Upper Bevel Tightness

[gregwils]

I have done my best to search the forum and think I have my answer, but would like some feedback. Everything that I read suggest that upper bevel and cam should turn smoothly. However, I just stripped down a Monza Jr 160, which surprised me by turning out to be in excellent condition. I am confident that the motor had never been apart, so I am assuming what I found was from the factory in the mid-60's.

My question relates to the upper bevel. I expected it to turn smoothly, but it seems like every tooth mesh is a positive, step-like action and not buttery smooth. Has anyone seen anything like this before? Do you think I am wrong about it being the original factory setup.

I included a link to a video that helps convey what I am experiencing. You can hear the 'clicking', which is the positive or step action or the rotation. I don't know whether to tear it apart or assume that because it's from the factory, it's the correct setup.

I appreciate any feedback.

https://drive.google.com/file/d/1Gdad_3H-6pz_95ZATOYsxtzpg3Yh_oV5/view?usp=sharing

[Bevel bob]

Could easily be one of the bearings is breaking up or full of crap. Has to come appart , absolutely.

[veloduke]

When I do this I support the lower end of the drive shaft at the bottom of the tube to centralise it.
I just turned a piece of aluminium that slides into the lower end of the drive tube, with a hole in the centre that slides on to the drive shaft.
In the Ducati workshop manual (the ones available to buy online from e.g Lacey/Mdina) there is a picture of this, labelled 'Assembly Tool Transmission And Protection'.
This holds the transmission/drive shaft central. With the drive shaft flapping about you can't assess the engaement of the bevels properly.

[gregwils]

Thanks for the responses. I just checked on the bevel shaft. It's currently unsupported since the head is off and there is virtually no side to side movement. The tension against the cam bevel does not has virtually eliminated any lateral play. I do think it's too tight. I will disassemble and, after inspection, I will consider adjusting the shims to achieve a smooth operation.

Thanks again.

[IanHood]

You will never be able to tell how it is truly running unless the bottom of the shaft is centralised as has already been suggested. The tiniest deviation of the shaft from the central position will result in the stepped action of the gears that you describe. Even if you replace the bearing, you will get the same symptoms and, in any case, you will not be able to shim it successfully without the centralising tool.

Ian

[ranton_rambler]

I don’t have the proper tool but used a socket which was a good fit over the shaft and inside the tube. Possibly used a couple of layers of tape to fine-tune the fit.

[LaceyDucati]

The top bevels can be set more accurately with the head assembled on the engine with the lower crank gear removed. I say more accurately because ultimately that's how the bevels will run and when the head is torqued down there will be a minor tightening of the clearance. The reason for the top "self aligning" bearing is that the alignment of the top and bottom bevel is seldom perfect. Small angular movements of the shaft may likely cause small changes in clearance, which is why I like to set the gears in situ as they will run, rather than with an alignment bush.

As for the tight 160 bevels, it's obviously not correct, albeit maybe factory original.....Generally "like new" is not always something to aspire to with Ducatis

Regards Nigel

[Jordan]

I like your suggestion, Nigel.
That's how I'll do it in future - if ever.

[gregwils]

Thanks for the additional comments. The head is stripped no including the cam and the bevel gear attached to the crank is off, so I can put the head back on to check the movement with the shaft centralized, though I don't believe it will make a difference.

I'm not entirely surprised that the original factory setup can be improved upon, thanks for confirming.

[insanity]

Does it have the grind marks on the gear Pair, if so how do they feel ?
When I did mine I did in situ as Nigel (the group helped me a lot) suggests, I just spun the back wheel to wear off the mesh paste.