Cummins Ism Flywheel Bolt Torque Specs
Eugene Hill
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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?
This chart from the manual says the m12 at 12.9 can go to 95 ft*lb in cast iron. Our crank is forged steel. (significantly stronger in tension) so I think the 101 ft*lb is fine if the fastener is 12.9 or stronger.
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.
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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.
Had a crankshaft break in a new 7230 combine two years ago from the front dampner bolts not being tight from the factory. Needless to say as much of a complain it is to shove around a dead combine. I'd rather take a little extra time to do it right on critical components than just drive it on home. Torque for the drive plate and ujoints is 80 to 85 foot pounds
But if you're on book time pay, or bill by book time they're fantastic. Do a job in 4 hours and get paid for 8. That's how I billed most jobs. Some were time snd material, but on those you usually had to give a lot of time away.
I'm not going to argue about whether this is a "critical" fastener, or when you should or shouldn't use an impact. I'm comfortable giving it as advice, but like I said, if torquing it makes you warm and fuzzy, then do it.
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
I'm not talking about the lug nuts on a tractor. I'm talking about any old 1/2" or 5/8" wheel stud on any standard pickup, car, truck, trailer running down the road right now that were put on with a 1/2" gun.
I am really sorry to hear about your daughters heart issues. I have had a friend have a heart attack recently and it is hitting a little to close to home and to age 51 for me. We have made a donation to the BC Heart and stroke foundation. I hope your daughter is resting and recovering.
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?