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What causes a broken axle?

I don’t see how a pot hole can do it.
The axle just gets pointed up and down b/c of the CV joint.
A pothole should not stress the axle at all.

Metal fatigue is often the cause of metal parts failing. This is a gradual process and will result in a sudden break.

I owned a Plymouth once with torsion bar front suspension. Both failed; one while I was having lunch and looked out the window to see the car’s front suddenly sag!

I also owned a 1976 Ford Granada with rear leaf springs. Both broke during the time I owned the car.

These things should not happen of course, but are the result of poor quality control or bad design.

A pothole is not just up and down. It can force a rotation as well as back and forth. It can break an axle easily.

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The CV-joint also allows articulation of the axle while the front wheels are turned.

So,if the pot hole was hit while making a sharp turn at speed, it can destroy a worn CV-joint.


On a late night stroll a few years ago I saw a fairly new car loaded with teenagers hit a speed bump going a little too fast, with a little too much weight in the car, both front axles appeared to break at the outer cv joints. As you might expect the car came to a screeching halt, mid-road; meanwhile the cv joint ball bearings broke loose & went whirling down the road.

I had a CV joint fail that I’m pretty sure was caused by making a hard right turn on an off ramp while braking hard. It took a few hundred miles for it to fail but I’m pretty sure the stress from the turn was the start of it.

I’m not talking about busted CV. I am specifically talking about an axle shaft that snaps. How?

What’s the axle and suspension configuration of the vehicle? I expect you understand nothing in a vehicle is indestructible. Everything will break if enough force is applied. Probably the strongest thing in a car is the horizontal brace inside the door, a safety feature. It is made of a very strong type of steel. Shops that do body & frame collision work use it to help re-jigger a bent frame sometimes.

Do you know if someone installed a cheap replacement axle?

The cheap axle has a thinner shaft than the OEM axle.


The OP offers up a good question, why doesn’t the CV joint just flex enough to accommodate the pothole. After all that’s what it is designed to do, flex. I guess what happens when an CV jointed axle breaks like that, with a deep enough pothole, possibly combined with steering, the CV joint reaches the limit of its movement; at that point the axle is stoutly connected between the wheel hub and the transmission and nothing in the CV joint left to flex.

  1. Lots’a weight
  2. Lots’a torque
  3. Both 1) and 2)

Perhaps you could tell us what you are talking about, maybe there was no pot hole, sometimes things break.

Back in 1960, a friend of my brother got a very good deal on a '57 Chrysler–a model year that was notorious for quality control problems–and it had very low mileage on the odometer because it had sat in a garage for two years after the owner died from “lead poisoning” (the type administered by The Mafia).

The car looked like it had just rolled out of the showroom, but the quality issues of that model would not be denied, and a few weeks after he bought it, he crossed some RR tracks a little too fast and both front torsion bars snapped at the same time.

Tell that to the tow truck drivers here in New England. They tow cars with broken suspension parts and axles every day during pot-hole season (March thru May).

A pothole will not break a CV axle. The axle does not carry the weight of the vehicle. It has nothing to do with suspension. The tire, wheel bearings, knuckle, strut and control arm do that. The only thing a CV axle does is propel the car. Brakes stop it. Which leads me to believe this damage as it appears looks like too much torque for the unit. It doesn’t appear rusted. When I was young, I would borrow the old mans Caddy and go out cruising with my buddies. We would do what we called “neutral drops”. Meaning we’d have the car in neutral, get about 5,000 RPM on the engine, slam it into drive. Boy you could do an awesome burnout! Found out it was easy to break axles doing that as well.

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Yea, that is what I think. The axle does not carry the weight. It just connects. Makes no sense it would break.

It was not torque. The car was being driven as a commuter car. Not a parking lot burnout machine.

Axle torque happens both on acceleration and braking. And there’s forces applied to the axle when the cv joint reaches its flex limit.

Since you don’t seem to like any of the previously suggested causes, here’s another.
Sometimes sh$t just happens.


Obviously from Tester’s pic, they break sometimes, somehow for some reason.

That and the sudden acceleration, in the Newtonian sense.
All those suspension parts have mass; and abrupt movements result in forces (F=MA) that don’t occur in normal use.
Forces that can break things.

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