why torque through bolt and nut??? motor mount install
03-13-2008, 03:45 PM
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why torque through bolt and nut??? motor mount install so I have the new prothane mounts in the car and everything is torqued down except the 2 giant 18mm through bolts. The manual says 70 ft lb on the bolt and 59 ft lb on the nut. Why do you need to torque both - does this make sense? Not a big deal to do it, but I don't want to over tighten. Thanks!
03-14-2008, 08:05 AM
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so I have the new prothane mounts in the car and everything is torqued down except the 2 giant 18mm through bolts. The manual says 70 ft lb on the bolt and 59 ft lb on the nut. Why do you need to torque both - does this make sense? Not a big deal to do it, but I don't want to over tighten. Thanks!
The bolt is much longer and will slightly twist. The bolt will also elongate slightly because of the much longer length when compared to the nut. Also the area of head engagement may be slightly larger (area wise) than the nut which will require more torque due to increased friction.
There are several factors without going into great detail.
If its easier to get to the bolt head, then torque it to 70 Ft*Lbs, if you can tighten the nut easier then torque it to the 59 Ft*Lbs.
Either way you'll be good to go.
03-14-2008, 08:20 AM
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You don't have to torque both, you pick one and go with it.
The bolt is much longer and will slightly twist. The bolt will also elongate slightly because of the much longer length when compared to the nut. Also the area of head engagement may be slightly larger (area wise) than the nut which will require more torque due to increased friction.
There are several factors without going into great detail.
If its easier to get to the bolt head, then torque it to 70 Ft*Lbs, if you can tighten the nut easier then torque it to the 59 Ft*Lbs.
Either way you'll be good to go.
The bolt is much longer and will slightly twist. The bolt will also elongate slightly because of the much longer length when compared to the nut. Also the area of head engagement may be slightly larger (area wise) than the nut which will require more torque due to increased friction.
There are several factors without going into great detail.
If its easier to get to the bolt head, then torque it to 70 Ft*Lbs, if you can tighten the nut easier then torque it to the 59 Ft*Lbs.
Either way you'll be good to go.
