How Difficult Is the Spline Lube?

[PickledBrick]

I have the 90' k75rt in blue with 50,000 miles. Just purchased. How difficult is the spline lube job ? I intend to change all fluids, fairing, shock and headlight.

[Laitch]

It's mostly a nut-and-bolt operation. You'll need tools, patience and a workplace with room enough for the rear drive, swing arm and transmission. You'll also may need Liquid Wrench and a heat gun. It's all broken down by Chris Harris here.

[frankenduck]

It's mostly a nut-and-bolt operation. You'll need tools, patience and a workplace with room enough for the rear drive, swing arm and transmission. You'll also may need Liquid Wrench and a heat gun. It's all broken down by Chris Harris in this video but you don't need a hydraulic lift; sawhorses will do.

I've done dozens of clutch spline lubes and never had any need for either Liquid Wrench or a heat gun.

And you only need one sawhorse.

[Laitch]

 

[Laitch]

And you only need one sawhorse.

I believe Michaelovich has proven that a surface of block pavers is a more elegant and effective medium for dismantling a Brick than working while seated in a quarter-lotus position on gravel, and having somebody just hold the rest of the moto while you work not only saves lumber but provides companionship. Furthermore, use of a dog's tail to remove dust and other particles from the work area is also useful. There are many alternatives, Pickled Brick. 

[alexg]

Not trying to highjack the thread, but ...
My bike has a little over 15k miles, but it is still 29 yrs old. Do I need to do the lubing of the clutch spline? I have done the rear spline only when I bought it 5 years and 5k miles ago.

Thanks for the suggestions.

[Laitch]

Do I need to do the lubing of the clutch spline? I have done the rear spline only when I bought it 5 years and 5k miles ago.

Concerning shaft spline maintenance, attached is an extract from BMW's service checklist. 40K is what I follow for the transmission input shaft; I clean and re-lube the rear drive splines every tire change.

[The Mighty Gryphon]

Clutch splines can be lubed by supporting the transmission on a pair of the longest M8 bolts you can find.  Mine are about 125mm long. 

Put one in on each side of the transmission so you can slide it back from the engine far enough to to see the output shaft splines.  About an inch and a half is good.  Then you can use a metal handled parts brush stuck on the shaft of a screwdriver or a 1/4" dowel to reach in and put the lube on the splines.  There's no need to completely remove the transmission if there are no oil leaks at the o-ring or the rear seal.

[frankenduck]

Not trying to highjack the thread, but ...
My bike has a little over 15k miles, but it is still 29 yrs old. Do I need to do the lubing of the clutch spline? I have done the rear spline only when I bought it 5 years and 5k miles ago.

Thanks for the suggestions.

I would. I clutch spline lube every new-to-me K bike right when I purchase it.

If you start getting false neutrals shifting from 4>3 and/or 3>2 then that it usually a symptom that the clutch splines are dry and wearing.  If you're experiencing that then definitely lube the clutch splines as soon as is convenient.

[frankenduck]

Concerning shaft spline maintenance, attached is an extract from BMW's service checklist. 40K is what I follow for the transmission input shaft; I clean and re-lube the rear drive splines every tire change.

My 1990 K75RT completely stripped the clutch splines at 36K. (Conveniently stranding me 1,200 miles from home.)

This was back when I was a Knoob and did not know that the downshifting false neutrals I started getting at about 25K were a symptom of clutch splines needing lubrication.

On the bright side, I did get 11K miles from when they started getting "dry" until they completely stripped.

[alexg]

Thanks for all the replies. Will consider doing a bike-wide spline lube in the winter. Even though the miles are not there, cannot believe the spline grease would not have hardened in 30 years, decreasing the lubrication performance.

[milq]

And you only need one sawhorse.

I don't fold up like that!

[frankenduck]

Thanks for all the replies. Will consider doing a bike-wide spline lube in the winter. Even though the miles are not there, cannot believe the spline grease would not have hardened in 30 years, decreasing the lubrication performance.

If you are getting false neutrals when downshifting than I'd do it sooner rather than later.

[alexg]

For now it is working flawlessly. Thanks !

[Laitch]

Even though the miles are not there, cannot believe the spline grease would not have hardened in 30 years, decreasing the lubrication performance.

Molybdenum is classified as a dry lubricant. The paste containing it is used to carry it onto the surfaces of the splines where the molybdenum in the paste then bonds with the metal and fills imperfections in its surfaces as the the shafts start engaging during engine operation. The carrier paste can dissipate. Moly's lifespan as a lubricant in this application doesn’t depend upon the length of time since it was applied but rather the length of time that the surfaces to which it has bonded have been engaged in operation with each other. In Bricks, that length of time is measured in miles of operation.

[alexg]

Good, then maybe in 2024 I will lube those splines.!

[Laitch]

Good, then maybe in 2024 I will lube those splines.!

We'll leave the light on for you.