Spline lube question

[Rockosmith]

I am seeing lots of discussions of rusty splines in the driveshaft/final drive connections.  Some even to the point of being inseparable.  I know that rust is not a good thing but is there normally any motion in that connection?  If that joint is rusted solid, is there any damage that is likely to result?  

[MikeB60]

@Bernie and I both saw significant rust in the driveshaft final drive u joint. You pose a good question and there is plenty of discussion on the issue on the advrider forum. It would have bugged the crap out of me so I cleaned it up and put a light coat of moly 60 on the splines. Plan is to check it at the next tire change.

[Cap]

51 minutes ago, Rockosmith said:

I am seeing lots of discussions of rusty splines in the driveshaft/final drive connections.  Some even to the point of being inseparable.  I know that rust is not a good thing but is there normally any motion in that connection?  If that joint is rusted solid, is there any damage that is likely to result?  

 

This is one of those religious arguments...  BMW does not include inspection of the final drive spline in their 12k major service for wetheads.  Speculation by some owners is that, as you say, there is no longitudinal motion of that joint after assembly, and thus no need for lubrication.  Also, removing and replacing the rubber boot requires some skill, and if done improperly might cause more damage than simply leaving it alone.

 

Personally, I think I am capable of removing and reinstalling the boot correctly, and I like to inspect the condition of the final drive joint.  So, I favor cleaning and lubricating the joint at the 12k major service interval.

 

Cap

[dirtrider]

1 hour ago, Rockosmith said:

I am seeing lots of discussions of rusty splines in the driveshaft/final drive connections.  Some even to the point of being inseparable.  I know that rust is not a good thing but is there normally any motion in that connection?  If that joint is rusted solid, is there any damage that is likely to result?  

Morning Rockosmith

 

There is no rear snap ring & the drive shaft itself doesn't have a slip joint so it is designed to slide a little back there IF it needs to. 

 

The overall design of the rear swing arm/torque arm pivots is designed to pretty well keep the drive shaft required length constant-- BUT!, keep in mind that there are rubber bushings on the control points so under hard acceleration, hard braking, full suspension articulation, etc  that could force the rear joint to slide a little.

 

As for damage?-- a frozen drive shaft at the rear sure won't do the pinion bearings, transmission output shaft bearings, or U joints any good so best to keep it operating freely if possible.  Plus, if it rusts up severely you will have a difficult time disassembling it if you ever need to. 

[Skywagon]

I think shaft greasing is a must on most things. Not related really but here is an example from Suzuki on my outboard. This shaft spins but no u joints. The prop is tight on those splines. I pull the prop and lube the splines every year. Those who don’t always ask how do o get my prop off. It’s stuck 

[Rockosmith]

Thanks D.R.  That is pretty much whatI thought.  I was going to tilt my final drive a few days ago and it would not move at all.  Looks to me as if either the splines are rusted badly or the pivots on the bottom of the drive are stuck.  I think I may have to remove the final drive and driveshaft as a unit and then attempt to separate them. This is on a ‘17 with 7000 miles.  Interestingly enough, I lubed the splines on my ‘15 with 116,000 miles on it and not a speck of rust to be found.   The splines had never been looked at before.

[realshelby]

What is the trick for removing the driveshaft to look at the other end?

[Boxflyer]

It will pull right off the transmission output shaft with its annular groove.  The snap ring stays captured in the front end of the driveshaft.

The HARD part is getting it back on.

You most likely have to undo the special zip tie on the front boot, slide it back some, then use a screwdriver or similar to be able to tip up the nose of the loose U-joint so it will engage the splines on the transmission. 

The left pic is from the front end of the driveshaft looking back and the right pic is the front U-joint looking forward…so you can see the snap ring captured at the aft end of the front splines.

Edited March 5, 2021 by Boxflyer
Added pictures

[Dave_in_TX]

Based on discussions in the advrider forum it seems that some bikes are coming from the factory without any grease on the rear shaft. Most of them are greased and don't generally have problems unless the rider does a lot of water crossings

 

[Cap]

I just finished a major service on my 2017 R1200RT at 22k miles.  My last major service was at 9700 miles after I bought the bike with 6k miles on it.  At the previous major service, Boxflyer took me through the steps to lube the spline on the final drive.  So, I was curious to see how it looked after about 12k miles and about 2 years.

 

I used a Castrol spline lube, and copious amounts of "Staburags"  (the NBU 30 PTM goo).  

 

I have attached pics below.  The final drive separated cleanly from the drive shaft without pulling the drive shaft out of the forward coupling.  There was no evidence of water intrusion.  I am showing the use of a boat strap to control the weight of the FD while you lower it, so you have both hands available to ensure separation of the drive shaft and FD.  Also, the strap makes reassembly easy so you can use one hand to control the angle of the drive shaft while you fiddle with the FD to get it properly engaged, and to verify by rotating the brake rotor.

 

Note that the splines are rust free.  And the rubber boot is shown with most of the old Staburags and dirt wiped off.  The remaining Staburags was still tacky, you can see the footprint of the original application 12k miles previously.  I really slathered it on, and it worked.  In contrast, when I did the first service at 9700 miles, there were just a few faint hints of the OEM treatment of the rubber boot, and all of it was dry and wiped off easily.  Note to self: don't try to go light on the goo.

 

Oh, one more thing... when the boot has a full coating of Staburags on both ends, it pops on both sides really easy.  Wear gloves!

 

 

[Alfred02]

Good job there Beer

I am dreading of what I am going to find. Still waiting for the NBU 30 PTM to arrive. It's coming from the USA because that's where I got it the cheapest LOL

I have the rest, including Honda Moly 66, which I used when I still had the Oil Head.