Nashville TJ's Build - Continued

[NashvilleTJ]

You guys may know how much I like my tools, so I though you would get a kick out of this. My mom sent me a power turkey carver, so I had to give it a shot.

Happy Thanksgiving!

Jeff

 

[NashvilleTJ]

Well, with Covid I found myself with little to do after my wife and I had Thanksgiving dinner, so I figured I'd relax in the shop for a few minutes (can you feel a sense of foreboding?).

There was some damage on the differential case, but I thought it was superficial and didn't think much of it to tell the truth. I'd planned to throw a file at it to make sure all was smooth and be done with it. So I did. But while doing so I noticed one of the bolts securing the cylinder cap to the case had been sheared off. And the other bolts were loose - 3 were missing the retainers.

So I popped the cylinder cap to remove the broken bolt and I found this: one of the four tabs on the piston (the black piece in the picture) had broken off.

And when I looked more closely, I could see that the case is cracked right where the bolt head was sheared.. Tough to see in this picture, but it's there.

And that was not it. The case is cracked in three places - here is another:

But the worst thing is, I needlessly spent $22 at Northridge for the shim kit and o-rings. Turns out, both of those things come with a new locker....

 

[Mike_H]

Doh!

 

[Apparition]

Well, with Covid I found myself with little to do after my wife and I had Thanksgiving dinner, so I figured I'd relax in the shop for a few minutes (can you feel a sense of foreboding?).

There was some damage on the differential case, but I thought it was superficial and didn't think much of it to tell the truth. I'd planned to throw a file at it to make sure all was smooth and be done with it. So I did. But while doing so I noticed one of the bolts securing the cylinder cap to the case had been sheared off. And the other bolts were loose - 3 were missing the retainers.

So I popped the cylinder cap to remove the broken bolt and I found this: one of the four tabs on the piston (the black piece in the picture) had broken off.

View attachment 206054

And when I looked more closely, I could see that the case is cracked right where the bolt head was sheared.. Tough to see in this picture, but it's there.

View attachment 206058

And that was not it. The case is cracked in three places - here is another:

View attachment 206059

But the worst thing is, I needlessly spent $22 at Northridge for the shim kit and o-rings. Turns out, both of those things come with a new locker....

At least now is a good time to buy

 

[Wildman]

Damn Jeff when you FUBAR something up you don't do it halfway...

My ARB was able to be repaired when I FUBAR'd the case.


Since you're at this point and you need to get a new ARB maybe you should contact Carl Jantz and find out if you can put the Dana 70 R&P into you housing? Then either send the gears you just bought back and get a Dana 70 R&P or hang onto them for your front?
I know you were worried about it not fitting BUT? Reading his description you need 3/8" clearance around your Dana 60 ring gear for the Dana 70 ring gear to fit.

He also sells a load bolt like you were talking about the Currie Rock Jock axles have.

Jantz Engineering: Jana Load Bolts (jantz4x4.com)

Not trying to add more to your project but if it'll work you gain strength in the Dana 70 R&P..

 

[NashvilleTJ]

Damn Jeff when you FUBAR something up you don't do it halfway...

My ARB was able to be repaired when I FUBAR'd the case.


Since you're at this point and you need to get a new ARB maybe you should contact Carl Jantz and find out if you can put the Dana 70 R&P into you housing? Then either send the gears you just bought back and get a Dana 70 R&P or hang onto them for your front?
I know you were worried about it not fitting BUT? Reading his description you need 3/8" clearance around your Dana 60 ring gear for the Dana 70 ring gear to fit.

He also sells a load bolt like you were talking about the Currie Rock Jock axles have.

Jantz Engineering: Jana Load Bolts (jantz4x4.com)

Not trying to add more to your project but if it'll work you gain strength in the Dana 70 R&P..

That's a good thought, Rick. The down side is that if I go that route, I'm still stuck with the semi-float axle - and I've killed three of those already - all before the Hemi. I'm giving serious thought to biting the bullet and replacing the axle. Maybe a full-float, low pinion 60, or something like the Rock Jock Hi-pinion 70 full float and 40 spline shafts.

Now that I'm into a repair bill of over $1500, and I could probably sell the current pro-rock 60 for a nice chunk of change - even without the ARB and gears - that's a nice head start on a new axle.

Or, I just go ahead and fix it and wait for the next carnage.

Don't know.

 

[Wildman]

I like where your thinking is going Jeff. Can you get larger axle shafts for the semi-float? I mean if you could get a 40 spline ARB and then 40 spline axle shafts along with the Jantz76? I don't know if it is worth putting a ton of more money into it.

What does a RJ70 run? I know they ain't cheap. I got my TeraLow CRD60 for $3200 because the guy was selling off all his parts.

A lot to think about. I don't envy you right now. I know I'd have spread sheets out with pro and cons of both routes. And then price sheets of both down to the last dime. It's why I get shit for looking at stuff too much sometimes.

 

[NashvilleTJ]

I spoke with Currie and Dynatrac yesterday, considering the RockJock 70 high pinion, full float, 40 spline, and the new HD60, low pinion, full float, respectively. The Currie is about $9700, the Dynatrac about $7500. Unfortunately, both are about 8 weeks out for delivery (as I actually suspected would be the case).

I’ve also considered building a shaved 14 bolt, but my dilemma is this: to get to the current stretch and still keep a tank under there I had to make things pretty tight. Not much clearance at all between the current Pro Rock and the tank. I’ve checked measurements, and a 14 bolt will not fit without changing the tank. Neither will a ProRock 80, which I also considered. And - I don’t think the Currie will fit either because the angled diff housing pushes the lower half of the case further back and I think that will hit the tank as well. Still evaluating that issue.

So, since I don’t want the rig sitting around immobile for 2 months, I’ve ordered a new ARB (should be here tomorrow) to rebuild the current ProRock axle - knowing that the engine and drive train are way to much for it. But, I do plan to replace the axle near term. At this point I’m leaning toward the HD60 mainly because of the fitment issue. As a bonus, I can reuse the new ARB in the HD60 and save about $1200, and also save the labor on the setup if I do it myself.

The issue with my current setup is definitely the high pinion and the semi-float axle shafts - both of which have now failed multiple times. The HD60 has been redesigned and is much stronger compared to the design of my current axle. Bigger ring gear, carrier and pinion bearings, structural changes to the case, and 4” tube. And it will fit - and may be the only option that will without extensive changes to the rig. I do think the Currie would be at least as strong or stronger (high pinion compared to the HD60 low pinion), but I just don’t think it will fit.

That’s where my head is right now, but since I’m rebuilding the current axle as a short term solution I’ve bought myself a little time to make a good decision.

Any advice?

 

[Wildman]

That's all some mighty BIG & HEAVY thinking you have going on there. And having the fuel tank thrown in there just makes it even harder to really make the right choice.

My first concern would be is the HD60 going to be strong enough? I'm gunna say YES but I don't know that 100%.
What is the strength of a RockJock 70? Is it stronger than the HD60? And then the 14Bolt?? Where does it fall into the strength of the other two choices?
If the only choice is the HD60 without having to redo your fuel tank then I'd maybe look that route.
I know back when I was looking at options TeraFlex use to offer full float kits for the CRD 60. I don't know strength wise or anything else as to how well they work. But if you could convert your current axles even if you needed to remove the ends to have have spindles welded onto. Then go with either HD gears or Dana 70 gears & a 4 spline ARB while keeping your current axle?

Now if none of that would work I'd look into the the HD60 first and then the 14 bolt and the RJ70 last. Can you get hubs drilled in the 5x5.5 BP for these axles? Which of the 3 require you to change out your fuel tank? Which of the 3 is the strongest? Which of the 3 can you get hubs drilled to match your current BP?

Sort of sucks that you are only putting a band=aid on on your current setup but I understand.

I think in this case I'd have to make me a flow chart with the pluses and minuses listed on it. And include what would be required to run each axle.

 

[NashvilleTJ]

That's all some mighty BIG & HEAVY thinking you have going on there. And having the fuel tank thrown in there just makes it even harder to really make the right choice.

My first concern would be is the HD60 going to be strong enough? I'm gunna say YES but I don't know that 100%.
What is the strength of a RockJock 70? Is it stronger than the HD60? And then the 14Bolt?? Where does it fall into the strength of the other two choices?
If the only choice is the HD60 without having to redo your fuel tank then I'd maybe look that route.
I know back when I was looking at options TeraFlex use to offer full float kits for the CRD 60. I don't know strength wise or anything else as to how well they work. But if you could convert your current axles even if you needed to remove the ends to have have spindles welded onto. Then go with either HD gears or Dana 70 gears & a 4 spline ARB while keeping your current axle?

Now if none of that would work I'd look into the the HD60 first and then the 14 bolt and the RJ70 last. Can you get hubs drilled in the 5x5.5 BP for these axles? Which of the 3 require you to change out your fuel tank? Which of the 3 is the strongest? Which of the 3 can you get hubs drilled to match your current BP?

Sort of sucks that you are only putting a band=aid on on your current setup but I understand.

I think in this case I'd have to make me a flow chart with the pluses and minuses listed on it. And include what would be required to run each axle.

Thanks for the reply, Rick. Comparing the strength of the DT HD60 to the Currie RJ70 - I have no actual idea. And I can't really find any actual comparisons. My gut tells me that apples to apples - meaning both hi pinion or both low pinion - the 70 is stronger. Comparing the hi 70 to the lo 60? Not sure. I do know that when I bought my pro-rocks a dozen years ago Dynatrac told me that the hi pinion 60 was 20-30% weaker than the lo pinion 60. So who knows - although the 70 has a load bolt which supposedly helps the HP a lot.

I'm pretty sure that the 14b is stronger than both of 'em.

Since the RJ70, the 14 bolt, and the ProRock 80 all stick out further in the back than my current pro-rock, that's where I think I'll get the fitment issue. It's pretty tight to the tank as it is, and I don't want to go to fuel cell. A smaller tank - for instance GenRights smaller dimension comp tank - also holds a lot less fuel (funny how that works), and my current 19 gallon GenRigtht tank only gets me so far at 10mpg...

I did consider converting the current axle over to a full float - not too big of a deal. A new spindle, and little cuttin' and a little weldin', and done. But, I'm still stuck with the high pinion in that case. Maybe the 70 gears - if they would fit - would help, but that's a big risk if it turns out they don't make enough of a difference.

I can do 5x5.5 on the 60 or the 70, but I don't think I can do that on the 14b - but again not certain. I've actually always wanted to try shaving a 14b, but the size of the pumpkin is the issue for me.

I don't see getting the current axle back up and running so much as a band aid, but rather a practical decision which keeps the rig from being immobile for two months. And given what's going on now with Covid I wouldn't be surprised if it takes a lot longer. Also, if I do go the HD 60 route I have the option of using the locker I just bought and save the cost off the new axle. Alternatively, although I would not get the full return on the cost, I can sell the old axle for more $ if it includes a new locker.

Yea, flow chart....

 

[Wildman]

I guess if I was trying to figure this all out and with your past experiance with your ProRock I think you're on the right track with looking for an upgrade. I'm shocked at the fact that you have had the problems with it that you have. And yes I remember reading some place that a HP axle in the rear is 20-30% weaker than a low pinion. It's also why a HP in the front is suppose to be better. I guess if I was in your shoes I'd be looking at a low pinion axle as my next choice. And I get not wanting to go to a smaller tank with the MPG you are pulling down. It was one of my big things as I was modifying my TJ. I hated loosing the 24 gallon tank and I am still not happy about the idea of running a fuel cell but for me it might be my only choice.

I guess I'd be giving that HD60 a hard look and if you can get it with 40 spline shafts in a full float IMO it's your best choice without having to change your fuel tank. And I'm sure you're sitting there wondering if you did decide to try out the HD60 and then find out it still wasn't strong enough.... That is what I do in situations like this. And having to clear the tank just adds to all this.
I guess the other option would be to get the RJ70 and then either get your tanks modified or get a custom tank built? I know it wouldn't be cheap but if you got a custom tank that gave you the same capacity as you have now that would be great. But I'd have to make sure that the RJ70 is stronger than a HD60 before I did anything.
And I'd be talking to Jantz 4x4 to see if you can run the Dana 70 R&P in your housing. If you can do that then I'd be seriously looking at that. To me that would be the best bet..

 

[NashvilleTJ]

Well, it showed up in all of it's two-piece-case glory - different design than my old RD35. I guess I should think about learning how to install this beast. I think I have a tape measure around here somewhere to measure backlash...

Time to make some setup gears, I guess.

 

[Wildman]

Awesome. Glad you got it so fast. And you have the new design locker too. Wonder if it is any stronger than the other one?

 

[NashvilleTJ]

Awesome. Glad you got it so fast. And you have the new design locker too. Wonder if it is any stronger than the other one?

I sure hope so. I think the one I had was a high pinion locker. So, 20-30% weaker...

 

[Wildman]

I sure hope so. I think the one I had was a high pinion locker. So, 20-30% weaker...

And don't forget to use the left hand fitting wrench for installing it. I'm told that adds 5-10% strength to your install.

 

[NashvilleTJ]

I've delayed digging into the R&P a bit because I had the shop set up for a woodworking project. I built a toy box for my grandson for Christmas.

...and it is Jeep related - I did a little subtle hand carving:

 

[NashvilleTJ]

And today I started digging into the R&P. The first order of business was pulling the pinion races. The ProRock uses a proprietary Dynatrac inner pinion seal which rides with the shims behind the inner pinion bearing- I believe to help with oiling the high-pinion bearinging - which I thought I could remove without damaging it. No such luck. There is an oil baffle which rides immediately behind the race to which the seal is spot welded - and there is no way to use a puller on the race. There is also no way to get to the race from behind with a punch to remove it. The only way is to destroy the oil seal. Here is what is looked like why I got done with it (note that I also found the head of the bolt which started this entire cascade):

But, I did get the races out. And that cavity between the inner and outer pinion races was stuffed full of busted ring teeth and metal shavings. It was a real mess.

Since this was a bit of a surprise to me - that seal and baffle are not used in a standard '60 - I'll have to give Dynatrac a call tomorrow a get a new one shipped out to me.

 

[NashvilleTJ]

With the races out and the diff housing cleaned, I started to do some actual work. First order of business was to make a test bearing race for the inner pinion bearing. To set the pinion depth, shims are used behind this race (along with that additional pinion seal/baffle thing) and during set up this race needs to come in and out (over, and over, and...). It was a quick task to take off a few thou with the belt sander.

I took off just enough to allow me to put it in and get it out with my fingers.

Here it is in place:

 

[NashvilleTJ]

I usually take pride in always having the right tool for the job. Consequently, I have a bearing race and seal installer kit which is supposed to work on Dan 60, 70, and 80 bearings. Emphasis on "supposed."

Not a single one of these fancy tools fit the outer pinion race. So, I reverted to the old standby and used the old pinion race to drive home the new one. I put the race/seal kit back in the tool box so I can not use it again at some point in the future...

But, I got it done and it's in for good.

 

[NashvilleTJ]

To the best of my knowledge, a standard dana 60 uses shims between the bearing cones and the carrier case to set preload and the horizontal position of the ring gear. So to set up a standard '60 you need to make test carrier bearings that can be easily removed to install various and differing shims during setup. On this new version of the ARB, shims are used between the bearing races and the diff housing on both sides, so the carrier bearings can be pressed on immediately. I knocked that out next - first the non-ring-gear-side (NRGS):

And then the ring-gear-side (RGS):