Dana 35 27 Spline Lockers: What are their limits?

Doctor Bone Smash

Doctor Bone Smash

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Ox, ARB, Eaton E Locker, Grizzly Zip, and a few more lockers are all available for Dana 35s with 27 splines. I get that 30 spline axles would obviously be stronger than 27 splines all else the same. What are the practical limits of a 27 spline axle? They can’t all just snap instantly if reputable companies are still manufacturing lockers for them. How far will stock axles go? How far will 27 spline alloy (1541H) axles take you?
 
There are few threads on this, and in summary: no one knows.

There is so much shit floating around about Dana 35 and 27 splines, that any success story sinks in that shit before it has any chance to float. After few years of observing this forum, i will go as far as saying that it has become a religion to shit on that combination.

Axle shaft strength percentages are all over the place, ranging from 10% to 40%, and those numbers come from god knows what tests.
With appearance of Dana 35 suppers, people have mixed and confused 1541s with chromolies back and fourth, and on top of that confusion started assigning % strength that is confusing and not justified by anything to begin with. So as a result, there is a giant bowl of shit and confusion based on the confusion and random numbers that are based on someones opinion.

Then there are claims that with 30 splines somehow you are able to go up and down the mount Everest with no issues, yet with a millimeter less of material in 27 spline everything just falls apart.
God forbid you fart in your Jeep on 27 spline axle shafts after having a burrito, your axles will snap in the middle.



IN MY OPINION, not based on any experience, if 1541 material is superior to carbonwhatever OEM has, 27 spline 1541 = 30 spline carbon... So then look at what can original 30 splines handle that come on our Jeeps, and use that as a guide.
 
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I had driven mine for over 11 years with a Dana 35, stock shafts and a stock Traclok with 33's and 3.07's. I never broke anything, but I don't beat on the Jeep. When I regeared to 4.10, I added Trutracs and 1541 axle shafts for some added confidence. I probably wouldn't lock a Dana 35 on 27 splines, but I do agree with the above poster, that the difference between a S35 and 27 spline alloys cannot be that huge.
 
I wouldn't run any locker on any stock Dana 35 with stock carbon steel 27 spline shafts. None, nada, nope, no matter what the tire size is. I might consider a locker on aftermarket 1541H 27 spline shafts with a tire size of maybe 31" tire size but I'd still be nervous. My standard recommendation for how to run a locker in a Dana 35 is to install a true Super 35 kit which includes 30 spline 1541H shafts like you can get from Revolution Gear, that kit handles a locker and up to 35" tires without a problem... within reason of course.
 
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Jerry is a good example.
Always supports super Dana 35 and references some people running 35s on super Dana 35 with lockers in MOAB and all sorts of valleys, yet maaaaaaaaaaaybeee okay with 31s on 1541 27 splines with a locker....
What influences this "maybe" ? Where is it coming from?
 
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Rob5589 said:
I'll put it another way; if you're spending a grand on a locker, why not spend another 300 for axles of 30 spline flavor?
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I agree with this, if the locker one is going to buy is available in the 30 spline variety, there is no good reason not to. If the Detroit Truetrac was available in 30 spline, I would have used 30 spline shafts since I was buying new shafts anyway.
 
Rob5589 said:
I'll put it another way; if you're spending a grand on a locker, why not spend another 300 for axles of 30 spline flavor?
Click to expand...

That actually is a valid and a very good point!
I forgot that i was going to go with a 30 spline for the same reason, but discovered that there is no truetrack for 30 splines, so i went with 27 splines.

Wow, enlightenment just blasted me in the face.
OP, if the locker that you want comes in 27 and 30 spline version, go with 30, difference in price is like two tanks worth of gas.
 
With the expense of a locker and gear setup the same between 27 and 30 spline, why even choose 27 spline?
To save a few pesos on the shafts? Just get a super 35, it's proven to work.
 
GASnBRASS said:
With the expense of a locker and gear setup the same between 27 and 30 spline, why even choose 27 spline?
To save a few pesos on the shafts? Just get a super 35, it's proven to work.
Click to expand...
I didn't want or need a rear auto-locker, like the Detroit locker which costs hundreds more than my Detroit TT, or the even more expensive ARB, and the added expense and complexity of an air compressor. The Detroit TT and 27 spline axles shafts come into play. That's why I use that setup.
 
GASnBRASS said:
With the expense of a locker and gear setup the same between 27 and 30 spline, why even choose 27 spline?
To save a few pesos on the shafts? Just get a super 35, it's proven to work.
Click to expand...
That’s the logical choice. I just think there has to be a bit more potential in the 27 spline axles than people realize. I can see where 33” tires would be way too much, but there has to be a reasonable application of those lockers.
 
I ran stock 27 spline axles with a LSD on 33’s and 4:11 gears without a issue I beat the snot out of it.

On the other hand I just put a Revolution S35 kit in with a air locker and 35’s and haven’t broke it either.
It really depends on what you would like to have verse what you really need and plan to do with it.
 
If someone is on a super tight budget, or their traction aid is only available in 27 spline, then I can understand.
I just have a habit of overbuilding things stronger than I need, so I will usually choose the beefier option.
 
eastbloc said:
That actually is a valid and a very good point!
I forgot that i was going to go with a 30 spline for the same reason, but discovered that there is no truetrack for 30 splines, so i went with 27 splines.

Wow, enlightenment just blasted me in the face.
OP, if the locker that you want comes in 27 and 30 spline version, go with 30, difference in price is like two tanks worth of gas.
Click to expand...

A TT is far less harsh on axles. Plus, if running TT's you aren't likely running it as hard as locked. A 27 spline 1541h should give you all the strength needed in that instance.
 
GASnBRASS said:
If someone is on a super tight budget, or their traction aid is only available in 27 spline, then I can understand.
I just have a habit of overbuilding things stronger than I need, so I will usually choose the beefier option.
Click to expand...
I should note, I spent $2600 on mine. Not really expensive, nor just chicken feed. I could have, and would have, spent more if it did something I needed. In my case I only needed what I bought.
 
Larger shafts of the same material will be modestly stronger. A 27 spline axle has a diameter of 1.18". A 30 spline axle has a diameter of 1.31". That's only 11% larger in diameter, or a 23% increase in cross-sectional area. But in torsion, the 1.31" shaft is 36% stronger. Shaft strength in torsion follows the cube of the diameter.

A 35 spline axle (1.50") would be 50% stronger than a 30 spline, or 105% stronger than a 27 spline.

Likewise, the strength in bending will also be proportional to the cube of the shaft diameter. However, most shafts fail in torsion. Sometimes they can fail in combined loading, or even bending, such as when you jump your Jeep.


And that's of the same metal. Add in a slightly different alloy and you could easily see 50% or better increase in strength.
 
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For what it’s worth I did reach out to several of the manufacturers to find out what they recommended to use 27 spline lockers. Only 1 of 3 replied. There was a privacy clause in the email so I can’t really quote or disclose who it was. They gave the usual Dana 35 is a turd but if you insist on using it then it should be trussed because of housing deflection. 1541H is supposedly 15% stronger than stock and 4340 is 25% stronger than 1541H. 27 spline lockers are “usually sufficient” with 31-33” tires and a “smooth driving style”, go with 30 spline if you are using 33” or larger or have an “aggressive driving style”. As stated earlier in the thread, the slight cost increase of higher spline shafts is probably worth it.
 
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