LU 1655-7332 Parts Diagram?

[BB63QM]

Does anyone have a parts diagram for lower unit number 1655-7332, which is on my 1973 850 Thunderbolt? Spec’s part is 1655-7333, so perhaps mine was made with leftover parts or got a replacement in the last 50 years. Anyway, time to replace the gears, so need part numbers (I ordered for the 7333, and the heats didn’t match; slant versus strait, no reverse bearing vs roller bearing behing reverse in the carrier.

Thanks in advance.

 

[alldodge]

Have you looked here?
https://www.mercruiserparts.com/850-6-cyl--1460999-thru-1766823

 

[Faztbullet]

You will need to reshim the unit or new gears will fail.

 

[BB63QM]

Have you looked here?
https://www.mercruiserparts.com/850-6-cyl--1460999-thru-1766823

I’m sorry…I don’t understand. I don’t see 1655-7332 on the page indicated (or anywhere in the Mercury catalog for that matter), which is why I’m asking here.

 

[BB63QM]

You will need to reshim the unit or new gears will fail.

I have yet to understand what the shims do or why they are needed, but understand that they are necessary, except where they are specifically stated as not being needed do to changes in the design of the LU in the 80’s-90’s (I saw a note but I don’t recall where)

First things forst, I either need to find a crap for the OEM (1973, 850, first series, long shaft) gears I have (for 1623-6052A4 (compete: 1623-7339A2 or 1655-7333A25) https://www.perfprotech.com/mercury...ly-complete-page-1/assembly/461/200?model=874
—or either 1623-6052A4 or 1623-4021A6 bother of which w are we specified in Mercury’s official catalog by Serial Number. (No idea how to tell which mine came with as far as I can tell)
or get someone to confirm that they can be put in the case I have or get new gears (mine worked for 5 minutes and then wouldn’t engage after that..too tight..too loose..too work..:can’t tell. Prior to that my clutch dog was compete lit swedged and the slide snapped (not sure which happened first or what caused…she is “New2Me”.

 

[brodmann]

First things first, please proof read your posts so we have some clue as to what you are asking. Please.

 

[alldodge]

The link is the parts breakdown for the 850, might look in it to see if you can find what your looking for

Did type in 1655-7332 and it says part not found, but does list a 1655-7333

 

[Chris1956]

Shims go behind the gears to achieve correct tooth mesh. Too little will strip the gears, too much mesh will cause breakage of gears.

Take a look at the crowleymarine site. Gearcases from IL 4/6 motors 1973 up to and including a'77 Merc inline 4/6 will fit your motor. Likely others will too, but I do not know that info.

I have a good gearcase from my '77 1500, here on the Jersey Shore.

 

[Faztbullet]

I6 lowers will fit but makes em a dog even when reducing prop size...just makes em good for riding and crusing.

 

[BB63QM]

Thank you all for the replies. Sorry for the typos, brodman.
Here’s the situation: I bought new gears for my “new” ‘73 Mercury 850 based on the parts list for my serial number, only to then find that my LU is not OEM. Instead, it is part1655-7332 (which alldodge correctly pointed out is unlisted). So now I need one of two things, 1) the right LU for the ‘83 850 first series (so I can use the gears I bought and can no longer return)—I found a couple empties but piecing all the innards together is going to cost a mint, so my goal is to find a “for parts” LU that I can slap my gears into and maybe replace a couple other parts) , or 2) a parts diagram/list for the 1655-7332, so I can buy the right gears for the LU I have…as my gears are swedged on the dog-mating surfaces. (Or option 3…get confirmation that the gears I bought for the OEM LU will work just as well in the other LU (noting that I have all of the alternate parts since the gears I bought use a different carrier and bearing assembly)). I suppose that this is a possibility, given that many specified part numbers are ready replaced by parts with other numbers. But I don’t know.

 

[Chris1956]

Gee, so you are looking for a gearcase with bad gears? I would not expect them to be hard to find. I had one I tossed out, 20 years ago.

 

[BB63QM]

One man’s trash is another man’s treasure. Found one on eBay, with frozen prop, but seller has not yet confirmed the model number.

 

[Faztbullet]

Angle gears will not work in straight cut gear housing.

 

[merc850]

Here's a diagram showing straight cut gears- inline 6's use a 2:1 gear ratio and the 4's use 2.3:1.

 

[BB63QM]

Update: I bought a full 850 for parts, and scavenged the LU first. All I did was swap the LU from the “new” motor onto mine, and replace the gear oil.
Then I took it out.
Once on the lake, it appeared to be fine for about 2 minutes, then lost 80% of its thrust…we pushed ahead and managed to put around the lake until it simple stop rotating the prop altogether.
I still have not taken the LU apart to see what’s going on. I was just surprised to see the new LU doing the same thing as the old LU (ie, starting out in gear, then losing thrust, then failing).
What does this sound like…what should I be looking for when I get it open?

—btw: how can I test on land. It always seems to work well on muffs and then fails under actual conditions. Is there a safe way to mimic lake conditions on shore?