We loosened one of the ZF to bell housing bolts when we were doing the lift to put the engine in. I can't find the torque spec for those bolts to tighten it again. I know the bell to block is 25 FtLbs. What say you?
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I did not know this but it varies by the grade of bolt you are using. Higher grade bolts require more torque to achieve the same clamping force (so says the web). I would think the bell to block is more than 25. They are 7/16 - 14" bolts? Same with ZF I believe? Will be curious to hear what others say here.
I use these guys and their resource pages are excellent:
Here's one web input:
My 70 book says 40-50 ft-lbs bell to eng.
28-40 bell to trans case
That's for a Mustang
@panterapatt posted:I did not know this but it varies by the grade of bolt you are using. Higher grade bolts require more torque to achieve the same clamping force (so says the web). I would think the bell to block is more than 25. They are 7/16 - 14" bolts? Same with ZF I believe? Will be curious to hear what others say here.
I use these guys and their resource pages are excellent:
I disagree, higher grade bolts support a higher tightening torque if you want to apply a higher clamping force, but for a given tightening torque the axial force is the same regardless of the grade of steel.
What modifies the axial force for the same torque is the surface condition of the threads and the lubrication.
For standard 10 x 150 metric bolts, the typical applied torque is 50 Nm, or 37 ft-lbs. If you use high-grade bolts, it can go up to 70 Nm, or 52 ft-lbs, and with the best ARP lubricated bolts, up to 70 ft-lbs, or 95 Nm.
https://arpcatalog.com/37/#zoom=true
Can only tell you what people that sell bolts publish:
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@panterapatt posted:Can only tell you what people that sell bolts publish:
That thing is misleading…
aside from grade 8 - grade 10.9 is missing (those are the only two that really matter ) and you have stainless steel on it… (for the little non-essential Mickey Mouse stuff I use stainless steel, just because it looks pretty, but for stuff that really has to hold up, I won’t)
the rest of it is chewing gum… common sense has to be Applied as well..
if you have a M12 with threads in aluminum it doesn’t mean you go by what is published for to specs on M12…. It just means that the manufacture uses a larger diameter with more threaded area to hold in the aluminum.. (torque to manufacture specs)
you can use better/higher grade bolts, but you still use the original torque specs as published by the manufacture of the part not of the Bolt!
The torques published by bolt manufacturers are the maximum torques required to avoid exceeding the yield point.
The torques indicated by manufacturers correspond to the tightening force with which they intend to hold their assembly.
As LeMans850i points out, they take into account the material into which the bolts or studs are screwed. They also take into account the forces that will be exerted by the assembly and therefore add to the tightening force. The sum of these forces must remain below the yield point, except for special assemblies where this limit is deliberately exceeded to reach the consolidation zone, and for which the bolts are not reusable and must be replaced each time they are disassembled.
The ZF assembly studs with the clutch housing are 10 x 150 mm bolts, therefore slightly larger than 3/8". In Panterapat's table it is recommended 33 ft-lbs for grade 8, so it is consistent with the 37 ft-lbs that I indicated.
What he said…
… much better than my babbling…