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Subject: Differential bolt torque

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Steve Dabrowski    Posted 07-24-2024 at 14:23:39 [URL] [DELETE]        [Reply] [No Email]  
  • Differential bolt torque
  • Anyone have a value for the tightening torque for the 8 differential half bolts. Can find nothing in specs and don't know the bolt strength for sure. I usually default to grade 5 with Ford bolts, but on this it may be grade 8 so torque would go to 119 ft-lbs, versus 78 ft-lbs for grade 5. appreciate any input before I make a mistake.

    Farmer Brown    Posted 07-26-2024 at 05:16:41 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Differential bolt torque
  • Torque specs are based on the load and application, not the grade of bolt used. Bolt grades each have torque limits and vary according to size, those torque limits have nothing to do with their actual application.
    Just because you use a higher grade bolt than the original for the same application doesn't mean you torque that bolt higher.

    Steve Dabrowski    Posted 07-28-2024 at 14:47:57 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Differential bolt torque
  • My reference for torque values indicates differing values for both grade of bolt and fine or coarse threads, that was what I was referencing. I agree regarding application which is the basis for my question. I assumed that since none of the Ford manuals or instructions give a value for this that it is not great importance. So I just used my impact wrench at the highest value to tighten the eight bolts with loctite H.S. to make sure they don"t move later.

    Bruce(OR)    Posted 07-25-2024 at 15:24:58 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Differential bolt torque
  • I might be tempted to strip it clean of all oil, thread lock and German Torque.

    "Guttentight".

    Clean and thread lock is a certainty.

    Steve Dabrowski    Posted 07-28-2024 at 14:49:14 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Differential bolt torque
  • Thanks Bruce, that is exactly what I did.

    Bruce(OR)    Posted 07-26-2024 at 01:12:01 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Differential bolt torque
  • No one else has chimed in? Look at the heads of the bolt and then see if those are Grade 10 bolts.

    Steve Dabrowski    Posted 07-28-2024 at 14:51:13 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Differential bolt torque
  • I assume these are the original 1939 bolts, they just have SS forged on the the top.

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