New info on the Front Diffs

[HummBebe]

Originally posted by PhilD:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by HummBebe:
I don't think we can do that on the three's, has something to do with the computer thingy.

Bet you can, even if you have to start pulling fuses until it works. </div></BLOCKQUOTE>

Ok, we discussed that on the trail with the HUMMER mechanic.....I called him 2 seconds after I was off the trail....to order parts :-)

He mentioned that Stabilitrac would/could prevent the whole vehicle from operating if disabled.

That was honestly the first thing I thought of, I just wanted to go home

[Chinkierol30]

Originally posted by PhilD:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Chinkierol30:
find the broken teeth and use JB Weld to glue them back on again?

This is special, just like your idea of super gluing lug nuts on.

For future reference, fixing vehicles is more of a mechanical thing, and less of an arts & crafts thing </div></BLOCKQUOTE>
So you don't think it will work?

According to their advertising it’s an alternative to welding!!

“Our flagship product, J-B WELD is the world's finest cold-weld compound. It's a remarkably easy, convenient, and inexpensive alternative to welding, soldering, and brazing. J-B WELD is the smart way to repair something ...”

Or are you saying you can’t use a regular welder to re-attach the teeth either?

[f5fstop]

One question for Neo and Bebe, did you have traction control turned Off?
Also, was a front wheel in the air, and then it hit rock, or were both on the ground when the axle took a dump?

[PARAGON]

Originally posted by CO Hummer:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PhilD:
Hardly an osbatcle you'd expect to start blowing diffs on though. One may be expected, but two vehicles blowing stuff on the same obstaacle tends to make me think there is eiether a more general issue with drivetrain strength, or just bad luck.

I totally agree. There IS a general issue with the drivetrain strength. I was standing right there and I couldn't believe it when I saw what happened. Bebe and Neo hardly gave it any gas before I started hearing that ugly sound of the teeth breaking off. Especially Neo - he wasn't even up the part of the steps where both his front and rear were against ledges! Only his back wheels were pressed against the ledge when a little torque shattered everything.

Bebe was fully pressed against two ledges - both front and rear wheels. She had tried it a couple of times, and it snapped around the 3rd attempt. She was being very careful and I was getting on her about needing MORE acceleration. Ironically, when I was telling her about needing more momentum she said "I'm just trying not to break my truck". 30 seconds later....Snap.

Something must be done to beef up those diffs. If not, I would not wheel Golden Spike with an H3 again unless I planned in advance to winch up the H3's over the obstacles requiring serious torque. </div></BLOCKQUOTE>It's looking like this is not systemic problem. Already, it appears that some ring gears can possibly make it through the system into the front of the trucks without proper hardening for the harder type wheeling that Golden Spike requires.

I'm betting that you could take 2 others through there, under the same setup and conditions and not experience that same problem. I can also bet that GM is all over this right now and have even seen the pictures of the Neo's diff since a failure like this is so uncommon. It might fall back on trying to figure out in AAM's process, what could have occured to allow for the metal to not properly cure.

[ketcat]

Originally posted by PhilD:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ketcat:
I was saying that I am thinking of getting an H2 or H1 and that I would rather bent a tie rod than blow a diff.

Why do you think something in the steering will blow befor something in the driveline? While there is a realtionship, I've seen H2 diffs blow with vehicles with stock tie rods and there was no stress on them at all. Likewise, the H3 tie rods are hardly beefy, and they did not blow instead of the diffs.

The concept that the tie rod is a pressure relief valve for the drivetrain is a false one. </div></BLOCKQUOTE>


From what I read an H2 bent 3 tie rods and two different H3's broke differentials. Not saying one would go before the other just the difference in the experience they had with two different vehicles on the same obstacle.

[ketcat]

PARAGON:

"The H2 did not bend 3 tie rods on Golden Stairs. It was on the entire trip that day, that at best is a 9 hour trail day of hard wheeling. Golden Stairs is just one short obstacle where the 2 H3s spun the ring gears.

Huge difference."
________________________________________________
Correct, it's a huge difference! Thanks for setting me straight.

[RubHer Yellow Ducky]

RubHer Yellow Ducky
Hummer Professional

Posted 04-28-06 04:26 AM
I want all of you who went to Moab to know that yesterday I did the South Florida Neighberhood Speed Bump Challange twice and nothing broke.

I even did the Jump the Curb Side Event and as a BONUS ran over 6 little Blue Haired Old Ladies but I still only placed 4th, behind the Morris Mini, the MGA and the Ford Station Wagon.

BUT

I did get lucky last nite...

SERIOUSLY

I'm glad you all had a good time and wish I could have been there.

OH, also sorry about the breakdowns !

RYD

[f5fstop]

Originally posted by PARAGON:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by HummerNewbie:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
...But there might be a relationship to the two trucks through the front ring/pinions because their build dates are fairly close together...

I agree completely especially since there are now three since HI's has to be replaced. I would really like to see some investigation into this since the three vehicles that I know of with this problem were all purchase right at the same time. Of course any one of them could have been sitting on the lot for a while but I really think this needs to be looked into. Based on VIN numbers I would think it would be fairly easy to check the lot numbers for the gears in each truck. If the lot numbers are all different then that probably counts out a hardening issue but if they are all the same it would narrow down the possible problems in my book. </div></BLOCKQUOTE>I promise, it's being investigated. </div></BLOCKQUOTE>

Oh yes, it is being investigated, and maybe some more.

A few notes on other comments.
The axles already come with synthetic fluid, and the fluid is not the problem. The problem appears to be hardness.

Does GM put the minimal parts in the vehicle? Yes and no. The specs on these axles was high, whether or not AAM is cutting corners remains to be seen.

They won't put the largest axle available, for that would be a waste of money, but they won't put the weakest either; especially in something they know will be off-roaded by a certain number at places most would mess their drawers thinking about.

All I can say on this board is that as the numbers of destroyed axles rises, and as of yesterday, there were very very few, people will start asking questions. The three that we have on this board have not hit the warranty reports until the repairs are completed, and the dealer submits the labor op for payment. That is how the warranty numbers are run by engineering.

I can say, that some are raising their eyebrows with just the one photo I sent to engineering and mentioned there were two of these on one day. Tomorrow, I will let them know there are three that I personally know of.

If they jump on this like the cylinder head issue, it will not take many more to explode. The cylinder head issue was researched and the head re-designed with an extremely low number of failures; especially considering the number of these engines are on the road since '04.
I can't say for sure, since I'm low on the totem pole, but I would bet if there is a problem found, there would never be a recall, due to the low numbers of axles that will be replaced. However, I would bet a lunch, that if a problem is found, new axle specs will be established, and these new axles will be put into production, and shipped to service parts, so that the replacement axles, if needed, will be the stronger axle.

That is all I can really say on the matter; except please stop breaking your H3s. For some odd reason, when something big happens on one of these vehicles, I get pushed into the middle to help the situation, and I'm already busier than a one legged man in an ass kicking contest. (I'm trying to be funny... )

[PARAGON]

What about just dropping the lower control arm?

In a had-to situation, I'm talking about. And mind you, I have no clue and am just thinking out loud. But if you get the ball joint undone and can get the knuckle turned and then move the whole upper control arm and knuckle up, would you have enough deflection along with the CVs to get it out?

[cestwick]

Originally posted by Alec W:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Alec W:
All this is great if you have the time and tools, however with only 2 wheel drive you can’t drive out from the middle of Golden Spike anyway. Sometimes it’s better just to get the tow strap out and drag a dead truck to the shop

I'm guessing Golden Spike is not the only place something like this could occur and some people that own the vehicle were interested in know what possibilities were out there.

Doing the above can get you 500 miles back to home on the highway instead of stranded in some small town with a single mechanic or a large tow truck bill. </div></BLOCKQUOTE>
I was merely pointing out that sometimes it might be better to simply tow the broken vehicle off the trail and figure out the longer term solution in the morning. Not all of us are gearheads

I did however dutifully copy all of the pertinent notes from this thread for future trail side H3 recovery endeavors </div></BLOCKQUOTE>

Taht is why you have gearheads like us around..We don't mind gettin dirty.

[HummBebe]

In either case I personally would wait and see if more differentials break because it's under warranty now and once you install aftermarket parts the warranty is gone. If it ends up being a bad gear issue and not related to the differential itself then upgrading is probably a safe beat

Well if the 35" tires don't affect the warranty....really.

Then changing the R&P shouldn't?

It is a minor modification to a inexpensive part.

Why not?

[HUMTECH]

Correct, an H-1 uses esentially an AMC model 20, actually A very strong differential just got the bad name as you said the 2 piece axles were the problem. A model 20 has A 8 7/8" ring gear which is only an 1/8 smaller than A ford 9" just doesn't have A pinion pilot bearing to steady the pinion gear like the 9". As for using A lower gear ratio to try to increase strength is backwards. the lower the ratio the smaller the pinion gear gets and creates A new weak point but at the same time requires less input torque to rotate the tires so it's kinda A catch 22 situation.

Originally posted by ketcat:
Just my 2 cents.....

4.88:1 with 35's puts you back to about stock with 33's so that sounds good. Problem is the lower (higher numerically) the gear the more teeth which equals less metal per tooth so in theory with all things being equal a 4.88:1 is weaker than a 4.56:1.

As I recall the H1 uses an AMC model 20 differential which was used in CJ’s etc……and not known to be the most durable differential in the world especially the two piece axles. The reason it holds together in an H1 is because they run a 2.56:1 or 2.73:1 gear ratio and multiply at the geared hub.

My opinion if people are breaking gears finding stronger ones is a good idea but I’m not sure going to a lower gear is the best idea. At least if it’s stock the dealer will warranty it for 50k miles.

[NoMoGMPG]

Originally posted by HummBebe:
I might need someone to verify before I go forward....


I spoke with a very knowledgable person at the Salt Lake Hummer Dealer. He said the first thing I need to do if I am going to keep wheeling like this is to replace my front and rear ring and pinion gears with Yukons (as in GM). He said either 488's or 513's. If this pans out.....we could have a fix.

F5fstop.....can you verify?

Bebe,
It was very clear to me that crawl ratio is not the issue here, it is gear material strength. It appears that the gears are too brittle for high impact driving, so the 'fix' would be a stronger material. As an example, the ring and pinion gears used in a 200 HP S10 Blazer 7.625" differential are exactly identical physically to an SS Camaro LS1 with 330 HP. The difference is that the Camaro gears are made for high impact driving. They are made to absorb the shock by being more resilient.

I would venture to say that GM will probably come out with a different material replacement R&P for vehicles with your 'symptoms'.

[cestwick]

Just got back from talking to Parts manager. Was going to get pick of broken diff but we had to send it back to gm. Good indication they are trying to figure out what is going on.

[Chinkierol30]

I’ve been off-line for a while (moved to a new house without cable) so I do not know if this has been suggested yet.

Would it be possible to strip a broken front differential down, find the broken teeth and use JB Weld to glue them back on again? I know this probably would be a bad idea for a permanent fix but it might get you off the trail?

[PARAGON]

Originally posted by ketcat:
I don’t know if the gears were hardened correctly or not but I do know this has happened more then we have discussed. I can’t be specific but I heard about a couple of issues in the PHX area back in September.

People might not like me for this but I think the differential is too small. We are talking about a 4900 lb vehicle with 33” to 35” tires and a 56:1 to 69:1 crawl ratio. That’s a lot of traction, weight and torque multiplication for a 7.2” ring gear to handle.

A Dana 30 which is larger and is probably stronger than the differential in the front of an H3 is marginal in a TJ with 33’s. That’s why Rubicon’s have Dana 44’s front and rear and they run 31’s from the factory.

Someone mentioned SAS which is what I’m thinking although I’m not sure how feasible it is. High pinion Dana 44, 4 link and coilovers.

I love my Hummer but am not going to be left stranded in the Mountains. I'll fix the problem or get an H2 or H1 which I am seriously considering before I walk home. I can fix a tie rod on the trail but not a differential.

From all accounts you can count on your fingers and maybe toes how many times this has occured throughout all of testing and the thousands and thousands of vehicles that are out on the road now. If it was a stress reason, it's likely you would see the rings shattering. With the type of damage occuring it leads to a flaw in the gear itself.

This was not a grenading of the diff, this was spinning teeth off and is a completely different animal than what is normally seen.

A Dana 60 up front won't make any difference if the gears aren't properly hardened due to some impurity in the process.

I will promise you this. You do a SAS and get into other mods to do wheeling and you WILL be stranded because you are going to break something. It's just the nature of wheeling and you don't have the R&D budget that GM does to figure out what works and what doesn't at the cost of breaking things.

Blowing the front diff does not end your day. If you can do a SAS and fix a tie rod then you should be able to pull half shafts and the front driveline and drive it out in rear drive only.

[CO Hummer]

Originally posted by PhilD:
Hardly an osbatcle you'd expect to start blowing diffs on though. One may be expected, but two vehicles blowing stuff on the same obstaacle tends to make me think there is eiether a more general issue with drivetrain strength, or just bad luck.

I totally agree. There IS a general issue with the drivetrain strength. I was standing right there and I couldn't believe it when I saw what happened. Bebe and Neo hardly gave it any gas before I started hearing that ugly sound of the teeth breaking off. Especially Neo - he wasn't even up the part of the steps where both his front and rear were against ledges! Only his back wheels were pressed against the ledge when a little torque shattered everything.

Bebe was fully pressed against two ledges - both front and rear wheels. She had tried it a couple of times, and it snapped around the 3rd attempt. She was being very careful and I was getting on her about needing MORE acceleration. Ironically, when I was telling her about needing more momentum she said "I'm just trying not to break my truck". 30 seconds later....Snap.

Something must be done to beef up those diffs. If not, I would not wheel Golden Spike with an H3 again unless I planned in advance to winch up the H3's over the obstacles requiring serious torque.

[PARAGON]

Originally posted by HummerNewbie:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
...But there might be a relationship to the two trucks through the front ring/pinions because their build dates are fairly close together...

I agree completely especially since there are now three since HI's has to be replaced. I would really like to see some investigation into this since the three vehicles that I know of with this problem were all purchase right at the same time. Of course any one of them could have been sitting on the lot for a while but I really think this needs to be looked into. Based on VIN numbers I would think it would be fairly easy to check the lot numbers for the gears in each truck. If the lot numbers are all different then that probably counts out a hardening issue but if they are all the same it would narrow down the possible problems in my book. </div></BLOCKQUOTE>I promise, it's being investigated.

[HummBebe]

Originally posted by ChasH3:
All I know if there is a problem I rather have it identified and a recall in place, then wait till I get off road somewhere and get stuck....

It will not likely be recalled.....not enough trucks (H3's) that will wheel enough to break it.

[f5fstop]

All H3s have 4.56:1 gearing.
Now, as for replacing the R&P, the only warranty item that would be affected would be the axle itself. Some overzealous service managers might say a better gear would affect the axle shafts, but my answer to that would be BS. Besides, if you did break an axle shaft, no tech will be removing the cover to see what R&P gear you are running, and most wouldn't know the differnce if they did.