Transom thickness on an 1985 mercruiser 140 with alpha 1

[Rellik546]

Hey guys,

I'm over in boat restoration doing a transom stringer and deck replacement.

In the mercruiser manual it says the transom is suppose to be between 2" and 2.25" thick with no more than a 1/8" deviation around the key hole.

Here's my problem. The keyhole on the bottom is 2" but 1.75" on the top. The difference happened due to much more clamping pressure up top of keyhole which squeezed out the resin putty used to bond the transom to the hull. Is this acceptable? Or do I need to make it 2" all around? The only reason I ask is because I was able to mount the transom plate and gimbal assembly flawlessly. However the lower unit was not in. And there is where I think the problem would occur with not the proper thickness.

If this is gonna be a problem/and any has had this problem how do I fix it? Just layup more glass, gradually getting thicker (more layers)as I approach the top of the keyhole?

 

[produceguy]

Re: Transom thickness on an 1985 mercruiser 140 with alpha 1

I would lay up more glass and make it 2.
.25 seems to be to far off. I don't think it would take to many lay up's to get you were you need to be.

 

[oops!]

Re: Transom thickness on an 1985 mercruiser 140 with alpha 1

i just saw this thread.......

this is CRUTIAL !

it is called flatness and parelellism.....
the transom MUST be in factory specs.....we go for 2 ins....i believe the manual calls for 2 and 1/8? please check the merc factory manual. there are tollerances with the amount of thread on the studs of the outer plate. but you cannot be too thick or the studs will not be long enough to go thru the transom, as well.....there will be steering arm issues.


the hole must be exactally the same all the way around or your transom will leak. (this is called paralellism)
it must be perfectly flat on both sides.....and it also must be of a paralell thickness. all the way around the hole.


the transom should also be at a 110 degree slant to allow for proper trim of the vessel.

 

[Bondo]

Re: Transom thickness on an 1985 mercruiser 140 with alpha 1

i just saw this thread.......

this is CRUTIAL !

it is called flatness and parelellism.....
the transom MUST be in factory specs.....we go for 2 ins....i believe the manual calls for 2 and 1/8? please check the merc factory manual. there are tollerances with the amount of thread on the studs of the outer plate. but you cannot be too thick or the studs will not be long enough to go thru the transom, as well.....there will be steering arm issues.


the hole must be exactally the same all the way around or your transom will leak. (this is called paralellism)
it must be perfectly flat on both sides.....and it also must be of a paralell thickness. all the way around the hole.


the transom should also be at a 110 degree slant to allow for proper trim of the vessel.

Ayuh,... Agreed,... Excellent explanation....