prop wont fit right on new lower end?

[owencs]

story goes, I got a used lower end and the prop off my ol lower will fit but its loose and moves back n forth, is it ok to have play? need service manual for a 1971 mercury 65hp, to see if I have the right drive shaft for the proppeller,,, can I put spacers in, think im missing a piece, the proppeller drive shaft ol one has a tapered bottom and the new one is straight, the fella said it came from the same motor, also I just noticed the ol one has fine threads and the newer one has course threads, dont know if I had different lower end on in the first place,,,, just looking to get the proppeller on the new lower end unit, with the straight shaft, can I put washers behind the proppeller?

 

[Texasmark]

Re: prop wont fit right on new lower end?

The propeller has to be locked securely to the shaft. Torque spec on mine is 55-ft-lbs. The taper shaft you had also had a tapered thrust washer. The prop was pushed against the tapered washer, whose movement was limited by the taper of the shaft, and then the locking washer, ring, and nut followed.

On what I see here, I see nothing to limit the forward movement of the prop. Right where your finger is in the 2nd photo, does the shaft just disappear into the bearing carrier, or is there a slight raised washer of a sort that turns with the prop. In short, if you had a flat washer on the shaft is there something to stop it before it gets to aluminum? Seems to me there has to be otherwise the first time you hit the throttle the prop will be jammed into the rear of the housing.

Assuming that there is some sort of shelf there you need to add some sort of thrust washer for the prop to push against and to space the prop back far enough on the shaft to not hit the housing and to allow the locking washers and nut to function properly on the other end.

When you say fine and coarse threads are you talking about the prop nut? My '02 has coarse threads.

Mark

 

[owencs]

Re: prop wont fit right on new lower end?

The propeller has to be locked securely to the shaft. Torque spec on mine is 55-ft-lbs. The taper shaft you had also had a tapered thrust washer. The prop was pushed against the tapered washer, whose movement was limited by the taper of the shaft, and then the locking washer, ring, and nut followed.

On what I see here, I see nothing to limit the forward movement of the prop. Right where your finger is in the 2nd photo, does the shaft just disappear into the bearing carrier, or is there a slight raised washer of a sort that turns with the prop. In short, if you had a flat washer on the shaft is there something to stop it before it gets to aluminum? Seems to me there has to be otherwise the first time you hit the throttle the prop will be jammed into the rear of the housing.

Assuming that there is some sort of shelf there you need to add some sort of thrust washer for the prop to push against and to space the prop back far enough on the shaft to not hit the housing and to allow the locking washers and nut to function properly on the other end.

When you say fine and coarse threads are you talking about the prop nut? My '02 has coarse threads.

Mark

you got it right mark, one has a taper shaft and the other one is a straight shaft,,,, what you see in the picture on the straight shaft at the end is a washer, but I do think I need to find my self a spacer to lift the prop away from the housing,,, wasnt sure if there was suppose to be a different kind of spacer on a straight shaft? or do I just have the wrong proppeller? for the straight shaft...the spacer from the taperd shaft I slid on the straight shaft, but proppeller still sits on the housing and to loose when I slide the lock washer on top, around 1/2 inch play! wish it was easy to find a diagram of both styles,,, good description of the tapered shaft mark! exactly how it would fit together!,,,,,, yes tapered shaft is fine thread, and the straight shaft is course,,,, was wondering on that is, when did they make the change from the tapered to straight,,,, maybe this lower end unit was worked on or from a different year,,,, fella said it was from the same engine as mine 1971 mercury 65HP

 

[Texasmark]

Re: prop wont fit right on new lower end?

Probably in the time frame that the multi cylinder original designed, cross flow engines were replaced with the 3 cyl loopers.

You must have something for the prop to push against. You have to have a lip or something at the front of the prop shaft that rotates with the prop shaft.

I can think of two instances where there may be no lip. One is that the splines on the prop shaft stop short and the prop is forced against the termination of the splines by the nut and rear washer. The other is that there is a hole drilled at the end of the shaft and a pin is inserted through it. OMC did it that way for years but there were no splines. I see no hole in your new prop shaft and it is splined.

Measure the length of the prop shaft from the housing to the start of the threads on both shafts.

Measure the length of the splined area start from the housing on both shafts.

On props, go to the iboats prop section and pull up Merc and plug in your hp and look at the options you have. As I recall, for the prop that will fit my '02 90 2 stroke engine the window on that sticker starts in '71. So that tells me that the geometry of the splines and length of all those years, from thrust washer to threads is identical.

Mark

 

[owencs]

Re: prop wont fit right on new lower end?

so after a little more looking at the bottom unit, and the propeller shaft, your right mark that washer does spin, I thought it was stationary, so I was thinking it would cause friction and I would need a spacer with bearing,,,, but that washer does spin, so me and a friend ended up making a custom spacer to lift the prop up from the housing unit,,, she fits perfect, spin and no play on the shaft now having propblems sliding the unit into place, but thats a nother topic at a nother time, Thankx Mark for your help~ Owen

 

[Texasmark]

Re: prop wont fit right on new lower end?

now having propblems sliding the unit into place,

Care to elaborate? You talking about having a problem getting the lower unit to fit into the mid section?

Before you answer, line the two LUs up side by side and take measurements to ensure they measure identically. If they do, when in the installation process are you having a problem?

Shifter in the LU should be in N (center) detent. Wiggle shift rod on LU to ensure its in the center of the N detent. Prop spins freely.

Set the remote control to N and wiggle to ensure it too is centered.

Put a small amount of grease on the splines, not top, of the shifter shaft and the drive shaft.

Locate the water tube and ensure that you know that it will be seated in the powerhead and the water pump when finished. A slight bend is ok, but no kinks.

The drive shaft splines have to mate with the splines on the bottom of the crankshaft. Usually they don't mesh so you have to move something. Since you have the shifter is in N, which I prefer because it is the most precise of the shift positions, you need to turn the flywheel while putting slight pressure on the LU until it slips in. Usually this alignment is what's needed when everything goes together except for the last roughly 1".

Keep an eye on the shift shaft and water tube while seating the drive shaft.

HTH,
Mark