Dana 30 upgrade / weak point

[UKTJ]

Replacement axles are much harder to come by in the UK. No obvious donor vehicle options and shipping cost for replacement axles are eye watering. I am therefore looking at doing the best I can with a Dana 30. It is worth noting that the conditions in the UK are similar to the US East coast (not any deserts around here), so it is simply impossible to avoid wet and muddy conditions much of the time.

One option that is a possible replacement axle is a HP Dana 30 from an early XJ. If I upgrade an HP Dana 30 with a truss, 4.88 gears, ARB locker and chromoly shafts and run 35s, what is the most likely weak point in the set up given the typical UK conditions. Would 30 spline Chromoly shafts or RCVs change the answer?

 

[mrblaine]

Replacement axles are much harder to come by in the UK. No obvious donor vehicle options and shipping cost for replacement axles are eye watering. I am therefore looking at doing the best I can with a Dana 30. It is worth noting that the conditions in the UK are similar to the US East coast (not any deserts around here), so it is simply impossible to avoid wet and muddy conditions much of the time.

One option that is a possible replacement axle is a HP Dana 30 from an early XJ. If I upgrade an HP Dana 30 with a truss, 4.88 gears, ARB locker and chromoly shafts and run 35s, what is the most likely weak point in the set up given the typical UK conditions. Would 30 spline Chromoly shafts or RCVs change the answer?

What does the truss do for you?

 

[Jerry Bransford]

Replacement axles are much harder to come by in the UK. No obvious donor vehicle options and shipping cost for replacement axles are eye watering. I am therefore looking at doing the best I can with a Dana 30. It is worth noting that the conditions in the UK are similar to the US East coast (not any deserts around here), so it is simply impossible to avoid wet and muddy conditions much of the time.

One option that is a possible replacement axle is a HP Dana 30 from an early XJ. If I upgrade an HP Dana 30 with a truss, 4.88 gears, ARB locker and chromoly shafts and run 35s, what is the most likely weak point in the set up given the typical UK conditions. Would 30 spline Chromoly shafts or RCVs change the answer?

The weak point in both the XJ HP Dana 30 and TJ Dana 30 is the size of their ball joints, not the axle housing. For 35's the ball joints are not an issue, nor is axle flex a problem that a truss is for. With chromoly shafts up front together with a good u-joint like the Spicer 5-760x your existing Dana 30 will be fine with 35's.

 

[UKTJ]

What does the truss do for you?

The honest answer is I was merely reflecting what many on Youtube who claim to be building the "ultimate Dana 30" have included in their list of modifications. I see from @Jerry Bransford's answer below that flexing / bending of the axle tubes is not a concern. So I guess it would be unnecessary, which I also presume is what you were getting at. Correct?

 

[UKTJ]

The weak point in both the XJ HP Dana 30 and TJ Dana 30 is the size of their ball joints, not the axle housing. For 35's the ball joints are not an issue, nor is axle flex a problem that a truss is for. With chromoly shafts up front together with a good u-joint like the Spicer 5-760x your existing Dana 30 will be fine with 35's. Your LP Dana 30's R&P gears are fine with 35's too.

OK thanks, @Jerry Bransford. Given that, would a WJ knuckle swap (meaning a change to WJ knuckles, if I understand correctly) provide additional strength in that area?

 

[Jerry Bransford]

OK thanks, @Jerry Bransford. Given that, would a WJ knuckle swap (meaning a change to WJ knuckles, if I understand correctly) provide additional strength in that area?

Additional strength is not needed in that area for 35's, the TJ's front Dana 30 and Dana 44 knuckles and ball joints hold up all day every day for 35's even in extremely tough wheeling conditions. My front Dana 30 and front Dana 44 axles were used almost exclusively on tough rock crawling trails with 35's and lockers and I never had a problem in that area. When I replaced my ball joints just as a precautionary thing while replacing my brakes with the Big Brake Kit from Black Magic Brakes I went with the same OEM Spicer ball joints the factory installed.

 

[mrblaine]

The honest answer is I was merely reflecting what many on Youtube who claim to be building the "ultimate Dana 30" have included in their list of modifications. I see from @Jerry Bransford's answer below that flexing / bending of the axle tubes is not a concern. So I guess it would be unnecessary, which I also presume is what you were getting at. Correct?

Those same fuckwits will also put a truss on a Superduty Dana 60 front which has a higher front axle weight rating for the vehicle than the entire weight of even a highly modified 40" tire running TJ Unlimited. As stated, the ball joints are the weak link and if the slippery conditions you play in require wheel speed with the possibility of tires grabbing traction from time to time while doing that, the ring doesn't have enough strength to take that very many times before you are ruining gear sets. What we can get by with in the rock on 35's changes entirely when you introduce tire spin.

 

[mrblaine]

OK thanks, @Jerry Bransford. Given that, would a WJ knuckle swap (meaning a change to WJ knuckles, if I understand correctly) provide additional strength in that area?

No

 

[P man]

People spend alot if money to fix problems that don't exist. I have bought jeeps that some half wit used a stick welder to glob on a truss that is barely hanging on yet managed to distort and generally rat fuck the entire assembly.

 

[UKTJ]

Those same fuckwits will also put a truss on a Superduty Dana 60 front which has a higher front axle weight rating for the vehicle than the entire weight of even a highly modified 40" tire running TJ Unlimited. As stated, the ball joints are the weak link and if the slippery conditions you play in require wheel speed with the possibility of tires grabbing traction from time to time while doing that, the ring doesn't have enough strength to take that very many times before you are ruining gear sets. What we can get by with in the rock on 35's changes entirely when you introduce tire spin.

OK thanks again, that makes sense. If I am understanding correctly, if the ring and pinion is a weak point because of the nature of the places I wheel, then the swap to a high pinion Dana 30 would be helpful, given that is reputed to give an increase in strength said to be somewhere around 20 to 30%. Or am I just being given bad info by the Youtube crowd? Or is there any other way to give it more chance of survival.

I'd love to be able to swap in a stronger axle, but like I say it is hard to see how I do that without selling a kidney. Given that I am just trying to get to the best answer I can with what I have to work with.

 

[mrblaine]

OK thanks again, that makes sense. If I am understanding correctly, if the ring and pinion is a weak point because of the nature of the places I wheel, then the swap to a high pinion Dana 30 would be helpful, given that is reputed to give an increase in strength said to be somewhere around 20 to 30%. Or am I just being given bad info by the Youtube crowd? Or is there any other way to give it more chance of survival.

I'd love to be able to swap in a stronger axle, but like I say it is hard to see how I do that without selling a kidney. Given that I am just trying to get to the best answer I can with what I have to work with.

My reply was based wholly around the fact that you were going to try and make the HIGH PINION version of the Dana 30 work out of an early XJ.

The HP gear set while being driven on the drive instead of the coast side will reduce the likelihood of broken teeth when set up correctly with extra preload. It will not however, survive tire spin with sudden traction grabs often or at all depending on the shock load.

They don't have any Wagoneers in the salvage yards over there? You can make a low pinion 44 last a lot longer than a HP 30.

 

[UKTJ]

My reply was based wholly around the fact that you were going to try and make the HIGH PINION version of the Dana 30 work out of an early XJ.

The HP gear set while being driven on the drive instead of the coast side will reduce the likelihood of broken teeth when set up correctly with extra preload. It will not however, survive tire spin with sudden traction grabs often or at all depending on the shock load.

They don't have any Wagoneers in the salvage yards over there? You can make a low pinion 44 last a lot longer than a HP 30.

As far as I can see the Wagoneer was never sold in the UK. No F150/250 or 350 and no Superduty in the UK either. The only option I am aware of for an axleswap would be the Dana 44 from a JK, but I heard the Dana 44 in the JK was not great.

 

[mrblaine]

As far as I can see the Wagoneer was never sold in the UK. No F150/250 or 350 and no Superduty in the UK either. The only option I am aware of for an axleswap would be the Dana 44 from a JK, but I heard the Dana 44 in the JK was not great.

The JK 44 is not that great when you try to put larger than 35" tires on it. For 35's, it would be a stellar swap for you. Especially if you can tweak a few things to tune it up. Given that the tube is the same diameter and wall thickness as the TJ but a bit longer with a horrid upper mount on the right side or long side tube, it can benefit greatly from a vestigial truss/stiffener like is used on the Savvy Midarm. Avoid the inner sleeves but do stiffen the long side, inner C gussets because they need it where the TJ doesn't, throw some good balljoints in it and go have fun. You don't have to run the double steering set up but that may be easier than anything else.

The only things that will bite are the width so you may have to run some higher backspaced wheels and then a small wheel spacer at the rear to get it back to tolerable track width.

If I was doing it, I'd cut the inner C's off, use the TJ C's and set it up to run TJ Rubicon 30 spline shafts, C's, and knuckles. I was going to do exactly that but I found a Rubi 44 before I got into it.

 

[UKTJ]

The JK 44 is not that great when you try to put larger than 35" tires on it. For 35's, it would be a stellar swap for you. Especially if you can tweak a few things to tune it up. Given that the tube is the same diameter and wall thickness as the TJ but a bit longer with a horrid upper mount on the right side or long side tube, it can benefit greatly from a vestigial truss/stiffener like is used on the Savvy Midarm. Avoid the inner sleeves but do stiffen the long side, inner C gussets because they need it where the TJ doesn't, throw some good balljoints in it and go have fun. You don't have to run the double steering set up but that may be easier than anything else.

The only things that will bite are the width so you may have to run some higher backspaced wheels and then a small wheel spacer at the rear to get it back to tolerable track width.

If I was doing it, I'd cut the inner C's off, use the TJ C's and set it up to run TJ Rubicon 30 spline shafts, C's, and knuckles. I was going to do exactly that but I found a Rubi 44 before I got into it.

That's extremely helpful, many thanks.

 

[mrblaine]

That's extremely helpful, many thanks.

Key bit of info I overlooked is during my research, I only found one locker that would work with the 30 spline Rubi 44 shafts out of the TJ which is the stock JK Rubi 44 e-locker. I say that in hopes someone will come along and correct me with some other versions that will work.

If it helps, I have a new OEM JK e-locker I bought for the project that I am unlikely to use now if you find yourself in need.

 

[UKTJ]

The only things that will bite are the width so you may have to run some higher backspaced wheels and then a small wheel spacer at the rear to get it back to tolerable track width.

I've been doing a bit more research online. As I understand it the OE wheels on a JK Rubicon come with 6.25" of backspacing fitted with about 10" wide tyres. I have read that to run 35x12.5" tyres requires a spacer of at least 1.5", effectively taking the backspace down to 4.75". But that is due to rubbing on the frame. As far as I can see a JK frame is about 925mm (just under 36.5") wide at the front versus a TJ's frame at the front of 843mm (about 33.2"). That means the wheel mounting surface of a JK Dana 44 will be about 1.6" further out from the frame on each side than it is on a JK ((36.5-33.2)/2). Does this mean I would likely be able to run a 35x12.5" tyre on a stock 6.25" BS wheel with a JK front Dana 44 under a TJ?

They are pretty strict on tyre coverage here, so I am trying to get to the position of the outer face of the tyre on the JK Dana 44 versus my current set up. Assuming the answer above is "yes"...

...with my current set up I have an axle width of 60.5" (wms to wms), my stock wheels have 5.25" back space, but I run a 1.25" spacer giving a net 4" of back space. My current tyres are 285/75/16 a quoted width of 11.2". Taking that, my understanding is my current set up gives a distance between the out edge of the tyres of 74.9" (60.5-8+22.4). The JK Dana 44 is 65.5" wide, with 12.5" wide tyres on 6.25" BS wheels I make the total width 78" (65.6-12.5+25). So on each side the tyre would be about 1.5" further out. Does that make sense?

 

[macleanflood]

Bunch of previous posts on JK axles...googling wranglertj forum JK axles on a TJ got me a list of forum posts...

https://wranglertjforum.com/threads/jk-axle-swap-for-tj.33305/
Why not order a set from Dana, G2 or a couple of other providers?

I did a Super 30/35 conversion on mine (and a front truss and sleeves since I can weld and know how to heat up and cool down an axle). 30/44s all share the same outters and that's your weak link/fuse.

We wrecked my wife's JK and if it were me we'd buy a TJ replacement, convert it to an LJ, LS swap it and put her 5.13 e lockers JK 44 axles on with coil overs. She wants a JKU...so...yeah.

-Mac

 

[mrblaine]

I've been doing a bit more research online. As I understand it the OE wheels on a JK Rubicon come with 6.25" of backspacing fitted with about 10" wide tyres. I have read that to run 35x12.5" tyres requires a spacer of at least 1.5", effectively taking the backspace down to 4.75". But that is due to rubbing on the frame. As far as I can see a JK frame is about 925mm (just under 36.5") wide at the front versus a TJ's frame at the front of 843mm (about 33.2"). That means the wheel mounting surface of a JK Dana 44 will be about 1.6" further out from the frame on each side than it is on a JK ((36.5-33.2)/2). Does this mean I would likely be able to run a 35x12.5" tyre on a stock 6.25" BS wheel with a JK front Dana 44 under a TJ?

Pretty sure you have it.

They are pretty strict on tyre coverage here, so I am trying to get to the position of the outer face of the tyre on the JK Dana 44 versus my current set up. Assuming the answer above is "yes"...

...with my current set up I have an axle width of 60.5" (wms to wms), my stock wheels have 5.25" back space, but I run a 1.25" spacer giving a net 4" of back space. My current tyres are 285/75/16 a quoted width of 11.2". Taking that, my understanding is my current set up gives a distance between the out edge of the tyres of 74.9" (60.5-8+22.4). The JK Dana 44 is 65.5" wide, with 12.5" wide tyres on 6.25" BS wheels I make the total width 78" (65.6-12.5+25). So on each side the tyre would be about 1.5" further out. Does that make sense?

It does.

 

[Mike_H]

The JK 44 is not that great when you try to put larger than 35" tires on it. For 35's, it would be a stellar swap for you. Especially if you can tweak a few things to tune it up. Given that the tube is the same diameter and wall thickness as the TJ but a bit longer with a horrid upper mount on the right side or long side tube, it can benefit greatly from a vestigial truss/stiffener like is used on the Savvy Midarm. Avoid the inner sleeves but do stiffen the long side, inner C gussets because they need it where the TJ doesn't, throw some good balljoints in it and go have fun. You don't have to run the double steering set up but that may be easier than anything else.

The only things that will bite are the width so you may have to run some higher backspaced wheels and then a small wheel spacer at the rear to get it back to tolerable track width.

If I was doing it, I'd cut the inner C's off, use the TJ C's and set it up to run TJ Rubicon 30 spline shafts, C's, and knuckles. I was going to do exactly that but I found a Rubi 44 before I got into it.

Another little easter egg, from everyone's favorite bunny!

 

[UKTJ]

Bunch of previous posts on JK axles...googling wranglertj forum JK axles on a TJ got me a list of forum posts...

[URL]https://wranglertjforum.com/threads/jk-axle-swap-for-tj.33305/[/URL]

Why not order a set from Dana, G2 or a couple of other providers?

I did a Super 30/35 conversion on mine (and a front truss and sleeves since I can weld and know how to heat up and cool down an axle). 30/44s all share the same outters and that's your weak link/fuse.

We wrecked my wife's JK and if it were me we'd buy a TJ replacement, convert it to an LJ, LS swap it and put her 5.13 e lockers JK 44 axles on with coil overs. She wants a JKU...so...yeah.

-Mac

As per my initial post, the short answer is cost. Admittedly I have not had quotes from all possible suppliers, but the one I did get a number from suggested it would be about $10,000 to ship a front and rear axle. Then I have to pay c. 25% import taxes on the cost of the axles and the shipping. Starts to get a bit pricey.