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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? 

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  • Flexplate to crank: 105 lb/ft

  • IBM,   I agree I found both of the different references you found....   I think the bolts are M12.   Need to know the class of bolt.  (and materials to be fastened)  Metric 12.9 (s

  • The converter to flex plate bolts torque to 38 lb/ft.

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IBM,

 

I agree I found both of the different references you found....

 

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.

image.png.59fe01f4d36d77ba4bb6f204a18fb34f.png

 

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. 

 

HTH
 

Hag

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Flexplate to crank: 105 lb/ft

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  • Staff

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.

I red lock tightened mine too after cleaning bolts and threads in crack

 

Are you using a billet flexplate ?

Edited by JAG1

  • Owner
19 hours ago, IBMobile said:

you would think the 35 ft. lbs. of torque on the six bolts holding the flex plate to the convertor is to low.

 

Kind of like the 44 foot pounds holding a dual disc pressure plate... 

21 hours ago, IBMobile said:

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.

The converter to flex plate bolts torque to 38 lb/ft.

  • Staff
11 hours ago, Evan said:

I red lock tightened mine too after cleaning bolts and threads in crack

 

 

:think:

33 minutes ago, JAG1 said:

:think:

Almost sounds illegal.

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1 hour ago, dripley said:

Almost sounds illegal.

No, I think he was on the phone when posting and they were giving the final report on a magniflux  for his Ford engine :thumb1:

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On 9/13/2019 at 9:09 PM, Evan said:

Are you using a billet flexplate ?

@Dynamicincludes an HD SFI 29.1 rated flex plate with the " Stage 2" Transmission  build package.

I think he recomends the billet. 

 

The other sfi stuffs goood to I think its designed to be a fuse

 

I was curious about the sfi 29 so I looked it up.

 

It basically means it passed an hour spin at 12500-13500 rpm without failure.

 

I do not know if the billet plates have been tested.

 

More research needed very interesting 

Edited by Evan

The SFI 29.1 flex plate is included with the Stage 2 build. Stage 3 and higher include a full billet flex plate. 

 

No builder would intentionally put a "fuse" in the system. The flex plate is no exception. The SFI 29.1 flex plate is more than most people will ever dream of needing.

Just something I read you know how stuff is that you read on this damn interweb

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Welcome To Mopar1973Man.Com LLC

We are privately owned, with access to a professional Diesel Mechanic, who can provide additional support for Dodge Ram Cummins Diesel vehicles. Many detailed information is FREE and available to read. However, in order to interact directly with our Diesel Mechanic, Michael, by phone, via zoom, or as the web-based option, Subscription Plans are offered that will enable these and other features.  Go to the Subscription Page and Select a desired plan. At any time you wish to cancel the Subscription, click Subscription Page, select the 'Cancel' button, and it will be canceled. For your convenience, all subscriptions are on auto-renewal.