How tight are the hinge arms bolts supposed to be? I was looking in my shop manual for a 56 F100 and towards the back where they list such things I could not find a torque spec. The hood opens and closes good. It just every now and then every couple of years, one of the bolts strip out. Yes they are safety wired togethet. I usually take a 5/16 NF repair tap and then thread in a new hood arm bolt and it's good to go. Just curious how tight they are really supposted to be.

 

From what I have read, not real tight. I think so that everything is free to move and hence the safety wire....

But what do I know? I'm having problems now with my hood. I put new hinges on and discovered on the drivers side the one captured nut is missing and the other nut is crudely welded in place but it is not fine thread, so I had to be a course thread bolt in there instead of a shouldered hood bolt.

Mid-fifty sells an over sized hood hinge bolt, but can I tap a course thread nut into a fine thread?

 

The safety wire is a dead giveaway...stretching the bolt (a measure of which is the torque reading) is not necessary when the bolt is held in place with safety wire. I would use some Loctite 271 threadlocker on the bolts the next time you replace them and they won't wobble loose again.

 

I think I remember reading somewhere on this forum, (maybe Ax Racer?), was saying something about them being just hand tight with a 3/4" socket. Mine were tighter than that I know. In fact the wire I did use, just plain old mechanic's wire, would eventually break due to the fact I am always opening and shutting the hood to work on the truck, and the bolts would eventually turn so much, they would break the wire! Maybe I'll just skip the lock wire, and just snug them up every time I am done under the hood. I think though next time I have the hood off, I am just going to re-drill and re-tap all of them to 3/8" and use the larger diameter bolts from Mid Fifty.


About your problem of the wrong threaded nut a PO welded in. A few years back when I first had this issue of stripping hood arm bolts, I took I think a 5/16" X 1 1/4 long bolt, and I found a steel spacer at the hardware store, that was 5/16 I.D. and IIRC close to 7/16 outer diameter. Put a fender washer over the bolt, slipped on the steel spacer, and then after using a thread repair tap, threaded it in. It worked great until I got the new hood bolts! Good question though about the 5/16 NC vs 3/8 NF conversion. I would think you could do it. Me, I would try it on a random nut in a vice to see what happens.

 

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Hey Charlie, is the Loctite 271 the Red stuff? I tried Loctite Blue on them and they got loose again with the safety wire used.

 

Yep...high strength, the kind you need to heat to break loose. Sounds like the anchor nuts have some worn threads, the Loctite will help to fill in the gaps. I use stainless steel wire when safety wiring, if done correctly it will never come loose.

 

Good advice, Hooler, about trying to talk a fine thread into a course thread nut on a random but first before I try it on the nut in my hood.

So with the fender washer and the spacer you made your own shoulder bolt? How did it work and last for you?

 

Torque specs for 5/16-24 (NF) @80% Yeild strength.
These specs are assuming the material it is being bolted in to has the same tensile strength as the bolt and has adequate thread count.


Grade 2 Tensile strength (Minimum) 74,000 PSI 14ft lbs
Grade 5 Tensile strength (Minimum) 120,00 PSI 22ft lbs,
Grade 8 Tensile strength (Minimum) 160,000 PSI 31ft lbs

 

It really worked pretty good i thought. The bolt was actually a little longer than it needed to be. So there was some side to side movement of the arm
But it never seemed to effect the way the hood opened, stayed in the open position, or closed. I just used it as a "temporary" repair until i got the real ones. And this was only on one bolt. It was the top one on the passenger side. It just looked a little "shade tree". I think Gina at Mid Fifty told me some years back that someones you have to get creative to keep these old trucks on the road. She was right about that!

 

Hey Matt, Thanks for this information! It very helpful and I appreciate it very much.

 

No problem I seem to recall that these bolts are softer than the hood hinge and designed to wear instead of the hinge so I would stick to the torque setting for grade 2 bolts and safety wire them. I imagine that is why Ford had provision for lock wire.

Safety wiring 2 bolts/nuts should look something like this. See below.
Jay Z has a good tutorial on lock wire on you tube.

 

Even more good stuff here Matt. Thanks again! Now I will try to torque mine as you suggest. And use the proper lock wire technique. I think this will help a lot!