1964 40 hp Evinrude Big Twin driveshaft

[Bill Wilson]

Model #40453S / Serial #E02622<br /><br />I just dropped the lower unit on my 40 hp. I was expecting to find a splined end or key at the top of the drive shaft but it was smooth. As a complete novice, I thought there would be a positive connection at the top. Am I missing something or is the connection a friction type fit?<br /><br />Thanks

 

[Paul Moir]

Re: 1964 40 hp Evinrude Big Twin driveshaft

Yes, the top of the driveshaft has a spline.<br />Sounds like you twisted the top of the driveshaft right off when the l/u exploded & seized! If you peer up to the crankshaft with a flashlight, you should see the splined section still lodged in the end of the crankshaft. It might not be very visible since there's an obstruction 3/4 of the way up.<br /><br />Looks like you have some work ahead of you digging it out... Time to pull the powerhead.

 

[Laddies]

Re: 1964 40 hp Evinrude Big Twin driveshaft

The early 40s with a untapered driveshaft did that alot, when you put it back together try to find one of the necked down ones--Bob

 

[Bill Wilson]

Re: 1964 40 hp Evinrude Big Twin driveshaft

Thanks for the response.<br /><br />Unfortunately you are right Paul; I think that the drive shaft twisted off. It looked so clean –almost like it had been machined! My concern now though is that the receiving end of the drive shaft may be destroyed, so I am hesitant to take the time to remove the powerhead. What has been your experience with this situation – if I remove the powerhead will I find that a new lower unit won’t work unless I replace the receiving fitting?<br /><br />Bob, your right – the driveshaft is untapered.<br /><br /><br />Bill

 

[Paul Moir]

Re: 1964 40 hp Evinrude Big Twin driveshaft

The 'receiver fitting' is actually the end of the engine's crankshaft. It's drilled and splined to accept the male splined end of the driveshaft. The crankshaft is forged steel, so there's a good chance it's alright.<br />It's time to start investigating. The only way you're going to have a good look at the end of the crankshaft is to remove the engine from the adapter plate/midsection. This is easier said than done if this is a saltwater engine. There will be 7 small and 2 large bolts holding the powerhead on from underneath. Up top, way underneath the carb there are two hard-to-get-at nuts holding it down (a crescent or box-end wrench works well on these). Remove all 11 fasteners, disconnect the fuel lines & wires, and pull the engine.