Differential Qs for X-Unlimited (Dana 30 & 44) - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 21 Old 01-02-2010, 11:14 PM Thread Starter
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Differential Qs for X-Unlimited (Dana 30 & 44)

Okay guys, my rig build-up has gone well so far... However I must turn to you all for some much-needed advice, as I do not wish to "recreate the wheel", rather to benefit from your experiences...

While this is my daily driver, it's come to the point where I want/need to prepare it for some serious trails and outings (Sierra Trek or Rubicon), as I live in NorCal.

My understanding, is now that I have addressed the mods below, my next challenge/obstacle/weak point is going to be the front & rear ends, lack of lockers, and tall gears.

I have wanted to change gears for a while, but have been a little leary because I don't want to spend all of the money, only to find that I need lockers too, then only to find that all of the money I invested into my Dana 30 (front) & 44 (rear), was wasted, because I blew them up (axles, etc.)

SO... My three questions for you guys are:

1) Running an automatic, with a 35-inch tire (although I have considered going to a 37-inch tire) , what gear should I go with to keep driveability and reasonable revs on the highway, yet maximize my "crawl."

2) Since I have an Unlimited "X", there are no lockers, and I am assuming that I have the piddly Dana 30 up front. So, what lockers do you recommend?

3) Considering what I have built so far, and that I do not want to dump money only to have to rebuild immediately, is there a different approach that you guys have had luck with on your "Xs", by swapping out entire front/rear assemblies, with lockers, etc. into your Jeeps?

Sorry for the length of the post, but I could really use some serious advice!

Thanks -- Rick


2008 JK Unlimited "X" (Black)
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post #2 of 21 Old 01-02-2010, 11:24 PM
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Most are going to tell you to run a 5.13 gear w/ the auto.

You do have the D30 up front. I can only say that if you drive in snow much, then you're gonna want to have a selectable locker up front. Not sure what's made for the D30.

You might want to look for a Rubi front D44 to swap in, but you'd want to get it before you spent $ regearing your D30.


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post #3 of 21 Old 01-02-2010, 11:34 PM
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Thats a tough one as everyone has their own opinion.

Gears - 4.88 or 5.13 ( I have an X auto and went with 5.13, not to bad on Highway I get about 15-16 mpg using cruise. I have nice throtle response and decent torque.)

Locker - ARB makes a locker for the D30. It is the ARB RD-100, I believe.

Maybe someone else will chime in with the different approach.

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post #4 of 21 Old 01-03-2010, 08:32 AM Thread Starter
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Originally Posted by jk_techcrash View Post
Thats a tough one as everyone has their own opinion.

Gears - 4.88 or 5.13 ( I have an X auto and went with 5.13, not to bad on Highway I get about 15-16 mpg using cruise. I have nice throtle response and decent torque.)

Locker - ARB makes a locker for the D30. It is the ARB RD-100, I believe.

Maybe someone else will chime in with the different approach.

Hmmm, good stuff.

If you don't mind me asking, what are your revs like on the highway in Drive or Overdrive with your 5.13s?

RC

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post #5 of 21 Old 01-03-2010, 08:40 AM Thread Starter
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Originally Posted by jeeperjkj View Post
Most are going to tell you to run a 5.13 gear w/ the auto..
Sounds good. My only concern was revs on the highway, but it sounds like everyone is doing it, so it must work.

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Originally Posted by jeeperjkj View Post
You do have the D30 up front. I can only say that if you drive in snow much, then you're gonna want to have a selectable locker up front. Not sure what's made for the D30..
Well, I drive in the snow a little, but I seem to end up in sloppy, slippery, mud, even more. I know I want a locker, but I'm torn on the most cost-effective way to go, without respending money. I once built a 550 hp smallblock chevrolet for a friends camaro, and we spend twice as much money on it, simply because we didn't plan it out well in advance. Had we started from scratch with the end in mind, we would have gone down ONE road to get there, and spent fewer buckets of money.

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Originally Posted by jeeperjkj View Post
You might want to look for a Rubi front D44 to swap in, but you'd want to get it before you spent $ regearing your D30.
Gotcha. Boneyards, I suppose? Hmmm... I'll dig around online.

Thanks for your reply, I really appreciate it!

RC

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post #6 of 21 Old 01-03-2010, 09:04 AM
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Heres a link to just one of the gear ratio charts I found.
There is also a few formulas if you wanna dive in to simple math.

http://www.4x4offroads.com/gear-ratio-chart.html

If put cruise on at 70 mph the tach reads 2400 to 2500 rpms. I know my results are a bit lower from what the chart reads and I assume it was the Superchips Flashpaq that brought my numbers down. I would have to say that once I did the lift, tires, and gear swap, that the single most valuable investment was the Superchip Flashpaq. That thing is worth its weight in gold. Once I plugged it in and set it to the preprogrammed 87 octane setting I immediately gained back my HP, torque, more accurate speedo, and better fuel econ.

IF, I was to do it over? I may have gone 4.88 as most of my driving is pavement and my rig has not seen many trails YET. BUT, once I can get out on the trails, I may be very happy I had went with the 5.13. Only time and use will tell.

I have learned that mods to the Jeep are not cheap. I associate it with a Harley. (HD) stands for Hundred Dollars. Need to replace a part on a Harley? It will be no less than a HD.

Or JEEP. Just Empty Every Pocket.

Good luck.

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post #7 of 21 Old 01-03-2010, 09:13 AM Thread Starter
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Quote:
Originally Posted by jeeperjkj View Post
Most are going to tell you to run a 5.13 gear w/ the auto.

You do have the D30 up front. I can only say that if you drive in snow much, then you're gonna want to have a selectable locker up front. Not sure what's made for the D30.

You might want to look for a Rubi front D44 to swap in, but you'd want to get it before you spent $ regearing your D30.
Quote:
Originally Posted by jk_techcrash View Post
Heres a link to just one of the gear ratio charts I found.
There is also a few formulas if you wanna dive in to simple math.

http://www.4x4offroads.com/gear-ratio-chart.html

If put cruise on at 70 mph the tach reads 2400 to 2500 rpms. I know my results are a bit lower from what the chart reads and I assume it was the Superchips Flashpaq that brought my numbers down. I would have to say that once I did the lift, tires, and gear swap, that the single most valuable investment was the Superchip Flashpaq. That thing is worth its weight in gold. Once I plugged it in and set it to the preprogrammed 87 octane setting I immediately gained back my HP, torque, more accurate speedo, and better fuel econ.

IF, I was to do it over? I may have gone 4.88 as most of my driving is pavement and my rig has not seen many trails YET. BUT, once I can get out on the trails, I may be very happy I had went with the 5.13. Only time and use will tell.

I have learned that mods to the Jeep are not cheap. I associate it with a Harley. (HD) stands for Hundred Dollars. Need to replace a part on a Harley? It will be no less than a HD.

Or JEEP. Just Empty Every Pocket.

Good luck.

That helps a lot, actually.

I have the Flashpaq sitting in my garage, however I have yet to connect it to my Jeep, since I've only done the lift and tires, not gears. I was thinking to do it all in one fell swoop, then hit it with the Flashpaq.

I have the mantra of the "Just Empty Every Pocket", ha! It seems to be shared by many. This is specifically why I am trying to ask a lot, before spending monies that I'll end up needing to respend.

Thanks for all of your help!

RC
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post #8 of 21 Old 08-09-2011, 09:20 PM
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i have talked with quite a few people and I have my 5.13s sitting in my garage waiting on my next purchase rear ARB. I am running an Auto as well and have 34.6"tires and will be going to 37 when a wear these out. I also heard the programmer is a great purchase ...as everyone has said...no slow throttle respnce is what i cant wait for..

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post #9 of 21 Old 08-10-2011, 04:30 AM
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My plan is 5.13's with a Aussie "lunch box locker" up front. Then sleeve, inner C gussets and probably a truss front and rear. That should get you enough strength to run 35's without spending too much money.
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post #10 of 21 Old 08-10-2011, 04:41 AM
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"Had we started from scratch with the end in mind, we would have gone down ONE road to get there, and spent fewer buckets of money."

If I was in your position, I would look for a rubi D44 to swap, because beefing up the D30 requires a lot of welding. Even if you can weld the D30 it is still weak axle. Especially since you plan on doing some " serious " trails. Just my opinion. As for gears, that up to you.. the majority are going to say 5.13s though, which I neither disagree or agree with, I upgrade my tires and havent touched my gears, and I havent noticed any loss in power so I just saved alot of money and hours installing.
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post #11 of 21 Old 08-10-2011, 05:47 AM
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Quote:
Originally Posted by Ringworm View Post
"Had we started from scratch with the end in mind, we would have gone down ONE road to get there, and spent fewer buckets of money."

If I was in your position, I would look for a rubi D44 to swap, because beefing up the D30 requires a lot of welding. Even if you can weld the D30 it is still weak axle. Especially since you plan on doing some " serious " trails. Just my opinion. As for gears, that up to you.. the majority are going to say 5.13s though, which I neither disagree or agree with, I upgrade my tires and havent touched my gears, and I havent noticed any loss in power so I just saved alot of money and hours installing.
A Rubicon dana 44 has the same tubes and C's as a Dana 30. Therefore requiring the same "lots of welding" to "beef it up". If you increased your tire diameter, you raised the effective overall ratio, therefore "losing power". If you noticed it or not, it happened. Not only does that affect driving down the road, but your crawl ratio off road is also affected. Which increases the wheel speed while "crawling", which usually isn't what you want.

The Rubicon Dana 44 has a bigger gear set, and larger axle shafts (joints/spline count). If you plan on doing serious trails and have stock everything Dana 30 with no money invested in it......I'd save my pennies for a Pro Rock and get it all at once with a better built, reliable axle.

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Last edited by Goodysgotacuda; 08-10-2011 at 05:53 AM.
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post #12 of 21 Old 08-10-2011, 08:33 AM
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I'd have to agree with Goody. I would save for an aftermarket 44 or 60. I know it is a lot of money but you can buy with the locker you want and the gearing you want for about $3000. Think about what youd spend beefing up your stock axles. Sleeves, gussets, the lockers, gearing, labor (unless you can DIY). That's easily 2,000 or more then to blow up your 30 on the trail = no fun.

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post #13 of 21 Old 08-10-2011, 08:43 AM
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I agree with goody too. If you want to run the hard stuff get some d60s front and rear if you want piece of mind. I've had more trouble out of my rear d44 then the d30 in the last two years. The rear does most of the work. All the weight is usually on the rear when tackling a obstacle. I will be running a d60 d30 combo for a few months till I can afford a new front axle. My Dana 30 has been through hell and back and it has out lasted the rear d44. I'm on 37s one day 40s

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post #14 of 21 Old 08-10-2011, 08:58 AM
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Although I completely agree with beefing up or completely replacing the D30, no mistake there. I look at it this way, you already have that D30 sitting under there and it functions. Having said that, regear and get a soft locker or selectable for now. Beef it up if you're really worried about bending the housing, but, drive the crap out of the stock axle until it fails and then replace it. A lot of guys do far less than what I described above and are still using the stock axle without many or any problems. That gives you time to save for the heavy stuff while still enjoying your rig. I used the stock Dana in my TJ the whole time I owned it with 33's, did a lot of pretty difficult trails in it. That was while I was still learning how to pick my lines, use the throttle, and all while open/open with no 4:1. Never bent or broke anything much to my surprise. The only thing I did to that housing was weld skids on the LCA brackets.

I guess I'm trying to say that although making your drivetrain bulletproof is great, it's not 100% necessary to enjoy wheeling it.

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post #15 of 21 Old 08-10-2011, 09:14 AM
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If your rig is wearing 35s - and maybe going to 37s - I would stick to the front Pro Rock 44 / rear upgraded stock combo. Unless you are loaded down with a ton of extra weight and have turned your Jeep into a pig, the 44s will be more than strong enough, cheaper, and just as importantly a lot lighter. Having a lighter rig is a boon while wheeling. Try not to get yourself into the mentality of 'The Jeep gained 200 pounds, I need something stronger which is heavier, which will make the Jeep gain 200 pounds, so I'll need something stronger which is heavier, which will make the Jeep gain 200 more pounds...." It's self-defeating.

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post #16 of 21 Old 08-10-2011, 09:27 AM
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I'll kind of take a bit from everyone here, and give you what I'd do if I did all of my axle stuff at once (I did it as I got to be a better wheeler, and needed a bit more gear).
Since it's mainly a D30, leave it alone. Slap a set of 5.13's in there, weld on some C gussets and inner sleeves, and leave the front open. That's a grand or so right there. Then, save the extra grand from not buying a locker, and put it towards a PR44, down the road.
The D30 is not that weak. I know plenty of guys wheeling on factory D30's for years in the TJ and JK's with no problems with 35's and 37's. The reason you hear of so many fails is the weak C's- so reinforce them! Other than that, wheel smart, and don't try to be a hero. Yes, be aware that the D30 is not as strong as a D44 or 60, of course, but it's plenty strong for the occasional trip if you're smart about it- Mark W.

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post #17 of 21 Old 08-10-2011, 10:48 AM
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I'm going to take the advise above and go one step further-
I wouldn't add a nickle to your existing 30. I'd either do your PR now, or if that's not possible at the moment, buy someone's already built 30 and save for the good stuff. Either way, it's going to be better than adding money to your existing 30 that you'll end up discarding anyway.
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post #18 of 21 Old 08-10-2011, 11:03 AM
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I have my Cs gusseted and run 4.88 with 35 tires. No problems so far. I am contemplating doing the 5.38 in the D30 and see how long they last. Where I wheel I haven't seen a need to lock the front so that's an expense I can avoid. I am going to 37 tires when these tires wear down but I think it's all in how you wheel and finesse goes along way.


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post #19 of 21 Old 08-10-2011, 01:41 PM
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I put an Aussie Locker in my D30 for a trip to Moab and that was all I was spending on it. I have a Nicely built PR44 up front now and don't worry about things breaking as easily now. Money well spent the first time around.
Holy old post revival. What happened to Cruzcode?
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post #20 of 21 Old 08-10-2011, 02:12 PM
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post #21 of 21 Old 08-10-2011, 07:17 PM
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I have a dana 30 front with C gussets, LCA skids, diff cover, 5.13s and an Aussie installed. I have wheeled it hard and often and I run 35s. I just destroyed a passenger side axle shaft. I am either replacing it with cromoly or going even cheaper and replacing it with a used stock shaft...and possibly saving money for a different axle. If I go to cromoly, I'll be running 38s on my dana 30 and we shall see how long it lasts...

I dont think the JK dana 30 is that much weaker than the JK dana 44 other than the ring and pinion. Too much of the components are similar in strength to really say the Rubi 44 is so much stronger.

If i got with a different axle, it'll either be Pro Rock 44, an old school junkyard 44 or 60, or a ford 9. Depends on my budget at the time.

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