Making a Cushier Cush Drive

[Guest ratchethack]

FWIW, over on WG they've been discussing the joys of dislodging rusted-solid cush drives via the progressively "bigger hammer" technique. Looks like they've got as many over there who've never given 'em a thought as we've got over here. . .

 

http://wildguzzi.com/forum/index.php?topic=13527.0

 

Dan Kalal posted this shot of his technique for persuading a drive plate to part company with the bearing carrier when it's rusted solid. Note that the only significant change over the years has evidently been a doubling of the number of screws it takes to get the retaining ring off. Thankfully, on V-11's, they also chose to threadlock 'em with Luigi's petrified tomato sauce just to make extra extra sure it wasn't going anywhere.

[richard100t]

You know it sure would be nice if there was a groove cut into either side of that drive plate. Something just big enough to get two nice flat blade screwdrivers to pry it open.

[Lamedog]

Hate to beat a terribly dead horse, but I performed Greg's modification about as he recommended. I had four screws that stripped, not two. The recommended practice of slotting, heating and driving with a punch worked as stated. Installed three drilled rubber and silicone-greased blocks. The change significantly reduced the amount of whack I sometimes get when I'm late rolling on the throttle in a corner. Seemed like fine advice and I still have three stock rubber blocks in case I ever want to go back.

I would recommend the change as a safe and low cost way for new forum members to acquaint themselves with the workings of the cush drive.

[Greg Field]

I'm glad it has worked for others but do not take any credit for the idea. I'm not sure who first did this or how I first heard of it. But, the point that it works was recently driven home, again. Micha, the service manager at Moto I, insisted I take for a ride a Coppa that he had recently tuned after reports that it was untunable. After tuning and a test ride, he described it as the smoothest and best mannered V11 he had ever ridden. Yes, the engine was smooth, but my comment when I got back from the ride was, "The cush drive's frozen solid. The driveline is very harsh." The difference between that one and mine was immediately noticeable. Take that for what it is worth.

[big J]

I simply cant believe that hydraulic drive hasnt been discussed yet.

 

Surely the simplest way to avoid all these problems would be to mount a small hydraulic pump on the gearbox output shaft and drive a motor within the rear hub.

Self lubricating too.And considerably lighter than that ring and pinion.

[Ryland3210]

I simply cant believe that hydraulic drive hasnt been discussed yet.

 

Surely the simplest way to avoid all these problems would be to mount a small hydraulic pump on the gearbox output shaft and drive a motor within the rear hub.

Self lubricating too.And considerably lighter than that ring and pinion.

 

The downside is less efficiency. For the heavier bikes, a simple 4 way valve would also provide reverse.

 

While we are at it, how about eliminating the transmission too, and replacing it with a variable displacement pump.

[Skeeve]

I simply cant believe that hydraulic drive hasnt been discussed yet.

 

Surely the simplest way to avoid all these problems would be to mount a small hydraulic pump on the gearbox output shaft and drive a motor within the rear hub.

Self lubricating too.And considerably lighter than that ring and pinion.

 

Lighter? You're forgetting all the mass of that working fluid. Also, regrettably, horribly inefficient [thus the general scarcity of hydraulic drive lines, even tho' they've been showing up periodically on "concept" bikes from various manufacturers since, what, the '70s?

 

Not much in the way of engine braking, either.

 

Let's face it, the best [in terms of a balance of efficiency, longevity & mass] driveline is an enclosed chain; Guzzi's driveshaft w/ the floating hub is probably the best choice for their longitudinal engine design. And of course, lower maintenance than open chains...

[Ryland3210]

Lighter? You're forgetting all the mass of that working fluid. Also, regrettably, horribly inefficient [thus the general scarcity of hydraulic drive lines, even tho' they've been showing up periodically on "concept" bikes from various manufacturers since, what, the '70s?

 

Not much in the way of engine braking, either.

 

Let's face it, the best [in terms of a balance of efficiency, longevity & mass] driveline is an enclosed chain; Guzzi's driveshaft w/ the floating hub is probably the best choice for their longitudinal engine design. And of course, lower maintenance than open chains...

 

The mass of the working fluid could be kept quite low compared to the mass of the typically steel pump and motor. Engine braking would remain, as the motor and pump reverse roles in deceleration. Open chains are far more maintenance free these days, with O-Ring varieties commonplace. I agree with all your other points. Also, there are the belt drives, also more efficient than gears, which are virtually maintenance free. If I had my way, my Guzzi would have a belt drive.

[richard100t]

The mass of the working fluid could be kept quite low compared to the mass of the typically steel pump and motor. Engine braking would remain, as the motor and pump reverse roles in deceleration. Open chains are far more maintenance free these days, with O-Ring varieties commonplace. I agree with all your other points. Also, there are the belt drives, also more efficient than gears, which are virtually maintenance free. If I had my way, my Guzzi would have a belt drive.

I agree with you about the belt drive.

That would shed probably 20lbs, low maintenance to boot.

I think that the shaft drive is a Guzzi "thing" so its probably going to stay.

[Guest ratchethack]

Ohlins and Yamaha jointly developed a lightweight hydraulic drive about 10 years back for the front end of the WR450F 2-Trac. Engine braking is much more significant with this design than with conventional chain drive alone.

 

Details (including photo's and description of hub and drive components) from Dec. '04 Australian Dirtbike Magazine here: <a href="http://www.allthingsmoto.com/forums/f-20/y...-trac-wr-18476/" target="_blank">http://www.allthingsmoto.com/forums/f-20/y...-trac-wr-18476/</a>

 

Considering that on the V-11 Guzzi, you'd be replacing a bevel drive that weighs 20 lbs., not to mention the shaft and U-joints that feed it, the weight of drive fluid would seem relatively negligible.

 

Could something like this be adapted to a V-11? Well, I reckon if it's possible to make a V-11 motor into a helicopter or put a Saturn V rocket motor underneath it , -- you can say anything's possible. . .

 

The question is -- is it even worth the effort of fantasizing about, if it obviously ain't either practical or economically feasible?

 

Oh-oh. . . Did I say, 'fantasize', and, 'ain't either practical or economically feasible??'

 

Where's Dave? This could set the man on fire!

 

Why let little things like "ain't either practical or economically feasible" get in the way of any excuse for a solid rocket booster launch free from the repressive confines of terra firma into full extra-terrestrial FANTASY/SPECULATION MODE?!

 

Why, it's merely another little twist on the infamous urethane cush drive idea -- and that's been good f'er 18 pages. . .

[dlaing]

So I finally popped open the cush drive.

I only had to chisel and impact hammer out one screw. <_>

Inside the friction disk was clearly greased, and Cracked! So, I should order a new one.

The core was greased. (interesting grooves)

Not a hint of rust.

The rubbers had some grease on them but it could have been fed from the greased core.

I pressed on the rubber with a screw driver and estimated the durometer at about 60-70A.

No I don't have a durometer, but it was harder than my motorcycle tire, and softer than a 75A skateboard wheel.

I wedged one in a door and it compressed very nicely. Probably about 50% compression with maybe one pound of force on the 30inch door.

Anybody want to calculate the foot pound of rear wheel torque and how much pressure it would exert on each rubber?

I imagine it will squish nicely without drilling.

I saw no reason to drill, but out of respect to all those that claim an improvement, I made a compromise and I drilled all the deceleration rubbers, but only one drill hole, 5/32", going from outer circumference of the pie towards the center, but not all the way through. This should provide a hair more movement when nearly locking up the rear tire and create a small 'air spring' / 'air damper'!!!!

If the rubber had been approaching 100A or even 90 durometers, then I would have considered a softer cush made of urethane, but there is no need as the rubber is soft enough, and is holding up fine. If it was around 80A, I would have drilled it more.

Anyway, I added some silicone grease to the rubbers and put mobile one synthetic grease on the core and on the friction disk.

Despite the previous lube from either the factory or the wise benevolence of my dealer who has not touched it in 30,000 miles, the friction disk appeared to be wearing into the metal plates, so lubing seemed to be the sensible thing to do.

I do think the friction disk's purpose is to dampen the cush, otherwise it should have been made of a bearing surface like nylon or bronze. As the rubbers are compressed, they expand, pressing the drive vane against the friction disk. Even lubed, it should function like a wet clutch. Simply brilliant!

But I am sure most of you will remain skeptical.

The next step is the test ride.

The drilling was very minimal, but it is now better lubed, so I may notice smoother downshifts, etc., but it may also be bouncier.

[Ryland3210]

Thanks for the update, Dave.

 

When I changed my wheel recently, I found a thin layer of a relatively slippery, dry, contact patch material on one mating surface. The mating aluminum surface had been polished, either during manufacturing or by the motion of the contact patch. I thought about greasing it, but changed my mind, once I realized that the dry material might have more static friction than a greased surface, but effectively zero viscous friction. I left it dry on purpose.

[Guest ratchethack]

I do think the friction disk's purpose is to dampen the cush, otherwise it should have been made of a bearing surface like nylon or bronze. As the rubbers are compressed, they expand, pressing the drive vane against the friction disk. Even lubed, it should function like a wet clutch. Simply brilliant!

Dave, In deference to your remarkable triumph of reason over folly here, I bear an olive branch.

 

First, I'd like to CONGRATULATE YOU for finally tackling a long-overdue task. It wasn't all that difficult after all, was it?

 

I b'lieve you're very fortunate that someone had greased the cush drive collar for you at some point.

 

I'd also like to CONGRATULATE YOU (Part II) for finally refusing to welcome the silly Urethane Cush Drive Demon in through your window! After all the discussion in this thread, it must've been one walloping, fearsome temptation for you to mix up and pour something awful and truly regrettable into your cush drive, and make a spectacular mess of it -- But in any case, it appears that when it actually came down to doing wot you'd been speculating about doing so enthusiastically, you SOMEHOW RESISTED THE TEMPTATION!! I'm sure that at least a few of us (myself included) are relieved that you didn't entertain THAT particular demon, despite the tenacity and the remarkable depth and breadth of your, um, speculation on it -- sight of your own cush drive then yet unseen. . .

 

NOW THEN, let's repeat from way back on Aug 8, when yet ANOTHER DEMON was seemingly floating outside your window and beckoning -- beckoning to you, ever so seductively. . .

 

(just like Little Danny Glick in the Stephen King novel, Salem's Lot. . .) Things that make you go, WHUVVVEDDEGGA!

 

I refer, of course, to THIS -- just to refresh your memory:

 

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!

 

May we kindly -- mercifully -- dispense with any more folly and confusion than absolutely necessary?!?!

Evidently, looking at the thing apart hasn't provided you with an understanding of its function after all. Dave, I'm begging you. Let this one go, too. Please . . . [sigh] . . .

I do think the friction disk's purpose is to dampen the cush, otherwise it should have been made of a bearing surface like nylon or bronze. As the rubbers are compressed, they expand, pressing the drive vane against the friction disk. Even lubed, it should function like a wet clutch. Simply brilliant!

But I am sure most of you will remain skeptical.

Yes, I know how hard it is for you to resist the Demons of Wild and False Speculation. . . But you've got to be STRONG, Dave! I just know you can do it. Look how you cast out the Urethane Cush Drive Demon! That one was nasty enough to keep you fully mesmerized for 18 pages and 5 months -- but it seems to've come mighty close to costing you years!

 

Open the window, Dave. Open the window. Open the window, Dave. Open the window. Open the window, Dave. Open the window. Open the window, Dave. Open the window. Open the window, Dave. Open the window. Open the window, Dave. Open the window. Open the window. He commands it. . .

[docc]

I'm only a little less baffled now. True, the ring appears to be a, say, fiber washer or 'fibre' gasket of sorts. Yet, there is no doubt friction as evidenced by the wear pattern etched in the "Plate With Gearing" (Shop Manual F10).

 

I did put a coat of moly on mine this last assembly. If you fail to do this you will miss out on the thousands of miles of black mess flung on your wheel and the precious concern of your riding companions. I've so earnestly reassured them that, "A Guzzi with no grease on the wheel is a Guzzi with no grease." ( I always say "greeze" just to squirrel the absurdity.

 

The whole cush drive concept (there is the one in the rear drive and the one in the gearbox) may smack of its own absurdity as we attempt to 'cush' the power-to-weight ratio of a P51 mustang.

 

Big bore Guzzis are about as cushy as a 7.62 NATO rifle.

[Ryland3210]

I'm only a little less baffled now. True, the ring appears to be a, say, fiber washer or 'fibre' gasket of sorts. Yet, there is no doubt friction as evidenced by the wear pattern etched in the "Plate With Gearing" (Shop Manual F10).

 

I did put a coat of moly on mine this last assembly. If you fail to do this you will miss out on the thousands of miles of black mess flung on your wheel and the precious concern of your riding companions. I've so earnestly reassured them that, "A Guzzi with no grease on the wheel is a Guzzi with no grease." ( I always say "greeze" just to squirrel the absurdity.

 

The whole cush drive concept (there is the one in the rear drive and the one in the gearbox) may smack of its own absurdity as we attempt to 'cush' the power-to-weight ratio of a P51 mustang.

 

Big bore Guzzis are about as cushy as a 7.62 NATO rifle.

 

In my case, the surface was polished smooth which is what I would expect with a fiber washer intended to be slippery. I'd worry about abrasion if there were any sign of it. As it was, I left it dry to avoid viscous friction.