47 Pickup Banjo Rear-End Blues

[dorvedahl47pu]

Good evening,

Where to start? I've got a 4 speed 6-cylinder 47 pickup with the banjo rear-end. Over the past 10 months I have managed to get the engine running and cleaned up the tranny. One thing I noticed a while ago was that with the tranny in neutral, rear wheels on the ground, I could rotate the drive shaft by hand. Hmmmm. That doesn't seem right.

I decided to try to figure out what the problem with the rear end was a couple days ago, now that the engine and tranny are good to go. I took the drive shaft out yesterday. Sure enough, the pinion turns freely, again with wheels on the ground.

Today I jacked up the rear end and pulled off the rims. No broken axles as the drums didn't budge. Much to my surprise, when I rotated the drums, the darn pinion turned. Likewise, when I rotated the pinion, the wheels turned. When I grabbed a drum, it stopped but the pinion would keep turning.

This my first experience with trying to solve a rear end issue, but I am stumped. None of this makes any sense to me. I don't hear or feel any grinding or clanging when things move. Is the whole thing a piece of junk?

Thanks in advance.

[modela4shane]

Pull the brake drums and check for a sheared or missing key way on each axle. Just a thought, I hope thats all it is. Best of luck to you.

[GB SISSON]

Doesn't sound right, that's for sure. I can't imagine a good rear end would be hard to find with all the resto-modding, street rodding, frame swapping, and 9" conversions we see all around us. Edit: I just sent you a PM concerning this.

[cas3]

By golly, a fella could lay awake all night thinking on this one !!

[deuce_roadster]

My vote is for a missing or sheared axle key (or both keys). With an open rear end the axle that can turn fastest will and with no key it will spin inside the hub and drum. Also possible to be a sheared axle.

[Mart]

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If an axle key has sheared the drum will be turning on the shaft.

Here's what I would do to test it.
Jack up the left wheel only and have the trans in top gear. (driveshaft in place.)
Rotate the left wheel/drum and see if the shaft is turning with the wheel or staying still.

If turning with the wheel then repeat the operation on the right side.

To be honest if a key has sheared there ought to be witness marks where the nut has been turning against the washer and hub. Look closely in this area.

Mart (Transmission engineer (retired)).

Edit: I Just re-read your post and it all makes perfect sense. 99% probability it is a sheared key.

[Tim Ayers]

This is interesting. With the Morse taper and having the correct 200 ft lbs of torque on the nut, that key isn't really doing much.

I didn't believe this at first until I was checking fitment of my brakes. I had the hub on and off checking the brakes. Final step I lapped the hub to the axle. After lapping and pressing the hub back on with some force, I needed a hub puller to get it off to install the key. I was pretty amazed by that.

If it is sheared, make sure you re-tighten the nut to 200 ft lbs. I would also suggest lapping the hub to the axle to ensure a tight fit on both components.

[dorvedahl47pu]

Thanks to all for your insights and suggestions! I was watching The Andy Griffith Show re-runs last night and I ran across the episode where Barney buys a car from a sweet lady who only drove it to church on Sundays. I was starting to think maybe I would find a bunch of saw dust in the rear end. So, here's what I have found so far today. Reinstalled the wheels and blocked (still jacked up) them in an attempt to get the axle nuts off. Drivers side nut loosened right up. After removing the washer, I saw the key right where it should be. Over to the passenger side. Axle spins right along with the nut. Could be either a missing key or a broken axle I suppose. Can't see the key with the nut and washer in place.

Any ideas on how to remove the nut from a free axle?

Thanks again!

[Mart]

Ok we're getting somewhere.

Try an impact driver.

Or try tightening first an small increments until the hub bites on the taper then undo the nut and use a puller to get the hub off the taper.

An impact driver would be great in both cases on this job.

Mart.

Edit: reinstall the driveshaft and have the opposite side wheel on the ground. Engage top gear. Jack up the suspect wheel and the shaft should not turn.

If it turns it is broke, or the other side is broke.

If it is broke the drum and shaft should pull right out. The brake might be holding it so make sure you can see what is going on.

I had one that was broke but did not pull all the way out. It had been welded and the weld would not pull through the seal/axle casing.

[dorvedahl47pu]

Mart...well, I was able to get the nut off using the business end of a large crescent wrench as a hammer to turn the nut. Pulled the brake drum off and there she was, the key, well about half of her anyway. The key had worn down to the contour of the axle so not doing much good. I've got a new set of keys on order. Thanks for the great advice!

[V8COOPMAN]

Originally Posted by dorvedahl47pu

Mart...well, I was able to get the nut off using the business end of a large crescent wrench as a hammer to turn the nut. Pulled the brake drum off and there she was, the key, well about half of her anyway. The key had worn down to the contour of the axle so not doing much good. I've got a new set of keys on order. Thanks for the great advice!

You have all the answers to all of your problems right there. The reason the drum came off so easily is because the nut was never anywhere near tight enough. That axle is tapered for good reason. When the axle NUT is tightened anywhere near the suggested ~200 ft. lbs., the taper in the hub and axle fit together so precisely, and tightly, that they seem LOCKED together, which is what that design is intended to do. It works just like a "Morse-taper" works. That KEY in that KEYWAY is NOT what is designed to be driving your wheel and tire. You have the destroyed parts in your hand to prove it!!

Coop

.

[Newc]

I drove a 34 off the trailer , stepped on the brake and it just kept going-AT a show! Missed the other cars. No keys at all!! Nuts not tight. Newc

[Tim Ayers]

Looking at the first pict, I suggest you lap the axle and hub. It looks like only the front 1/3 is making contact. I'm a fan of a product called Timer Saver lapping powder.

You can order it on line and most Model T vendors have it. I think you want to the green label for hard metals.

Lapping the hub to the axle and getting that nut to 200 lbs. upon install should keep that from happening again.

[cas3]

Time savor is good stuff ! Hard to see in the pics, but in a perfect world the key would fit snug in the axle. For now, if you get a good fit lapping it in you may get away with it until a complete overhaul is on the list

[GB SISSON]

Originally Posted by Newc

I drove a 34 off the trailer , stepped on the brake and it just kept going-AT a show! Missed the other cars. No keys at all!! Nuts not tight. Newc

That's a dirty trick!

[Mart]

The other half of the key ought to be in the keyway in the hub.

But as this truck is new to you who knows what a previous owner may have done.

Glad you got to the crux of the matter.

[Tim Ayers]

Originally Posted by cas3

Time savor is good stuff ! Hard to see in the pics, but in a perfect world the key would fit snug in the axle. For now, if you get a good fit lapping it in you may get away with it until a complete overhaul is on the list

Great point. I normally order a few keys because they all seem to be slightly different. I then file it to be a snug fit. Do not hammer into place if it's too snug.

[dorvedahl47pu]

Thanks everyone! You guys are awesome! Lapping compound on order.

[jimTN]

you can buy key stock at some hardware stores and at bearing houses .Comes in lengths and you cut it to length.