Mercury 9.8 drive shaft issues

[billw]

Well, the way I see it, your motor has a part # of 45-75034A1. serial 7049108 and up has a drive shaft 45-75034…..WITHOUT the A1. I checked supercessions on Mercnet and they don’t cross with each other. Even I can’t believe the head ache that this part generates in a parts search; but it’s a prime example of how you have to be careful. I am not saying the two definitely will NOT interchange. Sometimes the "A1" means a kit; so the drive shaft 75034 MIGHT just be part of the A1 kit. With such similar numbers, I would speculate that this is fairly likely, but not a guarantee.

As a side light, the "45" is what Mercury calls a "class number." It means a shaft of some kind. "27" would be gasket, "10" is a bolt, screw or the like. "47 is an impeller, and so on. Mercury doesn’t really care about class number. It is for the dealers’ and customer’s convenience. For instance, They would call your 9.8 impeller simply a 89981, not a "47-"89981. And there would be no such part as a 10-89981. That’s probably why some sites list your drive shaft with a "45" and some don’t.

Long live American manufacturing!

[billy-t]

Okay if I find a parts motor would I be able to swap out the whole lower unit regardless of serial numbers and parts matching? I have a lead on one but he serial number is in the 702…range

I know mercury motors run good but they are not easy to work on like the old OMC stuff for parts.

[billw]

Well, the chances are pretty good….but do some measuring….particularly the length of both the shift and drive shafts. It is possible that you can have two "short shaft" lower units but still have a slightly different shaft length. Also note the length of the spline cuts, o-ring groove/no o-ring groove; you get the idea.

Long live American manufacturing!

[billy-t]

Hello still on the case of the replacement drive shaft. The problem is most of the sites dont recognize my Canadian serial number either.

The part numbers that I have found so far are:

45-39078 (used on 1969 7.5 and 4 HP)
45-64257, replaced by 45-75034A1
45-74851, replaced by 45-75034 (which was also used on the 9.8 HP)
45-95873A1 (Stainless Steel upper portion, used on 4.0 and 9.8 HP)

So I am wondering if I can use the 45-75034 without the A1? Or do you physically have to use measurements and side by side comparisons?

Boy working with Mercury requires you to be both a mechanic and a detective.

[Author]

Posts