2019 Yamaha 150 mounting torque specs

[TidewaterDub]

I have a 2019 Tidewater 210lxf. I recently added a power pole braced bracket between the motor and transom. I have everything snugged back up but I can't find the torque specs for the upper and lower mounting bolts that attach the motor to transom. My dealer says the service manual says firmly tighten but I don't like that. There has to be a spec to go by. Any info would be appreciated.

[fairdeal]

from the Yamaha Manual:

[DennisG01]

Probably darn near impossible to get a torque value going into a flexible surface like a transom. Sometimes Yamaha knows more than you.

[robert graham]

Heck, and if makes you sleep better, put some Loctite on the locknuts.....

[fairdeal]

Suzuki, however, believes in a torque spec,
this is for the DF150 - DF250:

[boscoe99]

I can't find anything in Mercury service manuals either about a specific torque value.

I would guess there are too many transom stiffness variances to try and guess at a torque value. Although Suzuki does.

[boscoe99]

Evinrude says torque to 40 pound feet.

[DennisG01]

Wondering outloud here... and by no means am I an expert on this subject. But if torque values are there to keep two items tight together or to keep the nut/bolt from loosening... the use of a nyloc nut gets rid of the latter issue, right? And the "tightness" of the engine bracket to transom only needs to be tight enough to keep it from sliding around, right? And that is easily figured out by anyone with basic experience in turning a wrench. And, further, it's less about keeping things tight together and more about tightening something equally, such as an engine head or even a car wheel. And that issue (equal tightening) is really a non-issue in the case of an engine bracket. Am I off base on this line of thinking?

[TidewaterDub]

Thank you all for the info. The reason I asked this here is because my dealer told me 80lbs and I thought that was crazy. I started low and when I got to about 50lbs the bolt and washer on the lower two inside started to sink into the transom. It wasn't too bad so I backed it out and ordered a lower transom plate and posted the question here.

[boscoe99]

Wondering outloud here... and by no means am I an expert on this subject. But if torque values are there to keep two items tight together or to keep the nut/bolt from loosening... the use of a nyloc nut gets rid of the latter issue, right? And the "tightness" of the engine bracket to transom only needs to be tight enough to keep it from sliding around, right? And that is easily figured out by anyone with basic experience in turning a wrench. And, further, it's less about keeping things tight together and more about tightening something equally, such as an engine head or even a car wheel. And that issue (equal tightening) is really a non-issue in the case of an engine bracket. Am I off base on this line of thinking?

Think of a bolt as a stiff spring. Which it is. When it is torqued then it stretches. Being a spring it wants to spring back to its original shape and in so doing clamps components together. For sealing. To prevent movement. To prevent fatigue damage to the bolt. For other reasons.

Now since you want it to keep acting as a spring, pulling with XYZ force, you don't want it, or its nut if one is used, to turn and loosen. Which would reduce the clamping force. So any number of ways are implemented to keep it from loosening. In aviation they use all sorts of means. Nylocs, safety wire, safety tabs, torque seal, locktite, etc..

[panasonic]

Think of a bolt as a stiff spring. Which it is. When it is torqued then it stretches. Being a spring it wants to spring back to its original shape and in so doing clamps components together. For sealing. To prevent movement. To prevent fatigue damage to the bolt. For other reasons.

Now since you want it to keep acting as a spring, pulling with XYZ force, you don't want it, or its nut if one is used, to turn and loosen. Which would reduce the clamping force. So any number of ways are implemented to keep it from loosening. In aviation they use all sorts of means. Nylocs, safety wire, safety tabs, torque seal, locktite, etc..

Or good old fashioned peening the end threads of the bolt after the nut is on. We used to have Bae 146 jets years ago and there were some bolts on the landing gear that required the threads sticking out pass the nut to be peened over to keep them from backing off!!! Brilliant design.

Also on the same aircraft the inlet lip on the engine nose cowl was held on with say 100 plus 10-32 countersunk screws. These screws would go into self locking anchor nuts riveted on the mounting flange inside the cowl. If one of those screws happened to back out it would go through the engine...bad things would happen.

So for double safety they made special screws for this area. The screw had about five threads at the end, then an area without threads and then more threads up to the shank and head. Put the screw in the hole and turn about 5 turns, that part would pass through the nut, screw would then fall in some and then pick up on the second section of thread and finally tighten up.

Easy peasy going in...how do you get them back out??

[DennisG01]

Stiff spring... that's a good analogy. I hadn't heard that before, but it makes sense.