MC-1 lower unit on alpha upper?

[500dollar744ti]

I am having some trouble keeping lower units from breaking. I had one break at the beginning of the season, and now I have another one broken 100 hours later at the end of the season on my last trip out. I don't know if it's the torque of my engine, it's the 270hp which seems right on the cusp of the 300hp breakage point people claim on an alpha one.

I've hit a rock once and bent a prop throughout the season so let's just attribute the broken lower unit to that. At least it makes me feel better, like there's a good reason.

From what I can see, it looks like the only difference between the generation 1 alpha lower units and older MC-1 lower units is the locating pin at the top of the input shaft.

Can I use the older style lower unit on my alpha gen 1 upper if I cut that locating pin off?

Is that the only difference in the lower units?

 

[achris]

Re: MC-1 lower unit on alpha upper?

I am having some trouble keeping lower units from breaking. I had one break at the beginning of the season, and now I have another one broken 100 hours later at the end of the season on my last trip out. I don't know if it's the torque of my engine, it's the 270hp which seems right on the cusp of the 300hp breakage point people claim on an alpha one.

I've hit a rock once and bent a prop throughout the season so let's just attribute the broken lower unit to that. At least it makes me feel better, like there's a good reason.

From what I can see, it looks like the only difference between the generation 1 alpha lower units and older MC-1 lower units is the locating pin at the top of the input shaft.

Can I use the older style lower unit on my alpha gen 1 upper if I cut that locating pin off?

Is that the only difference in the lower units?

NO!!! You MUST leave the pin on!!!! That pin has nothing to do with the upper. It's a pre-load pin for the top bearing in the LOWER housing...

If you want to use the MC-1 lower on the Alpha One upper, just bolt it on, don't cut anything off...

Chris.....

 

[500dollar744ti]

Re: MC-1 lower unit on alpha upper?

Ok, got it! Why don't the alpha's have that pin if it's for preload? So the alpha 1 gen 1 upper unit will accept any MC-1 or newer lower unit? Any downside to using the MC-1 lower?

I'm glad I came here first because I would have just cut that thing right off and stuck it up in there. I've learned over the years it's better to ask instead of just assuming when you aren't sure.

 

[thumpar]

Re: MC-1 lower unit on alpha upper?

My old boat had an alpha upper and lower was with pin. It worked fine for the 7 years I had it. Most people suggest not to use the upper o-ring and I didn't.

 

[haulnazz15]

Re: MC-1 lower unit on alpha upper?

Ok, got it! Why don't the alpha's have that pin if it's for preload? So the alpha 1 gen 1 upper unit will accept any MC-1 or newer lower unit? Any downside to using the MC-1 lower?

I'm glad I came here first because I would have just cut that thing right off and stuck it up in there. I've learned over the years it's better to ask instead of just assuming when you aren't sure.

It has to do with the design of the MC-1 lower unit bearing. The design was changed with the Alpha I lower unit, which has a redesigned bearing which doesn't need the preload pin.

 

[500dollar744ti]

Re: MC-1 lower unit on alpha upper?

Ok, that's good to know. Since my lower units don't seem to be lasting too long, I don't intend to pay too much for replacements. I got a real ugly alpha one lower with half a skeg on ebay for $80.. it's a real gem, look at the fine skeg and cavitation plate damage. I think it will work okay even with the damage.

 

[achris]

Re: MC-1 lower unit on alpha upper?

Seen 'em used a lot worse than that without any problem...

 

[Eric 3.7LX Alpha 1]

Re: MC-1 lower unit on alpha upper?

I am having some trouble keeping lower units from breaking. I had one break at the beginning of the season, and now I have another one broken 100 hours later at the end of the season on my last trip out. I don't know if it's the torque of my engine, it's the 270hp which seems right on the cusp of the 300hp breakage point people claim on an alpha one.

I've hit a rock once and bent a prop throughout the season so let's just attribute the broken lower unit to that. At least it makes me feel better, like there's a good reason.

From what I can see, it looks like the only difference between the generation 1 alpha lower units and older MC-1 lower units is the locating pin at the top of the input shaft.

Can I use the older style lower unit on my alpha gen 1 upper if I cut that locating pin off?

Is that the only difference in the lower units?

No... also the water pump base is different, the rest of the impeller kit is the same. So if you intend on putting in a new one make sure you double check and install the correct water pump base for it

 

[CharlieB]

Re: MC-1 lower unit on alpha upper?

If your old unit has the shared oil passage to the lower be sure to glue an O-ring in place on the bottom of the upper to seal the oil passage off or you will lose your gear oil.

 

[thumpar]

Re: MC-1 lower unit on alpha upper?

If your old unit has the shared oil passage to the lower be sure to glue an O-ring in place on the bottom of the upper to seal the oil passage off or you will lose your gear oil.

It is a quad ring and is part of the impeller kit. There is no glue needed.

 

[achris]

Re: MC-1 lower unit on alpha upper?

If your old unit has the shared oil passage to the lower be sure to glue an O-ring in place on the bottom of the upper to seal the oil passage off or you will lose your gear oil.

The lower has a cut groove in the top, around that passage. If you put a quad seal (NOT an 'O' ring) in the groove, do not glue one to the upper or you will loss oil....

Chris.......