Front differential failure questions

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

If you had a front differential failure please post or direct me to another post(s). I did a search and did not turn up anything relevant with "dana 30A", "broken front diff", front differential", and "broken drivetrain parts". Please educate me on the weak link. Could you include the following:

Where the failure occurred (housing, internals, mounting brackets)
Environmental conditions (street, trail, snow, mud, wheels spinning)
Tire and wheel size

Also if anyone has a broken one taking up space, I would be interested in it.

Rob

KJ04 · **Posted:** Sun Aug 27, 2006 6:56 am

It's the housing that cracks. Usually a chunk breaks out at the rear and a crack runs up the lower side. My ring and pinion gears were also damaged. Replaced with a used housing and carrier from a local junkyard for $531.00.

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

Did it crack any where else? Do you still have it or did you toss it?

KJ04 · **Posted:** Sun Aug 27, 2006 12:06 pm

Yes, I still have it.

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

No one else had a failure?

btolle · **Posted:** Wed Aug 30, 2006 7:05 am

There have been a number of failure pictures on the forum but that was before the forum moved to a new server and all the old messages disappeared. That is probably why you are not finding posts about it.

Every picture I saw showed the crack in the same spot as the picture shows.

My best guess is that the area where the pinion gear shaft exits the housing is the weak spot. I think a steel collar around the housing at that point would prevent the breakage.

I know that Jeep is aware of the problem and has warranted them when they broke. Some have broken at Camp Jeep and Jeep Jamborees where the Jeep engineers were present and had the defective parts sent back to the factory.

I think Jeep is aware of the weakness and could reinforce the diff but the cost to recall all the Liberty's would exceed the cost of replacing the few that have broken. Manufacturers often make decisions like that strictly based on the $$$ it would cost.

BTW, if you ever start "bouncing" the front tires while wheeling that is one very good way to break the housing.

Bearcatrp · **Posted:** Sat Sep 02, 2006 10:21 am

I have a video of a liberty blowing the front diff. He was going up a hill in the winter and the front grabed and boom. The case blew open. Seems it let loose where the shaft goes in the diff. Was not bouncing either. Wish someone would make a steel diff as the aluminum ones suck. Wouldn't care about the extra weight.
Randy

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

Here is a though why would someone spend the money for a tougher version of the dana 30a and be limited to two gear sets 3.73 and 4.10? For strength and durability? From the limited time I have been working on this it is not going to be cheap (ie >1K) for a cast iron replacement, just the housing not ready to install. Other considerations are what if I want more lift than the current 2-3 inches, so I can run larger tires say 33"-35" (hypothetically). At that point I would be looking to replace the stock gears for a minimum of 4.10 but more likely to 4.30, just to keep the same ~ rmp vs. wheel rotation or to add more mechanical advantage. However since I would be basically setting up a vehicle for off road use why stop at 4.30's it may be more useful to go to a numerically higher set.

What is the solution I am not sure yet. If a tougher stock replacement was produced it would almost result in custom numerically higher gears. Resulting in a stock replacement part that cost (Lets not get spun up on my numbers unless I am off by more that 25% on the current parts please):

Gears $250-400
Locker/LSD $450-600
Bearings installation kit $150-200
Housing $1-2k
Total $1800-3200

There are some on this board that complain that $800 for a lift is too much.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

pokey555 wrote:

Here is a though why would someone spend the money for a tougher version of the dana 30a and be limited to two gear sets 3.73 and 4.10? For strength and durability? From the limited time I have been working on this it is not going to be cheap (ie >1K) for a cast iron replacement, just the housing not ready to install. Other considerations are what if I want more lift than the current 2-3 inches, so I can run larger tires say 33"-35" (hypothetically). At that point I would be looking to replace the stock gears for a minimum of 4.10 but more likely to 4.30, just to keep the same ~ rmp vs. wheel rotation or to add more mechanical advantage. However since I would be basically setting up a vehicle for off road use why stop at 4.30's it may be more useful to go to a numerically higher set.

What is the solution I am not sure yet. If a tougher stock replacement was produced it would almost result in custom numerically higher gears. Resulting in a stock replacement part that cost (Lets not get spun up on my numbers unless I am off by more that 25% on the current parts please):

Gears $250-400
Locker/LSD $450-600
Bearings installation kit $150-200
Housing $1-2k
Total $1800-3200

There are some on this board that complain that $800 for a lift is too much.

Replacing the whole thing does make sense to me as well. I was thinking there could be some way to fix it, but the more I learn about it-- replacing it makes more sense. It apparently makes more sense to Jeep engineers as well-- because that is what they did with the Liberator-- they used a different differential. With a CRD, it makes me nervous knowing how much torque could be going through that front diff. I would spend the cash to replace it-- but would not be able to purchase right away-- too many other Jeep expenses. Is someone going to pilot some kinda tech article on this?

gone_jeepin · **Posted:** Sun Sep 03, 2006 11:13 pm

is there no way to reinforce the aluminium case? to make it stronger without having to totally replace it?

KJ04 · **Posted:** Mon Sep 04, 2006 7:04 am

gone_jeepin wrote:

is there no way to reinforce the aluminium case? to make it stronger without having to totally replace it?

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=9691&postdays=0&postorder=asc&highlight=collar+group+buy&start=0

A group of us odered a collar to help reinforce the housing awhile back.
Only time will tell if it's going to work out.

I had bounced my front end to death in loose dirt and wet muddy conditions with no problems. Untill I bounced going up a steep grade and came down on a large dry flat rock, the front left tire grabbed traction, boom.

InCommando · **Posted:** Mon Sep 04, 2006 9:27 am

Although this is a bit of a hijack, I still think that a well-engineered kit to swap in the IFS pig from a full-size chevy truck out to be a viable option. My brother has a k2500 GMC with 235/85/r16's on in that uses the 4wd regularly, and has 200,000 miles on it. Consdiering the weight of that truck, that diff should hold up well with any tire you can put on a KJ.

Mutt · **Posted:** Mon Sep 04, 2006 9:45 am

InCommando wrote:

Although this is a bit of a hijack, I still think that a well-engineered kit to swap in the IFS pig from a full-size chevy truck out to be a viable option. My brother has a k2500 GMC with 235/85/r16's on in that uses the 4wd regularly, and has 200,000 miles on it. Consdiering the weight of that truck, that diff should hold up well with any tire you can put on a KJ.

If you're going to spend that amount of money and do that amount of work, you might as well put a SFA under it.

Jeepjeepster · **Posted:** Mon Sep 04, 2006 9:53 am

Or why not just use the dana 44 from a grand cherokee since it already been done. :wink:

rs4mtnitro · **Posted:** Mon Sep 04, 2006 11:06 am

What year of Grand has IFS cause I looked at a 04 and it still had a SFA.

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

Jeepjeepster wrote:

Or why not just use the dana 44 from a grand cherokee since it already been done. :wink:

Is there a post about this, or any links.

Utilizing a different housing from a donor vehicle would reduce cost. I was thinking of using a ford 8.8; however, than would require a new "sub frame" for mounting and possibly new axel shafts and housings. Since I would be reinventing the wheel I might as well fabricate a lift and install larger front brakes as well. Currently I am just trying to gather information and gauge if this would be a useful project for myself and others. The GM idea is also a possible avenue of approach. It just comes down to how much time and money.

Here is some general question: What is the spline count on the front differential? I am assuming the abs sensors on at or near the wheel hub and not in the diff case, is this correct? Anyone have a shop manual for the Liberty and 05 Grand Cherokees, that they could make a copy of the front suspension/drivetrain?

Gone_jeepin,

I do not see why the current front differential could not be reinforced; however, in general a part that is made in aluminum eventually fail due to the finite fatigue life of aluminum. (aluminum will always get weaker with time, where steel will reach reduced strength level and maintain). This is where I would have to due some analysis of a cracked case and see if it is possible to band-aid.

Rob

CarNutCertifies · **Posted:** Mon Sep 04, 2006 1:24 pm

i agree, you would think that there is some kit out there to pull an ifs unit out of a chevy truck, Is it a matter of building brackets?

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

No kits that I have found, please post a link if anyone finds some information. It will be a trial and error fit for the guinea pig, namely my wife’s CRD. Just have to pick which direction to pursue and finish my current engine swap, which should be finished by the first of the year.

KJNick · **Joined:** Mon Jul 11, 2005 12:00 pm **Posts:** 56

pokey555 wrote:

Jeepjeepster wrote:

Or why not just use the dana 44 from a grand cherokee since it already been done. :wink:

Is there a post about this, or any links.

<snip>
Rob

Here's the GC 44 in the Liberator. If you look past the rear diff in the second picture, you can see the GC 44.

cicciouk · **Joined:** Wed Mar 06, 2013 7:22 pm **Posts:** 43

KJ04 wrote:

It's the housing that cracks. Usually a chunk breaks out at the rear and a crack runs up the lower side. My ring and pinion gears were also damaged. Replaced with a used housing and carrier from a local junkyard for $531.00.

http://img819.imageshack.us/img819/9167/x2pd.jpg

This is what happened to me last Sunday...

Front differential failure questions

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