Replacing reverse gear only?

[Bobbywolf]

Hi guys,

2004 2stroke Merc 40hp ELPTO

I'll give the story before I get to my question.

I drove this thing into a rock, hard, while on plane at about 1/2 to 3/4 throttle. I got towed back to shore because the prop would no longer turn (Even though the engine sounded fine.)

The prop no longer spun concentric, showing me I had bent the prop shaft, and the driveshaft had sheared off at the spines in the engine crank. Fun. It didn't take long pricing up the 2 shafts to realize that a used lower unit was in order.

I found a lower unit that looks in remarkable shape. Paint is undamaged, and even the skeg shows no damage. One thing I don't like about it is the prop bearing carrier outer edge is chewed up from having something wrapped around it at some point. (I'm not able to attach a pic for some reason)

The question. Can replace the damaged carrier with my old one, and leave my old reverse gear on it? There are no chips or damage, and the gear pattern appears well centered. My thought is that reverse is rarely under load, and these 40's are not shimmed anyways.

The other option is to use the reverse gear from the "new" lower unit on my old carrier, but I believe that would involve replacing bearings as well since they are damaged in the process.

Am I way off in wanting to swap in the the different reverse gear?

Rob

 

[Bobbywolf]

Well, the answer to this question is that you can swap reverse gears IF you are smart enough to count gear teeth. I figured it out in this other thread:

Lower unit noise investigation

Looking for a bit of insight, input. 2004 2stroke Merc 40hp ELPTO I recently replaced the lower unit with a parts one, and it all seemed in excellent condition. Upon installing it onto the power head and running it, I can hear a noise coming from the lower unit in neutral. At first I thought...

forums.iboats.com

 

[Texasmark]

Other thing is that gears "wear in" with their counterparts....little peculiarities. Mating a new surface to a "run in" gear "could be" of concern from a noise standpoint but considering the location with it immersed in gear oil and the water upon which the boat is moving, probably not noticeable if at all.

 

[Texasmark]

Other thing is that gears "wear in" with their counterparts....little peculiarities. Mating a new surface to a "run in" gear "could be" of concern from a noise standpoint but considering the location with it immersed in gear oil and the water upon which the boat is moving, probably not noticeable if at all.

Buttttt you need to check your oil for metal chips when you do your "annual" lower unit fluid change......and the possibility of such would help you to be sure to do that LU service.

 

[Bobbywolf]

I ended up using a matched fwd, rev & pinion in the end, but I can't see why it wouldn't work, considering that the reverse gear is only idling on the pinion with no load for 99% of its life.

As a side note, I've learned that the reverse gear is pressed into a straight roller bearing, which is installed as light press fit into the housing. It is not much effort to pull the old gear and bearing as one, and swapping it over to complete the set. The part of the manual I was hung up on mentions bearing damage, but that is only if you attempt to remove the bearing from the gear itself.

Rob