K1100 Drive shaft knock.

[Shinybeast]

Hi,
It started with the seal breaking on the final drive.  On inspection it turned out that the bearing had shredded and caused a leak.
Swapped that over, and changed the final drive and swing arm bearings.  All running great and smooth as silk, but when I run the bike stationary, ther's an intermittenk knock somewhere between the gearbox and the final drive.  Driveshaft is all solid and the 'ears' are set right so it's not unbalanced.  All splines lubed with Moly grease.  All fluids in good order.  75-w140 in the gearbox as well as Liqui Moly additive. 75-w90 in the final drive.

Is this ok?  Can't feel it at all when I'm riding.

[frankenduck]

How many miles on it?

[Shinybeast]

How many miles on it?

Hi,

72k miles.

[Laitch]

Was that flange nut being used on the pivot pin in the photo before this repair?

[Shinybeast]

Hi Laitch,

It's not a flange nut, one side is a fixed pin and the other (the side you can see) is adjustable).  The pin on that side it tightened up relatively loosley, so the final drive is almost supported,  then the ring nut is torqued up tight.  I've upgraded to a set of motorworks' bearings which are easier to grease, but the only torque spec is "don't over tighten", hence why I've marked it to make sure it doesn't loosen off.

Here's the upgraded part...
https://www.motorworks.co.uk/final-drive-pivot-bearing-upgrade-kit-tra11092-1.html

[Laitch]

That's called a flange nut over here, anyway. I guess we're still separated by a common language.   



I didn't recall that aftermarket assembly, but it seems popular with those who have installed it. Anyway, I'm more accustomed to seeing an OEM plain nut locking the pin. It's frustrating to finish a job and have a glitch like that. If it isn't the bearing associated with that adjuster assembly at the root of this, more disassembly could be necessary.

[natalena]

Sounds sort of like the bevel gear isn't meshing smoothly without some pressure from the driveshaft. I don't have an 1100, so this is all nonsense, but were washer/shim parts removed from the bearing replacement?
Good luck

[Shinybeast]

Hi Laitch,
The nut is similar but there's no flange, just a symetrical flat ring nut. 



Screenshot 2025-08-18 at 19.40.53.png (431.39 kB . 432x576 - viewed 112 times)

That's called a flange nut over here, anyway. I guess we're still separated by a common language.   



I didn't recall that aftermarket assembly, but it seems popular with those who have installed it. Anyway, I'm more accustomed to seeing an OEM plain nut locking the pin. It's frustrating to finish a job and have a glitch like that. If it isn't the bearing associated with that adjuster assembly at the root of this, more disassembly could be necessary.

[Shinybeast]

Sounds sort of like the bevel gear isn't meshing smoothly without some pressure from the driveshaft. I don't have an 1100, so this is all nonsense, but were washer/shim parts removed from the bearing replacement?
Good luck

Hi Natalena,
Thanks for your suggestion.
There's a shim in the assembly but that's all safely back where it came from.  The manual has some info about reinstalling, but, as usual, it's a bit confusing. 
I might have another look at it.

Screenshot 2025-08-19 at 12.05.29.png (50.49 kB . 571x576 - viewed 109 times)

[Laitch]

Hi Natalena,
Thanks for your suggestion.
There's a shim in the assembly but that's all safely back where it came from. 

Thanks for the photo of the nut. The prior photo looked like it was flanged.
How did you decide shim thickness, or did you just use what you had?

[Laitch]

Here's a thread describing how one rider experience determining shim thickness and preload adjustment to repair a rear drive without special tools. I've started it off at the most relevant section of the thread.

[Kaos]

But if its knocking, have you asked it to stop doing so?
Anyway. I think it might be helpful if you let it idle in neutral and check up close where the knock is coming from.

[Shinybeast]

Thanks for your help Laitch.
Looks like she's coming apart again!

Here's a thread describing how one rider experience determining shim thickness and preload adjustment to repair a rear drive without special tools. I've started it off at the most relevant section of the thread.

[Shinybeast]

Hi Kaos,

It's only an issue when it's turning the shaft and final drive.

But if its knocking, have you asked it to stop doing so?
Anyway. I think it might be helpful if you let it idle in neutral and check up close where the knock is coming from.

[Shinybeast]

Hi,
I foolishly assumed that BMW would put the right thickness shim in there to start with.
Now I've investigated a bit it looks like this is a common cause of shredded bearings.

Thanks for the photo of the nut. The prior photo looked like it was flanged.
How did you decide shim thickness, or did you just use what you had?

[natalena]

Motobins is great for parts. Cheers

[Shinybeast]

Hi Kaos,

I've used Motobins a lot over the years and their service is great, but I usually find that Motorworks is a bit cheaper.

Motobins is great for parts. Cheers

[Laitch]

Hi,
I foolishly assumed that BMW would put the right thickness shim in there to start with.
Now I've investigated a bit it looks like this is a common cause of shredded bearings.

It's likely that shims of different thickness are available to accommodate production variations or wear. Your makeover and the concomitant wear after years of use changed clearances. It also could be that the most common cause of shredded bearings is lack of regular lubrication.

[Shinybeast]

Hi Laitch,

It's all back togeteher again now, looks like I got the shim from the old part and the replacement mixed up.  They look identical, though having now learned the importance of the thickness, I measured them both and it turns out there's a 0.2mm difference.  I disovered another method of testing the preload, the "drag method'.  I thought that the drive should just spin free but apparently there should be 1.1-1.8NM drag.  Once I put the right shim back there was some resistance when I tried to turn it, but not too much. Now it's back together and there's no knock.  I'll call into my local bike shop and get them to test it properly later this week as I don't have a torque meter that can measure that low.

Also, I must apologise.  I discovered that it is indeed a flange nut on the bearing. 


IMG_1721.jpeg (40.69 kB . 768x526 - viewed 78 times)

I'm guessing they've added this because the new bearing doesn't come with a pre set torque, just says "don't over tighten". The original pins had to be torqued to 150 and 105Nm.  I've torqued the new pins to 80Nm and marked them to show any loosening.  Maybe the flange is to give a greater reistance by having a bigger surface area?