TOPIC: Ok, next question in for LU rebuild

I'm doing a rebuild of a 1960 Merc 300 lower unit.
(I've been getting a lot of great help from everyone here, which is very much appreciated! I hope I don't wear out my welcome )

I've installed the forward bearing/gear (with the original three shims) and installed the drive shaft (with new bearings) and the pinion gear. I included the original two drive shaft bearing/housing shims that where there when I took it apart. Now, when I turn the drive shaft it sounds ok..until I put a little downward pressure on it, then it makes a sound like the gears aren't meshing correctly...which, I assume is not correct. There is a very little up/down play on the drive shaft which I think is allowing this to happen. Could it be that the bearing width is slightly smaller than the original? If so, I assume I would add shims? Here is a very short video:

vid1004.photobucket.com/albums/af163/cprs1/Mercury%20LU/IMG_2290_zpsa5cbc5fe.mp4

Video is great. Everything looks good, the reason for the noise is that you do not have the prop shaft in and the reverse gear and bearing. The forward gear is simply not supported, so it does not interface properly.

Thanks Dave. Much appreciated! Tomorrow I'll try installing the other components.

Here are some more videos with the near complete assembly done. The water pump component isn't installed.

Ok, this is after the remainder of the bearings are installed. Is that sound still ok? (half way through the video you can hear when I push down (as in, towards the skeg) on the drive shaft)
vid1004.photobucket.com/albums/af163/cprs1/Mercury%20LU/IMG_2292_zpsf414327d.mp4

And, looking for some general input (looks right, sounds right or other wise) on these videos:
Shaft is not engaged when holding the drive shaft:
vid1004.photobucket.com/albums/af163/cprs1/Mercury%20LU/IMG_2295_zps2c582880.mp4

Shaft engaged only one way when holding the drive shaft:
vid1004.photobucket.com/albums/af163/cprs1/Mercury%20LU/IMG_2294_zps5f9278a3.mp4

Shaft is engaged both ways when holding drive shaft:
vid1004.photobucket.com/albums/af163/cprs1/Mercury%20LU/IMG_2293_zpse2187df1.mp4

Hmm, the video where you are turning the prop shaft in neutral sounds fine. The other videos surprised me I would not have expected to hear that much gear interference. It is hard to tell without actually feeling the gear mesh when you turn it. It is possible that the forward gear is shimmed out too much.

Hoping GEORGE G might chime in on this one.

I'm betting that it quiets down once you put the gear oil in.
It sounds pretty typical as a dry unit IMHO.
doc

Dr_Frankenmerc wrote:

I'm betting that it quiets down once you put the gear oil in.
It sounds pretty typical as a dry unit IMHO.
doc

Thanks for chiming in Doc, I agree the lack of oil is likely the issue, just wanted another set of ears. Yours, as always, are appreciated.

You are supposed to pull UP on the driveshaft when checking for gear mesh and smoothness !!!!

Thanks for additional input guys.

I'll add the gear oil and see how it goes.

Pull up on the driveshaft....I guess there is some kind of mechanical principal for that. It seems anti-logical for someone like me without that knowledge. I'm guessing that the spinning of the gears drives them apart, pushing the drive shaft up, countering gravity. Thanks for the information.

you are correct.

Most driveshafts / lower units have a thrust bearing to look after the upward forces when motor is running / working when in gear.