1970 C10 Longbed 2 Pc Driveshaft Bolt Torque 1/2"-20

[Gromit]

I'm stuck - cannot find the torque spec for the 1/2"-20 bolt that holds the bolt-on yoke to the splines of the two piece driveshaft / propeller shaft at the center support on this truck. (Not the nut at the rear pinion, but the BOLT at the center support yoke to driveshaft) Maybe this is a 1970 C10 longbed thing only; because I can't find anything about it.

I searched the forum, checked the Chilton, Checked the Haynes and Googled it to kingdom come and am at a loss.

Standard torque for a 1/2"-20 fine thread Grade 5 bolt like this is max about 100 ft lbs. But I don't think it was that tight when I took it apart.

Also this torque may affect the center support bearing so I would like to get it right.

Here is a photo that bollybibs put up a while back it is the bolt near the right edge of his photo - (it would have been more polite to ask him first if I could use his photo but I'm hoping he will understand when it is Sunday and you want to just get the rig together - Thanks Bollybibs!!)

Thanks for listening

[Gromit]

Right quarter of the photo, not exactly the right edge... its the only bolt in the photo

[donpr]

im reading 64 lbs....https://www.boltdepot.com/fastener-i...ed-Torque.aspx

[Gromit]

Thank you! with the help of your insight I found this too (please see below for breakdown): (and I should have known to point out that there is a nylon patch on the threads):

TORQUE TIGHTENING ANALYSIS RESULTS

Analysis of a 1/2 inch UNF bolt

FASTENER DETAILS
Fastener Diameter = 0.500 inches
Fastener Shank Diameter = 0.500 inches
Thread Pitch = 0.050 inches
Included angle between the thread flanks = 60.000 degrees
Thread Pitch Diameter = 0.468 inches
Thread Root Diameter = 0.439 inches
Diameter related to the Thread Stress Area = 0.454 inches
Thread Stress Area = 0.162 inches�
Thread Root Area = 0.151 inches�
Bearing Area under Nut/Bolt Head = 0.198 inches�
Fastener Outer Bearing Diameter = 0.720 inches
Fastener Inner Bearing Diameter = 0.516 inches
Fastener Clearance Hole Diameter = 0.516 inches
Effective friction diameter of nut/bolt = 0.624 inches
Fastener Yield Strength = 92000.00 Lb/in�

JOINT ASSEMBLY DETAILS
Black oxide steel external thread, no finish on steel
internal thread, no lubricant. Black oxide steel nut
or bolt, no oil, machined steel bearing surface.
Prevailing torque caused by a nylon/polyester patch
on the threads.
Thread Friction Value = 0.120
Nut/Bolt Head Friction Value = 0.120

TORQUE TIGHTENING ANALYSIS RESULTS
Yield Point Tightening Factor specified = 0.90
Total Tightening Torque = 80.21 Lb-ft
This torque is composed from:
Torque needed to extend the fastener = 6.50 Lb-ft
Torque needed to overcome thread friction = 26.47 Lb-ft
Torque needed to overcome nutface friction = 30.55 Lb-ft
Prevailing Torque Value = 16.70 Lb-ft

FORCE ANALYSIS RESULTS
Fastener Preload = 9796.47 Lb
Direct Force that would Yield the Fastener = 14860.46 Lb
Preload as a percentage of Yield Force = 65.92 %

MAXIMUM STRESSES INDUCED INTO THE FASTENER
Percentage of the yield strength utilised = 90.00 %
Von-Mises Equivalent Stress = 82800.00 Lb/in�
Tensile Stress due to Preload = 60649.18 Lb/in�
Torsional Stress due to the applied torque = 32544.92 Lb/in�
Surface Pressure under the Nut Face = 49468.75 Lb/in�

[Gromit]

http://www.boltscience.com/pages/torque3.htm

Thanks Donpr!

[donpr]

I work for caterpillar reman. some threads and nuts on trans. and hydrulics have plastic built in as retainer or lock. kinda like lock tight. wouldnt loosen off..

[brad_man_72]

Take it to a driveline shop. It needs to be balanced as an assembly now anyways.

[Redline novdog]

I also work for Cat. You have a whole lot of info there! Did you check the 1E0279 spec? That is usually what I use. I am at home or I would look it up.It is probably net accessible also