Topic: Correct 1/2-13 Nut for 1965 Motor Mount to Bracket

[meltdwn65GT]

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[CharlesTurner]

The AMK nuts match what I have found on original cars.  Looks like a bigger version of the lock nuts holding the strut rods to the LCA's.  Also should be a thick washer.

[jwc66k]

I don't know what source document you're looking at, but the only 1/2-13 threads on the front engine mount area are the two bolts that hold the cross member to the frame rails. Everything else is 7/16-14 (or 7/16-20) max (no pun intended). The locking mechanism the nuts use is called "Stover" for what I'm seeing for the motor mount to the bracket. And verify, you are looking for a 289 installation.
Jim 

[JKWilson]

I believe this is the correct nut and washer:
http://www.npdlink.com/store/products/mustang_mounting_kit_motor_mount_to_body-105036-389.html

[CharlesTurner]

I remember an issue with this now.  The AMK nut size was incorrect.  Think I restored some originals last time I needed a pair.

[jwc66k]

I just looked at my 65 GT Fastback (May 65, San Jose), which the engine supposedly has never been removed (or opened, aka untouched, I've owned it for 20 years) and the nut was a center lock hex. That type uses deformed threads made by either a small rectangular depression (0.090x0.125 in est) or, in my case, a round depression (0.090in est) on the side on one of the hex surfaces (it was very visible on the front left side on my GT). I have measured an engine mount (C3AZ-6038-D) and it is definitely a 1/2-13 thread. There are two possible nuts that were use in this application. They are shown in the "AMK Products Guide To Ford Fasteners" pages 186-187 and they are: 55828-S (0.490-0.510in T, GR5) and  55848-S (0.427-0.448in T, GR8). Based on what I have on the shelf that are of this size and style removed from wrecked Mustangs, the nut is a grade 8 by thickness. It does not appear that this style and size nut is used in any other application. These are my conclusions, which are based on the information I provided. To sum it up, the nut looks like the one used on the 64-66 hood dowel (Ford's description) aka hood post, for size and shape with a "dimple" lock.
Jim

[jwc66k]

I found the drawing of the installation in my Ford Car Parts book (Illustration Section 60.1 page 5, bottom) which shows the service replacement nut as 33845-S which meltdwn65GT entered in a previous post. Keep in mind that items shown in the Ford Car Parts books are service items, not assembly line items. For service purpose, many items were eliminated and replaced by an acceptable equivalent. The irony is the part number for the nut shown, 33845-S, is the one for the hood dowel (aka,  post).
Jim

[rockhouse66]

The one on my NOS motor mount is not a locking nut, though that doesn't mean it wouldn't have been one on the original installation.  Maybe this just confirms what Max told you that the service parts were not lock nuts.  The fact that there is a lockwasher on this service part suggests it doesn't need to be though.  Is the 44735 washer shown in the diagram a lockwasher or flat washer?

[jwc66k]

Your washer comment caught my eye. The 1964 1/2 - 1965 Chassis Assembly Manual shows the washer as 373596-S100 which is documented in the AMK Guide to Ford Fasteners as a 1/2 inch ID, 1.00 inch OD, and 0.110 inch thick flat washer. The service replacement washer is shown as 44735-S and defined as a 1/2 inch ID, 1.25 inch OD, and 0.086-0.132 inch flat washer. An "eyeball" measurement of the washer on my 65 shows it to extend about 1/8 inch further on each side from the 3/4 inch hex dimension of the nut, which indicates that it is a 1.00 inch OD washer. The thickness is about 0.110 inch (less than an 1/8 inch) which is close to what the Assembly Manual states.
Just another step closer to what the factory used, in San Jose at least.
Jim