'92 K75S - Spline Lube, with video

[grosbeak]

When I bought the bike earlier this year, though high in mileage it appeared to be in excellent running condition. But there were no service records, so I bought it knowing I was taking a bit of risk. All of the evidence I've seen shows that it was well maintained, but I put together a long list of to-dos nevertheless, and the big one was the spline lube. I got it done this week - I was pleased that all of the fasteners appeared to have anti-seize on them, and doubly pleased that the splines were in excellent shape with plenty of lube remaining. Here's a video I made of the experience.

1992 BMW K75S - Drive Shaft Spline Lubrication

 

[MTSweger]

Well done! Thanks for sharing.

 

[98lee]

Welcome to the MOA Forum!

Thank you for your effort in producing your video on spline lubes Unfortunately, I must comment so others don’t get misled by some of the items in it.

As others have told you, after you posted your video, your splines are indeed severely worn!!!

The splines at the final drive end should have the same shape as the splines at the transmission end. Because the snap ring at the transmission end does not allow the shaft to slide in and out on that end, there will be virtually no wear at that end. Virtually all wear will be at the final drive end. If you look at the still photo of the splines on the final drive end of the shaft before you start the video, you will see that each tooth of the spline looks like a very pointy mountain with a very large distinct step on one side. The tooth SHOULD look like a very symmetrical mountain with an almost 1/16” wide flat top. Any lack of symmetry on both sides or narrowness of the flat top is all wear. The large step on the driven side of each tooth indicates a very worn shaft. The narrowness of the peak indicates very little mileage left before the shaft strips completely out.

The lube you used, even though it is what is recommended by Clymers and iirc at one point by BMW, has proven over the past 38 years by people who have put many hundreds of thousands of miles on early Kbikes (especially the 20 spline driveshafts that came on the ‘86 and later non paralever bikes) to be sorely lacking in performance. Early Flying Bricks require a good high pressure (unlike Optimol) grease high in molybdenum disululfide (above 50%) preferably with some tacky additive like provided by Wurth 3000 to prevent washout. A highly recommended spline lube is sold by Ted Porter’s Beemer Shop. I also belive the spline lube sold by Euromotoelectrics is a suitable lube.

The amount of wear on your shaft might (or may not) indicate similar wear on the final drive input splines.

Best option is to buy very good used replacements with little wear. PM me if you are having trouble finding good replacements. Most of what I see on Ebay are as bad as what yours are, even though the sellers say they are fine. Buyer beware!

Another tip for those watching your video, never allow the swing arm to sag much more than where the shock allows it to travel. The boot between the swingarm and transmission could be as old as 40 years old and brittle. Excessive droop could tear it, adding $56 (as of this date) to the cost of your spline lube. I see you did put a jackstand under the swingarm, but it was after you had already allowed it to go to full droop while disconnecting the shock.

A few other tips, either place a 2x8 or 2x10-12 board under the centerstand (if you are strong enough to get it on the centerstand with the board in place) or roll the rear tire up on a 2x and then place another 2x under centerstand, put it up on centerstand, then remove board from under rear tire. You will then be able to fully remove rear tire without removing rear license plate section of rear fender. Or you could just remove the license plate section of the rear fender to get tire out.

Another tip, do not remove the rear shock at either end. After the final drive is disconnected from the swingarm, just slide it back and pivot it 90 degrees and let the shock support it while you remove the driveshaft. Don’t remove the speed sensor, just disconnect it at the connector by the coolant overflow bottle.

What ever the method, relube the splines AT LEAST at EVERY rear tire change!!! New driveshafts are currently $750 from BMW and will only go up before they will be No Longer Available (NLA). Re lubing and inspecting the splines is cheap!

 

[grosbeak]

Welcome to the MOA Forum!

Thank you for your effort in producing your video on spline lubes Unfortunately, I must comment so others don’t get misled by some of the items in it.

As others have told you, after you posted your video, your splines are indeed severely worn!!!...

Thanks for setting me straight... I was unaware and will update the video description - the last thing I want to do is mislead anyone. I have ordered replacement parts.

 

[robsryder]

On airhead final drives the spline wear is often found where the splines mate to the rear wheel. Final drives on BMW bikes convert rotational force in one direction into a rotational force that is orthogonal (at a right angle). Thus there are bearings and parts that require shimming at two angles. These shims are in a case (final drive housing) that requires heating to install and remove parts. The labor for such an iterative activity can be quite high (I understand that this is 5 or more shop hours for the airhead final drive). The final drive gears can be damaged if the shims are not set properly. For airheads it has become more common to repair worn splines by welding and re-machining the splines; such an activity is much less costly than purchasing new parts and then incurring the labor to properly fit the shims.

I wonder if such a process is used to renew the worn splines on a K75 final drive. (The drive shaft is easily replaced and would not be repaired). For airhead spline repair I have used Hansens in Oregon (now out of business) and Bombars Beemers (when they were in Durham, NC - the shop is now in Wilmington, NC).

Bmw And Euro Motorcycle Service | Bombar's Beemers | Wilmington

Bombars Beemers BMW, Triumph, Moto Guzzi and European Motorcycle Service. 919-491-4875 Wilmington, NC

www.bombarsbeemers.com

 

[98lee]

The two places that regularly did this for Bricks were Bruno’s in Canada (out of business for some time due to health issues) and Hansen’s in Oregon (before the fire in 2020). Last I heard they were rebuilding the business https://forums.bmwmoa.org/threads/hansens-bmw-in-oregon-burned-down.98421/page-2 But even if things have gone well, I can’t imagine them reestablishing the driveshaft capabilities for a 38 year old bike any time soon,if ever.

 

[98lee]

I have ordered replacement parts.

Make sure the drive shaft is good BEFORE you install it (you may be able to send it back). Your final drive splines MIGHT be OK. I couldn’t tell from the video. If you’re not SURE you could post a clear closeup photo of either here and we could advise.

Putting a new driveshaft on worn final drive splines will hasten the wear.

 

[robsryder]

Just a follow up - I spoke with Peter Bombar today and he does not do the spline repair on K bikes. He does do the spline repair on an airhead final drive (using the Siebenrock part - involves cutting off old splines and aligning and re-welding on new spline end). Peter Bombar did indicate that Bruno has passed away and the machinist that was at Hansen's in Oregon appears to have retired for good. Better keep those splines well lubricated!!!

 

[grosbeak]

Here's the refurbished shaft I got from KPartsHolland. Based on what I've learned in the past couple of weeks it looks pretty good to me:


The shaft


The back end


The front end


Something extra

 

[gregfeeler]

The two places that regularly did this for Bricks were Bruno’s in Canada (out of business for some time due to health issues) and Hansen’s in Oregon (before the fire in 2020). Last I heard they were rebuilding the business https://forums.bmwmoa.org/threads/hansens-bmw-in-oregon-burned-down.98421/page-2 But even if things have gone well, I can’t imagine them reestablishing the driveshaft capabilities for a 38 year old bike any time soon,if ever.

A friend of mine sent in his K75 rear drive to Hansen's for a rebuild a year ago did get it done, but during the time they had it Craig announced that he lost his machinist and wouldn't be able to do rear drive spline rebuilds any more. This is a big, big loss to the classic K-bike community.

 

[gregfeeler]

Welcome to the MOA Forum!

Thank you for your effort in producing your video on spline lubes Unfortunately, I must comment so others don’t get misled by some of the items in it.

As others have told you, after you posted your video, your splines are indeed severely worn!!!

The splines at the final drive end should have the same shape as the splines at the transmission end. Because the snap ring at the transmission end does not allow the shaft to slide in and out on that end, there will be virtually no wear at that end. Virtually all wear will be at the final drive end. If you look at the still photo of the splines on the final drive end of the shaft before you start the video, you will see that each tooth of the spline looks like a very pointy mountain with a very large distinct step on one side. The tooth SHOULD look like a very symmetrical mountain with an almost 1/16” wide flat top. Any lack of symmetry on both sides or narrowness of the flat top is all wear. The large step on the driven side of each tooth indicates a very worn shaft. The narrowness of the peak indicates very little mileage left before the shaft strips completely out.

The lube you used, even though it is what is recommended by Clymers and iirc at one point by BMW, has proven over the past 38 years by people who have put many hundreds of thousands of miles on early Kbikes (especially the 20 spline driveshafts that came on the ‘86 and later non paralever bikes) to be sorely lacking in performance. Early Flying Bricks require a good high pressure (unlike Optimol) grease high in molybdenum disululfide (above 50%) preferably with some tacky additive like provided by Wurth 3000 to prevent washout. A highly recommended spline lube is sold by Ted Porter’s Beemer Shop. I also belive the spline lube sold by Euromotoelectrics is a suitable lube.

The amount of wear on your shaft might (or may not) indicate similar wear on the final drive input splines.

Best option is to buy very good used replacements with little wear. PM me if you are having trouble finding good replacements. Most of what I see on Ebay are as bad as what yours are, even though the sellers say they are fine. Buyer beware!

Another tip for those watching your video, never allow the swing arm to sag much more than where the shock allows it to travel. The boot between the swingarm and transmission could be as old as 40 years old and brittle. Excessive droop could tear it, adding $56 (as of this date) to the cost of your spline lube. I see you did put a jackstand under the swingarm, but it was after you had already allowed it to go to full droop while disconnecting the shock.

A few other tips, either place a 2x8 or 2x10-12 board under the centerstand (if you are strong enough to get it on the centerstand with the board in place) or roll the rear tire up on a 2x and then place another 2x under centerstand, put it up on centerstand, then remove board from under rear tire. You will then be able to fully remove rear tire without removing rear license plate section of rear fender. Or you could just remove the license plate section of the rear fender to get tire out.

Another tip, do not remove the rear shock at either end. After the final drive is disconnected from the swingarm, just slide it back and pivot it 90 degrees and let the shock support it while you remove the driveshaft. Don’t remove the speed sensor, just disconnect it at the connector by the coolant overflow bottle.

What ever the method, relube the splines AT LEAST at EVERY rear tire change!!! New driveshafts are currently $750 from BMW and will only go up before they will be No Longer Available (NLA). Re lubing and inspecting the splines is cheap!

I vouch for Lee's lube recommendation. I use a 50/50 mix of Honda Moly 60 (NLA) and Wurth's SIG 3000 (much credit to Paul Glaves for this witch's brew) and it has virtually stopped all my spline wear. I had the rear drive splines on one my K75s rebuilt by Hansen's in Oregon in 2000, mated it with a new drive shaft, and have lubed them with that mixture every rear tire change and they look like brand new. Since Honda Moly 60 is no longer available. I second Lee in recommending Ted Porter's moly lube.

 

[98lee]

I’ve always gone by Paul Glaves’s recommendation on spline lube based on the fact that he’s been riding and maintaining K75s since they were introduced. He’s heard of and personally been through all the difficulties that were caused by BMW’s poor selection of spline lubes (they tried several with unsatisfactory results).

Paul came up with up with what became the gold standard for K75 and K100 spline lube (Honda Moly 60 mixed with a bit of Wurth 3000). Paul personally worked with a oil field lubrication lab/producer (TS Moly) to come up with up with a proprietary mixture that had all the benefits of the Honda Moly 60/Wurth 3000 mix. This was called Guard Dog Moly. This became the new go to spline lube when Honda discontinued Honda Moly 60 8-10 years ago. Guard Dog was discontinued when the guy at TS Moly retired. It was subsequently revived when Ted Porter (The Beemershop) agreed to be a distributor for it. It is now known as Spline Lube TS60.

Over the past 15 years, I’ve had excellent results with the Honda 60/Wurth 3000 mix. That’s hundreds or thousands of miles between my bikes and customers bikes with mostly no wear and good lubricant retention between shaft lubes.

Out of curiosity, about 10 years ago,I tried the Staburags NBU 30 PTM spline lube based on the fact that it was what BMW recommended decades ago and Chris Harris said that’s what to use (he’s an ex-dealership mechanic so that is what they used). It is very expensive. I tried it on two of my regular customers bikes. A couple of months later, one bike was almost totaled when a cager made a right hand turn from the left hand lane OVER my friend’s bike. He was OK, but the bike required a lot of work. When I removed the final drive, the Staburags lube was GONE!!! The bike had around 1500 miles since the lube service! I called the other owner that I had also used Staburags on and immediately changed it to the Honda/Wurth lube on my dime. His shaft only had about 600 miles since I had lubed it. It still had some indication of lube, but not like the H/W would have. I just don’t trust the Staburags.

If you want your splines to last, use TS60 from Ted Porter’s Beemershop! I don’t know Ted. I’ve spoken to him twice on the phone. But, I do know the history of the TS60 product he sells. It’s the best bet to keep your driveshaft in good shape. As of today, new driveshafts from BMW are $750. Lube them AT LEAST every 5000 miles if you don’t want to risk it.

 

[gregfeeler]

I’ve always gone by Paul Glaves’s recommendation on spline lube based on the fact that he’s been riding and maintaining K75s since they were introduced. He’s heard of and personally been through all the difficulties that were caused by BMW’s poor selection of spline lubes (they tried several with unsatisfactory results).

Paul came up with up with what became the gold standard for K75 and K100 spline lube (Honda Moly 60 mixed with a bit of Wurth 3000). Paul personally worked with a oil field lubrication lab/producer (TS Moly) to come up with up with a proprietary mixture that had all the benefits of the Honda Moly 60/Wurth 3000 mix. This was called Guard Dog Moly. This became the new go to spline lube when Honda discontinued Honda Moly 60 8-10 years ago. Guard Dog was discontinued when the guy at TS Moly retired. It was subsequently revived when Ted Porter (The Beemershop) agreed to be a distributor for it. It is now known as Spline Lube TS60.

Over the past 15 years, I’ve had excellent results with the Honda 60/Wurth 3000 mix. That’s hundreds or thousands of miles between my bikes and customers bikes with mostly no wear and good lubricant retention between shaft lubes.

Out of curiosity, about 10 years ago,I tried the Staburags NBU 30 PTM spline lube based on the fact that it was what BMW recommended decades ago and Chris Harris said that’s what to use (he’s an ex-dealership mechanic so that is what they used). It is very expensive. I tried it on two of my regular customers bikes. A couple of months later, one bike was almost totaled when a cager made a right hand turn from the left hand lane OVER my friend’s bike. He was OK, but the bike required a lot of work. When I removed the final drive, the Staburags lube was GONE!!! The bike had around 1500 miles since the lube service! I called the other owner that I had also used Staburags on and immediately changed it to the Honda/Wurth lube on my dime. His shaft only had about 600 miles since I had lubed it. It still had some indication of lube, but not like the H/W would have. I just don’t trust the Staburags.

If you want your splines to last, use TS60 from Ted Porter’s Beemershop! I don’t know Ted. I’ve spoken to him twice on the phone. But, I do know the history of the TS60 product he sells. It’s the best bet to keep your driveshaft in good shape. As of today, new driveshafts from BMW are $750. Lube them AT LEAST every 5000 miles if you don’t want to risk it.

Can I like this like a zillion times?