New info on the Front Diffs

[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?

[HummBebe]

YES PLEASE!!! the more the merrier or is it....misery loves company?

[ree]

Originally posted by Chinkierol30:
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?

OMG, no winky?!?!?! You can't be serious. Have you ever tried to glue anything that broke (that excludes glues carpentry and rubber patches where vulcanization happening)...it never works. If there's enough force to break a [suposedly] homogenous material, then glue's not going to hold it.

[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 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. </div></BLOCKQUOTE>

[HummBebe]

Originally posted by 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?

Yes.
When the truck is in 4lo lock with the rear locker on, the Stabilitrak system is turned off. Both of my wheels, front and rear were on the ground. I was essentially crawling up when mine spun.

[CO Hummer]

One other thing i noticed about the H3s is that they have NOISY rear diffs. At trail stops, I kept hearing noise that sounded like radio static coming from Bebe's rig. I had thought it was her CB and the squelch was turned up t0o high until she informed me that H3 rear diffs were very noisy. It was amazing how loud that rear diff sounds while just sitting there in park!

[Sewie]

Originally posted by Alec W:

You have 35s too if I am not mistaken?

Not yet. But I had planned on getting them before going to Moab in August.

[f5fstop]

Originally posted by cestwick:
<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 HummBebe:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">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 </div></BLOCKQUOTE>You can simply pull the half shafts and front driveline without pulling any fuses.

All of the traction control, Stabilitrack and ABS runs off of the wheel speed sensors and maybe a sensor at the output shafts of the t-case.

If you are moving the wheels are are all turning and the computer doesn't know if power is going to the front or not. </div></BLOCKQUOTE>

I'm not sure if any of you have ever pulled a front shaft on the H3 but it isn't the simplest job to do. You basically have to pull the front knuckles off to get the shaft out. Also I'm not 100% positive about the H3 at this time but I do know that on most GM 4x4's the outer joint assembly is what holds the hub/bearing togather and is actually suposed to be tightened to 191 ft lbs. I have seen where the drive shaft nut wasn't tightened and the bearing went out in a very short period. </div></BLOCKQUOTE>

Not easy that is for sure. However, there are four large bolts securing the hub to the knuckle and these bolts are torqued at 180 N.m each. The tire is then attached to the hub. I have never tried it, but the vehicle should be able to be driven without shafts.
The shaft torque is actually 235 N.m (ball buster). The torque is high since the shaft is fairly large.

I may just try this, because I'm not too sure if you really have to remove the knuckle completely. You might (as someone stated) be able to remove the tie bar and get enough swing on the knuckle to slide the shaft out. Happen to have a Hummer on the rack with the cylinder head out.

Maybe if the shafts were weaker, the shaft would go before the diff. (Then we could call it a Jeep )

I guess, if you had a metal saw, and didn't mind the extra 200 or so for the shafts, cut 'em and remove. That would be an easy job.

[cestwick]

Thanks for the welcome Newbie. Most of what we did was mud runs but when we went out to play we used to camp and wheel in the Oceola national forest. Find a campsite, pick a trail and see where it goes. Obveously not as good rough stuff but we had fun. I had a 79 Blazer, 38" swampers 383 stroker and 4:56's. It would do a 200' mud hole in 5 seconds.

Besides the 2 front diffs breaking, were there other noteworthy breakdowns?

And congrats are in order for the true H3 testers.


S.

[PARAGON]

Interesting info NoMo. AAM has something called PowerDense ring/pinions they are using in the front (I don't know about the back). I don't like the idea of something that has to have a special name to do something it is already supposed to do.

Anyway, Phil, I think you and I are on the same page. I just couldn't necessarily see that a lower gear ratio would mean a stronger gear, but could see how it would break the tires free sooner, but that's as far as I could make it.

Here is a link to some more info that was started in the H3 tech section on this:

http://elcova.com/groupee/forums/a/t...1/m/9351068971

[HummerJim]

I agree with the previous posts. You are going to be very unhappy with that high a numerical ratio on the road, unless this is for offroad use only. When you go with the stronger gears, everything needs beefing up in the drivetrain. Years of drag racing has proven to me, that EVERYTHING in the drivetrain must be compatible or the weakest link will break. I've seen universals twist off of driveshafts, transmission splines stripped, pinion gears without teeth etc. It's boils down to how fast you unload the torque to the drivetrain from the engine, and I would just go with stronger diff gears. Quaife will make you berylium hardened gear sets that are virtually indestructible, but they are VERY EXPENSIVE and then you have to wonder if the transfer case, tranny or clutch, driveshaft etc will handle that torque.

[HummBebe]

Originally posted by 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.

[NEOCON1]

hey f5 , we were in low with rear locked tractin cotrol off message is always shown for me when in 4 low we were BTMing with all four tires on the ground .

thanks for the input on all this .

[CLAYDOG]

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 f5fstop:
...my first glance is a hardening problem.

Here is a shot in the dark but how close were the built dates on Neo's and Bebe's rigs? Could it possibly be that there was a problem in the production/hardening of these gears and by dumb luck, they both had gears from this batch? Sorry Bebe and Neo, just looking for a silver lining for the rest of us </div></BLOCKQUOTE>

My feeling is, this is likely the problem, and wouldn't afect most owners unless they're really pushing the truck hard. Something as straight forward as a high load ring gear failure would have shown up in preproduction testing if it was a design issue and not a manufacturing issue.

[HummBebe]

Originally posted by evldave:
chances are if you have access to a welder in the field, you've also got access to someone that can pull half-shafts & DS and you can just drive out in 2WD.

I think you'd have just as much luck with bubble gum vs JB weld on ring gears...

I don't think we can do that on the three's, has something to do with the computer thingy.

[PARAGON]

It's apparent that there are is not some widespread issue with the front diffs. What's sort of wierd is that there were probably other things that Bebe and Neo did that one would think would have popped the ring long before they made it to the stairs that day.

I think someone on one of the threads probably hit on the likely issue. It sounds like maybe there could be a ring or two here and there that was not "hardened", or whatever the process is, to the degree others are and to where it should be.

I doubt we see this occur very often.

[cestwick]

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 cestwick:
I'm not sure if any of you have ever pulled a front shaft on the H3 but it isn't the simplest job to do.

Even easier if you've blown a CV.

You basically have to pull the front knuckles off to get the shaft out.

Can't you just disconnect the tie rod and swing the knuckle around. That is what you do on a H2, but I haven't looked at a H3 close enough to see if it would be the same.

FWIW The H2 axle nut is only torqued to 155 lb/ft and requires a 35mm socket. </div></BLOCKQUOTE>

No you can't. On the H2 you have the luxury of a halfshaft that bolts to the diff. H3 the shaft goes into the diff housing. Not enough room to turn knuckle and pull shaft.

[f5fstop]

Originally posted by cestwick:

Not that it matters but I am not sure where you got your shaft torque figure. This is out of SI for the H3.Fastener Tightening Specifications
Application
Specification

Metric
English

Front Wheel Drive Shaft Nut
260 N·m
191 lb ft



I have done an axle swap and tried just turning the knuckle and just undoing the upper ball joint but was just fighting it so did the bottom too.

Opps; mine was off the engineering drawing which is lower. The 260 N.m is the correct spec for repair.

[ketcat]

Cranky Steve:

I'm agree with you.