Is it required to run 30 spline axle shafts in my Dana 30 with a selectable locker?

TJim

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Hey!

My plan is selectable lockers. Most possibly ARB Air lockers.

I am going to do it in a few months, when I re-gear. I am running 31x10.5r15 BF KO2s in a TJ 2.4L (4-cylinder). My stock gears are 4.10. I am going to go for 4.56 or 4.88, but thats a question for another day!

I cannot find any TJ Dana 44s in my area, so I decided to keep my axles (Dana 30/35)

The plan is to install 30 spline axle shafts in my Dana 35. BUT, what about Dana 30? Is it required to install 30 spline axle shafts in Dana 30 as well in order to run selectable lockers without worrying too much? Or is it up for the task?
 
You'd be smart to add 30-spline locker to your Dana 30 and then add 30-spline alloy axle shafts.

In fact, there it would be a waste of money to do otherwise.
 
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You'd be smart to add 30-spline locker to your Dana 30 and then add 30-spline alloy axle shafts.

In fact, there it would be a waste of money to do otherwise.

Are you saying that for being future proof? If I decide to go bigger? Or maybe If I decide to sell the axle? Or you think that it is a challenge for Dana 30 to run lockers even with 31"?
 
X2, 4340 27 spline inner/outer shafts will hold up very well with 35's and a locker even on very tough trails. That's what I installed into my previous TJ after breaking a factory shaft no more problems.

Are 4340 spline inner/outer shafts much cheaper than 30 spline shafts for Dana 30?

If I replace factory shafts before installing a locker why install a 27 spline instead of a 30 spline shaft?

Or are you referring to it as a solution if I have a 27 spline locker installed and break a shaft, so I cannot install 30 splines shafts?
 
Are 4340 spline inner/outer shafts much cheaper than 30 spline shafts for Dana 30?

If I replace factory shafts before installing a locker why install a 27 spline instead of a 30 spline shaft?

Or are you referring to it as a solution if I have a 27 spline locker installed and break a shaft, so I cannot install 30 splines shafts?
Because you need to also install 30 spline manual locking hubs to go with 30 spline outer stub shafts. There are no 30 spline unit bearing hubs worth installing. Milemarker came out with a set of 30 spline unit bearing hubs and they didn't hold up. And if you have a 27 spline locker you cannot install 30 spline shafts without replacing the locker with a 30 spline model.

Don't be concerned with "only" having 27 spline shafts up front if they are 4340 alloy. The front shafts seldom see more than about 50% of the load seen by the rear axle shafts.
 
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Because you need to also install manual locking hubs to go 30 spline outer stub shafts. There are no 30 spline unit bearing hubs worth installing. Milemarker came out with a set of 30 spline unit bearing hubs and they didn't hold up. And if you have a 27 spline locker you cannot install 30 spline shafts without replacing the locker with a 30 spline model.

Don't be concerned with "only" having 27 spline shafts up front if they are 4340 alloy. The front shafts seldom see more than about 50% of the load seen by the rear axle shafts.
Τhanks! I'm just trying to figure out the budget I need! I'm really close!

Do you think that stock shafts will hold or do I need to install the 4340 alloy ones right away?
 
Τhanks! I'm just trying to figure out the budget I need! I'm really close!

Do you think that stock shafts will hold or do I need to install the 4340 alloy ones right away?
With 31’s locked with stock shafts will be fine until they break. They will eventually if you are rough on it
 
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Τhanks! I'm just trying to figure out the budget I need! I'm really close!

Do you think that stock shafts will hold or do I need to install the 4340 alloy ones right away?
You're fine with your 31" tires as-is, within reason as described below. I'd think seriously of 4340 front shafts with 33's and definitely go with them with 35's.

The part of the axle shaft that usually breaks is what holds the u-joints in, the "ears". The factory shafts are not heat treated there and the non-heat treated u-joint ears break when they see too much load. Too much load there normally happens when the steering wheel is turned to or close to all the way to the steering stops and too much gas is given, especially when in 4Lo.

Just make it a point to never give it a lot of gas when the steering wheel is cranked hard over.

This is where they typically break, this photo is from when I broke mine. And this is why you need to replace both the inner and outer stub shafts when upgrading to 4340 alloy axle shafts. It was the outer stub shaft that broke on mine.

DSCF0048withArrow.jpg


One last important thing to keep in mind. If you break an outer stub shaft like happened above, remove only the INNER axle shaft and limp out of there in 2wd or gently in 3wd. NEVER remove the outer stub shaft and try to drive on it, the unit-bearing hub will fail and that wheel will come off before too long. A friend of mine in my former 4x4 club was killed on the highway while returning from a 4x4 trip after having removed the broke outer stub shaft. Leave the stub shaft installed, it holds the unit bearing hub together.
 
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You're fine with your 31" tires as-is, within reason as described below. I'd think seriously of 4340 front shafts with 33's and definitely go with them with 35's.

The part of the axle shaft that usually breaks is what holds the u-joints in, the "ears". The factory shafts are not heat treated there and the non-heat treated u-joint ears break when they see too much load. Too much load there normally happens when the steering wheel is turned to or close to all the way to the steering stops and too much gas is given, especially when in 4Lo.

Just make it a point to never give it a lot of gas when the steering wheel is cranked hard over.

This is where they typically break, this photo is from when I broke mine. And this is why you need to replace both the inner and outer stub shafts when upgrading to 4340 alloy axle shafts. It was the outer stub shaft that broke on mine.

View attachment 240063

One last important thing to keep in mind. If you break an outer stub shaft like happened above, remove only the INNER axle shaft and limp out of there in 2wd or gently in 3wd. NEVER remove the outer stub shaft and try to drive on it, the unit-bearing hub will fail and that wheel will come off before too long. A friend of mine in my former 4x4 club was killed on the highway while returning from a 4x4 trip after having removed the broke outer stub shaft. Leave the stub shaft installed, it holds the unit bearing hub together.
Thanks for the detailed response!

Τhe only step left is to determine whether I should choose 4.56 or 4.88. I have couple of months to make up my mind.