Some thoughts on the Aluminum front diff

[Sennin]

Ok, so after some "brand bashing" this side (all in the name of fun obviously) i was thinking.....

My hummer has the aluminum cast front diff, and I don't yet want to upgrade to the CI with difflock.

What usually happens when the frond alu. diff gets destroyed on a trail?

is it theoretical possible to remove the front driveshaft and front diff gears, lock the centre diff and then drive the Hummer as a 4x2 home?

as a mechanical engineer, this sounds feasible to me, but one might have to remove the halveshafts as well, what is your opinion on this hipothesis?

 

[Bigunit]

In theory, that would seem to work to get you home but I'm not sure that will work with the H3. I believe that the common opinion is that there is no way to turn the H3 into a 2 wheel drive vehicle because of the H3's electronics/computer. Your comment about being able to remove the drive shaft does make sense though. Curious to see if anyone has done this. I wonder if you removed the halfshafts, front drive shaft and gears, plugged the holes to avoid loss of t-case fluid, if you might be able to drive. I think the common solution would be to get dragged out to where a tow truck can take you home. If you are being dragged out, remember to put the t-case in neutral to disengage the engine & tranny from the rest of the drivetrain (to put the transfer case in neutral, push the 4Hi street mode button and the 4Lo button at the same time - hold it for about 8 seconds and the "N" should light up).

 

[06 H3]

When I blew my diff I was dragged home. When I got my new diff and did the install it was late and we turned the project into 2 days. I actually drove the h3 with no front diff at all after I pulled it out. I had no driveshaft or diff. It 4hi unlocked it wouldn't move. In 4hi locked it drove. So its possible u must be in 4 high. What I would do is pull the driveshaft and halfshafts and drive home in 4 hi lock then u have 2wd.

Sent from my DROIDX using Tapatalk

 

[bebe]

Yes you can run it. Here is the "WHola" thread where I ran it that way from April to July 2009 just before I started my build:

So here is the final plan -

Rick is going to pull the ring gear and we are going to put the Half shafts back.

I am going to run the truck with no front drive line and the t-case in 4 hi lock with the gutted diff (have to leave the carrier in it) and the half shafts in place.

I will have limited use all week, and then 300 mile round trip all freeway from Auburn Ca to Cupertino Ca one day per week. It's mostly flat with one grade (1100ft).

 

[4speedfunk]

H3 front axles are like alternators, or water pumps...you don't rebuild em. Its far cheaper and easier to just drop-out the broken one, and bolt-in a complete new (or gently used) assembly. Even if you could somehow "shut-off" the front diff for the trip home...a broken AAM-7 is rarely re-buildable. They like to turn themselves inside-out! When you break a front diff on an H3...you might as well just put the T-case in 4HI-Lock...turn up the Monsoon...and hit the highway! You ain't gonna save anything by pulling the front driveshaft...the diff will continue to rotate from the wheels on the ground. Now I suppose you could carry some plastic plugs for the front axle, and pull the half-shafts, and drive-shaft if you break the diff. and still want to drive home. But, thats alot of work to do on the side of a trail! And to be totally honest...my experience says there won't be much in there worth saving. So...deal with the Rice Crispies, and bolt-in another complete assembly when you get home. BTW...You don't need a plug for the front driveshaft on the T-case (its a fixed flange). Don't believe for a second that a Cast Iron case is the cure for your problems. Sure, its an improvement but, only a slight one.

Come to think of it...a stripped-down AAM is so small and lightweight...its totally possible to carry a trail spare. (now thats pathetic!):emb:

 

[bebe]

When you break a front diff on an H3...you might as well just put the T-case in 4HI-Lock...turn up the Monsoon...and hit the highway! You ain't gonna save anything by pulling the front driveshaft...the diff will continue to rotate from the wheels on the ground.

I'm going to disagree with you here...Disconnect the Drive shaft.

If it jams up and implodes more as you are driving it broken, you may spare your t-case the shock load. (and the rear end) Cheap insurance that will cost you 10 minutes or could cost you thousands.

 

[MUTAINT]

If it ever happens (front diff goes boom) and you need to get home without a wrecker I suggest you pull the 1/2 shafts AND the front drive shaft and put it in 4HI Lock. I know this becasue it happened. The intermediate shaft broke and the piece of the shaft "wedged" itself between the ring gear and the case (cast iron). This stopped ALL forward and reverse movement. I tried driving it thinking "I'm getting a new diff anyway", then boom, crack, boom it moved, then BANG no movement at all and the front tires screached!

This is what it looked like @ the dealer:

 

[4speedfunk]

Good point Bebe....hadn't thought about the shock being transmitted back to the t-case. Considering you can pull the front driveshaft in ten minutes...I guess it is cheap insurance. Mute...I've broke two intermediate shafts in the same indentical fashion (just outboard of the carrier splines), and they looked just like that. Seems that when they blow, the destruction is so complete its hard to tell what actually causes it. I'm bettin the shaft is the first component to go. Then once that chunk gets thrown into the clockworks...the rest is history.

 

[bebe]

If you are going to wheel it, I would take the short shaft out and have it cryo'ed. More cheap insurance.

When the intermediate shaft breaks - you're toast, because it is a c-clip style application. Google "C-Clip Axles" and click Images and see what comes up!

 

[4speedfunk]

I think that shaft comes from Brazil. I keep a spare with me at all times and I should take it into my shop foreman and have him Rockwell it. This would tell us if its real steel or old tin cans (South American unknownium). It would be a very simple item to make, and if I thought it would strengthen the axle I would already have them for sale. I don't think the metalurgy is the issue...there's more to it than that. It doesn't matter what you make that shaft from...unless you can stop the drivers-side axle tube from getting pulled and yanked back & forth, you will continue to have problems. That shaft is applying lateral leverage to the diff housing and eventually it pops the carrier out of its caps and/or changes the lash on the ring & pinion to the point of failure. A cryo-shaft would definately help the shaft breakage...but I don't think it would do a thing for the assembly as a whole. The real problem is the housing and how it is attached to the truck.

 

[Sennin]

This is exactly the info I was looking for, thanks guys and girls :thumbs:

 

[reaper]

I have a spare for sale, if anyone needs one!!!!