Crankshaft Dampner Separated -- Arghh!

[patrickt]

I received a surprisingly good bit of feedback via email, PMs, etc. so here is a summary of my findings:

The ARP Torque Table: The figures that are found in the ARP table are general guidelines only and different applications (rod bolts versus something else, for instance) require a different interpretation of the table in light of the functional relationship that the fastener has with its surroundings. As an example, if the OEM fastener was originally "oversized," the torque values found in the ARP table may be inappropriate, as they obviously do not take in to account the object that is being fastened or the type of stress that may be involved. Further, ARP recommends that if you are adhering to the values in their chart that you reduce the torque value down to 75%. Thus, if we blindly follow the ARP chart for an ARP Ford Crank Bolt 5/8-18 it would be 142 ft/lbs. with moly.

The Original Ford Specs: I have an original 1967 Shop Manual, so I looked it up with my own two eyes. The torque specs for an original Ford OEM bolt (which hasn't been made in years) are 70-90 ft/lbs. with no mention of anything on the threads, by the way, in the shop manual R&R procedure, just "lubricate the inside diameter of the hub and line up the key...."

What People Tell Me They Actually Do: 1) The majority of mechanics put nothing on the bolt (meaning no oil, no moly, no thread locker, nothing at all). Rick and one other person use red loctite; a few use blue). The vast majority of mechanics are torquing in at or under 90 ft/lbs regardless of the manufacturer of the bolt. As an interesting side note, the older the mechanic, the lower the torque setting seems to be. 50 and 60 ft/lbs. were not uncommon numbers that were sent to me by some of the really old FE mechanics.

Does it Really Back Out? -- No one reported a crank bolt loosening or backing out on an FE even when torqued to a relatively "low figure."

So What Am I Going to Do? -- I'm going to torque it to 90 ft/lbs with blue loctite. And at the suggestion of one respondent, I'll paint a little white line on the bolt that easily shows any backing out that may occur.