Loose rear axle key '39 rearend

[Jake H.]

I did a couple searches, but did not find the info. I need.

When I removed the rear drums on my '39, recently, the axle key on the driver's side rear came off with the drum. It was stuck in the groove of the drum, and intact.

I've removed the drums, twice before, and this didn't happen.

Should I be concerned? I simply re-installed the key back into the axle, and installed the drum, like normal.

I made a couple shakedown runs around the block, with no drama.

[MuskegonFlatheadFan]

That shouldn't make any difference. Just make sure that the taper is clean and properly torqued. (250lb/ft)

[Charlie Stephens]

Check to axle carefully for any cracks that might be starting. Put on safety hubs or safety clips just in case (we should all have them anyway).

Charlie Stephens

[Fe26]

Check the fit of the Key in the Axel Keyway. If the keyway has become enlarged you may be developing a problem. There should be no sideways movement of the Key.

[Bassman/NZ]

Originally Posted by MuskegonFlatheadFan

That shouldn't make any difference. Just make sure that the taper is clean and properly torqued. (250lb/ft)

250 is too high.... 200-220 is the recommended torque.

[Jake H.]

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Thanks for all the help, guys.

I am going to fab up some safety clips for the drums.

I made sure the keyway was really clean, and it didn't seem like there was too much side to side play.

Axle did not look cracked. I will re-torque since it was driven pretty hard.

I was testing my new rear sway-bar/tube shock setup.

[ford38v8]

Jake, did you know where to look for cracks? Ford axles will develop a crack at the inner end of the axle key slot. When this happens, it is visible, and not long before the axle breaks. The cause is of course, a loosly fitted drum to axle taper. The key is not intended to drive the wheel, the taper is.

[Jake H.]

Thanks, I did not look there.

Now I'm feeling a little paranoid.

I might as well pop that drum off, again, and look exactly where you described.

Thanks again, everybody!

[deuce_roadster]

You can clean the area and use a dye penetrant to see if there is a crack starting.

[Jake H.]

Aaarrrgh...

So, I checked the keyway for cracks, and everything looked good.

Put the drum back on, tightened the axle nut with a breaker bar.

Then, I got my buddy's newly calibrated, county-issue torque wrench. Set it for 200 lbs. and got about a quarter turn before the threads ceased to exist.

Nut came back off by hand, and the axle end is totally stripped.

Damn....

[deuce_roadster]

Well, think of it this way, a rear axle problem in your garage is infinitely better then a rear axle problem on the road. Good luck finding a replacement, not quite as bad as finding a good block.....

[Jake H.]

Yea, I AM glad I found this weak spot inside the garage.

I drove this car up and down I5 last summer, with the wife and kids. Yikes...

I am putting feelers out for a good axle, in the PNW area.

Looks like I might have an opportunity to swap out my 3.78's for something more roadworthy, too.

It's always something....

[ford38v8]

Jake, There is no axle ratio more roadworthy than 3.78's. This ratio is the best all round ratio for city, highway, and mountain driving. If you want more speed, consider that there is no speed limit in the USA that can't be broken in your car with those gears. Faster and you're a major hazard to yourself and others.

When searching for an axle, note that Ford axles from 1935 to 1941 will all fit your axle housings. Pairs of these axles have either 16 or 18 teeth, along with the correct spider gear for the pair, are all good. The original axles on your car had 16 teeth, but count the teeth to be sure, as previous owners of your car could well have changed them out several times over the years.

[JWL]

Your stripped threads is another reason I suggest 150 ft lbs. Then drive for several miles and recheck at 150 plus the next serration to fit the cotter pin. If the taper fits properly you will never have a problem.

I have re-threaded several stripped axles to 9/16" while the axle remained in the car. It isn't easy to do but it works just fine.

[G.M.]

Clean ALL of the grease and oil off the axle and inside of the drums taper with a good solvent. Take a large fine file and just clean all raised marks off the axle. I would mic the key and inspect the sides for a line showing wear and replace if warn. Install the drum again making sure it's oil free and dry. I tighten the axle nuts with a power bar damn tight. This dry friction fit on the taper is what drives the axle, the key is more of a safety item. G.M.

[Jake H.]

Thanks, Alan.

That's good food for thought. I'm no speed demon. Just want the car to be safe and fun to drive.

I will hunt down some '35-'41 axle assemblies.

I was hoping to do some other stuff to the car this holiday weekend. Oh, well, a rebuilt banjo will offer a lot of peace of mind, anyway.

[Planojc]

Try using a new nut and re torque. You may have only striped the threads on the nut. I have had the same thing happen on a model A and from now on, every time I remove a drum, due to the high torque requirement, I install a new nut which are cheap. It seems that the nuts are not made as hard as the axle.

[KiWinUS]

some real good info here , I also like to lap the hub/drum onto the axle with valve grinding paste !!
A very important step is as "GM" said , file off the high spots !!!!
Its hard to get back off , but loctite green is a lifesaver !!!

[ford38v8]

Loctite on a taper shaft? NEVER! What were you thinking?

Dry Dry Dry Dry Dry!

[KiWinUS]

Loctite is the perfect repair for the axles & habs that are already scored up from a sheared keyway previously !!! We can always just replace the axle & hub .Has worked for me many time over the years when changing parts was not an option.