Prop Locking Question (Reverse Locking Cam?)

[BB63QM]

Looks like $90 eBay; $275 store) for the dog,
FWD: 125-200
REV: 99 (or less on eBay)

Full LU: $1250-2500

 

[Chris1956]

Inline 4 and 6 cylinder gearcases from the 70's and early 80's of the correct shaft length will fit your motor. Most of the shaft lengths were 20" on those motors.

The gearcases had a locking tab, with a "donut" shaped nut that screwed into threads of the hub of the gearcase. By this point the threads are usually gone. I am therefore not sure your removal tool will provide value.

Once you get the nut off, you will need a puller or at least a slide hammer to remove the bearing carrier. It is a real PIA. After that, you will need to pull the three gears, dog and propshaft and inspect all components.

Let's pretend that only the three gears and dog are bad. replacement will be at least $1200, but all are NLA. You also need specialized knowledge to shim the pinon gear properly.

A used gearcase will be $400-$500 or less.

 

[BB63QM]

Point taken.

For now, I am back to having FWD, Neutral (though still not as free as i would expect), and REV. I have new grease in the LU and I'm trying to raise it up and into the shaft housing.
Two issues:
1. The water tube is giving me hell aligning with the water pump housing, and my fingers don't bend the right way to guide it. Looking at the schematics, it looks like there is supposed to be a guide (bigger than water tube, smaller than water pump hole) that doesn't seem to be there, so the water tube is just banging against the top of the hole.

2. When I dropped the LU, a rubber ring fell out (origin unknown)...it looks to be the same as the one at the base of the shaft (but as the catalog indicates, there is only supposed to be 1); I slipped it on at the splines, and its now 3" from the based, having been pushed down.

could this be something else? I figured that it came off the shaft, since its the same and I 'put it back', but it doesn't seem to serve any purpose. Any ideas?
-could these issues be related/ (did the rubber grommet come off of the water tube where it served an alignment purpose (i could see it functioning well in that regard, but I don't see anything like it in the diagram or parts list)?
---or maybe, as indicated above, they are sold two at a time and someone thought randomly tossing it in there was as good a place as any to store the extra.

 

[Chris1956]

The slinger should be installed over the driveshaft, on top of the waterpump housing. It is heavy rubber and will not move on it's own. Your driveshaft may have a groove for an oring, just below the spline. Some do, some don't. If you have the groove, install and oil an oring.

Mercury's always use a plastic tube that fits into the waterpump outlet, and fits over the water tube, to guide their mating. The old one is often on the water tube, up a few inches. Normally you get those in a waterpump kit.

 

[BB63QM]

Thank you, Chris. I did find the tube, hiding and stuck several inches up…used a wire hanger to fish it out…I saw it earlier, but it didn’t want to move and was the wrong color so I wasn’t sure.
The power is out here, so working by flashlight was a must and turned out to be what I really needed. Went together like a champ (twice since I dropped the shift/reverse lock shaft aligned the first time)

She’s all back together, and no worse for wear. Fingers crossed for tomorrow morning when I go out to check everything in the sunlight.

Never figured out what the extra slinger was for, but it’s in the spares bag now.

Thank you for all of your help.

 

[Chris1956]

Let's hope that the new gear oil fixes your shift issue. Otherwise, I fear the gearcase is bad.

Inline 4 cylinder motors have a lower gear ratio than IL 6 cylinders motors. I think (not shared by all) that a 2" drop in pitch makes them compatible.

 

[jimmbo]

The 65, 75, 80, and 85hp inline 4s had a 2.3:1 Ratio, and most inline 6 s, but not all, had a 2:1. In the mid 1980s the 2.3 was offered as a High Altitude Option on the 115 IL6.

 

[BB63QM]

I don’t understand what you wrote above, but I think I’m headed that way. Today was my birthday, so we took her to a local lake…where she fell on her face but good. Roared like a mighty beast (so the tune up worked…although her RPMs are still too high), but then she limped out on the lake in not quite neutral.

After the lake cop towed is in, I dropped, adjusted and raised the LU, this time in reverse, but as soon as we shifted out of reverse it was dead, unable to shift into anything.

Dropped it again…still lashed to the ramp dock, standing in 4 feet of water…unable to find forward at all…just reverse and only until she back on the shifter (shifting manually at the spline, I could go into reverse a dozen times like clockwork, but rotating the other way only found neutral…raise the LU and shift from the remote and it pops out of reverse into a free spin (perfect neutral) and a flapper for forward, and then can’t find reverse again…the problem seems definitely in the LU. I half wonder of the shift shaft is stripped…not grabbing the the spine coming up from the LU…that would explain my I can’t shift back to reverse from the remote (whethe the strip is in the descending shaft or the LU stub-up, I wouldn’t know). But that doesn’t explain why I can’t find forward even when shifting directly at the stub-up with a wrench).

If there is any hope of a fox, I’m game to give something a try…otherwise, can someone point me towards a good gearbox.

A gearbox cracking wrench is coming on Monday, so I’ll break her open and see what’s inside (or find out that you were correct that that’s a fools errand), but I’m not holding my breath. Maybe it needs a new forward gear, maybe a new dog, or maybe she needs more than that.

Ok…advice time. Lemme have it.

Thanks
Gary (great time with the wife and kids in my birthday anyway…just not what we had planned)

 

[merc850]

I posted this for shift setup: This is how I do it in about 60 sec.: Turn the LU shift shaft by hand counter-clockwise until it
stops, then with Vise Grips tight on the bottom of the shaft turn it a
few more degrees CCW until it clicks into a stop, this
should be neutral - check by turning propshaft --
prop should spin freely.
Put control in N and go ahead and attach LU to driveshaft housing some turning of the flywheel will help the DS splines align.
Do not shift into reverse unless you turn the prop at the same time.
This might help you but seeing metal chunks on the drain plug is not a good sign.

 

[merc850]

The reverse lock cam is installed like this

 

[BB63QM]

Thank you for this. I’ve seen this posted elsewhere. In my case, I’m not finding a forward gear at all.

I can feel three distinct positions in the gear box, and those positions align with the three positions of the shifter in the motor and the handle in the remote. Reverse is the only gear that is solid (locking on the driveshaft in one direction and blocked in the other), and when shifted out of REV, only Neutral exists until shifted back to REV locally at the LU. If you push PAST reverse (CCW as you look down on the LU), shaft will complete the 360 rotation, showing at some point a FWD gear, then a NEUTRAL, then REV…all within 10-15 degrees of the next in 30-45 deg of the rotation (which makes sense given the shape of the shift cam, and until I removed it, the reverse lock cam). The issue I WAS having was that the shifter locked in reverse…NOW only reverse is fully working, and if you shift CW out of reverse (spring-pop), you are in NEUTRAL and can’t get anywhere else without a complete 360 degree turn (which is why you can only do it locally and with the reverse-locking cam removed).

Looking at the diagrams, I’m guessing that the shift cam is swedged or bent (perhaps from a hard shift before the RPMs we’re lowered, and/or from me trying to manually shift to REV without (adequate) prop rotation and/or from pressure applied trying to pop it out of REV.

I think the rubber won’t meet the road until I open the gear box itself to see what’s going on in there (tool arrives tomorrow).

 

[BB63QM]

The reverse lock cam is installed like this
View attachment 387556

This is what I did before heading to the lake. When that failed, and I did it again, except putting together in reverse, I removed the reverse-locking cam to eliminate it from the issue (so it wouldn’t be a distraction, since it is only a position indicator in terms of shifting…the shift can is the one that really matters)

 

[BB63QM]

The reverse lock cam is installed like this
View attachment 387556

Thanks for the pictures BTW, neither are in the (1966-74) service manual I have.

 

[BB63QM]

BTW: does anyone have a part number for a gear replacement set (a kit). I know they exist for some models but have not found a list. In the interim, I tracked down replacement parts for just about everything in the LU (except for a decent full LU replacement under $1K)

 

[BB63QM]

Question: I’m looking at a lot of LUs on eBay, I notice that many/most oook different in the case of the shift/shaft spline. It looks like the connector from the bottom of the upper shift shaft is connected to the top of the lower shift shaft. Mine is the opposite (so my lower shaft extends past the reverse-locking cam). Since the connector is female-splined throughout, I assume it makes no difference but I wanted to check. See eBay pic:
View attachment 387653

 

[BB63QM]

Check this out! I used the special wrench to remove the carrier retainer. And the. Set about trying to pull the carrier. While I was failing at that I noticed something bouncing around in the Outer LU

I have no way of explaining it, and I cannot imagine how it relates to my issues but I just found the slide from the end of the gear shift cable:

File that under WTF?!
So, now I have a spare centrifugal slinger and a spare shift cable slide…beginning to think that the prior owner didn’t have a tool box so they store all their spare parts in the lower unit.
Stay tuned.

 

[KJM]

Keep looking, maybe someone stashed some money in there too!

 

[Chris1956]

The shift shaft coupler (female) should be pinned onto the upper shift shaft. The reverse lock cam should fit over the lower shift shaft. That is the usual gearcase in a 1973 Merc 850. If you have something else, you have another motor.

I have lost the bubble on this. After you refilled the geartcase with new gear oil, were you able to shift it using a cresent wrench on the lower shift shaft? If in reverse, turn the shift shaft CW to find neutral first, and then turn some more and she should go into forward.

Clean out any debris, parts etc., from the gearcase.

If so, put the gearcase into neutral, the control into neutral, with the slide about 1/2 way on the shift slide, and reinstall the gearcase. I would leave out the reverse lock cam for now. Installing the gearcase in forward or reverse is a fools errand.

 

[BB63QM]

Thanks. Current situation: with the LU dropped, I can shift to reverse with a wrench, but when it pops (in either direction, there is nothing, and if that is after I raise the LU, it cannot be sifted back to reverse.

So something is definitely not right in the gearbox (either a dog issue or a bad shift cam I’m suspecting).
—btw: upon draining the brand new gear oil, it was, again, black as night and a lot of silvery metal was collected on the magnet. This tells me that, at a minimum, there is/was wear in the gearbox and that draining and refilling the gearbox was not sufficient in getting it cleaned out. So it’s time to break open the gearbox.

I’m working with the LU connected (Is this OK?) and have removed the prop, and the carrier retaining ring. The carrier itself doesn’t seem to want to budge, so far, so I’m going to get a puller from Oreilly’s (rental) and see if I can coax it out.

Any hints in this regard would be appreciated.

Once I have it apart, I’ll see what needs to be replaced…I figure that I can pretty much replace everything in the gearbox for less than half of what a used gearbox will run, so repair is my first choice, since I assume only 1 or 2 parts will actually need replacing.

—-are there some parts that should always be replaced? If so, I want to get those on order ASAP. Otherwise, I’ll replace whatever looks off, reinstall the rest, and see what happens.

On the pictures above, as I was shopping for replacement LUs, I was just trying to reconcile why the shift shaft (male) was not extending from the LU in the unit for sale (ie, given that the connection on the shift shaft is female, is it an incompatible unit or do they just have the shift shaft connector sitting on the top of the lower shift shaft in the picture?).

 

[Chris1956]

If you can get gears and dog at a low ebay price and they are good, and you have the knowledge to install and shim them, you have a chance. Most folks do not have that expertise. I would recommend you source a used gearcase, in case you need it.