How straight are our axles?

[wanderinthru]

Same horse walker project, but just to over come ignorant. How straight should an axle be to be straight. This thing is dialed in the 4 jaw to a 1/2 thousand using their center on the spline end and its running out 65 thousand .065 in the middle.

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[bucket]

I'm not sure, but now I'm curious as well. My hunch tells me that factory original axles of that time would often have that much amount of runout.

 

[wanderinthru]

I'm not sure, but now I'm curious as well. My hunch tells me that factory original axles of that time would often have that much amount of runout.

You could be correct. This thing looks like your turning a banana.

 

[dvdswan]

Think about this...

the length of 30", with a tiny bend in the middle, as it spins the bend will want to force itself outward creating a vibration.

A driveline is balanced just like a tire is balanced to 0 so there is not vibration. Same goes for axle shafts.

 

[wanderinthru]

Think about this...

the length of 30", with a tiny bend in the middle, as it spins the bend will want to force itself outward creating a vibration.

A driveline is balanced just like a tire is balanced to 0 so there is not vibration. Same goes for axle shafts.

So? You saying the bend is there for a reason?
Hard for me to understand how one could balance a bent shaft.

 

[1985c20]

That’s not a machined surface it’s as-forged so I wouldn’t think it matters. .065” seems a little high but I don’t know what’s they’re manufactured too. What are you clamping on in the chuck? What does it measure on the ground surfaces?

 

[wanderinthru]

That’s not a machined surface it’s as-forged so I wouldn’t think it matters. .065” seems a little high but I don’t know what’s they’re manufactured too. What are you clamping on in the chuck? What does it measure on the ground surfaces?

It's a chain sprocket welded to it in the chuck. Dialed it in on the machined surface right behind the bearing, with the tail stock center in just enough to hold it. It's not out of round .065 its a long bend, can see it's turning true on either end and swings like a banana.

 

[dvdswan]

So? You saying the bend is there for a reason?

No the bend is NOT there for a reason. The bend is there for who knows why, age, weight loaded, time, who knows. it should not be there.

 

[wanderinthru]

No the bend is NOT there for a reason. The bend is there for who knows why, age, weight loaded, time, who knows. it should not be there.

What I thought you were saying. Though my gibblet mind read it the other way as well.

 

[wanderinthru]

For ***** and giggles I put the other shaft in on centers. This 3 jaw is dialed in dead nut. Shows .005 run out at the bearing and .055 in the center..ish. just a fwiw, and my continued confusion.

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In case any one was wondering.

 

[shiftpro]

This story sounds familiar. I think these axles are all like this. As far as balance is concerned, perhaps the moment of inertia or rotating inertia is
low enough it doesn't cause issues.

 

[wanderinthru]

This story sounds familiar. I think these axles are all like this. As far as balance is concerned, perhaps the moment of inertia or rotating inertia is
low enough it doesn't cause issues.

Familiar story? Is there a recent thread on this subject?
I agree with the inertia theory. Or, some kind of engineering math where it gets straight with heat??

 

[idahovette]

I would bet that axles will distort severely when the right foot is planted to the floor.....of course all this is dependent on amount of pressure(HP) being applied??

 

[Vbb199]

Science says twisting would occur when the juice it put to the tires... but....

.055-.065 out on the center seems drastic to the general reader here, but if you hold a caliper up to your face and visualize a .060" eccentric, on a cast iron surface, over a distance of like, 3.5 feet,

.060" over a distance of 6 inches would be bad, but i'd say it doesnt matter over the length of that shaft... now if bearing surface over to the splines was out that much, i'd be concerned.

Its not like its .250" off center. And its also being supported at 2 points of contact. (Bearing, carrier)

That runout in the center wouldnt bother me, your tires are gonna create more vibration than that would....
BUT
I kinda wanna pull an axle shaft and put it in the lathe and see the runout.

 

[wanderinthru]

Science says twisting would occur when the juice it put to the tires... but....

.055-.065 out on the center seems drastic to the general reader here, but if you hold a caliper up to your face and visualize a .060" eccentric, on a cast iron surface, over a distance of like, 3.5 feet, i'd say it doesnt matter.... now if bearing surface over to the splines was out that much, i'd be concerned.

Agree. Though if you will look at where the indicator is running, it's on a lightly ground (my guess, can't see any tool marks) round surface.