Rear/front diff

[PARAGON]

Originally posted by Mr. I - Man:
It looks like a metalurgical problem the teeth don't look stripped or sheared off in the case of a high torque load, it looks more like they cracked off due to porosity (bad alloy mixture,bad casting or bad block of raw material if they are a machined and forged parts )

I think you are on to the answer. I am not sure what this new PowerDense entails but maybe it's new technology and there are imperfections that can occur.

Many times items are run through a heat/cool cycle to enhance hardness and durability and maybe the process allows for one in xxxxx amount to come amount improperly "cured."

[Sewie]

Paragon - I hope you're right and I hope that means the new one they put in mine won't be prone to the same kind of breakage. **fingers crossed**

Only time will tell I guess.

[cestwick]

I replace a fornt diff on an H3 2 weeks ago that looked exactly like this one and it was on our dealer demo with 800 miles on it. Happened on the test track at the dealership. Truck was stuck in snow and mud on the mogals, pulled truck back front wheels had traction rear wheels in snow and it chewed it up. No wheel hop not spinning wheels hard or anything.

[PARAGON]

Originally posted by cestwick:
I replace a fornt diff on an H3 2 weeks ago that looked exactly like this one and it was on our dealer demo with 800 miles on it. Happened on the test track at the dealership. Truck was stuck in snow and mud on the mogals, pulled truck back front wheels had traction rear wheels in snow and it chewed it up. No wheel hop not spinning wheels hard or anything.

Can you get the VIN and details to F5Fstop. It sounds like he might be able to track some of this or check it out more or whatever.

[HUMTECH]

Haven't seen any issues with diffs in our shop other than the ones f5 was talkin about with the lapping compound in the rear diffs. Have had 0 front diff failures, could be isolated cases, possibly A bad production run, never seen A diff come apart like that without some serious driver abuse and A lot more torque and hp than an H-3 produces. I sure hope it does not become A widespread problem. As for warranty it should be covered but depending on your dealer don't offer info on where the failure occured. If ya told me you were blazing up A hill bounced over A rock ledge and kept your foot in it I would say to you "cool, lets get the general to cover it" but thats me. I would rather see someone use there hummer and have some fun with it and be confident the dealer will stand behind the product.

[rkcrawl]

A couple of things to think about:

Were the rigs experiencing these issues Auto or Manual? You have to consider the torque convertor on auto when figuring the over all gear ratio... While the by the numbers ratio for a H3 with Auto, 4.0:1 TC gears and 4.56 gears in the axles the crawl ratio is about 56:1, when you factor in the Torque Convertor, you end up with approximaitely 100:1 ratios.

The next thing to consider: The front diff looks like its aluminum, which if stressed hard enough may allow for some case deflection. Possibly enough in high traction environments that you may start stripping off ring gear teeth.

I did this a couples time on a 9" Ford axle that was in the front my competition buggy using stock Ford 9" carrier. I stripped teeth much in the same way as shown in Bebe's picture. (Note, I also broke bearing caps which contributed to the teeth breakage). I did this 3 times before I installed a stonger case (Ford 9' axles use a drop out third member like Toyota axles).

The last thing to consider is that GM used a standard cut gear in the front which is well known to be weaker when used in a front axle application (vs a revese cut gear, think Hi-Pinion diff in the front). This is because the gears are running on the "coast" side of the ring gear teeth.

Add that to a fairly small ring gear..

I hope that this is isolated, but larger tires, lots of torque, good traction, heavy rig.... you might just be pushing the front diff past its design limits.

I hope not, because while my H3 is my DD, it will server some double duty as a toy and see Tellico, Windrock and who knows where else.

Jim O
www.etoracing.com
06 H3 Lux/Adv

[cestwick]

I checked the data on our demo this is the build data for front diff. Build date on truck is 6/27/05 last 8 68114896.

Component Code : 63 - FRONT AXLE/FRONT CRADLE WITH FRONT HUB ASSEMBLIES
Source Plant : X
Part/Num Broadcast : UK5 Traceability : 16750177
Date Scanned : 06/27/2005 Time Scanned : 12.46.00 Scan Station : 06

[HummerNewbie]

Originally posted by cestwick:
I checked the data on our demo this is the build data for front diff. Build date on truck is 6/27/05 last 8 68114896.

Component Code : 63 - FRONT AXLE/FRONT CRADLE WITH FRONT HUB ASSEMBLIES
Source Plant : X
Part/Num Broadcast : UK5 Traceability : 16750177
Date Scanned : 06/27/2005 Time Scanned : 12.46.00 Scan Station : 06

That could fall in with the others that have had this issue.

[HIHUMMER]

How do you check build date?

[f5fstop]

Originally posted by HIHUMMER:
How do you check build date?

You have a PM. Sorry to hear about your front axle.

[f5fstop]

Originally posted by cestwick:
I checked the data on our demo this is the build data for front diff. Build date on truck is 6/27/05 last 8 68114896.

Component Code : 63 - FRONT AXLE/FRONT CRADLE WITH FRONT HUB ASSEMBLIES
Source Plant : X
Part/Num Broadcast : UK5 Traceability : 16750177
Date Scanned : 06/27/2005 Time Scanned : 12.46.00 Scan Station : 06

The other two were built within a month of that date.

Off topic question on the front rear link replacements. Was this due to squeaking noise while going over bumps? I'm trying to track my squeaks, and I believe this is the areas where they are coming from.

[HIHUMMER]

Was this due to squeaking noise while going over bumps? I'm trying to track my squeaks, and I believe this is the areas where they are coming from.

I also had the squeaking noise look into as well. They said that it was caused by the 4 bolts that hold the front cross member(?) to the frame. All 4 bolts were loose and 1 he was able to unscrew by hand it was so loose. So, whenever the frame flexed over a bump, that's what was causing the squeaking noise.

[fourfourto]

Could build date be estimated by sticker on frame on drivers side between the 2 doors?

Mine says 06/20/06

I have pic dont think it will load?

There was an FTP (file transfer) error. The detail is 'Upload to '/testdir/test.txt' failed. Detail: '552 Transfer aborted. Disk quota exceeded


Nope Dam !

[HIHUMMER]

06/20/06

WoW...that's impressive!

[HummBebe]

New question:

What does HUMMER consider a normal measurement for Backlash???

The tech who put in my new R&P said the old one was at .022 (thousandths) and that normal was from .006 - .010.

He said he thought along with the possible inconsistency with the hardening process, that the backlash was way off. He shimmed it to .010 thousandths.

[HummBebe]

Originally posted by fourfourto:
Could build date be estimated by sticker on frame on drivers side between the 2 doors?

Mine says 06/20/06

Shhhhhh.....no honey.

[PARAGON]

Originally posted by rkcrawl:
A couple of things to think about:

Were the rigs experiencing these issues Auto or Manual? You have to consider the torque convertor on auto when figuring the over all gear ratio... While the by the numbers ratio for a H3 with Auto, 4.0:1 TC gears and 4.56 gears in the axles the crawl ratio is about 56:1, when you factor in the Torque Convertor, you end up with approximaitely 100:1 ratios.

The next thing to consider: The front diff looks like its aluminum, which if stressed hard enough may allow for some case deflection. Possibly enough in high traction environments that you may start stripping off ring gear teeth.

I did this a couples time on a 9" Ford axle that was in the front my competition buggy using stock Ford 9" carrier. I stripped teeth much in the same way as shown in Bebe's picture. (Note, I also broke bearing caps which contributed to the teeth breakage). I did this 3 times before I installed a stonger case (Ford 9' axles use a drop out third member like Toyota axles).

The last thing to consider is that GM used a standard cut gear in the front which is well known to be weaker when used in a front axle application (vs a revese cut gear, think Hi-Pinion diff in the front). This is because the gears are running on the "coast" side of the ring gear teeth.

Add that to a fairly small ring gear..

I hope that this is isolated, but larger tires, lots of torque, good traction, heavy rig.... you might just be pushing the front diff past its design limits.

I hope not, because while my H3 is my DD, it will server some double duty as a toy and see Tellico, Windrock and who knows where else.

Jim O
www.etoracing.com
06 H3 Lux/Adv

I don't think case deflection would be an issue up front with this IFS setup. Even if the axle case flexed I don't think it would to where it would pull the pinion away from the ring.

I say that, but I really don't have a clue what the freaking case looks like, but IFS has other points before it gets to the case to allow for any twist to be absorbed.

There is nothing standard about the front and rear axles. It's some new technology that AAM has come out with. The gears are made using what they call PowerDense material which is "lighter" but stronger, or so they say.

Apparently the torque load for this axle is well within specs for the H3 and would easily assume more torque from a larger engine or some type of forced induction, but it might be the weakest part of the driveline. It all remains to be seen.

[fourfourto]

HummBebe
Hummer Guru

Posted Apr 27, 5:58 PM
quote:
Originally posted by fourfourto:
Could build date be estimated by sticker on frame on drivers side between the 2 doors?

Mine says 06/20/06



Shhhhhh.....no honey.

T & A Affilliate
Fo T & A Monitor


HummBebe called me honey

[HummBebe]

Originally posted by HummBebe:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by fourfourto:
Could build date be estimated by sticker on frame on drivers side between the 2 doors?

Mine says 06/20/06

Shhhhhh.....no honey. </div></BLOCKQUOTE>


Look at the date.....It hasn't even happened yet.

[NoMoGMPG]

Originally posted by HummBebe:
New question:

What does HUMMER consider a normal measurement for Backlash???

The tech who put in my new R&P said the old one was at .022 (thousandths) and that normal was from .006 - .010.

He said he thought along with the possible inconsistency with the hardening process, that the backlash was way off. He shimmed it to .010 thousandths.

Holy Shiite! .022"?!?!? That's horrible!

I set mine up at .006" but acceptable is up to .009", that may explain alot. I wonder if the case is distorted, no way GM would allow that kind of excessive clearance.