Dana 60 Big 35 Spline Inner and Stub Axle upgrade from 4WDFACTORY.com
By BillaVista


Part 3 - Old vs New shafts

Please note that all dimensions and measurements quoted here were measured by me with a pair if inexpensive digital calipers. They are likely only accurate to within +/- .020 inches, and should not be used for precise machining purposes or exact layout. They do however clearly illustrate comparative differences.

Here's the spline end of the original, pre 1981 stock long-side inner front GM Dana60 shaft. Prior to 1981 was when the shafts "necked down", which you can clearly see in the picture.

One other thing is well illustrated here. On an older axle shaft, even a 1981 and later "big" shaft, there will likely be a lot of wear and corrosion. this can be a significant weakness, as very often, when a shaft breaks, it does so at a place where there is a stress riser - frequently caused by surface corrosion, nicks, or flaws. That's why Drag racers polish their shafts to a mirror finish - to remove surface stress risers.

This pic of the stock Dana60 front 30 spline stub shaft also clearly shows where it reduces in diameter to about 1.258"

It also shows quite well the "bluing" marks on the body of the shaft created as the shaft passes through the coil in the induction hardening process.

Here's a comparison shot of the Dana60 30 spline stub shaft versus the 35 Spline Dana70 stub shaft. Note that both are exactly 12.0 inches long.

The other dimensions in the pic are:

  Old 30 spline New 35 Spline
A 1.500" 1.500"
B 1.258" 1.377"
C 1.281" 1.472"


Another shot of the 2 stub shafts, clearly showing how much bigger the 35 spline stub shaft is.
All the old next to all the new.

Comparison of old and new long-side inner shafts:

  Old 35 spline New 35 Spline
A 1.492" 1.473"
B 1.494" 1.441"
C 1.494" 1.441"
D 1.568" 1.566"
E 1.318" 1.584"


Comparison of old and new short-side inner shafts:

  Old 35 spline New 35 Spline
A 1.495" 1.475"
B 1.495" 1.445"
C 1.495" 1.445"
D 1.567" 1.565"
E 1.318" 1.590"

It seems odd, and I have no hard factual or tech data to back this up, but the splines on the old shaft actually "look better" to me. I don't know if they actually are or not. But the real story is the dimension "E" - much larger on the newer shafts!

This comparison is actually an interesting optical illusion. Because the main operating diameter of the newer shafts is so much bigger than in the older shafts, it actually appears as if the newer shafts are smaller at the yoke. this is not actually true, and they are bigger, or at least the same size as the old shafts ...

...as this picture and table illustrates. These are the long-side inner axles.

  Old 35 spline New 35 Spline
A 1.338" 1.467"
B 1.568" 1.601"


35 spline stub on the left, stock 30 spline on the right.

Reason enough to buy the kit right there!

Here are a bunch more comparison pics:

So it seems pretty clear, based on size, condition, lack of corrosion, and very likely improved manufacturing techniques and metallurgy over 25 years or more, that the new "big" inner axles and 35 spline stub shafts are a real and significant upgrade.

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