THE FRONT AXLES
I’m going to let the cat out of the bag right away and tell you that the Spicer Ultimate Dana 60 and the Mopar Dana 60 are the exact same axle package. The only difference is that one says “Jeep” on the differential cover and the other says “Spicer”. From here on out I’m only going to refer to the Spicer because they have published more details about them than Mopar has, and lets face it, Spicer makes them for Mopar. So what ever applies to Spicer applies to Mopar.
Below is a chart with all the companies that I could think of that offer bolt-in JK/JKU axles. Some companies offer more than one series of Dana 60, so I picked the series closest to the Spicer Dana 60s. All of these axles are the full-float version, they all have 4340 chromoly axle shafts, and they all have plug-and-play sensors to maintain factory ABS and traction control.
|Dynatrac||ProRock60||PROROCK60||$8,000||Does NOT include calipers, reuse JK|
|Currie||RockJock III 60||JK-RJIIIF||$5,550||Does NOT include locker or R&P
Does NOT include calipers, reuse JK
|Spicer||Ultimate Dana 60||10005778||$7,000||No Tie Rod|
|* These are the best prices I could find on the internet as of January 2016. The Spicer Ultimate 60 is putting downward pressure on the pricing for these axles as the traditional vendors move to compete so you should check current pricing.|
FRONT AXLES STANDARD SPECS
|Width||68.5″+||68.75″+||67″ or 70″||67″||?|
|Accept Super 60
|Outer Axle Shaft||30 spline*||35 spline||35 spline||35 spline||1.31″/30|
|Standard Yoke Size||1310**||1310**||1310**||1350|
|Wheel Bolt Pattern||any||5-5.5″||8-6.5″||8-6.5″||5-5″|
|*Dynatrac offers 35 and 40!! spline as options.
** All of these companies offer an upgrade to 1350 (or larger) as an option. This chart only shows what’s included for the price shown.
Comparing these specs reveals some important differences. Let’s break it down:
For most JK applications (which is the focus of this article) this probably won’t be an important factor, however I’m including so you can decide for yourself. If you need a custom width than the Spicer’s Ultimate 60 package is out, it’s 69″** or nothing. Teraflex is slightly better with only two widths available, but Dynatrac and Currie both have you covered with custom widths. I don’t know how the width will effect the price.
** corrected: I originally had 67″, credit to Marcus at River City Offroad for letting me know.
Tube Diameter and Thickness:
We have to look at these together because overall bend resistance is a factor of both values. We can see that Currie, with the smallest diameter and second smallest wall thickness, is the weakest. This is not to say that the Currie axles is weak, because it’s a massive increase over stock, I am just comparing it to the other Dana 60s. Determining the relative strength of the rest is tricky. I’m no engineer but here is some insight from Teraflex comparing their current axle tube to a previous design and how the change effected the strength and weight;
…the axle housing has been increased from 3.00″ diameter tube to 3.25″ diameter. At the same time, the tube thickness has been reduced from 0.500″ to 0.375″. The axle tubing is approximately 14% lighter and 3% more resistant to bending…”
With this information we can deduce that despite Dyntrac’s .500″ wall thickness, the Teraflex and Dynatrac are going to be close in strength. Teraflex says their 3.25″ x .375″ tube is stronger than their old 3″ x .500″ but Dynatrac’s additional .125″ diameter must make it very similar to the current Teraflex. The Spicer is the thinnest tube at .370″ but having a tube 1/4″ greater than the next closest more than makes up for the meager .005″ deficiency in wall thickness, making it the clear winner in strength.
Dispite the Spicer tube being the strongest, it does it without being the heaviest. The cross-sectional area of the Dynatrac front axle tube is 4.12 square inches, Spicer is 3.64, Teraflex is 3.39, and Currie uses the lightest at 3.09. As you would expect the Currie tube is the lightest, but the Dynatrac tube, although not the strongest, is the heaviest. This doesn’t mean that the weight of the entire assembled axle will necessarily finish in this order, but it’s an ingredient.
The differences here are enormous. Spicer blows everyone away with 14.17″ rotors and dual piston calipers as standard. The Tera60 unit includes their Big Brake kit, but that uses the smaller 13.3″ rotors and single piston calipers. I couldn’t find anything offered by Currie to take you beyond 13″ rotors and reusing the stock calipers. The only other company that competes with Spicer on brakes is Dynatrac who offers a couple options. Their ProGrip brake package uses 13.5″ rotors and single-piston caliper, which is not much better than the Tera60 but their optional ProGrip II is impressive. It features 14.25″ rotors and six-piston calipers. That’s some serious brakes but it’s more money on top of an already expensive axle. When it comes to bang for your buck, nobody beats Spicer’s standard brakes. Besides being the best standard brakes, Spicer’s brake package has an added bonus, the entire works is just factory RAM 3500 series brakes, this makes identifying and finding service parts easy, you can pick them up at your local NAPA or Chrysler dealer.
When you make significant axles changes you have to buy new driveshafts, so why not go big? Spicer went 1350, everybody else defers to the smaller 1310, requiring an upgrade to get 1350’s. Spicer wins here too.
Photo from fourwheeler.com
A surprise loser here is Dynatrac going with 30 spline outer axles as standard. The 30 spline outer is just 1.31″, comparable to what the Rubicon stock Dana 44 has. Everybody else uses the much stronger 1.5″ 35 spline as standard. If your willing to pay more Dynatrac offers an upgrade to 35 spline, and they can go even bigger with a 40 spline axle available too, an option that nobody else has.
Spicer again beats the rest. They use the SPL-70 u-joints, the rest use the smaller 1480 (which are equal to Spicer SPL-55). Nobody else has the massive SPL-70 yet.
Wheel Bolt Pattern:
When upgrading from stock axles to full-float Dana 60’s you wont be able to re-use the wheels from the Rubicon, so bolt pattern most likely isn’t a deciding factor. Dynatrac offers 8 bolt as an upgrade along with several other patterns, Currie offers 5 and 6 bolt patterns but not 8. Spicer went with 8 bolt as their only option but if I had to pick one I’d have picked 8, too. Nothing says “1-ton axles” like 8 bolt wheels. The only factor that might play into the bolt pattern becoming a deciding factor is if you already have some wheels you want to use that are not 8 on 6-1/2″, otherwise I think this is a win for Spicer, if for nothing other than the cool factor of 8 bolt wheels.
Lets look at value. Only Teraflex gives you a complete bolt-in axle. With everybody else you’ll be scavenging parts from your stock axles to complete the installation, for Spicer it’s the tie rod, for Dynatrac and Currie it brake components. This not only means that you’re getting less for your money, but you’ll be impacting the resale value of the stuff your taking off. A complete axle is easier to sell and more valuable than an axle that’s missing the calipers or the tie rod. The prospect of scrounge up parts to complete an axle bought over the internet can give any potential buyer the hebejebes.
Dynatrac ProRock 60
Currie RockJock60 III
Spicer/Mopar Dana 60 for Wrangler
THE REAR AXLES
Lets look at the rear axles. There is not as much variation here because there are a lot less parts to a rear axle and I’m limting this comparison to full-float versions. If you are not familiar with the differences between a full and semi-float axles there is an excellent write-up at 4wdhub.com. The big difference is that with a full-float axle the weight of the vehicle is carried by the axle housing and the axle shaft only transfers the torque to the wheel. With the semi-float design the end of the axle shaft takes the full weight of the vehicle. Because of this additional load a semi-float is more prone to failure than a full-float. Also, depending on the design and type of bearings, with some semi-floats when an axle shaft breaks the wheel will come off the vehicle.
Unfortunatly Teraflex doesn’t offer a JK specific rear axle, (or do they?)At the time of this writing (1/26/2016) Teraflex does not show a JK specific rear axle on their website, but I did find one at Northridge4x4.com SKU 3350510. It’s only $2,000 but it doesn’t include R&P, carrier, ABS sensors, or brakes. Since I couldn’t find any official specs for it I didn’t feel comfortable include it in the comparison. This axle might be something to look into because total price to complete this axle would only be around $4,000 (cost to get ABS working?). and since the focus of this article is to compare the Spicer Ultimate 60, which is JK only, against other “out-of-the-box” JK axles packages, I’m not going to include anything from Teraflex. Teraflex does make Dana 60 rear axle for the TJ, the CRD60, so check it out if you’re interested.
|Brand||Series||Model||Front Price||Missing Parts?|
w/Full Float Option
|Currie||RockJock III 60||JK-RJIIIRF6C||$4,865||Does NOT include locker or R&P. Does NOT disc brake hardware and ABS and ESP sensors, reuse JK|
|Spicer||Ultimate Dana 60||2023612-1||$4,000||Complete|
|* Dynatrac does not include brakes as standard equipment, you reuse the factory JK brakes, however with the upgrade to the full-float versions you get 13.9″ rotors and I assume new calipers. I think the 13.9″ rotor would be a bit big for the stock caliper.|
REAR AXLE STANDARD SPECS
|Wheel Bolt Pattern||5-5.5″||6-5.5″||8-6.5″||5-5″|
|* Dynatrac does not include brakes as standard equipment, you reuse the factory JK brakes. The version I’m using for this comparison is the 5 on 5-1/2 full-float package which gives you 13.9″ rotors.
** All of these companies offer an upgrade to 1350 as an option, some even larger. This chart only shows what’s included for the price shown.
With so many less components the rear axles are easier to compare.
As with the front axle, if you need a custom width, the Spicer’s Ultimate 60 package is out, it’s 67″ or nothing.
Tube Diameter & Thickness:
Dynatrac drops to the thinnest axle tube of any axle in this comparison, front or rear, but they maintain the 3.125″ tube so they are probably still on par with Currie in strength. Spicer sticks with the same massive tube they use in the front axle.
Spicer has the best standard brake package again. Dynatrac with the full-float option comes with very respectable 13.9″ but if you don’t get full-float the standard package reuses the stock JK brakes. Curries brakes are smaller than stock! That’s ridiculous.
A defeat for Spicer, they are the only company to go with a low pinion design whereas everyone else went high pinion. The high pinion offers better ground clearance and better drive shaft angles compared to low pinion axles.
Same as with the front, Spicer went big and the rest are 1310 standard with larger sizes as optional upgrades.
Well this is no contest, the Spicer is almost half the price of the competition, even after besting them in most catagories. The lone disadvantage of the Spicer rear axle is the low-pinion design. The full-float Dynatrac package is a strong 2nd place on features but it’s $3,300 more than the Spicer. Currie left you needing to buy a locker, the R&P gears, bearings, and an install kit, about $1,400 worth of stuff provided you do the installation and gear set-up yourself. That puts the Currie rear axle over $6,000.