Diff failure and rebuild

[mdes0]

Hey folks, have a 91 M998 that I've owned for a few years and have done many updates too, including a 2 inch body lift, Rod Hall springs, and 40" Iroks with PVC inserts. A few weeks ago while wheel'n in southern Mass I pushed the big girl a bit too hard try to climb a rocky slope a buddy of mine in a buggy made look so easy and blew up the front diff. At the time it didn't sound that bad, like something that was bound up released. I was able to drive it out of the woods in low and get her on a trailer for the ride home.

Once I got the front end out and opened up I found that I blew every work wheel off the drivers side and lost a tooth on the drivers side worm gear. Check out the carnage in the pics.

So I plan to push her up many more obstacles that cause white knuckles so I'm thinking of going to an ARB or Auburn locker. Doesn't seem like the Torsen diffs can take the need for frequent locking. Leaning towards the ARB since it gives me a good excuse to get an on board air system installed. Let me know if you have any opinions.

This will also be the first diff I put together so if you have any tips or tricks let me know.

Matt

 

[mdainsd]

Ouch! I ask the next question with no disrespect: Have you been taught or read up on how to drive up nasty obstacles with a Torsen diff? Also the 40 inch tires are probably adding to the problem.

 

[mdes0]

I have, was using BTM with very little tire spin. No throttle bashing or massive amounts of tire spinning. With the stock 37's wouldn't have been able to attempt the climb so I suppose the 40's gave me the opportunity, whether they actually contributed to the failure, I'm not inclined to think so. Plenty of civi H1's running around on 40's or bigger. I had heard early Torsens had a tendency to do this. Since the dif casing looks nothing like the replacement T1's I've seen I'm guessing mine is in the early category.

 

[Action]

If you are doing this at home, you may want the HMMWV diff spreader...
Things are always easier when you have the right tool.
I had one of these but lost it.

 

[Al Capone]

I was wondering recently how to remove the axles from one of these diffs .

 

[mdes0]

I saw that described in the TM, was thinking about making one. The ones I found during a quick search were pretty expensive.
Matt

If you are doing this at home, you may want the HMMWV diff spreader...
Things are always easier when you have the right tool.
I had one of these but lost it.

View attachment 723397

 

[mdes0]

If you're talking about the stubby output shafts you have to use a puller. Found the details in TM-9-232--387-24-2. What I don't know yet is if the bearings get destroyed pulling them out.
Matt

I was wondering recently how to remove the axles from one of these diffs .

 

[snowtrac nome]

I did the same thing to a diff in kotzabue , It comes from getting too aggressive trying to lock the diffs with the brakes.

 

[Action]

The diff spreader weighs like 40 pounds.
For output shafts, i just took thd nut off and pulled them out.

 

[Al Capone]

Action you just puked axle stubs out ? Or you mean you just pulled the hubs off. I did just pull off hubs but could not see how shafts came out or was retained

 

[Skrilex]

Did it ride on a trailer to go out wheeling? If so that’s your problem. Any rig that arrives on a trailer is guaranteed to break!

 

[mdes0]

Did it ride on a trailer to go out wheeling? If so that’s your problem. Any rig that arrives on a trailer is guaranteed to break!

Nope. I usually drive it out to every event, more fun that way. I was lucky that this time one of the members of the Jeep club I'm in was willing to drive me and my kids home an hour and a half out of his way to get my pickup and trailer. Think in the future I'll trailer for anything more than 30 minutes away .

 

[Gun Goober]

After more than 25 years of rock crawling all over the USA, I recommend the OX Locker, if you can get one for that diff. I can recount all the issues with the different styles of lockers but we don't have all day.

 

[Action]

Action you just puked axle stubs out ? Or you mean you just pulled the hubs off. I did just pull off hubs but could not see how shafts came out or was retained

I meant the output flanges that the rotor bolts to. I thought mdes0 said he needed a puller. It has been 5 years, bit i think mine just pulled off by hand.

 

[Al Capone]

Yes those just pull off . I was asking how to remove the axle stubs themselves once hubs are removed

 

[Awol]

Well, at least you were having fun while breaking parts! It's nice seeing a Humvee being worked hard, even if parts break.

Where were you wheeling in southern MA? Is it a public place? I've been looking for places to go.

 

[mdes0]

Well, at least you were having fun while breaking parts! It's nice seeing a Humvee being worked hard, even if parts break.

Where were you wheeling in southern MA? Is it a public place? I've been looking for places to go.

I joined a Jeep club. Those guys find all kinds of places to wheel. Mostly private land that they get permission to go on.

 

[Augi]

The stub shafts just pull out of the diff. I think I used a slide hammer. IIRC the bearing comes out with it. I replaced one about 5 years ago and I don't remember the details, but I do remember it being pretty easy.

Augi

 

[mdes0]

The stub shafts just pull out of the diff. I think I used a slide hammer. IIRC the bearing comes out with it. I replaced one about 5 years ago and I don't remember the details, but I do remember it being pretty easy.

Augi

You remember if you had to replace the output bearings or do they survive getting pulled out with the shaft with the slide hammer?

Matt

 

[Augi]

I know I replaced the bearing. I think I bought one in case the old one was damaged because I didn't have time to wait around for parts to arrive if I needed them. At that point I just put it in anyway. I think the old one was fine though. The races definitely didn't separate or anything. The press fit wasn't that tight.

Sorry it's not the most definitive answer.

PS Looks like you've already got the diff out of the truck or I would suggest doing the test in the -20 TM to measure the looseness of the bearings. You put a magnet mount dial indicator on the frame and touch the dial to the brake rotor. Then you push up and down on the half shaft end right where it's bolted through the brake rotor. If the rotor moves up and down too much then the diff output bearing is worn out and should be replaced. You can probably do that test on the bench still if you bolt the rotor onto the output flange. Or maybe just indicate off of the output flange. It may decrease your reading slightly because the distance to the pivot point is slightly shorter.