majicgoats

Kylek, I would be interested in seeing what part number your replacement differential has and whether or not it is the same as my replacement. I previously posted pictures of the tag from my original and replacement differential.

Kylek, How many miles did you put on your truck before the hum came back?

TRUCK IS FIXED!!! Dealer replaced entire front differential assembly and the truck is as quiet as a mouse! First picture is of the bad front differential sticker and the second picture is of the new differential. I am not sure what the numbers and letters exactly represent but I thought I might provide them here for reference.

Can anybody confirm if there is only one company and/manufacturing facility that produces the 1500 series differential assemblies? Maybe there are two different manufacture facilities but both owned by the same company... thus, same part numbers. And as I said before, if most of the trucks that are having the same issue are crew cabs then I am lead to believe that the Mexico assembly plant somehow is at fault or the Mexican assembled trucks (1500 series crew cabs) are receiving parts from a different and possiblly closer, for shipment cost saving, differentials compared to the double or single cab trucks.

I find it interesting that most of the trucks with issues appear to be the higher package trucks like, LTZ, SLT, and Denali. I also find it interesting that most of the trucks listed are crew cabs...same as mine. I do know that the 1/2 ton crew cabs are all assembled in Mexico now. I wouldn't think they have a different front differential assembly part numbers but maybe the differentials for the Mexican assembled trucks are produced and/or purchased from a different facility than those that have the American assembled double cabs. Just thinking out loud here...

I do not believe that something caused the components within the front differential to go bad. I believe that they were manufactured with error. I believe that it is a manufacturing error within the differential because of the remarkable consistency of the noise, and the speed at which it is audible, that most have reported. I feel that if it was something like a bad CV joint that set up a frequency that took out a differential bearing then some of us wouldnt have been experiencing the issue from "day 1" off of the dealer lot and I believe that the issue we have had would of started out very slight and grown worse and worse / louder and louder more quickly over time. Just my thoughts....

UPDATE: I dropped my truck off at the dealer yesterday (04/06/2015) for further investigation and repair. The service manager wanted to go for another test drive and again he confirmed the complaint. I just got a call from the service manager today informing that they ordered a new front differential assembly for my truck! I am looking forward to getting the truck back and no longer having to listen to that coming-and-going humming noise. Once I get the truck back I will let you know the results. (P.S. - My dealer was nice enough to provide me a comparable truck while mine is getting fixed...I am thankful of that and it goes a long way with showing customer appreciation and understanding to the frustrations of this issue. )

GM-GUY, The front differential assembly doesn't appear to be complete with gears. (http://www.gmpartscenter.net/oe-gm/23186399) When you received your new axle assembly replacement, did it come with all the internal components preshimmed and ready to go?

Kylek, glad to hear you got yours fixed! I am still looking forward to my next dealer appointment on April 6th, 2015 in hopes for them to make the repair. I'd like to say I have high hopes but they most recently told me the issue is coming from the rear end so that is where "they want to take a look". Would you (or any others) that have had a successful fix mind private messaging me with information as to any "case numbers" with gm or your dealer information? I am looking for anything that I may help my dealer get this fixed sooner than later.

Another update: I phoned my dealer again today requesting what the game plan is to fix my variable humming issue that I have been posting about. Dealer said that he just got back from a service conference and talked to engineers regarding the issue and they have informed him that my issue is due to "improperly cut rear differential gear teeth". I set up another appointment for April 6th to have it looked at. Based on my extensive research and after reviewing other same issues and fixes I am not confident that this problem is a rear differential issue. I am confident the issue is coming from the front differential but if the dealer wants to start at the back end and work their way forward then so-be-it. :/

Update: Long story short, no new news to provide. I have contacted the dealer on a couple more occasions and the dealer is telling me that their "service representative" is looking into the issue and is going to be discussing this issue with "technical assistance" within GM to decide a fix/resolution. I am sure that somebody within GM knows exactly what the issue is and if they don't I would be happy to provide GM my truck for a disection-repair to figure this issue out so that everybody and every dealer knows what to do to get rid of this problem!