03 GMC 2500HD 8.1 Allison G80

[z85]

I have taken the truck in to my local dealer who drove it and confirmed a rear end whine at speeds above about 50 with steady throttle. It is dead quiet when you take your foot off the throttle. However he said that the noise didn't increase any under aceleration and he didn't think that replacing the ring and pinion would make it any quieter. I left with his recomendation that I watch it and see if it gets any louder and if it did bring it back. He drove it when it had about 31000 on it. It now has 34000 on it and I have to admit that it hasn't really gotten any louder but it still is whining. How quiet are G80? I'm thinking of taking it back and seeing if they will at least pull the cover and take a look in it, see whats on the magnet. Any known TSBs or known issues?

 

BTW - It is a 4x4 if it makes a differance. 4:10 ratio that I ordered (NOT 3:73)

 

Thanks,

[GM-Tech]

I think there *might* be a TSB on this having to do with a revised propshaft, but I may be thinking of another model. I'll take a look when I get a chance.

 

The rule of thumb that GM gives us for ring and pinion gear noise is that, if you cannot hear it with the blower on medium speed, it is normal.

[GM-Tech]

I looked. No TSB on the '03.

[z85]

I looked.  No TSB on the '03.

 

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Thanks for checking GM Tech!

[vhato]

My 04 w/4.10's does the same thing. It drives me NUTS!!!!!

 

However, I do alot of gear swaps for people and I know there is nothing that can be done. GM *fixed* the problem on the S-Series (7.625 RG) and Half Ton trucks (8.625 RG) by revising the gear set. In 1999 for the NBS, GM dropped Motive Gear and went with a different company. Anyway, the diameter of the ring gear increased (from 8.5" to 8.625) and the cut of both pinion and ring gear teeth changed, slightly. This allowed for a tighter backlash of .003-.006 whereas the old style gears were .006-.010. This substantially reduced rear axle whine. GM's 14-Bolt 9.5", 10.50" and 11.50" (As found in the HD's and 2500 LD's) weren't subjected to this treatment, so that is why lower ratio's (4.10+) still whine.

[z85]

Z85,  If it's any consolation, I have the same 4.10 axle in my Suburban, and it makes the same noise.  If you hold between 50-55 at steady throttle, you will hear a whine.  Step on the gas or let off, noise goes away.  Go slower or faster, noise goes away.  I've got 60K miles now, and have changed fluid in the rear 3x since new.  No unusual indications of debris or wear.

 

I was told that lower ratio gears like this are more likely to be noisy than a 3.73 or a 3.42.

 

Interesting, it doesn't make any noise at all with 9000 lb trailer in tow.  I wouldn't worry about it...setting up a ring and pinion is so tricky, that changing parts may make the problem worse.  Last thing you want is the dealer tearing your truck apart on a fishing expedition.

 

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Thanks for the comeback Burbman,

 

Yes, it is some consolation, since you have 60K miles with no real problems, other than the whine. I use mine to haul my horse trailer with hay rack, tack, etc.

I haul to some pretty remote places sometimes and I sure don't want any surprises.

 

I'm coming up on 36K pretty soon and I need to take it in to have them look at a few things, Injector clean, lube, fluids, allison filter. So I thought about dropping the cover only to look inside. I don't want a fishing expedition unless I see something in there to justify the risk.

 

I also need to get the rear springs looked at as they make that clacking noise when you hit chuck hole. I've seen on this board that there is a TSB about this and you need to add some rubber "biscuits" to the end of the overload on the bottom of the spring pack.

 

Thanks,

 

Z85

[Burbman]

Z85, If it's any consolation, I have the same 4.10 axle in my Suburban, and it makes the same noise. If you hold between 50-55 at steady throttle, you will hear a whine. Step on the gas or let off, noise goes away. Go slower or faster, noise goes away. I've got 60K miles now, and have changed fluid in the rear 3x since new. No unusual indications of debris or wear.

 

I was told that lower ratio gears like this are more likely to be noisy than a 3.73 or a 3.42.

 

Interesting, it doesn't make any noise at all with 9000 lb trailer in tow. I wouldn't worry about it...setting up a ring and pinion is so tricky, that changing parts may make the problem worse. Last thing you want is the dealer tearing your truck apart on a fishing expedition.