Topic: Self Locking Bolt

[Bossbill]

I've seen the term "self locking bolt" (not nut) used in Jim's spreadsheet.

Although it appears this term could be used for a bolt with a captive lock washer, all of the bolts in question appear to be castle head style bolts without an apparent locking method. Flywheel bolts, for instance.

What are the technical details behind these bolts?

[jwc66k]

From what I remember way back in my Ford Aerospace days, a self locking bolt had: an interference fit by use of slightly oversize threads; an interference fit by use of threads that were slightly different pitch, usually at the head (example: 19 1/2 threads per inch for a 20 thread per inch spec); "teeth" under the head; a nylon "pin" in the thread.
Most were intended for a single use, then discarded. We used the oversize thread types on 60 foot dish antennas for bearing retention.
Jim

[Bob Gaines]

I have seen factory bolt examples that had a red locktite looking material applied to a sort length section of the bolt threads when disassembled.

[CharlesTurner]

Interesting info here... this is the style bolt I believe you're referring to?  These were used on crank pulley's and other applications, without lock washers.


https://wilsongarner.com/how-asymmetric-place-bolts-work/

[Bossbill]

I was looking up the bolts on the front of the engine (289 4V or K) and found two bolts on the adjusting arm of the alternator called out as a
"43000-S8 BOLT - 3/8-16 X 1.25 LOCK"
and looked it up in Jim's spreadsheet.
Comes up as:
"3/8-16X1 1/4HH,PLACE,1.00 THD L,9/16HEX,GR8  | BOLT,HEX,SELF LOCKING,PLACE"

After that I did a reverse search and found a bunch more.

[Bossbill]

Interesting info here... this is the style bolt I believe you're referring to?  These were used on crank pulley's and other applications, without lock washers.


https://wilsongarner.com/how-asymmetric-place-bolts-work/

So that's how these work. It's based on bolt stretch.

As for the crank pulley, the 67 289 uses three 378604-S8 which uses a captive split washer on non-P/S engines: SCR & LOCKWASHER ASSY.

The 67 289 with P/S replaces those 3 bolts with 42997-S8 Place/Lock style bolts.

I'm missing my place  bolts since the car was converted to A/C and longer bolts used. I had an aftermarketA/C pulley and had to find the correct C7 pulley.

The alternator bracket to timing cover has interesting mix of bolts. The Cleveland engine factory puts on flat washers under some of the bolts and the factory accessory build line removes these and puts in a C6OE-10156-A bracket. So nothing goes under the bracket bolts.

[CharlesTurner]

I have used that style bolt on 3 groove crank pulley's.  The AMK replacements seemed prone to shearing, not sure if they were over-torqued.

[rockhouse66]

I believe that a place bolt is a form of self locking bolt, so that may be the reference here.

[Bossbill]

Updated my reply #5 to indicate that the 3 damper pulley bolts change to place/lock style with P/S.

I'm working my way page-by-page through the engine ASM and hadn't come to page 67 yet!