MC-1 to Alpha Fitment Question

[Lancer76]

My 1976 MC-1 drive (SN 4518534) gave up the ghost today. The drive shaft still turns and there was not burned rubber smell, so the coupler is okay. With engine running I shift forward, and the motor revs, but no prop movement. Same with reverse. With engine off and the shift lever in neutral, prop spins freely each way. When the shifter is in the forward position, props spins in the clockwise direction with little momentary resistance and some clicking with the resistance. In the counterclockwise direction, there is more firm resistance, but I can overcome it by pushing harder on the prop. With the shifter in reverse, I can spin the prop in either direction fairly easily with a similar momentary resistance that is easily overcome.

I've read a few posts that suggest that my upper or lower are toast. I haven't taken the top off the upper. Is there a special tool that fits the 4 starred bolt heads on the lid of the upper?

I haven't taken off the prop, and while I would hope for a spun prop, I am dubious of that outcome.

So I think I have to find a used outdrive. My understanding is that an alpha one gen 1 upper and lower combo will mate to the MC-1 bell housing. Is that assumption correct?

My gear ratio is 1:1.50. If I find a 1987 1:1.5 alpha one gen 1, will that work regardless of what motor it was originally mated to (mine is a 233)?

Thank you. Any tips on diagnosing the outdrive issue would be appreciated. Also, will an outdrive SN be indicative of the gear ratio, and if not, how do I determine that?

 

[tank1949]

Dump some gear lube in a bucket and check for metal. You could have a linkage problem. You need a buddy to work shifter while you examine all connections including the part going into OD. I had an issue one time on an alpha where the male and femal keyways (lower unit) would not line up. You might have to worry about drive shafts and gimbal bearings too if you upgrade. Alphas were, in my opinion, a quantum leap over the previous MCs. Bravos are even stronger. It is my understanding that SEI sells turn key MC-1 replacement very reasonable.. Good luck.

 

[achris]

You could have chewed up gears in the upper, or a sheared drive shaft in the lower. Either way, a good second hand drive, or even a new SEI drive is going to be quicker and cheaper than trying to repair the current drive.

The screws for the top cover aren't anything special, they are a standard 3/8" 12-point socket. You could pop the top off and have a look.

The Alpha One will bolt straight up to the old MC1 bellhousing. The shapes are slightly different, but it's not a problem, and the gasket seals them up without a problem.

From the serial number we can get a model number, and from that it can see the ratio. But.... If someone has changed the gears in the upper, then the ratio may not be the same as original. I would suggest you do a turns count.

Mark the prop (or propshaft if there's no prop on it). Put the drive in forward gear and count the turns of the input shaft until you have 10 turns of the prop shaft. Divide your input shaft turns by 10, and you have the drive ratio.

Chris......

 

[Lancer76]

Well, popped off the top of the upper and found this. Toast. Is would think this gear should be bathed in oil, but it is not. I had not drained any from the drive before taking this photo and I filled the drive just weeks beforehand. Oh well. The channels in the drive at the bottom of the picture show drive oil, but it is not making it to the gears. I must have lost some oil...

Regarding the turning of the prop and the input shaft, I suspect that is not possible given the condition of the gears. I am pretty certain of the 1.5 ratio. It is the stock setup a shop painted that ratio on the outdrive, too. I see that this set up, 1976 Mercruiser 233 has a 22/20 gear count. Maybe I could just count vertical and horizontal gears to verify?

 

[Bondo]

Ayuh,..... Find yerself another 1.50:1 drive, either an MC-1, or Alpha 1,.....

 

[achris]

...Regarding the turning of the prop and the input shaft, ...

I gave you that so you could check the ratio of any drive you were considering buying. Or yes, pull the top cap and count teeth.

Chris......

 

[Lancer76]

"I gave you that so you could check the ratio of any drive you were considering buying"

Good suggestion. I missed the application. Thank you.

 

[Lancer76]

Update and question.
Update: I found an 888 1.5 ratio upper, and it seems to work. However, when I had the drive off, I thought I give another whack at securing the exhaust bellows to the drive. The exhaust bellows tool I have requires that I remove the shift shaft to insert the tool, but the shift shaft set screw was tight. To break the screw free, I threw some heat to it with a torch. Was not able to remove the shift shaft, so exhaust bellows remains unsecured and I can live with that. However, when I put the drive on and ran the engine on the muffs it would shift nicely into and out of forward, but would stall the engine when I put it into reverse. Looking at the shift plate, I could see that the shift interrupt switch is being activated as I shift into reverse. My initial thought is that the heat I applied to the shift shaft screw deformed the end of the lower shift cable sleeve, which is causing resistance and thus the activation of the shift interrupt switch (the shift cable was replaced last season, so heat deformation would be the only reason for binding). With that in mind, I purchased a new lower shift cable. In preparation for install, I am reading instructions and watching various videos, including the shift cable adjustment video prepared by achris. In that video, it is stated that 1976 and later drives had the brass barrel at 6" from the end of the cable, and 5-7/8" for pre-1976 drives. My brass barrel is presently set at 6". I don't know when my "new" 888 upper was made, though I see they were made from 1971 to 1977. My question is, assuming arguendo that the 888 upper is pre-1976, would the difference in the brass barrel adjustment result in the stalling that I am experiencing? The lower is an MC-1 with preloaded pin, but I think it is 1976.

Thanks a lot!

 

[achris]

The difference in measurement is caused by differences in the LOWER housing, not the upper.

In heating the lever on the upper shift shaft, you may have melted the plastic washer under the lever, and that may be binding up and causing your stall on shifting to reverse.

When you pull the drive and before you remove anything else, just roll the shift slide out of the way and make sure the upper shift shaft and lever turns smoothly and without restriction through its entire range.

Chris....

 

[Lancer76]

Is the "plastic washer under the lever" referring to a plastic washer on the shift shaft? I am remembering back to late last summer when I had it apart and there was a tender plastic washer. I assume you are referring to item 30 in the linked diagram, correct? It's referred to as the Upper Shift Shaft Lever Washer. If not, then where? And thank you yet again, achris.

 

[achris]

Is the "plastic washer under the lever" referring to a plastic washer on the shift shaft? I am remembering back to late last summer when I had it apart and there was a tender plastic washer. I assume you are referring to item 30 in the linked diagram, correct? It's referred to as the Upper Shift Shaft Lever Washer. If not, then where? And thank you yet again, achris.

That be the one...

 

[Lancer76]

Another update: The plastic washer was fine, but the end of the lower shift cable sleeve was pretty distorted from heat I applied (see photo). So I purchased the Quicksilver lower shift replacement and installed. Installation went fine. Checked engine alignment, and installed drive. I followed the cable adjustment procedure - both cables off the shift plate, lower shift cable in forward with helper turning prop CCW, measured free play, adjust brass barrel to 6" from center of plastic retainer hole, install lower shift cable, measure travel from forward to reverse on drive cable, turn plastic barrel so it fits over shift plate and them advance toward the end 4 turns and install.

On the trailer, shifting is fine, prop lock as it should in forward and reverse. On trailer w/ engine on - again does what its supposed to do.

In the water, the boat shifts into forward and reverse very easily and well, but will not shift out of either unless I shut the engine down. For some reason, the shift interrupt switch isn't activating. I looked at the shift plate while my son tried to shift from forward to neutral (to no avail). The second and third picture show the shift plate and interrupter switch in forward and then while trying to go from forward to neutral. In the last photo, it looks like the interrupter switch should have activated, but it did not. Would you agree.

I guess I need to test that switch. Anything else?

One other thing I should add - I also added a 10K ohm resistor to the tach wire from the negative side of the coil. The Pertronix system I installed wasn't behaving well with my tachometer. That's the only electrical work I've done since the interrupter switch last operated. The resistor did the trick.

Thanks.

PS I cleaned all the crap out of the bell housing before installing the new cable.

 

[achris]

Just check that the switch is wired into the ignition properly.

Chris.......

 

[Lancer76]

Aha! I think i found the issue. The tach wire from the coil also powers the shift interrupter switch. I put the 10K ohm resister in line right at the coil. I need to move that to under the dash - after the split to the interrupter switch. Or run a separate line to the interrupter switch.

 

[achris]

An extra 10k in the interrupt switch line? Yep, that'll stop it working...

 

[Lancer76]

Final post on this one - I moved the resistor so it is "after" the shift interupt switch and all is good again! "New" upper is inplace with new ujoints, shifting is clean, Pertonix fires well, and tach works again. Nothing more to do, but go boating! Thanks all!