Mounting bracket adjustment

[1970Thunderbird]

Hello,

I have a 1978 Mercury 800, 80 hp 4 cylinder engine. I just put it on my boat, a 1970 Thunderbird Seminole, today, but I was hoping someone could help me with regards to the mounting bracket.

The bracket has two large bolts at the top that end in a large, circular disc that presses against the transom. At the bottom, there is a length of metal, kind of like fingers, that has a bolt hole near the bottom. There is a "finger" on either side of the lower leg.

Is there any way to widen the spacing of this bracket? The top bolts aren't too much of a concern, as they don't go through the transom. The bottom bolts, however, are about a half inch off my original bolt holes. Since they're so close, I don't want to drill the transom, as it may crack. It looks as if this is adjustable, as the main bar connecting the two brackets is threaded on both ends and both ends also have a large nut.

Does anyone have experience with adjusting this? Or would I be better off getting some stainless steel plate, countersinking two bolts into it, running those into the bracket, and then drilling two holes in the plate and using my original bolt holes in my transom?

Thanks!

 

[Moody Blue]

Re: Mounting bracket adjustment

I am thinking you are describing the transom clamp assy? Two thumb screws/clamps at the top that clamp onto the transom and two lower through bolts.

No way to space out the two side mounting brackets because the part that pivots up and down between them relies on the side brackets for lateral support.

For a proper fix you should epoxy a wooden dowel into the existing holes and make sure the holes are completely plugged. Now drill two new holes to match you motor mounting bolt layout. Bolting through the transom is the only safe way to mount your motor.

 

[1970Thunderbird]

Re: Mounting bracket adjustment

I'm not worried about leaks as much as I am the location of the holes. My old motor mount holes and the new motor mount holes are less than half an inch apart. I'm worried that drilling new holes so close to old ones will basically end up cracking the material between the two holes.

I've got another fix in mind. I was hoping that an adjustment could be made.

 

[Moody Blue]

Re: Mounting bracket adjustment

I'm not worried about leaks as much as I am the location of the holes. My old motor mount holes and the new motor mount holes are less than half an inch apart. I'm worried that drilling new holes so close to old ones will basically end up cracking the material between the two holes.

I've got another fix in mind. I was hoping that an adjustment could be made.

Yeh, that was my point. You fill in the original holes so the structure is restored. You then drill new holes near/into/partially into the dowel plugs without compromising the surrounding structure.

Do a search in the restoration forum for posts on how to repair holes in the transom for more info.

 

[1970Thunderbird]

Re: Mounting bracket adjustment

Ah, ok. That makes sense. I'll give that a look. Thanks