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Johnson lower unit issues

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ShayneCastonguay

Contributing Member
I have a 1982 johnson 50hp outboard that I needed a new gear case for. I was able to get a new case and rebuild the whole prop shaft/ bearing carrier assembly. I am now rebuilding the drive shaft assembly. There is a few pieces called the "cone and roller assembly" that fit in a cavity around the drive shaft, but will not fit on the new case, it still fits snugly on the old gear case, any idea what could be the issue? Is the cavity too small and why?
 
I tried to press it in with an arbor press, i could get the front in but as it tapered it stopped. The gear case cavity looks clean of burrs, that was my first thought
 
It looks more or less the same as what i have here. The exception being that it has the different style upper thrust bearing and the cap has a cavity that goes around the bearing (that's what it looks like to me) everything else fits well except that bearing, might i be able to get away with simply changing out to the 1992 bearing?
 
My other option is to turn down the outer diameter of the thrust bearing jacket, I'm going to talk to a machinist and see how possible it is to do that.
 
I'm going to try remachining the bearing race first. I assembled the whole thing (minus the bearing) to verify that it all worked, and it did. So if i can make that bearing fit i think I'll be ok
 
Report: I was able to CNC the bearing race to a smaller diameter to fit the new casing. I put the gasket compound on everything, I'm just waiting for it to cure to put the bearing cover back on
 
I doubt it will stay together as the newer gearcase is machined to a different spec than your old one and you now have changed the entire pinion depth dimension's.
 
That's the most worthless video I have seen as there are no specs for backlash on a Johnrude lower unit and they do not make any shims to change it. It is a precision machined housing and only adjustment is pinion height.
 
Apparently you never have built a OMC unit as you use the driveshaft shimming tool and gauge. This gives you the correct measurement and number of shims needed to have correct height, once set you do not add or subtract shims to change any setting including non existent backlash specs. Since the newer housing uses a different bearing the height is different due to bearing thickness.The housing is machined to a certain spec and when you install driveshaft assy pinion and gears will mesh properly and be at machined backlash clearance.
 
I use the proper shimming tool as well. Very easy to use with no worry when you go to 5500 RPM.------Some of these you tube videos can be very entertaining in my opinion.
 
If he had used the correct year housing it would be a non issue as it would be just swap all parts from one housing to the other. Since he machined race to make it fit the measurement on his driveshaft has changed as bearing thickness is different between years.
That video is real helpful if you have the special tools and the proper measurement for his gearbox.
Click to expand...
You have to have this tool to repair a OMC gearcase if you install: new/used driveshaft, driveshaft bearing or gears
 
Found a casing for a 1987 48hp, all of the bearings match up part numbers. The drive shaft seems to have slight variations, which is fine because ill be using my drive shaft assembly. At least all the bearings will be a direct fit
 
Mine did not have a shim (I think, I'll check) but if it did, I'll have it in my parts bag. I don't have the measurement for the pinion height, but i ordered a new upper driveshaft bearing with the casing
 
Just got the new bearing and lower unit casing in. The casing came with a new bearing cap and a shifter seal cap which match my cracked 82'. But the bearing STILL does not fit, it appears to be a similar issue as with the 90' casing. Very frustrated. The part diagrams match for those driveshaft bearings on my 82' and on the purchased 87' 😡
 
It does! But what really confuses me is that they changed the bearing cap too, and this ebay casing has the same bearing cap as my motor, so why is the cavity different?
 
This bearing cap has 4 bolts. So what you're saying is that a special 1988 model has the 4 bolt bearing cap along with a flat thrust bearing? Because the bearing I bought said it replaced all sorts of models, including the 1987 and 1982
 
I just went through all of the 1988 50 and 48hp models and any of them that use a 4 bolt bearing cap (like my original and the ebay purchased one) have the "cone and roller assembly" which all have the same part number, that match the bearing i bought. I am so confused
 
I will. And most of the parts themselves did not have numbers on them. So i went by the tags on my motor for all of my original parts/part numbers. Then went by year on the new casings. At this point i might as well buy all the bearing associated with both iterations and see what works. But i will call seaway first.
 
Note.----------------The commercial models use the 3 cylinder gearcase.------2 cylinder gearcase / gears are not very robust.-----------Experience helps here.
 
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