Old time metallurgy.. Or metallurgist.
 

Most axle nuts have threads that are not perfect. I contacted one of the premier Model A parts houses and they said theirs are Grade 5.

I think the originals are somewhat harder than the modern Grade 5 designation. More like Grade 8.

Does any one know the original hardness specification in terms of modern hardnesses? Rockwell C?

Larry

Re: Old time metallurgy.. Or metallurgist.
 

I know that a file just skates over hardly making a scratch, in the parts book it is listed as (I think) S18, case hardened

Re: Old time metallurgy.. Or metallurgist.
 

Interesting! The modern grading system wasn't in place then, and the thread fit classes were similar to but not identical to the modern.
One thing is that it is listed as a "standard part," meaning normal hardware, rather than with a Ford part number as specially designed hardware received. Same piece served through 1948, and late in its run a very high torque spec was released...up close to 200 ft, lbs. Obviously it was made of good stuff to survive that...

Re: Old time metallurgy.. Or metallurgist.
 

Exactly. Take two socket head cap screws, one can be cut with a hack saw, yet it has a gummy feel to it when cutting. The other one will only have the blade skate across it. The gummy one is the Grade 8 and the other is only case hardened, it is tough but not strong. Mild steel can have a case put on it, while the better grades of steel, medium and high carbon, can be hardened throughout.

Re: Old time metallurgy.. Or metallurgist.
 

All true. Then, in your opinions, is a Grade 5 reproduction Axle nut sufficient to torque to 90 or 100 foot pounds?

Larry

Re: Old time metallurgy.. Or metallurgist.
 

Fastenal has a table of torque specifications for various nuts: ( https://www.fastenal.com/content/fed...0Gr8%20Gr9.pdf )

A grade 5 5/8-11 torques to 150 ft-lbs in the clean-dry condition and develops a clamp load of a bit over 14000 lbs.

A grade 8 same size torques to 212 ft-lbs and the corresponding clamp load is over 20,000 lbs.

Normal engineering practice is to use a hard bolt and a softer nut so the nut deforms to the bolt (axle) threads.

I have no knowledge of the hardness of the axles, but in reworking the threads, I'd guess they are not hardened and are about the same hardness as a mild steel. As mentioned above, this is not the same thing as the strength of the steel which can vary a lot, all the way from plain ole 1010 to chrome moly 4130.

John

Re: Old time metallurgy.. Or metallurgist.
 

"MAYBE" we could have STRENGTH & HARDNESS, just heat them to cherry red & QUENCH them in liquid VIAGRA:D
Bill W.

Re: Old time metallurgy.. Or metallurgist.
 

Thanks John..

How about the torque value of 5/8"-18? You said that a 5/'8"-11 will torque to 150 Foot pounds. If the 5/8"-18 is about the same, then a Grade 5 will work well, proving that Tom Jordan at Snyder's is stating the right fastener. Agree? If so, case closed.

Larry

Re: Old time metallurgy.. Or metallurgist.
 

Mr. Falter..

The intent of my original post was to determine which grade of steel nut was compatible with the Model A front and rear axles from a metallurgical and Engineering standpoint.

Mr. Witt gave one of the best answers based on my request.

Your demeaning response to my questions and subsequent response was totally uncalled for and do not belong on the Ford Barn.

In spite of what your name is.

Larry Jenkins

Re: Old time metallurgy.. Or metallurgist.
 

Why not just use a decent quality nut, torque it & be done? With the gripping qualities of the taper, it WON'T loosen or come off. A little Loctite on the threads, if that will make you feel safer.
Bill W.

Re: Old time metallurgy.. Or metallurgist.
 

Let me add this to the mix. The value on the charts are max values (well usually 75% of proof). They are not necessarily the values needed for a specific job. Let's take the 100lbs rear axle torque, since Ford did not use torque values during assemble of the Model A, where did this number come from?

Again as mentioned by a couple of people above strength is not the same as hardness. A diamond nut would not torque down the same a a steel nut.

Re: Old time metallurgy.. Or metallurgist.
 

Search on the V8 Forum. Ford used same nut, washers, etc. through 1948. In the last few years, they put out two service letters, one slightly over 200 ft lbs, then another backing down to slightly under 200. Real Ford number.
Marco has done several posts on torque-to-failure tests on Ford "Standard part" fasteners...look'em up.

Re: Old time metallurgy.. Or metallurgist.
 

According to the green book Ford didn't use the same nut 28-48.
28-37 34034-S18 5/8-18 (.72 X .93) Castle nut.
38-48 356074-S18 5/8-18 (23/32 X 1 1/4) Special hex nut.

Bob

Re: Old time metallurgy.. Or metallurgist.
 

Ay...you're right, sloppy research here.
But threads are the same. "Special" likely refers to the increased hex rather than grading, as the nut still has a standard hardware number unlike the Ford part number assigned to presumably extra stout fasteners like connecting rod nuts...
Were axle ends (which remained dimensionally the same in terms of taper, threads, and key) treated the same '28-48? Only factoid I have found is a circa 1946 Ford ad noting that there were three different heat-treat regions, presumably gear, shaft, and taper end...ad was flogging the blessings of Ford genuine parts.