Torque Spec For Flywheel Bolts On Isx Cummins 251
Melva Simons
When looking up the tightening specification for installing the bolts that hold the flywheel or drive plate to the crankshaft I found two different values. In the engine section under "Crankshaft Oil Seal - Rear" the tightening torque given is 101 ft. lbs. In the "Automatic Transmission 47RE- Torque Specifications" chart the number given is 55 ft. lbs. One of these is a mistake; which one is right?
I think the bolts are M12. Need to know the class of bolt. (and materials to be fastened) Metric 12.9 (similar to our grade 8) maximum suggested tightening torque is 123 ft*lb. grade 10.9 is suggested max 106 ft*lb. grade 9.8 is suggested max 83 ft*lb.
The "Automatic Transmission 47RE" chart also gives a tightening torque for the "bolt, torque convertor" of 35 ft. lbs.. If the tightening torque is 105 ft. lbs. for eight bolts holding the flex plate to the crankshaft then you would think the 35 ft. lbs. of torque on the six bolts holding the flex plate to the convertor is to low.
Funny, I never torque flywheel bolts. Never had a bolt break, or one come loose..... EVER. And I've put hundreds in. Every fastener has a torque. I'm not putting everything together with a torque wrench.
Point is, a lug nut has a torque and is definitely a critical fastener, yet many people use an impact gun without a second thought. As a note, a flywheel bolt is generally much harder than a lug stud.
The lug bolts on our Magnums are either 7/8 coarse thread or 22 mm coarse thread depending on the Vintage of the Hub. Their torque spec is 400 foot pounds. the torque spec for the bolt on the back of the flywheels 101 foot pounds matter fact I just put them on or 7140 when we did the rear main seal last week they're not a very big bolt . If I remember they took an 18 mm socket so I'm guessing it's a 12 mm bolt? One of those flywheel bolts would twist-off much quicker then one of those bolts on the hubs of the Magnum.
I don't have any clue what the capability of John's impact wrench is or what his air compressor pressure is set at in his shop. If he owns a torque wrench I would like to think that it's going to be close to other torque wrenches in respectable shape
Flywheel bolts : Can I reuse the bolts and flat washers that I have or should I get new ones? The manual says to use engine oil on the threads and torque to 22ftlbs +60 degrees after the 22ftlbs? is this correct? very afraid of breaking bolts.. Also, I have heard of people using loctite what are your suggestions? If loctite what colour? Or is oil needed for the correct torque etc..?
Torsion plate? I am installing a Suredrive MOD12, What length, grade of bolt and lock washers? the ones that I have that were on the original thin metal plate seem a bit short for the new plate? What also what about torque specs and and oil vs loctite for these bolts?
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