Dynatrac PR60 vs PR80 - ground clearance discussion

[highoctane]

Here's a video we made about the ProRock 80 back when it was introduced at SEMA a few years back. In it, you'll hear straight from Jim McGean, the owner of Dynatrac tell you how the clearance difference between a ProRock 60 and a ProRock 80 is only about a pencil thickness.

I think the 1" difference you're thinking of is at the yoke. And really, there are benefits to having a higher pinion including clearance and reduced driveline angle but for me, strength and the need for it takes priority. Again, the XD60 does utilize a bigger ring and pinion and that is a BIG improvement over ALL the other high pinion 60's out there.

Thanks for posting that video Eddie. I watched another video with Jim from Dynatrac showing the bearing sizes and other internal parts of the XD60 and explaining some other benefits, but did not watch this video. Definitely leaning towards the PR80 if thats all the lower it hangs at it's lowest point.

 

[RDE2ROK]

Here are a few pics of my 80, sorry for the quality, it was the best I could do. Trying to hurry off to work. As you can see it has been used heavily, but notice how smooth and no damage accept paint! I could clean it up and paint it and it would look good as new.

 

[highoctane]

Here are a few pics of my 80, sorry for the quality, it was the best I could do. Trying to hurry off to work. As you can see it has been used heavily, but notice how smooth and no damage accept paint! I could clean it up and paint it and it would look good as new.

View attachment 182792 View attachment 182793 View attachment 182794 View attachment 182795

Nice! Thanks for posting up. Looks like the bolts on the PR80 are also recessed a bit so that they don't get completely ground down on the rocks. That thing looks stout!

 

[mastrcruse]

For the most part, your understanding is correct and the strength of a 60 comes from the larger and stronger internal components. That being said, a high pinion rear 60 regardless of make WILL have the driving force on the "coast" or weak side of the ring gear. IF you actually play as hard and as often as you think you do, deflection in the housing will put stress on things like the ring gear and over time will cause it to fail. The XD60 is designed to mitigate the short comings of a high pinion 60 by using a BIGGER ring and pinion as well as even stronger internal components AND by having a housing that is more rigid to help prevent any deflection from occurring.

Thanks...I appreciate your input. So comparing the differences in tube thickness, would there be some worry going from a 3.125 X .5 tube to a 3.75" X .25 tube? Maybe the tube diameter makes up for the wall thickness. The thickness seems to be pretty thin at .25 when many upgrade their PR44/60 to .5 thickness. Just interested in your thoughts. I guess just comparing housings of a PR60 vs. XD60.

 

[highoctane]

Thanks...I appreciate your input. So comparing the differences in tube thickness, would there be some worry going from a 3.125 X .5 tube to a 3.75" X .25 tube? The thickness seems to be pretty thin at .25 when many upgrade their PR44/60 to .5 thickness. Just interested in your thoughts. I guess just comparing housings of a PR60 vs. XD60.

Dynatrac states on their website that the 3.75" x 1/4" XD60 tubes are the same strength as the 3 1/8" x 5/16" wall PR60 tubes, and they both weight the same. The XD60 3.75" x 5/16" tubes are 12% stronger and almost 20% lighter than the PR60 3 1/8" x 1/2" wall tubes. You get more strength with larger diameter tubing than you do with smaller diameter/thicker tubing. It resists bending better.



http://www.dynatrac.com/axle-assemblies/jeep-jk-wrangler/prorock-xd60.html

 

[wayoflife]

Thanks...I appreciate your input. So comparing the differences in tube thickness, would there be some worry going from a 3.125 X .5 tube to a 3.75" X .25 tube? Maybe the tube diameter makes up for the wall thickness. The thickness seems to be pretty thin at .25 when many upgrade their PR44/60 to .5 thickness. Just interested in your thoughts. I guess just comparing housings of a PR60 vs. XD60.

A larger cross section or in this case, a larger diameter tube will provide more strength even when using less material than would a smaller tube with more material. That being said, tube strength is only part of the equation - the actual differential "housing" itself and its ability to resist deflection is almost more important. In addition to running a larger ring and pinion, the XD60 is specifically designed to have a more rigid differential housing and that helps to prevent a failure at the gears.

Dynatrac states on their website that the 3.75" x 1/4" XD60 tubes are the same strength as the 3 1/8" x 5/16" wall PR60 tubes, and they both weight the same. The XD60 3.75" x 5/16" tubes are 12% stronger and almost 20% lighter than the PR60 3 1/8" x 1/2" wall tubes. You get more strength with larger diameter tubing than you do with smaller diameter/thicker tubing. It resists bending better.

Yup, this ^^^

 

[mastrcruse]

A larger cross section or in this case, a larger diameter tube will provide more strength even when using less material than would a smaller tube with more material. That being said, tube strength is only part of the equation - the actual differential "housing" itself and its ability to resist deflection is almost more important. In addition to running a larger ring and pinion, the XD60 is specifically designed to have a more rigid differential housing and that helps to prevent a failure at the gears.



Yup, this ^^^

Thanks guys! This is exactly the information I was looking for. So if building a platform that will last under a heavy JKU and no hemi/LS conversion, you'd recommend the XD60 over the PR60?

What didn't give me the warm feeling is I asked the same question to Dynatrac and got "It’s a new product, I don’t think that the additional strength is substantial enough to boast about. Since the current Pro Rock 60 we’ve been building and will always build into the future has no issues with strength".

 

[cozdude]

Thanks guys! This is exactly the information I was looking for. So if building a platform that will last under a heavy JKU and no hemi/LS conversion, you'd recommend the XD60 over the PR60?

What didn't give me the warm feeling is I asked the same question to Dynatrac and got "It’s a new product, I don’t think that the additional strength is substantial enough to boast about. Since the current Pro Rock 60 we’ve been building and will always build into the future has no issues with strength".

What they are saying that yes the xd will be better with an LS or hemi but ultimately it's still weaker than the pr80. The latter will be much better for those engine applications just because of the ring and pinion

 

[mastrcruse]

What they are saying that yes the xd will be better with an LS or hemi but ultimately it's still weaker than the pr80. The latter will be much better for those engine applications just because of the ring and pinion

Thanks! You guys have sold the XD to me more than the response. I mentioned nothing but asking them to sell me on the strength of the XD vs PR and that's the response. Didn't talk about PR80 or any type of engine conversions. Maybe his response was based on the lack of what I gave him though (turning it on me). Maybe he's thinking normal JKU with no need for that stuff.

My goal in mind is to end with new axles to run a 40x13.5-17 on trail ready beads. No engine conversion in mind but maybe supercharged.

 

[highoctane]

Thanks! You guys have sold the XD to me more than the response. I mentioned nothing but asking them to sell me on the strength of the XD vs PR and that's the response. Didn't talk about PR80 or any type of engine conversions. Maybe his response was based on the lack of what I gave him though (turning it on me). Maybe he's thinking normal JKU with no need for that stuff.

My goal in mind is to end with new axles to run a 40x13.5-17 on trail ready beads. No engine conversion in mind but maybe supercharged.

The Dynatrac Youtube page has a few videos where Jim @ Dynatrac explains the differences in size and strength of the XD60 compared to the PR60. 16% stronger ring & pinion is one of the things he mentions, along with a stiffer, more rigid center section/housing.

 

[mastrcruse]

The Dynatrac Youtube page has a few videos where Jim @ Dynatrac explains the differences in size and strength of the XD60 compared to the PR60. 16% stronger ring & pinion is one of the things he mentions, along with a stiffer, more rigid center section/housing.

Yep have watched it several times but just wanted a little more info. Y'all gave me all the info I was looking for to make my decision. I appreciate it,

 

[JoeB-JKURX]

Reverse Cut Gears

I have long wondered about why high pinion front differentials drive on the coast side of the ring gear when it would seem preferable to use a reverse cut ring and pinion to drive on the drive side of the gears. This thread seems a good place to ask the question.

 

[ttfhell]

Just an FYI a PR80 isn't a pencil width larger than a PR60. Dynatrac was comparing it to a standard Dana 60. See pic. I would bet the 80 is 1-1/2" larger than a 60. I have cleared obstacles where 80's have got hung up. However I would take the 80 over the 60 with 40's all day long.

 

[rubicrawl]

Just an FYI a PR80 isn't a pencil width larger than a PR60. Dynatrac was comparing it to a standard Dana 60. See pic. I would bet the 80 is 1-1/2" larger than a 60. I have cleared obstacles where 80's have got hung up. However I would take the 80 over the 60 with 40's all day long. View attachment 183173

All day long? What about all night long? What size rims with the 40's?

 

[wayoflife]

Just an FYI a PR80 isn't a pencil width larger than a PR60. Dynatrac was comparing it to a standard Dana 60. See pic. I would bet the 80 is 1-1/2" larger than a 60. I have cleared obstacles where 80's have got hung up. However I would take the 80 over the 60 with 40's all day long. View attachment 183173

This is correct and I was in error. The difference is compared to a standard Dana 60. That being said, I can't say that I've ever found myself getting hung up on any obstacles with my 80 pushing 40s but then, that's just me.

 

[ttfhell]

This is correct and I was in error. The difference is compared to a standard Dana 60. That being said, I can't say that I've ever found myself getting hung up on any obstacles with my 80 pushing 40s but then, that's just me.

You take better lines lol

 

[wayoflife]

LOL!! So, as dumb as it sounds, it just occurred to me that I actually own 2 JK's and both running 40's. One has a PR60 and the other a PR80. I just went out and measured both and the difference between the 2 was just a little over an inch. Specifically, only 1.125".

As you can see, the PR60 measures 12.5" from the ground to the base of the diff.


The PR80 measures 11.375"


Of course, both JKs are running different tires and I can't say for sure how equal the tread depth is on each or how much air but I think it's safe to say the difference between a PR60 and a PR80 is in fact about an inch.

Guess I pretty much confirmed what you were originally saying highoctane :crazyeyes:

 

[MR.Ty]

A little off topic, does the deflection happen the same in a full float and semi float 60 or is it lessened in the full float version?

 

[highoctane]

LOL!! So, as dumb as it sounds, it just occurred to me that I actually own 2 JK's and both running 40's. One has a PR60 and the other a PR80. I just went out and measured both and the difference between the 2 was just a little over an inch. Specifically, only 1.125". As you can see, the PR60 measures 12.5" from the ground to the base of the diff. <img src="http://wayalife.com/attachment.php?attachmentid=183180"/> The PR80 measures 11.375" <img src="http://wayalife.com/attachment.php?attachmentid=183181"/> Of course, both JKs are running different tires and I can't say for sure how equal the tread depth is on each or how much air but I think it's safe to say the difference between a PR60 and a PR80 is in fact about an inch. Guess I pretty much confirmed what you were originally saying highoctane :crazyeyes:

Perfect picture and good info. Thanks for measuring that and posting! With your measurements being taken on a PR60, it's probably safe to say that a XD60 with it's larger 10.1" ring gear will be slightly larger and have just a bit less clearance under the housing than the PR60.

 

[jorgelrod]

Is there a reason why Dynatrac doesn't make a LP PR60 for rear applications? I figure they do sell enough PR60's to the point where CAD design, testing and MFG would be viable vs just using the same pumpkins from their front axle applications for rear axles...