The Boating Forum - Simple outboard transom bolt question
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07-03-2012, 10:16 PM
I have a couple of simple questions.
1) What is the standard size and type of bolt for mounting a 150 outboard?
2) Anybody know what the dimensions are for the bolt pattern on the new Mercury 150 4-Strokes (NOT the Verado). Is it still something like 13" from center to center?
07-03-2012, 11:37 PM
Bolt patterns are standard on OB's.
07-04-2012, 02:02 AM
After further research on Google I found that apparently Mercury and Yamaha switched to using OMC's bolt pattern around 1984 but Force continued with their own pattern for a while longer. The engine I removed far predates that so, the new bolt pattern in fact is NOT the same as what I had previously. Since I am halfway through rebuilding my transom, it is not going to matter because I will just drill new holes. Google also tells me that the bolt size is 1/2" but I am not sure what thread count or type of stainless. They also said it is standard to use brass locknuts which I would not have guessed but should have. The research also said the standard size is 12-7/8" from center to center which surprised me because looking at some of the TH Marine transom support plates on their website, the dimension they list is 13" from center to center.