Axle Crack?

Paul in Colorado

Paul in Colorado

Senior Member
Axle Crack? SOLVED?

When I put my 1930 Model A Coupe on jack stands to adjust the brakes, I noticed that the right rear hub wobbled about 1/8" on the axle. I removed the cotter pin, and the axle nut was very loose. I know I torqued it correctly when I installed Flathead Ted's brake kit several years ago. I pulled the hub off by hand, and found the remnants of a shim. After cleaning the hub and spindle, I found what appears to be a crack or flaw in the keyway, but I cannot see or feel any signs of a crack on the surface of the spindle. I have attached pictures, but they are not very clear.

Is this something I should be concerned about, or should I put the hub back on with a new shim and watch it?

Paul

UPDATE

I replaced the shim and retorqued to 50 foot pounds. After driving 10 miles, I checked it again and the torque was only 25 foot pounds. I retorqued to 100 foot pounds, drove it some more, and the torque was about 50 foot pounds.

After further investigation, I discovered that the washer behind the nut is deforming, and would not hold torque. The washer was being drawn into the felt cavity, which had no felt in it. I got a new Grade 8 washer from Bert's, replaced the felt, and torqued to 100 foot pounds. After about 25 miles, I checked torque again, and could only move the nut one notch. On Saturday I was in a parade, and drove about 30 miles. I checked the torque again, and it is holding firm at 100 foot pounds.

It appears that my axle is OK, and that my problem was the washer. I will continue to drive it and check the torque periodically. I think the anomaly in the keyway is just where the keyway cutting tool chattered.

I am posting this in the hope that it may help someone else who is having the same problem.
 

Attachments

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i would change it as soon as i could, an axle is being subjected to to forces and flex it to directions, one is up and down as the wheel rolls, and the other is being twisted back and forth as the car is accelerated and decelerated, hardened stell does not like the be flexed as what is happening to your axle with a crack in it, cracks grow till they have a complete failure in the part, change it, my 2 cents worth
 
If the hub has been loose on the axle maybe the key has moved around and what looks like a crack may be just a worn spot. I would try to figure out if it's really a crack before I changed it out.
 
Mine had similar symptoms. I cleaned up all the chewed up shims, bearings and axel shaft. Dressed up the keyway, new key, shims, washer, & nut. Torqued it down to 100# and there she stays -- 1500 miles later.
 
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You could try liquid penetrant or magnaflux techniques to determine if it is really a crack - or just a fold in the metal.

A welder may be able to groove this out and re-weld but you will want the best welder possible - and someone who is familiar with weld cracking issues and the way to find them. And you'll still want to machine the taper straight when you're done - which will put the wheel even closer to your backing plate. An entire rebuild of your rear axle (and internal modifications) may be necessary to get past a shortened axle?

Maybe better to just find another axle shaft.

Joe K
 
Go ahead and run it. The worst thing that could happen is the axle will fail on the freeway. The wheel and brake drum will slip off of the car and take a fender with it. The car will go out of control and roll over. The wheel will cross the freeway and collide with an oncoming school bus that will go out of control... On second thought you would be crazy to even think of running it. Welding is not the answer. Get a new axle and have it Magnafluxed (sp?) before you install it. Cheap insurance considering the possible damage from an axle failure. If you can't afford to do it right, park it. It is not right to risk your life and the lives of others.

Charlie Stephens
 
Without a doubt find out if it really is a crack. I am sure you would feel bad if it broke and caused you to crash and hurt someone down the road. On our Model t's we junk the shaft right away and replace it with a new one.. they are much cheaper than a life.
 
Another thing. After you torque the axle nut initially you need to retorque them a couple of more times after you have driven the car a few miles.

Charlie Stephens
 
If you have a visible crack anywhere on a rear axle you should stop driving the car and immediately replace the axle as it will surely break and the wheel will come off the car.

Tom Endy
 
used axles at swap meets are much less expensive than a break down. When you think of it, even new ones are cheaper than an accident caused by a broken axle. Have it magnafluxed to verify it is a crack. Then if it is cracked, use it as a tent stake and get a new one.
 
I have a good friend have a rear axle break on the Grand Tour at the last MARC Williamsburg National Meet. The rear wheel and drum were caught upright under the rear fender and did not leave the car. Luckily he was only going about 35 MPH at the time so damage was minimal. We were able to buy a used axle at the show and rebuilt the rear end in the hotel parking lot. He drove the car 500+ miles back home, no problem then or since with our rebuild.
 
If it were just a case of dressing the keyway to find out if the flaw is deep or superficial, I'd say go for it, but since the axle also apparently didn't even hold a shim, either it or the hub is excessively worn. So, I'd replace the axle and check the hub carefully. It's a pretty big job, but what's your peace of mind worth?
 
Thanks for all your responses. They confirm my feelings. I will put it back together for now, see if it will hold torque, and then drive it five miles to the facility where my Town Sedan is stored, and bring the Town Sedan home. That will give me some time to plan a replacement. It's a good thing that I am near to Bert's.

Paul
 
When rebuilding a rear end MAGNA FLUX the axles. You can't always see a crack. The piece of mind is well worth the effort!!!
Bruce Davis
 
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