40" Tires on a Dana 44 - Moby Endurance Test 2009 : 9 Trails in 6 Weeks

After seeing several discussions regarding 40" tires and running them on a factory Dana 44 axle, I thought it might be good to revive an old endurance test that Cindy and I did back in 2009. At the time, we had just trashed our factory front Dana 44 axle while running a set of 37x13.50 Toyo M/T's and decided to use the opportunity to upgrade to a Dynatrac ProRock 60. So really, what we were testing was a set of Toyo 40x15.50's on a factory rear Dana 44 axle that came out of a Jeep JK Wrangler Sahara Unlimited. Back in the day, this was all new territory and Superior had just come out with a new prototype 35 spline chromoly shaft that could be run in this axle and with an ARB. With the added strength of 35 spline shafts, we thought we might be able to just make it work but, if there was one area that we weren't too sure of, it was the ring and pinion. In order to help restore lost power, we knew we had to run a 5.38 gear but, in a Dana 44, the pinion on it is really, really small. If anything was going to break, it was going be this, but of course, we wouldn't know for sure unless we tested it out.

Soon after Moby was ready to roll, we decided to spend the summer pushing Moby as hard as we could and as long as we could. During that time, we drove to Tahoe and back twice (almost 500 miles each way and totally about 2,000) and ran a total of 9 separate trails and the following is a list of them (not including runs bombing through the desert):

1. Twin Peaks - 07/10/09
2. Hell Hole - 07/11/09
3. Slickrock - 07/15/09
4. Deer Valley (in reverse) - 07/15/09
5. Wentworth Springs/Rubicon (to the Little Sluice) - 07/18/09
6. Cleghorn - 08/02/09
7. Niagara Rim (Trail, Lions Butt & Rockpile) - 08/08/09 ~ 08/09/09
8. Rubicon (in a day) - 08/11/09
9. Dusy Ershim - 08/28/09 ~ 08/30/09

As I'm sure you can guess, our endurance test ended just 6 weeks in and on our 9th run - the Dusy Ershim. It was here that the pinion in our Dana 44 rear axle finally decided to call it quits. In the end, our initial concerns were right - No matter how much you build up your axle housing and no matter how easy you are on the skinny pedal when taking on obstacles, your weakest link will always be your internal components. Of course, this is just our experience while running 40x15.50's on a factory rear Dana 44. We were easily able to trash our factory front Dana 44 just running 37x13.50's.

The following are a sampling of photos that we took on each trail run.

Twin Peaks













Hell Hole















Slickrock









Deer Valley











Wentworth Springs/Rubicon (to Little Sluice)















Cleghorn

Niagara Rim















Rubicon in a Day













Dusy Ershim


















To be clear, I'm not saying that it can't be done, this is just what we experienced.

Awesome pics :rock:
Was the 5.38 gearing enough or overkill to compensate for the lost power running the bigger tires?

Great detail, thanks Eddie. Did you bent any axle flanges?

Sent from my VS980 4G using WAYALIFE mobile app

Very detailed and thorough test and evaluation of the factory D44.

Here is the video of the Dusy.


R/
Will

Wow that's awesome. Thanks for sharing. I personally know my stock front D44 will eventually need to be replaced running 37's. Luckily I have a pavement princess so maybe not. :crazy eyes:

I'm glad you posted up pictures of Cleghorn, that's a fun, quick trail. But wait a second, Don said it was "practically a paved road."? :cheesy::cheesy::doh:

Eddie when you ran your 37's on the D44 did you upgrade any of the internals or did you just run it stock? I've been thinking about going up to 37's in the spring (Ran some stuff at RC and the extra few inches would have been nice. lol) Your thoughts on that would be great...

Thanks for the info on the stock 44. Great info. Off topic, but in most pics it looks like your not disconnected (sway bar) in the front. Are you still connected? If so, do you still wheel this way?

T&ERun said:

Thanks for the info on the stock 44. Great info. Off topic, but in most pics it looks like your not disconnected (sway bar) in the front. Are you still connected? If so, do you still wheel this way?

Click to expand...

The sway bar links are connected but the sway bar is disconnected. On Rubicon's the sway bar is electronically disconnected.

Confused?

In a nut shell the sway bar is electronically disconnected.

R/
Will

Canvas JK said:

Very detailed and thorough test and evaluation of the factory D44.

Here is the video of the Dusy.

R/
Will

Click to expand...

I was just about to say I thought I saw a video of the ring gear exploding on a run. Thanks for reposting the video Will

Yeah but that was the 9th trail!

Sent from my VS980 4G using WAYALIFE mobile app

Great pics like always Eddie:thumb: Great review as well. :clap2:

I have never seen this before...

wayoflife said:

Click to expand...

Is this a bump stop extension? :thinking:

StrizzyChris said:

I have never seen this before...



Is this a bump stop extension? :thinking:

Click to expand...

Looks like, and looks like he still had the evo sway bar system.

olram30 said:

...and looks like he still had the evo sway bar system.

Click to expand...

Looks like Currie Anti-Rock swaybar

StrizzyChris said:

Looks like Currie Anti-Rock swaybar

Click to expand...

I believe evo used to have a sway bar system.. people say Eddie never shows evo failures on film, but he actually did on keep it tight. The system is discontinued. Eddie will explain it better than me, but I believe that's how the story goes.
And other than that, I've never really seen any other evo failures.

JeepMayhem said:

Was the 5.38 gearing enough or overkill to compensate for the lost power running the bigger tires?

Click to expand...

:cheesy: At the time, Moby was still running the 3.8L motor. I don't know if any gearing could really compensate for the loss in power you see with tires this big let alone "over compensate" for them. I think I would say that the 5.38's made it just tolerable.

JK_b/c_yolo said:

Great detail, thanks Eddie. Did you bent any axle flanges?

Click to expand...

Didn't really have a chance to run them long enough to find out. I mean, maybe they were bent by the time we blew up our rear end but after that, I didn't really care. It was just time to upgrade to a ProRock 60 in the rear as well.

darkknight1999 said:

Eddie when you ran your 37's on the D44 did you upgrade any of the internals or did you just run it stock? I've been thinking about going up to 37's in the spring (Ran some stuff at RC and the extra few inches would have been nice. lol) Your thoughts on that would be great...

Click to expand...

Yes. At the time, we were running 5.13 gears and chromoly shafts. When it finally blew, the shaft unfortunately broke deep inside the axle housing which made removal of the whole shaft impossible on the trail. This is in part why I'm not a big fan of RCV shafts (beside the excessive price) but then, even the u-joints on this shaft proved to be stronger than the shaft itself...




Of course, had the darn shaft just broken at the U-joint, none of this would have happened. Here are a couple of shots of what it ended up doing to locker, bearings and housing...




Not saying that it can't be done but, I couldn't make it last. I should note that I had already gone through one factory locker during this time as well.

T&ERun said:

Thanks for the info on the stock 44. Great info. Off topic, but in most pics it looks like your not disconnected (sway bar) in the front. Are you still connected? If so, do you still wheel this way?

Click to expand...

Canvas JK said:

The sway bar links are connected but the sway bar is disconnected. On Rubicon's the sway bar is electronically disconnected.

Confused?

In a nut shell the sway bar is electronically disconnected.

Click to expand...

As mentioned, we have a Rubicon and they come with an electronic disconnect. The links stay attached and the sway bar itself is separated by an electronic motor.

StrizzyChris said:

I have never seen this before...

Is this a bump stop extension? :thinking:

Click to expand...

Yes. You are looking at the old EVO bump stop extension that would have been installed if you didn't get air bumps installed with your DTD.

olram30 said:

Looks like, and looks like he still had the evo sway bar system.

Click to expand...

StrizzyChris said:

Looks like Currie Anti-Rock swaybar

Click to expand...

Yes, you are also seeing the old EVO rear sway bar system. It was similar to the Anti-Rock system only it was a part of the EVO lever frame. I actually didn't care for it much it as it was super squeaky and had a torsion rate that was higher than I preferred. In the end, it did break on me on Billings Canyon and is documented on the Keep it Tight video.

olram30 said:

I believe evo used to have a sway bar system.. people say Eddie never shows evo failures on film, but he actually did on keep it tight. The system is discontinued. Eddie will explain it better than me, but I believe that's how the story goes.
And other than that, I've never really seen any other evo failures.

Click to expand...

:dont_tell: Mel is a personal friend of mine as well as an advertiser here. If people find out that I tell the TRUTH about ALL products including those belonging to friends/advertisers, people might get the idea that I'm an honest guy. :cheesy:

wayoflife said:

Yes, you are also seeing the old EVO rear sway bar system. It was similar to the Anti-Rock system only it was a part of the EVO lever frame. I actually didn't care for it much it as it was super squeaky and had a torsion rate that was higher than I preferred. In the end, it did break on me on Billings Canyon and is documented on the Keep it Tight video.

:dont_tell: Mel is a personal friend of mine as well as an advertiser here. If people find out that I tell the TRUTH about ALL products including those belonging to friends/advertisers, people might get the idea that I'm an honest guy. :cheesy:

Click to expand...

i sort of remember you being happy it broke in the video cause it didnt squeak anymore :cheesy::cheesy: