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?

[PARAGON]

I'm not so sure I agree, Phil. If it spun the teeth off the ring gear while stationary, it means there was enough torque flowing through to the pinion to do the job but the ring was not able to handle the torque and make the tires break free and spin over. (this according to what everyone said happened)

A truck "should" have enough strength to break the tires loose if the truck is immovable without breaking something in the drivetrain as long as it's not a jerk on the drivetrain, ie dumping a clutch. Static load vs. dynamic load.

Now, I have no idea if going to a lower gear ratio would solve this if the gear itself is too weak to handle the load.

I'm not real sure about this one.

[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'.

[NEOCON1]

hey phil , bebe and i are wondering if they ment the gears for a yukon or gears from a company called yukon ?

and thanks for the input NoMo maybe we should be looking for a stronger material

thanks guys

still in moab drinkin beers

[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

[f5fstop]

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 NoMoGMPG:
the 'fix' would be a stronger material.

That is good advice, stronger gears of the same ratio is a far better idea than the dealers on of running 5.13's. </div></BLOCKQUOTE>

I would have to vote for stronger gears too. From surfing through this thread and many others, my first glance is a hardening problem. But I will see what I can find out...unofficially.

[HummBebe]

Originally posted by f5fstop:
<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 NoMoGMPG:
the 'fix' would be a stronger material.

That is good advice, stronger gears of the same ratio is a far better idea than the dealers on of running 5.13's. </div></BLOCKQUOTE>

I would have to vote for stronger gears too. From surfing through this thread and many others, my first glance is a hardening problem. But I will see what I can find out...unofficially. </div></BLOCKQUOTE>

Thanks, I appreciate everyone's opinions on this.

Going from a 4:56 with 35" tires to 4:88's with 35" tires, may not make that much more of a difference. But I appreciate the comments. BebeRhino is my daily driver, however most of it is city, or congested freeways. No real need for high speeds.

As long as the Yukons are a stronger material, I may still look at this as a viable option.

Someone has to be a guinea pig

[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.

[HummerNewbie]

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

[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.

[Desert Dan]

HummBebe

I missed the story on how you broke the gears.

Do you have an auto or 5-speed and do you have 35" tires?

KetKat is right about the 4.88's having smaller (more) teeth on the gears. Also with lower gears in the diff and bigger tires the cv joint might start to blow??

Also if you change out the front you have to do the rear (not under waranty) too.

[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.

[cestwick]

Hello all..new to forum first post but I thought I would put in my 2 cents. I am a Hummer tech in Sioux Falls SD. We have only had one H3 blow a front diff here. Actually happened on our Demo out on the test track. Truck had 800 miles on it. Got stuck in the mogals (snow and mud) we hooked a chain and pulled it out. Very little if any wheel spin but it was in 4low and as soon as front wheels got to solid ground all the torque was at the front and it shaved the teeth right off the ring gear. Last Dec. I was in South Bend talking to several other techs and at that time the only bigger things they were fixing was the front diff's. Like has been eluded to previously I believe the problemm is week material in the ring gear. I used to build and race 4X4's in the mud and clay of florida and we had trucks with a 1000 hp that never broke ring and pinions.

[NEOCON1]

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>


hey newbie , you may be on to something there , bebe and i both got our trucks early in the production run . not sure of production dates we have both had our trucks since aug. 05

[NEOCON1]

Originally posted by Desert Dan:
HummBebe

I missed the story on how you broke the gears.

Do you have an auto or 5-speed and do you have 35" tires?

KetKat is right about the 4.88's having smaller (more) teeth on the gears. Also with lower gears in the diff and bigger tires the cv joint might start to blow??

Also if you change out the front you have to do the rear (not under waranty) too.

hey dan , we were trying to get up a set of steps between waist and chest high a its a pretty gnarly obstacle . we both have auto's , adventures and 35's .

ther are alot of details in the h2 area under 06 moab thread .

still in moab drinkin beers

[f5fstop]

Originally posted by NEOCON1:
<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 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>


hey newbie , you may be on to something there , bebe and i both got our trucks early in the production run . not sure of production dates we have both had our trucks since aug. 05 </div></BLOCKQUOTE>

VINs are ok, but I would like to track the date stamp on the axles.