Torque Specs

[Bobalouie]

I put a new jackplate on the boat today, and was wondering about what you all torque your stuff to? I called Allison and asked them, and they said just torque it like you torque a tire on your car. So, on the transom to jackplate interface, the upper two 5/8" (I think they were 5/8") bolts, I torqued them to 100 lbs-ft, and on the lower two 1/2" bolts, I torqued them to 80 lbs-ft. On the engine bolts, all 4 of them are 1/2" so I torqued them to 80 lbs-ft also.

Those were the recommended torques from the machinery handbook, and coinsides with what you torque lug nuts to, but I was wondering if I torqued them too much?

 

[K.Kiser]

I don't know what is too much, but I usually go prolly 50-55 on top and 50(ish) on bottom... I would think that Allison woud have a more precise recommendation than they do about some things... There have been times that I may not have tightened to a full 50-6-lbs. and then later had to remove the plate and an engine wouldv'e hanged on it without the bolts in there, just on the adhesion of the sealant... So even at well less than you torqued, I'd say there is zero chance of the engine being able to shift the jackplate around... I've only had one Allison that was new enough to have the 5/8" bolts on top, and I probably tightened them to a little over 50 on top and a little less than that for the 1/2" lowers, and it is buttoned up tight with absolutely no chance of moving.. To me, tightening any more than necessary just stresses the fasteners thus bringing them closer to failure... Did You hear any crackiling or notice any "washer sink" inside the bilge area... I know the 5/8" up top is a fine thread bolt which clamps harder than standard thread @ a given applied torque, and 100 lbs. of torque has got to be a huge amount of compression...

 

[Bobalouie]

No crackling when I was torquing, and I just went out and looked at the bilge and the lower two are just as they were before, no sinking or anything. At 100 ft-lbs torque it is 9997 lbs of compression. That 100 lbs-ft was also only about 75% of max torque so there is still quite a bit of safety factor before the bolt yields. The 1/2" bolts are probably a little tight. They should have been at 75 lbs-ft for 75% of yield, and I put them at 80 lbs ft.

You think I should loosen them back up and retorque to 60 ft lbs? I dont want to screw anything up or put any undue stress on the transom.