Chromoly Front Output Shaft vs Stock

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Marlin Crawler Front Chromoly Output Shaft vs. Stock

First some basic Q&A...

Applications: All 1979-95 Gear Drive 4cyl transfer cases
Housing Modifications required? No, simple R&R.
Same gear size/pitch/specs? Yes, fully compatible with stock front wheel drive idler gear.
Does it use the stock flange? No, it uses a larger 30-spline flange. Besides, it is way too strong for the stock style flange, it eats them for lunch. Seriously, we had to develop a heavy duty flange just for it (more on this later).

Noticeable comparisons...

Two notches to stake the flange nut, double insurance (stock only has 1 stake)
Huge 24mm flange nut (stock is 20mm)
The smallest diameter of the stock shaft is found between the bearing race and the gear. We carried the bearing race diameter all the way across to the shank for maximum strength. Result is a 29.0% larger diameter with 67% more material.
One-piece design for maximum strength and reliability

Now for some size comparisons...

Feature Diameter Cross Sectional Area
  Stock Marlin Crawler Stock Marlin Crawler
Shank Diameter 1.48 in 1.81 in (+22.3%) 1.72 in2 2.57 in2 (+49.6%)
Sharp Taper After Race? 1.07 in 1.38 in (+29.0%) 0.90 in2 1.50 in2 (+67.0%)
Bearing Race Diameter 1.18 in 1.38 in (+17.0%) 1.09 in2 1.50 in2 (+36.8%)
Spline Diameter 1.09 in 1.22 in (+11.9%) 0.93 in2 1.17 in2 (+25.8%)
Thread Size 0.77 in 0.94 in (+22.1%) 0.47 in2 0.70 in2 (+49.1%)
Nut Size 20mm 24mm (+20.0%)

Now for some pics...

Below is a comparison of the stock 27-spline front output (left) and our 30-spline Chromoly front output (right). Notice how massive the 30-spline section is compared to the 27-spline section. As mentioned above, we carried the massive bearing race diameter straight across resulting in 67% more material.

We added an extra stake to make sure the flange nut stays put.
The stock 27-spline piece really looks minuscule in comparison.

And if it's massive size plus Chromoly alloy wasn't enough, we all know that no matter how well you polish the stock output, front or rear, the flange is a serious weak link. That is why we designed an oversized shaft, which of course required a larger flange.

During testing, we found that the thickness of the stock flange was insufficient. We simply have too much shaft for the flange. What's the point in using a heavy duty output shaft if you are just gonna break flanges all day long? Therefore we designed our oversized "4-30" 4-pattern 30-spline Heavy Duty flanges with a 135% thicker cross-section.


This is what happened when we used a flange on our 30-spline Rear Output shaft that had the same cross-section as a 27-spline flange. (Both our front and rear Chromoly outputs have the same exact spline dimensions.)

In conclusion...

Marlin Crawler's new 30-spline front output shaft has 67% more material where it counts, is made from Chromoly alloy, and is a 1-piece design. It uses a 135% thicker flange with an 11.9% larger spline. It comes with an EcoSeal to protect the environment. No modifications required, simply remove and replace the old components with our larger and stronger parts. And lastly, it's a Marlin Crawler!!