weighed in on the nature of driveline slack and/or cush drives. Each of them represent both personal livlihoods and professional businesses that are to a large degree driven by the credibility and the reputation they put on the line every time they make a public statement in their field of expertise -- either verbal, or at even higher personal risk to themselves, in print -- such as they've done here. I, for one, am deeply grateful to each one of them for the generosity of their efforts and for taking the risk of making their knowledge so freely available to us. They speak from professional experience, knowing that they open themselves up to all manner of wacky challenges from every wayward imbecile and fool with no professional reputation to lose, with the understanding that they're not necessarily very well positioned to respond to or defend themselves against abuse and worse on a public Forum. I have an abiding respect and appreciation for the HIGH VALUE of their knowledge, which never comes cheap, and their selfless nature, which is an increasing rarity.

 

If it doesn't yet occur to you, you ought to know that you've been treating them, their wisdom, and their experience worse than if it had no value at all. You've essentially called every one of them liars with your statements above, and others.

 

As for me, you've called me a liar and said that my arguments here are irrational. But then I'm merely a shade-tree DIY home shop mechanic -- not "in the trade", or even close -- who happens to have quite extensively serviced and rebuilt my own vehicles, including end-to-end drivelines on a variety of vehicles (FWD, RWD, 4WD cars and trucks, as well as a dozen motorcycles, of which I've rebuilt many, and did 100% of the service on all since the age of 16). Let's just say that in all of my time under vehicles doing clutch service and replacement, transfer case replacement, transmission rebuilding, U-joint replacement, driveshaft balancing and replacement, CV joint replacement, bearings, solid axle and transaxle replacement, etc., that I never managed to gain the faintest understanding of wot driveline slack means to those in the trades who work on these things for a living. We'll just say that not a bit of my experience counts for any knowledge or qualifications wotsoever here, and disregard it because it's never been my profession.

 

What I DO have, since I'm NOT "in the trade" is the ability to speak much more frankly in ways that the Pro's can't, but more'n likely wish they could. I sincerely gotta admire their restraint here, but this doesn't mean I need to follow suit!

 

Now then. What gives you the notion that you speak from any position from which to not only IGNORE, but to CONTRADICT any of the Pro's on this thread whose profession THIS IS, and has been for decades, and to infer that their hard-earned professional opinions and knowledge are all wrong, and that your silly ideas that often (this thread, for example) clearly don't have much, if any, experience behind them are right?!

 

I've been in neighborhoods of New York and New Jersey (LA and Detroit too, for that matter) where this kind of publicly expressed disrespect for the wrong Professionals can get you whacked.

 

What makes you think you can make up your own definitions for principles that are clearly entirely foreign to you out of thin air (ref. your two statements above), in a field of knowledge with which you clearly have very little experience -- if any whatsoever?! Do you imagine that you can just let your imagination run wild and broadcast your dreamt-up, deluded versions of reality on a public Technical Forum as if they were based on SUPERIOR industry knowledge to that of the Pro's, and not expect that your empty, baseless folly will be challenged by people who know wot they're talking about??

 

Or is this simply your "Need for grief" making itself public??

 

Enquiring minds, again rapt in wonder and disbelief (well, you know). . .

[pete roper]

I hope Greg or someone who has seen more than a couple of Guzzi splines could confirm your clarification.

Greg said,"Only in extreem circumstances. Bad wheel bearings or continual cycles of rusting and scraping off of rust are what most often takes out the wheel splines."

So, does that mean that in less extreme circumstances that the clutch splines going would be more common?

Why do they use springs instead of rubber at the clutch?

I would guess greater impact absorbtion within the space available, heat resistance, and a greater desire for durability out-weighed the natural damping of rubber.

 

 

Single plate clutches tend to use anti-rattle springs, (this, oddly enough, is why Scuras, Rosso Mandellos etc with the single plate clutch rattle when the clutch is disengaged!) these are one of the components in the clutch plate. The twin plate clutch has no anti-rattle devices. The only springs in there are the actual clutch pressure springs which sit between the flywheel and the pressure plate, you couldn't replace them with rubber or anything else.

 

One place where spline wear does very often occur is withing the clutch/flywheel assembley. With a twin plate unit when you engage the clutch, (Pull in the lever.) it de-compresses the friction and intermediate plates. The friction plates are splined to the input hub of the gearbox, the intermediate plate is splined into the flywheel. As the flywheel accelerates and decellerates between power strokes the plates will thrash bavk and forth on their splines and this will eventually cause *stepping* and wear on the splines leading to poor engagement and disengagement of the clutch and in extreme cases 'Creep' when the clutch is engaged at a standstill.

 

This thrashing is only really a problem at low engine speeds and is due to the 270/430 degree firing order of the V twin motor. For this reason it is unwise to set your idle speed low, (Guzzi recommend 1200RPM for a reason.) and likewise it is not good for the clutch componentry to sit at idle with the clutch pulled in. Another completely unrelated reason to keep the idle speed up is of course that the lower the crank speed the lower the oil pump speed. Set the idle really low and you may, in extreme circumstances, not have an adequate oil supply at idle to prevent boundary lubrication.

 

pete

[dlaing]

 

I've been in neighborhoods of New York and New Jersey (LA and Detroit too, for that matter) where this kind of publicly expressed disrespect for the wrong Professionals can get you whacked.

 

That sounds like a thread.

[dlaing]

snip

Thanks.

That was truly enlightening.

But regarding what Ratchet just went on about.

Sorry, but I am not sorry for suggesting that Polyurethane be used in place of rubber.

If you can't handle me suggesting polyurethane, then I guess you will have to hire hit men to take me out, or maybe you can do it when you pick up your Scura.

I'll even treat you for dinner and discuss politics with you before you whack me.

[dlaing]

snip

Same thing I said to Pete, applies to you.

I hope and suspect that you are big enough to take my disagreements with a few of your statements.

Your posts have brought great life to this forum, and saved countless engines.

Your knowledge is greatly appreciated, but if you think I am harassing you by suggesting fewer or smaller holes seems safer and urethane would be a better material, than tough.

I posted the suggestion of urethane not to undermine you, but because I think it is a good idea.

Ratchet has had it in for me ever since the global warming thread.

Now, he goes around dumping fuel around every flame.

I am not going to let Ratchet bully me around and censor me.

Both Pete's and Greg's experience and skill with motorcycles is well beyond mine and the reading audience is fully aware of it.

But if anybody, expert or not thinks the urethane is a bad idea, I am going argue.

[dlaing]

Dave is confusing slack / free play (an air gap) and cushion (a rubber or mechanical spring, regardlesss of how soft) Making it softer doesn't increase slack it just...makes it softer.

I suppose you are right.

When I think of slack like rope slack, you are correct.

My apologies.

From my perspective as a rider, the springs flexing in the clutch and rubber compressing in the cush drive are part of the overall driveline slack. But I see now from the merriam webster perspective, you are correct.

I think we need a word for slack plus cushion.

But I started arguing this when the word was drivetrain lash. Until I see a good definition of lash, I am sticking to the definition, lash equals slack or freeplay plus cushion and or stretch. BAA, YMMV and if you think of lash in terms of valve lash, then it is like freeplay or slack. I think of driveline lash as what the rider experiences dynamically in the sense of it lashes back and forth when decellerating. But it is all much ado about nothing.

If you define lash as slack or freeplay, I am not sure why one would even mention that drilling rubbers does not increase lash. Of course it does not. Maybe I got baited in for a battle of word defining. Oh well.

My only point is that making it cushier increases the slack plus cushion factor, which some may find undesirable.

I don't know if it will make the bike less controlled as the lack of jerkiness will help control, but the longer movement (that I am not allowed to call lash) may make the throttle control vaguer.

[g.forrest]

yet another UFT.... NOW does anyone have any definitive info on this climate change..........it may take up the slack.

rubber shackle bushings polyurethane as shackle bushings..

rubber with drilled holes..

[dlaing]

yet another UFT.... NOW does anyone have any definitive info on this climate change..........it may take up the slack.

rubber shackle bushings polyurethane as shackle bushings..

rubber with drilled holes..

Global Warming would have to get real hot to speed up the decay on all the polyurethane in the land fills.

Everybody please forget that I ever suggested polyurethane as it is clearly more of an environmental hazard than rubber is.

Swiss cheesed rubber will probably decay in less than 500 years while polyurethane may take ten or twenty times longer.

Use rubber and swiss cheese it, please.

BTW why do you prefer rubber to urethane?

Can't you get the urethane in black?

Can't you get the urethane in the proper firmness?

Are you a stuck in the mud traditionalist?

Or do you just like paying more for rubber because you can?

Why did you turn Ratchet against me you evil man?

[g.forrest]

now seriously! just going from experience with poly versus rubber in shackle bushings in land cruisers. the rubbers were around 25% of the cost, and the polys were lucky to get twice the milage, but the rubbers were easier to replace, made for a smoother and quiter ride! the rubbers tended to wear more than compress and distort so were easier to remove. so on the whole it was better for me to replace rubber every year than poly every two. but than again this is just my experience as a simple country boy with shithouse keyboard skills. yours truly gazza.

ps. the rubbers did only come in black!

[Greg Field]

My experience with Jeeps tracks with Mr. Forrests's: Urethane used in bushings is significantly stiffer than rubber and actually makes ride feel harsher because of this extra stiffness. Perhaps there is a softer urethane? If so, it might be a good material for the cush rubbers. Certainly, no harm in looking at other materials.

[g.forrest]

yes'' the poly compacts doesn't cush very well compared to rubber! and distorts to the point it is noticably worse with time. ie. it performs worse with impact pressures than rubber.. IMEX

[dlaing]

yes'' the poly compacts doesn't cush very well compared to rubber! and distorts to the point it is noticably worse with time. ie. it performs worse with impact pressures than rubber.. IMEX

Interesting. I have thought that urethane behaved better with impact pressures than rubber.

I'll have to investigate further, but so far all I have found is high ratings for urethane in just about every category with better aging, memory, and tensile strength than nitrile.

The benefits that I forsee, are if it is made a little softer than the rubber, it will be a little cushier. But if making it softer significantly reduces its ability to handle impact and high pressures, that would not be a good thing.

Do you have a resource that shows the comparative resistance to impact pressures?

I found this chart for seal materials

http://www.rotamic.co.in/seal_materials.html

they don't cover impact resistance, but the urethane appears to be superior in just about every way but temperature resistance.

I imagine high heat from friction would be bad, so greasing the urethane would be a good idea.

[Guest ratchethack]

. . . so far all I have found is high ratings for urethane in just about every category with better aging, memory, and tensile strength than nitrile. . . .

PLEASE do it, Dave! I'm begging you. Just get it over with, f'er cryin' out loud.

 

I figure if I give you exactly this kinda encouragement, this is all you'll need to do it -- just to prove how WRONG myself, and everyone else is, o' course.

 

It's also obviously the ONLY way you're going to exorcise this particular personal demon, which apparently flew up to your window the day Greg posted this thread. You've obviously welcomed it in with open arms and a seriously naïve mind. Ever read Salem's Lot by Stephen King? Little Danny Glick just as naïvely did the same thing you're doing now when the demon appeared at his window. I highly recommend the book. It's a perfect metaphor for wot you've obviously well begun to commit y'erself to do here. You could read it in a tiny fraction of the time it would take to, er, set up and shut down your junk science project, you could deduce the results beforehand from wot you learn in the book, and not have any clean-up afterward. . .

 

Naaaah. That's not happenin'. . .

 

[. . . sigh . . .] So after it's taken six months or so to suck up a couple o' quarts o' y'er life blood in time and effort, with the rear wheel off the Guzzi a half-dozen times, and you finally get sick of doing it over and over (by sometime this Winter oughtta be about right), you can scrape out the mess in your cush drive, drill the rubber blocks, put 'em back in there just like Greg, myself, and everyone else who's done this for the last 40 years, and get on with your life. You might even get to actually ride your Guzzi then.

 

My recommendation for you, Dave, when you're mixing up your highly experimental urethane cocktails, is to just pretend that you're in 3rd grade Art class, and that you're mixing up nice, pretty molding compound to make a nice, pretty ornament for the dinner table on Kwanzaa Day. You can even put some nice, non-American, non-religious food coloring in there. Yeah. African Kwanzaa colors. Lovely!

 

By all means, be sure to take photo's and post 'em here.

 

Oh, and Dave -- you'd never forget Little Danny Glick. . . Do a search on him. He became a cult figure about 30 years back. . . Knowing wot happened to Danny would help you recognize garden variety demons at face value up-front -- the way most of us do. . .

 

Open the window. Open the window, Dave. Open the window, Dave. Open the window, Dave. Open the window, Dave. Open the window, Dave. Open the window, Dave. Open the window, Dave. Open the window, Dave.

 

Please! Let me in! It's OK, Dave, I'm your friend. *He* commands it!