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Mercruiser 120 lower unit

I want to remove the bearing cup that is above the oil slinger but the oil slinger is right up against the bottom of the cup hindering to get jaws of the slide hammer to grab it
I had to modify the jaws of my slide hammer by grinding them thinner to fit under the race. Will help if you can heat the gear housing, the AL expands pretty good with a little heat.
 
I've resealed #1 & EZshift models but never needed to change any bearings.
I assume if the pinion bearing needs to be replaced then the sleeve needs to come out to fit the driver down the hole?
1967 thru Alpha gen 1 many times. I have all tools; Pullers, drivers & shimming tools.
 
That EZshift lower has an oil level screw just below the water pump. There must be an air pocket after filling for expansion purposes. So the sleeve helps oil spiral up to the bearing.
If I recall, some 1967 thru 1969 drives still had that screw installed but because of the interconnected oil chambers the air pocket is now in the top chamber. Disregarding the oil passage issue for now, will a 1967 thru 1969 physically bolt on? I don't know but the driveshaft splines will mate.
Reason I mention this is if the replacement lower he bought is a 1967 thru 1969 unit, it will have the oil passage. While I believe the seal ring 26-45577 is installed in a recess machined into the lower & could as such be installed and seal up tight to the upper......how does one fill the unit to proper level? Dropping the unit a bit & filling to overflow would eliminate the air pocket. So that won't work. If the replacement housing has the upper screw installed then 1 could service oil to the proper level but without the sleeve installed I think the upper bearing would statve for oil.
The parts catalog states early build (so early 1967) units were built with the sleeve. I guess if his replacement unit has the upper oil level screw & the sleeve installed (whether originally or transfered from original housing) maybe it will work.
 
I've resealed #1 & EZshift models but never needed to change any bearings.
I assume if the pinion bearing needs to be replaced then the sleeve needs to come out to fit the driver down the hole?
1967 thru Alpha gen 1 many times. I have all tools; Pullers, drivers & shimming tools.
Yes, the sleeve needs to come out to get the driver tool down to the lower bearing...
 
You need a manual. There is a set up procedure and special tools required including a dial indicator. Not sure you want to invest all that money for one 1967 lower unit.

In the end, its your boat you can do what you want but, if its out of specification to much it can lead to catostrphic failure.

Maybe seek out a shop which has the tools and manuals to do it properly
 
I have the manuals, what I don’t understand is what would change if I was to just switch out the bearings and cups with the same shims. What changes in that process?
 
If I’m replacing the bearings and cups, can I use the same shims that were in place originally?
Maybe. by the use of shims essentially that is saying there is enough tolerance in the machining of the housing, race, and bearings that depending on what combo of pieces you have they are all custom fit. Starting with the old shims is a good place to start then take your measurements and rolling torques.

I did my Gen 2 last year on the upper vertical driveshaft I think I used the same shim thickness on lower for gear spacing but on upper bearing cup in the underside of the cover I had to change the shims to get the correct rolling torque.
 
I have the manuals, what I don’t understand is what would change if I was to just switch out the bearings and cups with the same shims. What changes in that process?

This statement raises issues.

First, Many here have factory training and many years of experience. The questions and answers are not given without a lot of experience behind those responses.
As stated above, there are tolorances for all parts. Those tolorances can stack up in the wrong way to change the set up and require shim changes.
At a minimum, all specs should be checked.
You seem to want a QUICK FIX.


If you have the manuals, I suggest you read thru the reassembly process of the out drive and in your case the lower unit.

It is clear in the manual how to do it and how to measure the several key specifications and what to do to change/correct to achive the desired set up factory specifications.

Other wise, Its your boat, do it the way you want even if it is short cutting the factory process/set up. If it works, your good to go. If it fails, you will understand why.
 
"You seem to want a QUICK FIX."

A quick fix would be to buy an SEI and be done with it. Or dropping it off at a shop and picking it up when it is done. Fixing it himself will be a slow, interesting, fix. He is probing whether that is feasible.
 
Should the bearings be shimmed periodically in the span of the life of the outdrive?
The way I understand it, having worked on exactly one outdrive, but after studying it thoroughly and with a lot of unrelated mechanical background, is that once the shims are set the first time at the factory the spacings don't change over time. You have to reshim if new parts like bearings or gears are swapped in.
 
Should the bearings be shimmed periodically in the span of the life of the outdrive?

"The life of the outdrive" is a loaded question....lol

I have worked on many older drives
unless sever gear teeth wear or bearing wear is observed, there is no need to check specification.


Yours is very old.
Mine is 30 years old. I have owned the boat since the year the new drive was installed. (I installed it at a shop I was working at and a week later bought the boat)(original owners insurance payed for new Mercruiser outdrive- Alpha 1 gen 1)

All original parts with the exception of normal maintenance parts and the prop shaft carrier Oring.
 
"You seem to want a QUICK FIX."

A quick fix would be to buy an SEI and be done with it. Or dropping it off at a shop and picking it up when it is done. Fixing it himself will be a slow, interesting, fix. He is probing whether that is feasible.
We are looking at a 1967 boat with what appears to be a left over 1966 1A,B,C with EZ shift engine & drive. (But even if it is a 1967 120-160 drive it doesn't matter.) The vertical driveshaft has course threads and will not mate. These SEI replacement drives have the 1970 & newer fine splines. You CANNOT mate a pre 1970 upper to a 1970 & later lower. Or the other way around either.

Go back to post #21 and look at the gasket requirements. The bellhousing studs are spaced closer on an EZshift than a 1967 & newer. So a complete SEI upper/lower assembly is a No Go either. Now if he measures his stud spacing & verifies the larger size then a complete SEI "should" work.

I say "should" because I have a MerCruiser service bulletin from the 80s introducing the MR (1st version of yet to be named Alpha) drive. It calls out service replacements to be used on an attrition basis. If I recall because of some minor variation in the throw of the shift crank travel there are long slot & short slot arms on the shift plate on the transom and corresponding initial cable length adjustments of either 5 7/8" or 6". The MR/Alpha wasn't called out as an early service replacement for drives with the long slot 5 7/8" arms. The shift arm slot length change was made early 70s but sometime after the vertical driveshaft spline change.

Can a short slot 6" drive be put on a long slot 5 7/8" 1967 & later transom assembly (for discussion purposes here, either MerCruiser or SEI)? According to the SB, no because of cable adjustment but physically it will fit. Can the cables be adjusted well enough to work? Probably so. I'm sure it has been done zillions of times. Also, if one is swapping a complete assy or just an upper, the MR/Alpha used the long "donkey dick" vs the pre Alpha short "donkey dick" on inline engines. So swapping the input shaft may be required. All model year V6 & V8 used the long shaft.

He says he has owned the boat over 50 years. I'm confused how the gasket issue has never popped up before during routine maintenance like greasing, ect.
 
We are looking at a 1967 boat with what appears to be a left over 1966 1A,B,C with EZ shift engine & drive. (But even if it is a 1967 120-160 drive it doesn't matter.) The vertical driveshaft has course threads and will not mate. These SEI replacement drives have the 1970 & newer fine splines. You CANNOT mate a pre 1970 upper to a 1970 & later lower. Or the other way around either.

Go back to post #21 and look at the gasket requirements. The bellhousing studs are spaced closer on an EZshift than a 1967 & newer. So a complete SEI upper/lower assembly is a No Go either. Now if he measures his stud spacing & verifies the larger size then a complete SEI "should" work.

I say "should" because I have a MerCruiser service bulletin from the 80s introducing the MR (1st version of yet to be named Alpha) drive. It calls out service replacements to be used on an attrition basis. If I recall because of some minor variation in the throw of the shift crank travel there are long slot & short slot arms on the shift plate on the transom and corresponding initial cable length adjustments of either 5 7/8" or 6". The MR/Alpha wasn't called out as an early service replacement for drives with the long slot 5 7/8" arms. The shift arm slot length change was made early 70s but sometime after the vertical driveshaft spline change.

Can a short slot 6" drive be put on a long slot 5 7/8" 1967 & later transom assembly (for discussion purposes here, either MerCruiser or SEI)? According to the SB, no because of cable adjustment but physically it will fit. Can the cables be adjusted well enough to work? Probably so. I'm sure it has been done zillions of times. Also, if one is swapping a complete assy or just an upper, the MR/Alpha used the long "donkey dick" vs the pre Alpha short "donkey dick" on inline engines. So swapping the input shaft may be required. All model year V6 & V8 used the long shaft.

He says he has owned the boat over 50 years. I'm confused how the gasket issue has never popped up before during routine maintenance like greasing, ect.


Based on his photos of the bearings it appears that the boat has not seen a lot of use. Other than the pitting they look relatively normal.
My bearings with ~ 1200+ hrs look much more worn than his.

That may explain the lack of reported issues/maintenance problems.

It may be best to do a really good job cleaning all bearings and housing, do a more detailed inspection and if any of the issues are just minor surface issues with no depth, He could reassemble, use high performance gear lube and simply use as is and hope for the best..
 
Based on his photos of the bearings it appears that the boat has not seen a lot of use. Other than the pitting they look relatively normal.
My bearings with ~ 1200+ hrs look much more worn than his.

That may explain the lack of reported issues/maintenance problems.

It may be best to do a really good job cleaning all bearings and housing, do a more detailed inspection and if any of the issues are just minor surface issues with no depth, He could reassemble, use high performance gear lube and simply use as is and hope for the best..
I had the same on some of mine/ When I bought the boat it was an 11 yr old boat with 37 hrs on it, never had any maintenance. I think the staining/corrosion pattern of the rollers the races is from sitting. I never would have opened my drive but got a line on the prop shaft and leaked some lube found some of that pattern/staining. By the time I took it apart to inspect all the bearings i just replaced them.
 
Can a short slot 6" drive be put on a long slot 5 7/8" 1967 & later transom assembly (for discussion purposes here, either MerCruiser or SEI)? According to the SB, no because of cable adjustment but physically it will fit. Can the cables be adjusted well enough to work? Probably so. I'm sure it has been done zillions of times. Also, if one is swapping a complete assy or just an upper, the MR/Alpha used the long "donkey dick" vs the pre Alpha short "donkey dick" on inline engines. So swapping the input shaft may be required. All model year V6 & V8 used the long shaft.
I used to have a herd of donkeys, but they were both females.
 
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