Greetings HAMBLand! I decided to pull the '40 V8 banjo that I had for the B4Cdan up to the garage and start tearing into it to see how bad it is. (keep in mind I've had this thing under a tarp for about 8 years, and it sat under a shell of a '40 sedan years before I found it! It has been into before as evidence of red paint on ALL the parts loaded on the backing plates so maybe its good inside...maybe not. So here where the "fun" begins! My biggest worry going into the job was that the keyways were shot, but to my relief, the keys/keyways look good. So I continued the teardown. Drivers side came apart fairly easily. Other side required some persuasion, but it all came apart. Up on stands and cleaning up for the afternoon, I ran the castle nuts up on the axle threads to keep passing jeans safe. THIS is when I noticed the threads on the end of the drivers axle were short and thin. I had trouble getting the nut started because it was so loose on the axle shaft. BIG QUESTION...Is this axle toast? Can the threads be repaired? Do I need to find a replacement? Thanks in advance for the help! B4C
I would replace it. There is a fix for some thread damage but that looks too far gone imho. 1928-48-ford-rear-axle-special-clamping-nut-for-worn-threads John
Axles aren't tough to find. Every year when I make my annual visit to the Early Ford Garage in San Dimas I am amazed at the pile of early Ford axles they continue to maintain.
I've undercut axles before due to stripping the threads by over torqueing. It worked like a charm... Just tap it the next size down and cut down on the torque when re installing.
I vote for replacing also. But since it is a tapered shaft, and there is a cotter pin to keep the nut from backing off, the question is, how tight is the brake drum? Does it pull up tight and not slide back and forth?
I had to buy a new axle for my 41. And the seller sent me the wrong one, but I kept it anyways, and it is in really good shape. So let me know the length and the spine count on the inside. And maybe we can make a cheap deal.
Sam, the hub/drum was tight prior to removal. and the keyway is nice and square as well. I'm really tempted to rethread the next size down and rely on the taper and keyway. "All" the nut does is keep things snug and the cotter pin will keep the nut in place. All the weight/power bearing parts will retain their strength...right?
Brian, from the Hot Rod Works website, all 39-41 banjos are the same. See below.... 1939-1941 32.85″ 16 (use 11 tooth spiders) DM me if your spare matches this spec.
You are correct about the splines. But over the years people have swapped parts out, and if you had grenaded a rearend in the past, you could put it together with different spline axles, and cariers, the guy that sent me my spare axle thought they were all the same. And I ended up with the 13 spline I believe
Bear in mind the design of the tapered axle requires the nut to be torqued to 200+ ft/lbs. The hub fit on the tapered shaft is most of the load carrying strength of the assembly, and less torque on the nut makes the key the load carrier...and it isn't supposed to be. It'll crack at the inner keyway area if not tight enough.
@chicken Just hypothetically....if 200 ft-lb results in a castle nut "high" being over the cotter pin hole, do you overtighten or back off?
I would replace it but if you decide to cut corners be sure to run safety hubs or brake drum clips. On second thought, run the safety items no mater what you decide. Charlie Stephens
@Charlie Stephens Going to do it right, hence why I'm asking questions. Clip recommendation well taken!
I just got my threads to come back by taking a good original castle axle nut (original, not any of the new ones as there is a big difference with quality) and running it on backwards, castles first. Slowly and with oil. My threads didn’t look quite as bad as those, but they sharpened up a lot. So far it’s holding 100 lbs as I work the torque up and seat the hub onto the taper. I am also using a special clamping nut on that axle bought from third gen auto. https://thirdgenauto.com/product/1928-48-ford-rear-axle-special-clamping-nut-for-worn-threads/ In my research, I also came across this model A procedure for rethreading. Seemed interesting. https://youtube.com/playlist?list=PLav-W1BC-Nj-T6al6Pk5bcpNJQdDfO5H8&si=Le1RKj9Vsz6OVYg3
@FritzFord As you mentioned, these are pretty bad. I still had slop running the castle nuts backwards.
I’ve seen advice to never loosen to get the cotter pin lined up. Tighten, or take the nut off, and sand the back of it a bit to get it lined up
@FritzFord Thanks, That answered my next question!! I've already started putting feelers out for a drivers side axle shaft...Checking close to home first!
You can try a re threader and try to re roll the material into a thread. Ask @Andy, he was fixing axle threads awhile ago. https://www.jalopyjournal.com/forum/threads/banjo-axle-thread-repair-help.1243747/#post-14224456
A little read for Torque specs.... I know later axles took more but the early stuff is lower. https://www.fordbarn.com/forum/show...unds,depending on how much you drive your car.
That special nut from thirdgen looks like it was designed for this kind of problem. It seems like a quick and effective solution,,,,,reasonable cost as well . Tommy
Fritz brings up a good point. Make sure you use an original Ford axle nut. They are hardened steel. Maybe check with Fred @ Southside Obsolete to see if he has NOS ones. You may get lucky with Fritz's method using a new, crisp Ford axle nut.
I gave up on early ford axles 50 wears ago, but common sense would be to ask : What is the next smallest thread size and what is it's torque rating?
@tubman Next size below 5/8-18 is 9/16-18…not sure on torque rating. But, everyone, please don’t lose sight of the fact that this banjo will need to hold up to about 85hp!!!
According to Google, 9/16-18 grade 5 is 127 ft/lbs, while grade 8 is 172 ft/lbs. Coarse threads are quite a bit less. It's probably not a good idea, but if everything else looked good, I'd try it.
You already answered your own question, doing it right is to replace the axle! The taper is what holds the hub on the axle, the key is a locating device. If you want to make it hold better, use valve lapping compound to make the taper match perfectly before installation.
The actual load in this assembly is resisted by friction when the tapers are pulled up tight. That's why torquing the nut to spec is important. If the drum is slipping on the axle enough to beat up the key or keyway there's already a problem. Needless to say, when a more powerful engine and a heavy right foot become involved these connections can be stressed beyond their design parameters.
^^^ Correct. A friend designs huge industrial pumps, even the best made parts loosen due to microscopic surface irregularities bedding in. He reckons warranty claims can be cut to zero if the right products are used on initial assembly to prevent any minute movement. All used taper fit hubs and axles will have some wear, most used keyways are minutely sloppy even if they look good, any slop at all is bad. Following his advice I always clean meticulously and use Loctite 660 on all shafts, splines and keys. A little heat on the hub and a puller will pop it off again. I've used it on badly worn output shaft splines of heavy recovery truck transfer boxes considered beyond repair and they have been good for a few years now. Just a satisfied user here, no connection the the company. https://www.travers.com/product/loctite-660-quick-metal-retaining-compound-83632
Before you finalize anything, a crucial step is to lap the hub to the axle's taper. Don't assume it is mating correctly. You can use some blueing to see high spots, but lapping the hub to the taper is an essential step. I like Time Saver lapping powered compound and have gotten good results with it. Valve lapping paste tends to make more of a mess and can be hard to clean off. You don't want any of the lapping compound left since it could ruin the bearing. With a good mating of the hub and taper, like others have said, once torqued down, that physics of the taper is what is holding it on there. The key is a secondary "safety".
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