The Stovebolt Site Forums The Shop Area Engine Shop 1954 3100 Bent Front axle?

Hi folks

Can anyone tell me if my front axle is bent? It bends in a very uniform manner - curved in the forward direction.The bend is so regular that I'm not sure if it was bent freakishly accurately, or if in fact the axle should have this bend. Help please!

Set the truck on a level floor & put a level against the sides of the tires. First jack up the front end & make shure the tires or wheels are not out of round & the wheel brgs. & kingpins are resonably tight. The bubble in the level should be near center.

I just checked my 54 half ton axle. I had remembered thinking it was curved to the front as well. So I pulled it out from under my completely disassembled frame. Killed a couple of Black Widow spiders and laid a straight edge on it. It is curved to the front just as I thought. It is curved enough to see easily, you don't need a straight edge to check it.

Perhaps someone knows why.

Lonnie

If you get the truck on a level surface, with the axle level and the wheels straight forward, you should see that the wheels tilt out at the top, something in the order of 1/4" to 1/2". That corresponds to the proper camber in the specifications.

The 1954 Shop Manual has an overhead-view drawing of a front axle. There is no forward bend in the axle.

[img]http://ares.cs.siena.edu/~lederman/truck/Photos/axletoein.JPG[/img]

The camber anlgle, as Truckernix described (out at the top by 1 +/- 0.5" for all size trucks), is shown below.
[img]http://ares.cs.siena.edu/~lederman/truck/Photos/axlecamber.JPG[/img]

Tim

Joe - who're "they"?? as Tim points out, the shop manual shows a straight axle [57 manual has the same pics] - it also points out that IF it's bent, great care must be taken to straighten it [cold - no heat on castings], and beyond a certain amount it should be replaced, and it's unlikely many of these ol trucks have had any front end adjustment done by bending the axle front to back - it's up and down that would be bent to change the kingpin inclination, and that's unlikely - everything else has specific adjustment points, and I've never seen a manual that advises any bending operation for alignment

Bill

As red58 states, bending the front axle front-to-back seems to be an unnecessary operation. The tie-rod toe-in adjustment should suffice. fletch seems to describing this type of distortion and asking if the distortion is normal.

The up-down bending (when both the king-pin and camber inclinations are out by approximately the same amount) was commonly and successfully done in both shops and under shade trees (usually done incorrectly - see below).

Oh yes, people also used to heat the axles to bend them. Even the shop manuals yell at us: "ALWAYS STRAIGHTEN FORGINGS COLD - UNDER NO CIRCUMSTANCES SHOULD HEAT BE APPLIED."

Also stated is: "As a general rule, when extreme bent conditions exist, minute fractures hardly visible will occur. Failure under ordinary conditions usually results." I have never known an axle to fail but I would not like to present when one does.

Tim

I don't know if bending the axle is common alignment proceedure, I do know that some folks think that thick piece of steel right there easy to get to, is a great place to wrap a tow chain around . . . ?

I gotta say this is a surprising thread. I've been around these trucks all my life and I've never heard of bendin an axle to achieve alignment. Guess this happens at tire alignment places. But if somebody suggested this to me I'd be askin a lot of questions--wonder what kinda tool they got to accurately bend an axle still on the vehicle? Oh well I probably otta get out more...another example of where workin on ur own truck makes u ignorant. :rolleyes:

I suspect the middle part of the axle gets bent forward due to hard impact(s) on the wheels. The front springs would act as fulcrums, forcing the middle of the axle to bow out in the forward direction. As others have stated, king pin angle is the most important dimension in a beam axle, as toe-in can be set with the tie rod.

Bending axles to acheive alignment is a big truck straight-axle procedure. It used to be considered a valid operation by the manufacturers, but has fallen out of favor in the past 10 years or so.