Torque on transom bracket bolts

[eli_lilly]

Hello,

I have a really old boat (1969) and I recently replaced the outboard. However, I have no idea if I tightened the mounting bracket bolts (connecting outboard bracket to transom) to sufficient torque. I did significant searches both here and on Google and didn't see a single mention of even a suggestion for torque specs. For now, I am going with "tightened yea tight", but if anyone has a better idea of how tight these bolts should be, I'd appreciate the information. I am afraid of underdoing it and having the bracket vibrations chafe the transom or overdoing it and busting the fiberglass.

Thanks,
-E

 

[Frank Acampora]

Re: Torque on transom bracket bolts

Standard torque on 1/2 ihch coarse thread bolts is around 55 foot lbs. and the fine thread is a little higher --I don't remember how much. 3/8 bolt is 270 inch pounds--about 25 foot pounds. 55 ft lbs may be tight enough to squeeze the bejesus out of your transom so you may not need to go that high. Use a fender washer and a locking nut for vibration resistance. One grunt with a standard wrench should do it.

And hint: next time you do it, chamfer the edges of the hole about 1/16 with a countersink. Then put silicone sealer. The chamfer makes the sealer act like an O-ring seal when you tighten the bolt.

 

[Salmonseeker]

Re: Torque on transom bracket bolts

I have a 2004 50hp Johnson on a 16 foot aluminum Crestliner. It says to torque to 40 ft. lbs. It also say to re-check twice a season.

 

[eli_lilly]

Re: Torque on transom bracket bolts

Thanks for the fantastic replies. "One grunt" is about what I used, but I'm heading out there with my torque wrench to double-check now. I did use 4200 on the holes and some nice washers, stacked in decreasing size, but I didn't chamfer the holes - great idea for next time.

Thanks,
-E

 

[Scaaty]

Re: Torque on transom bracket bolts

"One grunt" is about what I used,-E

And about all I ever used..yer fine​