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New BF50a lower unit won't spin in forward or reverse

O

OregonApe

Member
Just got a new old stock lower unit. Looks to be in near perfect condition. I haven't even installed it yet, but I noticed that the drive shaft absolutely will not spin in forward/neutral/reverse. The prop shaft will spin in neutral but not in forward or reverse. Pulling up or pushing in the shifter works fine.

In forward/reverse the drive shaft can turn just enough to turn the prop shaft maybe 1/16 of a rotation before it stops and makes a noise like it hit something.

It almost makes me think that it ships with something to lock it in place but before I tear this thing apart I figured I better ask.
 
Just make sure the key slot on the shaft hasn't been damaged and I wouldn't reuse that impeller.

Hope it all works out for you.

Good luck.
 
jgmo said:
Just make sure the key slot on the shaft hasn't been damaged and I wouldn't reuse that impeller.

Hope it all works out for you.

Good luck.
Click to expand...

Thanks. The key slot looks fine. In fact it looks like it still has some factory grease on it that is dried out (half green and half white). I'm not sure how the woodruff key could have come off or if Honda just doesn't install it from the factory. Given that this is new old stock who knows what happened while it has been sitting. Regardless, I have a whole new pump rebuild kit that I was planning to use on my old lower before discovering it was too damaged to be repairable.

The bigger issue now is that it is a 25" shaft and I need to swap my 20" shaft in. However I didn't think about how the shift shaft would also be 5" longer on this lower so I have to swap my old one in as well which is the plastic housing with rubber sleeve instead of the newer metal housing. Hopefully it fits.
 
Yeah, the shift shaft didn't pop up on my radar either until you mentioned it. So obvious but so easy to overlook!

The key probably just got dislodged due to the impeller slot getting a bit sloppy because the rubber dried out over all these years. And, most things I get shipped these days, the box looks like it was dragged behind the truck instead of in it!

Now, I hate to mention it but I think I must....
.....I hope that you don't run in to shimming issues with this.

I don't really see how just swapping the mainshaft would effect end play but you should measure it carefully anyway IMO. If for no other reason just to make sure it was done correctly from the beginning.

It would be a real shame to grind up your new unit in just a few hours of running.

Good luck.
 
jgmo said:
Yeah, the shift shaft didn't pop up on my radar either until you mentioned it. So obvious but so easy to overlook!

The key probably just got dislodged due to the impeller slot getting a bit sloppy because the rubber dried out over all these years. And, most things I get shipped these days, the box looks like it was dragged behind the truck instead of in it!

Now, I hate to mention it but I think I must....
.....I hope that you don't run in to shimming issues with this.

I don't really see how just swapping the mainshaft would effect end play but you should measure it carefully anyway IMO. If for no other reason just to make sure it was done correctly from the beginning.

It would be a real shame to grind up your new unit in just a few hours of running.

Good luck.
Click to expand...

Yeah, the shipping box is rough. The seller also didn't put anything over the splines of the drive shaft show they stabbed through the box in a bunch of places.

Regarding shimming, are you talking about the #20 shims here https://www.boats.net/catalog/honda...ay-lra-bays-3200001-to-bays-3209999/propeller ?

In theory, I shouldn't need to adjust anything since in theory nothing is changing with the clutch or the prop shaft assembly. I'm just replacing one drive shaft with another. Fingers crossed for sure.
 
Yes...I think!...but also 21....which I see are no longer available :(

Also, I don't remember the details as I think I only did one...on a BF8D...and it was many years ago. I do remember that it was a pain but the details of what is involved are almost lost in my fuzzy, fuzzy memory.

I only mentioned it so that you could think it over and make a decision. If you don't have the shop manual that explains what to look for, I guess it's a moot point anyway.
 
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