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Discussion Starter · #1 ·
The bolts that hold my power trim and tilt assembly have been shearing. One had the head sheard off about six months ago. I noticed two more were sheared after I returned from Montauk. Information from Yamaha indicated that the broken bolts are caused from loose motor mounting bolts.

Whether the transom is composite or has some wood in it, compression over time can loosen the bolts. The most stress is put on the transom and bolts during towing. The trip to Montauk is particularly jarring in the GW Bridge/Cross Bronx Expressway area. I stay in the center lane and mostly go 40 MPH but it is still rough.

In checking my four bolts I found that could each be tightened several turns. Yamaha said these bolts should be checked and tightened periodically. It makes perfect sense, but it is something I never thought of.
 

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Once you get yours tight- if there is enough thread left-run another nut on it.This might prevent it from coming loose.

If the transom squeezes in - it's time for a 1/4'' piece of aluminum as a backing plate.

Good info :thumbup: - one more item to check but sure beats shearing a bolt off.
 

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Discussion Starter · #4 ·
Once you get yours tight- if there is enough thread left-run another nut on it.This might prevent it from coming loose.

If the transom squeezes in - it's time for a 1/4'' piece of aluminum as a backing plate.

Good info :thumbup: - one more item to check but sure beats shearing a bolt off.
Good points Skip. Parker uses a heavy cast aluminum plate on the inside and double nuts on the bolts. It is a simple matter of material compression. If the Yamaha motor is allowed to move even a small amount, it puts strain on the trim and tilt system bolts. I was able to get one of the sheared bolts out with a vice grips. The other will require drilling a hole and using an easy out. I hope a standard drill will be able to reach it. I have almost as many tools as I have fishing tackle but never bought a right angle drill motor. Once every ten years I wish I had one.
 

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Discussion Starter · #6 ·
That's what I did and it has kept them tight so far.
I emphasize the nuts do not need to come loose, mine were locked down and did not loosen. The stern material compresses and creates the slop. This is possible on any boat unless the transom is all metal.
 
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