Chrysler 105 L/U

[stubtail]

I have a "project" 105 hp (model 1059BD SN 2222). I believe this to be about a '76 vintage. Not sure as to the extent of problems with the engine, but thought I would pull the L/U to replace the water pump impeller. There was no water in the oil, but the seals all need replacing, so I decided to pull the entire L/U apart. My question surrounds the method by which the pinion gear is secured to the drive shaft. At teardown, the pinion nut was loose, and shows signs of working on the "thrust face", but it hadn't fallen off. There is a tapered roller bearing pressed onto the pinion, and there is another tapered roller just below the water pump. The upper bearing is prevented from moving up on the driveshaft by a retaining ring (circlip) around the driveshaft. (The bearing is still a press fit.) I have a Seloc manual (and a Clymer for Force), but nowhere is there an illustration of this particular arrangement or assembly instructions. During a "dummy build", at 40 in/lb torque on the pinion nut, there is already excessive drag on the driveshaft, as the tapered bearings are being driven together, and the nut is still 1-2 threads out of safety. Do any of the Chrysler/Force Guru's have any suggestions?
I will thank all those who ponder this in advance!

 

[Frank Acampora]

Re: Chrysler 105 L/U

You are describing the two piece lower unit. The pinion is a press fit into the lower bearing cone and is usually shimmed at the factory. The pinion, bearing cup, and cone, nest in a relief in the upper half of the unit. This positively locates the pinion in relation to depth of engagement of gears AND location on the drive shaft in relation to the upper bearing.

The shaft splines are slip-fit in the pinion. The combination of the slip fit, circlip above the top bearing, and tightening torque pre-loads the top and pinion bearing. The pinion nut may or will not necessarily bottom on the threads. It is a deformed nut and should not be re-used UNLESS: If the nut has stake marks on the outside flat(s) take a punch and re-stake them so the nut only goes on about two turns by hand. If it has no stake marks, squeeze two flats in a vise to deform the nut slightly oval again to the point where it will only go on the threads about two turns by hand. Do it in steps so you don't go too far; it is possible to ruin the nut.

Now, tighten the nut only to the point where it pre-loads the upper bearing enough to take out any slop. The shaft should not be able to rise and should not wiggle in the upper bearing cup.

Because the lower bearing takes all gear thrust loads, both vertical and lateral, the pinion nut does not need to be "killer" tight. Its sole purpose is to take the slop out of the top and bottom bearings. The deformed threads keep it from backing off. That is why you do not re-use an old nut without re-deforming the threads.

Make sure that the upper bearing cup is fully seated in the machined recess in the case. It is possible to install them slightly cocked and not fully seated. If this happens and is not corrected, upon running, the pre-load will disappear.

While the two piece lower is perfectly functional, it is not as good a design as the one piece lower. Unfortunately, the two will not interchange. Still, there is a soft spot in my heart for the two piece. The late two piece lowers with the extended cavitation plate just look really nice. Unfortunately, there are no props made for it any more and you must find NOS or buy used at auctions. Thus: While you may not need one now, keep your eyes open. If one comes your way, consider buying it. iboats does not carry them but if you do want new, you can probably get one at franzmarine@aol.com. I have a couple of used. If you are interested, private message me.

 

[stubtail]

Re: Chrysler 105 L/U

Thank you Frank for the good information. I'm sure you will see more questions in the future, as I go through the rest of the outboard. I still have some time before the ice is off the lakes, as it is snowing as I jot this down!