Alum diff with ARB vs Steel with ARB?

HoosierJeeper · **Joined:** Sun Feb 15, 2009 8:23 am **Posts:** 1218

Thinking about the phase of mods on the KJ...I think locking diffs and a regear is order.

With an ARB locker, can the stock diff be trusted for more serious trails or is it still a liability? I was thinking about getting the rear locked first but I didn't like that fact that it would push me into things where the front would be more ask risk of breaking the front diff.

Any thoughts? Thanks!

Mountainman · **Posted:** Sun Oct 04, 2015 12:13 pm

I've been in the same boat for a while, and I'm going to get one eventually more for a little better COG than anything. If you don't spin the wheels when wheeling, then you're probably ok without a steel one. If you are spinning them and they grab traction all of the sudden, boom. I mostly creep through terrain where I can keep spinning to a minimum, but the CRD helps a bit with the low RPM torque over the gasser. But, then again, there's more torque, and weight, to blow the aluminum to bits as well. Too bad I already put the effort in to build a DTT in the front of mine. I guess I'll just have to upgrade to lockers :rockon:

u2slow · **Joined:** Sun Mar 11, 2012 7:26 pm **Posts:** 160

I wouldn't worry about housing breakage due to an ARB. Last I searched, the guys breaking them have open diffs. I installed a No-slip and its been in about 2 years without issues.

Mountainman · **Posted:** Sun Oct 04, 2015 4:53 pm

Yeah, come to think of it, with the ARB's the front won't be spinning nearly as much as an open dif. I'm sure Tom or some of the other experts will chime in eventually though.

tommudd · **Posted:** Sun Oct 04, 2015 5:02 pm

Responded over on JeepKJ
But yes installed a locker in front actually helps the D30a
Unless of course you just hammer down on it all the time anyways

WhitbyKJ · **Posted:** Sun Oct 04, 2015 6:05 pm

It's the side loading of the ring gear onto the pinion that causes a snap. Remember the whole backlash theory?

With open diffs when your spinning the wheel the the torque from the driveshaft (pinion) is being put 100% into the "free" wheel. When that wheel grabs traction, the force rapidly shifts across the diff to the opposite wheel and will try to turn it. Keep in mind that the driveshaft/pinion will always have power, but when the force is transferred to the opposite side, it will actually shift the carrier in the diff a couple of thousands of an inch. If your pinion bearings are worn... Then at that exact moment where the diff transfers power the ring gear will "stop" (for lack of a better word) and the pinion will climb the ring gear and snap the housing.

I believe the quadra drive t case??? Has some sort of viscous clutches in it?? With the clutch setup, in the exact moment where the driveshaft exceeds its maximum drive on the pinion (cause it's jammed on the ring gear) the t case transfers the power to the rear axle......

We're talking about two different vehicles here.. But the same concept, I believe

Mountainman · **Posted:** Sun Oct 04, 2015 11:12 pm

WhitbyKJ wrote:

It's the side loading of the ring gear onto the pinion that causes a snap. Remember the whole backlash theory?

With open diffs when your spinning the wheel the the torque from the driveshaft (pinion) is being put 100% into the "free" wheel. When that wheel grabs traction, the force rapidly shifts across the diff to the opposite wheel and will try to turn it. Keep in mind that the driveshaft/pinion will always have power, but when the force is transferred to the opposite side, it will actually shift the carrier in the diff a couple of thousands of an inch. If your pinion bearings are worn... Then at that exact moment where the diff transfers power the ring gear will "stop" (for lack of a better word) and the pinion will climb the ring gear and snap the housing.

I believe the quadra drive t case??? Has some sort of viscous clutches in it?? With the clutch setup, in the exact moment where the driveshaft exceeds its maximum drive on the pinion (cause it's jammed on the ring gear) the t case transfers the power to the rear axle......

We're talking about two different vehicles here.. But the same concept, I believe

So, with the iron dif you'd just snap an axle instead :5SHOTS:

WhitbyKJ · **Posted:** Sun Oct 04, 2015 11:21 pm

It's truly hard to say... Given the exact same scenario, what most like would happen is teeth would start getting sheared off the pinion/ring gear. My mock up axle for the diy kit had exactly that problem.. The teeth on the ring gear were all trashed...

The problem, specifically with the kj is that the diff casing is not thick enough to handle the force from the deflection at the pinion bearings, which is caused by the pinion gear trying to ascend the ring gear. Ever seen one break while someone was spinning the tires backwards??

The locker idea is an improvement in strength at most... Because given scenario again, say for whatever reason your wheels are spinning, this time... It's both of them, the ring gear stutters and the pinion tries to keep it moving... Snap. Same deal.

Strengthening the housing is the only solution.

WhitbyKJ · **Posted:** Sun Oct 04, 2015 11:24 pm

Let me try this a different way...

If the pinion gear goes up a couple of thousandths, the yoke, MUST come down a couple of thousandths.. Too many thousandths means snap. Doesn't matter what's in your diff.. The d30a will always be a Dana 30 a

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

Id rather break a 55 dollar CV shaft then a 500+ dollar front diff....

Mountainman · **Posted:** Mon Oct 05, 2015 12:32 am

4x4kayak2112 wrote:

Id rather break a 55 dollar CV shaft then a 500+ dollar front diff....

Yeah, now we just need to carry a die grinder for a quick way to cut the bad axle out. And maybe something to stuff in the hole since with a locker you could be running 3 wheel drive home :pepper:

WhitbyKJ · **Posted:** Mon Oct 05, 2015 8:13 am

If somebody applies brake pressure the axle but can be spun off.

If memory serves me correctly, the intermediate and drivers cv have retainer clips that catch the spider gears correct? If you break an axle, just leave the drivers inner joint in or the intermediate in the event of a passenger side break. At low speed, it shouldn't throw the piece out. ....... That is.... If has the retaining clip... I just can't recall

tommudd · **Posted:** Mon Oct 05, 2015 9:15 am

WhitbyKJ wrote:

If somebody applies brake pressure the axle but can be spun off.

If memory serves me correctly, the intermediate and drivers cv have retainer clips that catch the spider gears correct? If you break an axle, just leave the drivers inner joint in or the intermediate in the event of a passenger side break. At low speed, it shouldn't throw the piece out. ....... That is.... If has the retaining clip... I just can't recall

Friends,..... don't try that, would not work
has been tried with poor results :wink:

WhitbyKJ · **Posted:** Mon Oct 05, 2015 3:00 pm

It was definitely meant as a trail only, emergency style idea. For those situations, when your up the creek and have to at least try SOMETHING.

But that's why I carry two spares, under the passenger seat. And never wheel alone. Always have another vehicle to run for parts.

tommudd · **Posted:** Mon Oct 05, 2015 3:04 pm

But then its just a few minute job anyways to pull everything out
:wink:

Yes I carry spares as well , ya never know when " the other guy" is going to break down

WhitbyKJ · **Posted:** Mon Oct 05, 2015 3:07 pm

Thinking about it now.. The best way to get out of a "I broke my cv and the front end it useless" scenario would be to remove both cv and the front driveshaft. And just two wheel it home.

But you can apply the brake to get the axle nut off

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

I have spent many hours with drive shaft in and one side CV. No problem. Pull the bad CV and drive home in 2wd.

tjkj2002 · **Posted:** Mon Oct 05, 2015 7:01 pm

4x4kayak2112 wrote:

Id rather break a 55 dollar CV shaft then a 500+ dollar front diff....

Did that already..................

But wasn't no $55 shaft...................................

WhitbyKJ · **Posted:** Mon Oct 05, 2015 8:07 pm

I once got two skid plates, four cvs, a diff and a ton of other parts (used) for 50 bucks

WhitbyKJ · **Posted:** Mon Oct 05, 2015 8:07 pm

Standard Auto Wreckers

Alum diff with ARB vs Steel with ARB?

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