bad lower unit drive shaft

To make a long story short, I bought a boat (1960's vintage) and was told that it ran. I have been working to verify that it does run and have found that the enginge (gm 4 cyl 110 s/n:1633204) runs well, but the drive unit (120/140 decal on the side) had been somewhat neglected. The propeller shaft turned freely, but the lower unit gear oil was milky, so I drained it, pulled it, and found that the drive shaft was pitted and corroded. Also, there was some damage to the gear case housing itself that someone tried to fix with bondo or epoxy putty. A new drive shaft seems to be $200+, and even if I could replace it myself, I have that hole in the housing to fix. I have seen a number of lower units on ebay from $3-500 - is that an option? I am concerned about compatability, especially where the gear ratio is concerned.



My best guess is that I have a merc - I outdrive. I haven't found any serial number on it but I can say that it is a manual trim unit, and it does have the vent hole by the water pump.

Thanks in advance!

Re: bad lower unit drive shaft

After sleeping on it, it seems the best course of action is to replace that lower unit. Other than minding the gear ratio, are there other compatability issues I need to watch out for?

Of course, I could pull the gears and reuse them in the new unit, but after seeing that drive shaft who knows what they will look like.

Re: bad lower unit drive shaft

cap'n james said:

After sleeping on it, it seems the best course of action is to replace that lower unit. Other than minding the gear ratio, are there other compatability issues I need to watch out for?

Of course, I could pull the gears and reuse them in the new unit, but after seeing that drive shaft who knows what they will look like.

Click to expand...

Ayuh,.... Welcome Aboard,... Yer gonna have a Problem,....
Yer lower, the shaft all rusted is the ole course spline,....

They went finer spline at some point, newer...

I'd jump up to a late model, MC-1, complete drive, or possibly an Alpha 1, complete drive, will bolt right on,...
I believe...

Yer workin' on an Antique,... parts, 'n knowledge 'bout swappin', 'n mixin' 'n matchin' is rare...

I know abit of the general stuff, but "gotchas" are everywhere....

Re: bad lower unit drive shaft

If your transom shield, gimbal ring, and bellhousing and drive is all OEM parts for the 110, that was for the 1A-EZ series drives. They are not interchangable with the MC-1 drives.

(120/140 decal on the side)

Click to expand...

The early 120 4 cyl and 140 6 cyl (yes six cyl) also used the EZ series drives.

Re: bad lower unit drive shaft

Don S said:

If your transom shield, gimbal ring, and bellhousing and drive is all OEM parts for the 110, that was for the 1A-EZ series drives. They are not interchangable with the MC-1 drives.



The early 120 4 cyl and 140 6 cyl (yes six cyl) also used the EZ series drives.

Click to expand...

Ayuh,.... In that case, I'd Up-date from the flywheel cover Aft,.....

'ell,... Gut it, 'n do a total Refit....

Get yer driveline from a rotten hull, 'n a good runnin' 3.0l in it....
Anything up to current will do,... pre-90s are potential Rot victims...

Re: bad lower unit drive shaft

Thanks for the input. I have had a tough time identifying the drive, so that is indeed helpful. I certainly wasn't aware of the coarse vs fine splines. I have seen a number of lower units on ebay, and this one in particular looks promising.

http://www.ebay.com/itm/110831744967?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

The picture makes it difficult to see much detail, he does say that it's an "8 spline" I don't know if he's talking about the drive or prop shaft. It does have the vent hole by the water pump, like mine.

Alternatively, I could go with something like this:

http://www.ebay.com/itm/370622931424?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

if it will in fact bolt up.

The idea of a repower is attractive, but the boat is a 1962 Cruisers and I'd like to keep it original, if I can.

Thanks again everybody!