Thoughts about rear end drive set, and help needed

[Micha]

After getting tired of riding with my rear end slow transmission, designed to carry a sidecar, I thought long about purchasing a new set, ratio of 35:9. What kept me from the purchasing was the high price. After surfing countless hours on very many sites, I decided to try my luck and purchased a kit from a chinese manufacturer designed for the chinese Chiang-Jiang motorcycle, on the AliExpress website. After all it was only $ 50 including shipment that was at risk here.
I researched this excellent video: https://www.youtube.com/watch?v=1dBh7WkNVGQ
and chapter "Assembly of Rear Wheel Drive" on the R51/3 workshop manual, and I (think) understood what's going on there, so I went for assembly of that new set.
As I do not have all those high precision measuring tools you can see on that video, I went with a more simplistic approach:
I machined all the available sizes of that bronze pressure shim stated by BMW (from Salis site: https://bmwclassicmotorcycles.com/index ... 7-pcs.html) and went ahead and assembled that rear end each time trying an other bronze shim, until (I thought to myself) I will hit the right tolerance.
The problem I'm facing here and would love to hear some advice is, that on all sizes that I use, there is a strong noise while turning the pinion with the direction of travel and no noise at all while turning it reverse. I painted the toothed bevel gear but could not find any sign or damage to the paint.
So, am I right in stating that the next item to calibrate is the pinion that connects to the drive shaft? Or does the fact that there is no damage to the paint at all, mean that something else here is very wrong and before calibrating the pinion I have to keep messing with the bevel disc gear? I mean, I should at least get some hits or scratches on the thick paint I applied there, right?
Any idea, guidance and advice will be welcomed and thanked.

[jwonder]

what kind of noise? Could it be the pinion beating making noise? It is possible.

[Micha]

Morning James,
What do you mean with "beating"? - I think the language barrier is causing me a misunderstanding here, I apologize.
It's a kind of flat roar. Not a very "mechanically" noise, but some kind of a tremor accompanied by a loud buzz.
I will try to upload a sound file.
Although the motorcycle goes great, every time I leave/close the throttle, there is noise that can also be "felt". Not really shaking but I can definitely feel it. I have to point out that the noise is really loud and it is a bit awkward to ride like that.
The noise is there as soon as I leave the throttle, both when driving downhill in idle gear, and also
when I am in gear: as soon as I touch the throttle again and accelerate the noise disappears.
Lying disassembled on my desk, after the processes I described in the opening and I do not so much know what to look for next.
BTW, I got a pretty nice kit, well machined and appears to have undergone proper thermal treatment.

[schrader7032]

I think he meant to write "bearing".

[Micha]

Well, all bearings are new in there

[Micha]

Is it at all possible, to calibrate this little pinion, in and out?
Is shimming an option here?

[malmac]

I dont know about the older final drives.
With the /2 the pinion gear is set up first and then the backlash on the crownwheel is set and finally the bearing preload on the cover is set. To set the pinion gear you use a middle of the size range spacer on the crownwheel to get some clearence and then work on the pinion shaft. Having got the contact patch centred for the pinion shaft you revisit the spacer for the crownwheel to get the right backlash.
It may be that your pinion gear is way out of wack and it should be set first.

https://www.youtube.com/watch?v=dAqAqODmcj4

This youtube clip may be about cars but the essentials are here. Check it out.

Mal