I have a B100 (10hp), and the lower driveshaft needs to be replaced. It seems the one I have is carbon steel with chrome plating, and the area around the impeller pump pin has rusted away causing the impeller to spin on the shaft.

The 10hp is an early one sold in Canada. I haven't figured out it's age but it's the version with the mechanical points and advance weights.

The Model/Serial number is:
B100-1000791

The lower driveshaft appears to be NLA. Can I use a later BF100 shaft? Did they go to stainless at some point? Got one??

(Unfortunately, the engine runs perfectly and has very low leakdown!)

If need be, I can take photos, mic and describe the driveshaft.

Thanks a million!

- Paul Moir

No, it didn't supersede to any other part number. Not sure if newer shaft would work, would probably have to change upper and lower shaft.

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Boats.net
Honda Outboard Parts

Thanks for your help!

Looking further at the parts lists, one big difference between the older and newer shafts is that the newer shaft takes a different impeller (but the rest of the water pump appears to be the same). Perhaps it's a half-moon setup rather than the pin drive the original used. The upper driveshaft is the same, which is a positive sign.

I'm thinking I might order a later shaft and impeller (which I need anyway; removing the old lower driveshaft from the upper took some serious persuasion) and seeing if I can adapt them. I have a lathe and mill and can modify the part a bit if needed. I just can't make splines for the end or I'd just make a new one.

Just an update on this for anyone else with the same problem.

The later lower driveshaft is a direct replacement except it uses the newer (cheaper!), half moon impeller. It's also stainless steel for the part exposed to the elements, then transitions to steel inside the l/u. So this part is quite a bit better than the older pin drive driveshaft which is only chrome plated.

So all you need to convert is the lower driveshaft and the later impeller. Easy-breezy.