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Connecting Rod Torque

Old 09-30-2010, 09:38 PM
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Connecting Rod Torque

Hello and thanks for an awesome site. I've been soaking up all the good stuff for some time now.

I got my second SuperHawk earlier this summer as a project/basket case. It's been sitting for over 10 years and I'm the third person to get the bike and parts. But I will be the last as I plan on keeping this one for some time.

Since I had the motor out and torn down I had the bore honed as well as new rings and connecting rod bolts. The manual calls for replacing them every time. I've never done that before but I'm going to keep this one so what's another $20 bucks.

Anyway the torque specs call for 14 lb ft + 120 degress. Does that mean that I should get to 14 lb then go another 3/4 turn? I've never seen specs. like this so it just seems a little odd. If you have any info it would be much appreciated.

From the manual: TORQUE: 20N m (2.0 kgfm . 14 Ibft) +120'

FYI: I have a second engine in nice condition that I tore down. I will have parts online soon but if you need anything shoot me an email. Thanks.

Doug
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Old 09-30-2010, 09:51 PM
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Wow that was fast. Thanks!

I'm not sure why I was thinking it was 3/4. It seemed like a long way past the torque spec. I guess I should have asked my 5th grader before posting this.
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Old 09-30-2010, 10:11 PM
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um, you will need your wheaties on this one. I broke a socket in the process.
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Old 10-01-2010, 09:03 AM
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14 ft-lbs basically tightens it to the point of contact between mating surfaces. 120 degrees then applies the proper bolt stretch. It take the bolt to the yield point - defined as the point where, if you release the tension, the bolt no longer returns to it's original length.

Be sure to apply grease to the threads and underside of the bolt head. This is true for all of the crankcase bolts, as well. With these bolts, you are relying on proper bolt tension from an applied torque, so it is critical to lubricate them.
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Old 10-01-2010, 04:53 PM
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how about a ford v6. I did a set of head gaskets and the updated torque spec, which had been x ftlbs + 90 degrees, was updated to 180 degrees. We had 2 people on the breaker bar to get it to even turn. Scary as hell. Must have been somewhere about 200 ftlbs.
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Old 10-01-2010, 08:13 PM
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Originally Posted by RCVTR View Post
14 ft-lbs basically tightens it to the point of contact between mating surfaces. 120 degrees then applies the proper bolt stretch. It take the bolt to the yield point - defined as the point where, if you release the tension, the bolt no longer returns to it's original length.

Be sure to apply grease to the threads and underside of the bolt head. This is true for all of the crankcase bolts, as well. With these bolts, you are relying on proper bolt tension from an applied torque, so it is critical to lubricate them.
Use a 1/2 inch drive socket with a long handle 1/2 drive bar and you'll be able to knock this out pretty easily. Mark a point on the bolt head and 120 degrees clockwise from that point and line them up.
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