replacing lower unit- shaft length??

[dicus22]

I'm replacing my busted lower unit on my 2.0L mariner 135hp v6. I think it's about a 94,95 off a procraft bay boat. I want to buy a lower unit off Ebay but I'm not sure about what shaft length is. I keep seeing 20 and 25" shaft lengths. How do i measure shaft length? Is it not the actual physical length of the driveshaft? My driveshaft measures much more than the 20 and 25" lengths i keep seeing. If somebody could steer me in the right direction I would greatly appreciate it.<br />Also, are merc, and mariner lower units interchangable? Thanks Robb<br />Robb

 

[achris]

Re: replacing lower unit- shaft length??

Robb,<br />The 20" and 25" you are seeing are the transom heights, known as longshaft and extra longshaft. On the engine it's measured from the transom bracket to the anti-cavitation plate. For you the easiest method would be to measure the height of the transom on the boat. From where the motor sits to the bottom of the boat. And Merc and Mariner are the same, except the paint colour. Just be sure to get the right gear ratio. Yours should be 2:1. That is 2 turns of the driveshaft to 1 turn of the prop shaft.<br /><br />Chris............

 

[rickdb1boat]

Re: replacing lower unit- shaft length??

Maybe this will help:<br /><br />

 

[dicus22]

Re: replacing lower unit- shaft length??

Thanks guys, I appreciate the help! I'll go give it a try..<br /><br />Robb

 

[achris]

Re: replacing lower unit- shaft length??

Thanks Rick,<br /><br />Picture's worth a thousand words and all.<br /><br />How do you do that? Put a drawing up there.<br /><br />Chris.........