'88 85HP gearcase left out on backporch, top bearing froze

[RRitt]

1988 85HP gearcase. 25" single piece shaft.

I have a lower unit that was stored outdoors in an oceanfront environment. Internally the unit has very low hours and the gears/clutch are in great condition. However, the upper driveshaft bearing is corroded into place and the driveshaft does not spin. The lower driveshaft bearing may or may not have same problem. The gears themselves all have crisp edges and no rounding. However, I would suspect any and all bearings since they have surface rust (I assume that even you clean up a bearing even the slightest surface rust ruins it).

A). Is there a trick to removing the driveshaft? I have opened up the lower section and removed the nut. Driveshaft won't budge.

B.) Is it worth messing with? I think the bearings should be replaced and then it will be good as new. But can the bearings be gotten from a standard bearing supply house? If i have to buy bearings from mercury then I'd just as soon sell the parts.

What would the experts do?

 

[Frank Acampora]

Re: '88 85HP gearcase left out on backporch, top bearing froze

Bearings and seals are all standard BUT---even at a bearing house, the top bearing is 45-50 bucks. I know, I just bought one a while back.

The pinion is a locking taper on the drive shaft and sometimes it is difficult to pull off. But the pinion is the only thing that holds the drive shaft in the case. Once you pull off the lower water pump plate, there is a "crush" washer that holds the cup down onto the shims, but the cup is wide end up. Even if rusted, the cone should just pop out with the shaft. The lower bearing is a simple caged needle bearing, press fit into the case. I am not sure if there is a bottom land but I am reasonably certain it needs to be pressed up to come out. If it is rusted, then very likely the shaft is corroded also, as the shaft rides directly on the needles. If you can find a used shaft, then it is worth rebuilding. If not sell the gears and case assuming the gears are not corroded.

Even a small amount of corrosion --even if cleaned -- will affect the service life of the gears. Remember, they are under extreme pressure; especially Force which use smaller gears than Merc. and OMC. For just goofing around close to home, I would use gears with slight damage BUT I would not sell a gearcase that I knew had them and I would not use such a gearcase for anything any distance from port--Gear wear in this case is logarithmic and I would never know when they would completely fail.

Think about this: Would you take a trailer that showed slight spalling of the bearings out on a road trip? Clean and grease them and they might be fine to go a mile to the ramp and back occasionally. But more?-----

If you do replace the bearings and/or the shaft, remember that the gears must be shimmed again. Usual is .005 backlash. It can be done without the special tool but it takes a "Feel" or "Knack"

 

[RRitt]

Re: '88 85HP gearcase left out on backporch, top bearing froze

The gears are perfect, no visible wear and the surface rust was too light to even cause discoloration. The leading edge of clutch dog has 10 thousandths of wear. If the bearings are replaced this thing should have a lot of years left in it. The main problem is the top driveshaft bearing. There was a pinhole in impeller housing and the upper bearing is galvanically fused to all surrounding metal. After I get it out then the lower bearing may or may not be fused as well. The prop shaft, clutch dog, and spool are in great shape (I've already inspected them). The housing still has good skeg if I can ever get driveshaft out.

I am not in the mood to mess with it. My thoughts right now are to beat shaft with a sledgehammer and if it pops out then great ... if not then throw it away and sell clutch & spool for whatever I can get. What would you do?

 

[Frank Acampora]

Re: '88 85HP gearcase left out on backporch, top bearing froze

If the gears and case are good, then you are more than halfway there. I would be willing to bet that the forward and reverse bearings are in good shape too.

I would clamp the shaft in a really big vise with the case down and beat the case with a heavy rubber mallet to drive it off the shaft.

The top bearing is press fit on the shaft so the mating surface should be in good condition, regardless of the condition of the bearing and the shaft. And, if you can't get the bearing off, the races are dead hard so groove it and whack it with heavy ball peen to crack it off.

So, the condition of the lower bearing will decide for you. If it is good and the bearing surface of the shaft is unblemished, then you're in like Flynn. A little color is OK, but if it has corrosion or pitting that you can feel with your nail, AND if the corrosion is more than 20% of the length of the bearing surface, then it is no good. Less than 20% and the needles will ride over almost without noticing and service life will be acceptable.

I did use a crankshaft in a 125 with more than 20% on one crankpin. The corrosion was light but feelable, the length of the rollers. It was at the contact points of the rollers while it was sitting. That crank lasted 2 seasons. I was not surprised when it finally went.

Anyway: If you put 75 bucks into top and lower bearing and the lower unit is now run-able, then you are doing well. Good lower should go for 150 or more.

 

[RRitt]

Re: '88 85HP gearcase left out on backporch, top bearing froze

thanks for advice. It's going to be helpful. I'm not going to mess with bearings. IMO, they are perfect or they are trash. So it doesn't sound like it is worth fixing. Four bearings at $60 a pop? No thanks.