JK spec'd axles

[pcoplin]

I know some of you have swapped JK axle into your TJs, that's something I haven't done. I have a buddy that's interested in doing his RJ60 from his JK into his LJ. He was talking with another shop who had recently done JK axle into a TJ, and was saying there was excessive front driveline clearance, I believe it was the 4.0 drivetrain still in it.

I have to put a tape to the stuff when I get it, but is there any validity to it? I know the pumpkin is farther to the drive side than the SD60s and such that I've swapped before, but can't see how that's it worse than the TJ front axle. Any insight before I take it on would be great. Thanks!

 

[someguysjeep]

i would assume a RJ60 axle made for a JK would have come with the JK offset.
since we run the axles centered, what matters is pinion offset from center, the TJ Dana 30 is 8.25" ish IIRC, i think the JK Dana 44 is like 8.5 ish maybe closer to 9" i'll have to confirm that.
i find info that says the SD60 is in the ballpark of 10.5" from center, so it'd be the furthest away from center or closer to the frame.

 

[pcoplin]

i would assume a RJ60 axle made for a JK would have come with the JK offset.
since we run the axles centered, what matters is pinion offset from center, the TJ Dana 30 is 8.25" ish IIRC, i think the JK Dana 44 is like 8.5 ish maybe closer to 9" i'll have to confirm that.
i find info that says the SD60 is in the ballpark of 10.5" from center, so it'd be the furthest away from center or closer to the frame.

Awesome, that helps a ton. From what I was gathering, the JK had less of an offset, I couldn't believe that was the case. Appreciate the info!

I can attest the SD axle isn't the best for the TJ and JK. I shorted the long side 3 inches on my TJ and it was way better, but this JK I did had quite front driveline offset, makes for vibes in 4wd at desert speed. I'll be building a fresh center for the next one.

 

[mrblaine]

I know some of you have swapped JK axle into your TJs, that's something I haven't done. I have a buddy that's interested in doing his RJ60 from his JK into his LJ. He was talking with another shop who had recently done JK axle into a TJ, and was saying there was excessive front driveline clearance, I believe it was the 4.0 drivetrain still in it.

I have to put a tape to the stuff when I get it, but is there any validity to it? I know the pumpkin is farther to the drive side than the SD60s and such that I've swapped before, but can't see how that's it worse than the TJ front axle. Any insight before I take it on would be great. Thanks!

The only thing excessive front clearance would do is run the driveshaft over into a Genright style lower frame control arm mount. That can be dealt with via a smaller diameter front driveshaft.

 

[someguysjeep]

i went and looked again,
the Tj Dana 30 is 8.25 from center axle.
the jk Dana 44 looks more like 9" from center, (it's under the rig and a bit harder to get a tape across)
where the axle rest's under my jeep the pinion is 5.25" from the frame rail and the stock TJ front driveshaft's closest point is 4.5" off the frame. plugged into a 231 sitting on a savvy skid.

 

[Gilaguy23]

Any truth that the JK axle tubes are thinner walled? This comes from a former JK owner who bent his housing far to easily he says.

 

[someguysjeep]

Any truth that the JK axle tubes are thinner walled? This comes from a former JK owner who bent his housing far to easily he says.

i think they are 1/4 wall tubes.

edited: the specs linked below say .31 but that's just a fat 1/4.

 

[mrblaine]

Any truth that the JK axle tubes are thinner walled? This comes from a former JK owner who bent his housing far to easily he says.

Thinner than what? They are the same as a TJ front but they are longer so somewhat easier to bend.

 

[bty34]

If the axle is built with a stock JK pinion offset, it should be the same as a TJ front, or at least within the margin of error of my measurement.

https://wranglertjforum.com/threads/front-axle-pinion-offset.59839/

 

[someguysjeep]

If the axle is built with a stock JK pinion offset, it should be the same as a TJ front, or at least within the margin of error of my measurement.

https://wranglertjforum.com/threads/front-axle-pinion-offset.59839/

it should be close enough not to cause you issue.

 

[pcoplin]

i went and looked again,
the Tj Dana 30 is 8.25 from center axle.
the jk Dana 44 looks more like 9" from center, (it's under the rig and a bit harder to get a tape across)
where the axle rest's under my jeep the pinion is 5.25" from the frame rail and the stock TJ front driveshaft's closest point is 4.5" off the frame. plugged into a 231 sitting on a savvy skid.

So the JK axle appears to have the driveline 3/4in closer to the engine/trans if I'm reading right. For some reason that caused some issues on the build I was referring to.

Thanks for the insight, appreciate it.

 

[someguysjeep]

So the JK axle appears to have the driveline 3/4in closer to the engine/trans if I'm reading right. For some reason that caused some issues on the build I was referring to.

Thanks for the insight, appreciate it.

it is just a bit further from center axle..........so it's more driver side by a bit, it puts the axle end of the driveshaft and the pinion a bit closer toward the driver side frame rail.


i don't keep a ton of pics but this is my JK Dana 44 axle under my TJ.

red is JK, yellow is TJ and blue would be SD60 pinion offset from center axle

 

[Gilaguy23]

Thinner than what? They are the same as a TJ front but they are longer so somewhat easier to bend.

The claim was jeeps pre JK.

 

[Mike_H]

i think they are 1/4 wall tubes.

edited: the specs linked below say .31 but that's just a fat 1/4.

Or a skinny 5/16...

 

[mrblaine]

Or a skinny 5/16...

.31 is how most companies call out 5/16" since the .002 doesn't round up the 1. A fat 1/4" in my world is .260.

 

[someguysjeep]

what type of tube is used? DOM? i can't find it in that size.

and yes .31 is 5/16...... i was taking some liberty with that statement down playing the extra sliver of material, as not a significant enough to really credit it's strength as being much more than 1/4". am i off here?

but if it's listed as .31 the answer is .31.