Cush Drive

[Guest Nogbad]

Given that the cush drive is centred in the wheel by the spindle, bearings and spacers, why have I seen recommendations that it be lubricated?

 

Rubber to metal contact does not require lubrication, and indeed, the rubber blocks are likely to squirm less if they have a high friction coefficient with their corresponding metal vanes. There should be no metal to metal contact if the bearings are good, and the spacers the right lengths.

 

I consider a good anti-gall / seize compound essential on the metal to metal spline, but the rubber to metal drive should best be dry.

 

Lets hear your arguments!

[Paul Minnaert]

The rubber is theated real bad in there, so compressed and expanded under force. That means also moving along the metal faces. To make sure it doen't wear, I think they recommend grease.

[belfastguzzi]

Since putting my wheel back with everything greased, including the cush rubbers, I have been constantly wiping grease off the back wheel. So a lot of it just seems to be getting flung out, which isn't great.

[txrider]

I used a rubber lubricant called Syl-Glide during the take-it-apart-and-look-at-it new bike ritual I usually follow. As for why, I'm a lubrication junkie and it just looked like the thing to do. Plus, upon disassembly I found some rubber bits in the cavities and thought this might minimize wear of the rubber blocks.

[jrt]

A little lube will help reduce abrasion of either the aluminum or the rubber as well as keep the rubber from drying out as quickly.

[Guest ratchethack]

I use grease sparingly on the cush drive rubbers. If you drill holes in 'em as some have often done (myself included) to loosen up and improve the action of the notoriously stiff cush drive, the holes will "store" a little bit of grease and release it over the miles - very nice. But my take is that there's a more important part to pay attention to. I made sure to coat both bearing surfaces of the cush drive collar, which has a helical groove machined into it to retain grease (it's yet another metal-to-metal "low-rotation" joint that was obviously designed for grease that comes dry from Mandello). On the first ride afterward, mine threw out a little on the rim. After that it's been just peachy. I like boat trailer wheel bearing grease for this kind of application, as it has a high retention factor and resists water intrusion.

 

EDIT: I neglected to mention my take on the "Why lube the rubber?" thing. When I was last inside my cush drive it was very evidently the first time it had been open in 22K miles since new. A considerable amount of rust had developed, evidently from water coming in contact with bare steel in the drive collar - but also, and most significantly, from the large surface area of the webbed forging that retains the rubber wedges, which, if without any lubrication, is always rubbed bare and bright by the rubber blocks. I cleaned it all out and used a phosphoric acid-based oxide dissolver and penetrant. The progression of rust in this large area will be greatly slowed with a light coating of grease. My real concern with the rust in there is that it literally piles up and moves around, acting like grinding compound. I could literally pour it out. Over time this will open up the tolerance between the webbed drive hub and the collar. This isn't a critical tolerance fit here, but I consider it something worthy of attention at every other tire change or so - just to keep my baby "in her prime".

[Guest MikeC]

Hey all,

 

What is the procedure for getting to the cush drive rubbers.

 

Anyone have a cut-away drawing to post with procedure.

 

Thanks,

 

Mike

[Guest ratchethack]

Mike, someone posted a nice exploded view of hubs here recently for a few different year bikes, but you don't need it for servicing the cush drive and/or lubing the cush drive collar/sleeve. The wedge-shaped rubber blocks are behind the "pie plate" cover on the hub. The pie plate is visible once you separate the wheel from the bevel box by sliding it off the hub splines. The plate is held in place with 8 button-head allen screws (5 mm I think, but don't know the length, sorry), cemented in place at Mandello with some godawful powerful threadlocker. Whatever this stuff is, it's not actually solid, it's more like bubble-gum at 0 degrees Celsius. In any case, you're gonna have to use extraordinary means to get them out, as your allen wrench will be useless. Txrider slotted the heads with a Dremel tool and then used a straight blade screwdriver. I used a cold-chisel to get a bite on the periphery of each one and hammered them around until they came out. If you have a set of stainless replacement allen screws (button-head not necessary) ahead of time for replacement in your shop inventory, it's a relatively straightforward, but somewhat tedious job.

[txrider]

Mike, someone posted a nice exploded view of hubs here recently for a few different year bikes, but you don't need it for servicing the cush drive and/or lubing the cush drive collar/sleeve.  The wedge-shaped rubber blocks are behind the "pie plate" cover on the hub.  The pie plate is visible once you separate the wheel from the bevel box by sliding it off the hub splines.  The plate is held in place with 8 button-head allen screws (5 mm I think, but don't know the length, sorry), cemented in place at Mandello with some godawful powerful threadlocker.    Whatever this stuff is, it's not actually solid, it's more like bubble-gum at 0 degrees Centigrade.    In any case, you're gonna have to use extraordinary means to get them out, as your allen wrench will be useless.  Txrider slotted the heads with a Dremel tool and then used a straight blade screwdriver.  I used a cold-chisel to get a bite on the periphery of each one and hammered them around until they came out.  If you have a set of stainless replacement allen screws (button-head not necessary) ahead of time for replacement in your shop inventory, it's a relatively straightforward, but somewhat tedious job.

53630[/snapback]

 

Second that on removal of the 5mm cover screws. And thanks Ratchet, for the mention. Also, I used a hand-impact tool which made the difference once the slots were cut. Of course I had to replace those screws.

[Guest MikeC]

Thanks for update guys.

 

Looks to be pretty straight forward. I have a hand impact driver. I'll try that first with the allen sockets next time the rear wheel is off.

 

Does anyone know if the procedure is the same for a 2002 Califonia Special Sport. If I recall correctly last time I had the rear tire off on that bike I remember seeing a big retaining clip not screws.

 

Mike

[Guest bshpilot]

good lord in all my years of motorcyclin' ive NEVER heard of lubricating a cush drive.

 

and why on earth would it rust if its alum. !?!

 

ive never lubed a cush drive & ive NEVER seen a problem related to cush drive failure

[Guest ratchethack]

good lord in all my years of motorcyclin' ive NEVER heard of lubricating a cush drive.

 

and why on earth would it rust if its alum. !?!

 

ive never lubed a cush drive & ive NEVER seen a problem related to cush drive failure

53665[/snapback]

The center part of the cush drive is forged steel. It's a large webbed drive plate that retains the rubber wedges with a lot of surface area open to rust. You oughta take a look at yours sometime, you might be surprised at what you find.

 

I doubt if a cush drive could ever have a failure of a catastrophic nature, but I've heard of them freezing up solid from rust inside the collar (steel on steel and dry from the factory). Without attention, if water gets in there, the operation of the cush drive seems to degrade slowly over time until there's no "cush" left... Without the shock-absorbing cushion, the trans, splines, and UJ's will take all the shock and deteriorate faster, and shifting will feel progressively "clunkier".

[Guest bshpilot]

The center part of the cush drive is forged steel.  It's a large webbed drive plate that retains the rubber wedges with a lot of surface area open to rust.  You oughta take a look at yours sometime, you might be surprised at what you find.

 

I doubt if a cush drive could ever have a failure of a catastrophic nature, but I've heard of them freezing up solid from rust inside the collar (steel on steel and dry from the factory).  Without attention, if water gets in there, the operation of the cush drive seems to degrade slowly over time until there's no "cush" left...   Without the shock-absorbing cushion, the trans and UJ's will take all the shock and deteriorate faster, and shifting will feel progressively "clunkier".

53668[/snapback]

 

 

ok ill agree w/ you here...to clarify "cush drive" at least in my mind i meant

the rubber(s) that actually perform the "cush" metal on metal and dis-simular

metals can certainly benefit from lube.

 

but i saw folks discussing the virtues of lube on the rubber "cush"

[belfastguzzi]

Guzziology has a section on 'Lubing big-twin rubber cush drives'. He talks about problems of 'stuck cush drives' in bikes that came from the factory unlubricated (particularly in the mid 80's).

 

Because of this I lubed everything, including the rubbers, but I suppose it's possible that he was actually talking about the metal parts only, as folks here are saying. Makes sense.

 

He also goes on to say that it has been suggested that even properly lubed cush drives lack enough movement to effectively perform their job. He says that Teo Lamers take out half the rubber inserts and additionaly drill three holes in the remaining inserts, so they compress more. Apparently this dramatically increases the life of driveline splines and U-joints.

[Guest bshpilot]

Because of this I lubed everything, including the rubbers, but I suppose it's possible that he was actually talking about the metal parts only, as folks here are saying. Makes sense.

 

He also goes on to say that it has been suggested that even properly lubed cush drives lack enough movement to effectively perform their job. He says that Teo Lamers take out half the rubber inserts and additionaly drill three holes in the remaining inserts, so they compress more. Apparently this dramatically increases the life of driveline splines and U-joints.

53697[/snapback]

 

i guess a word of caution should be mentioned...certainly SOME rubber may NOT respond favorably to "oils/solvents" etc.

 

i thought the whole idea of a cush drive was to reduct the harshness in the

drive line (at the rear obviously)...it seems to me removing some of the

rubber might induce more "slop" and there for potential too much movement

in the drive line hardware....id be afraid it might cause additional wear in

STIFF components of the drive line...

 

before i get flamed too much here let me say that my experiance w/

cush drives is related to DIRECT DRIVE (chain/sprocket) set ups...my

bmw-LT (stands for light truck) and other drive shaft bikes ive worked on

dont even HAVE a cush drive.