G80 locker noise

Status
Not open for further replies.
Joined
Aug 11, 2011
Messages
6,264
Location
N.C.
I was backing my 2005 Chevy Avalanche with the G80 with the 342 gear ratio factory locking diff out of the garage Sunday and it made a popping noise. I stopped and went forward a few feet and everything seems to be fine now, no noise since. I have read on a couple Chevy truck forums that this isn't anything to worry about with the G80 locker. Truck has 172,000 miles and probably has never had the diff oil changed, I bought it used 1 year ago. I did drive it a little in the snow a week ago and it did lock a couple of times while climbing my inclined driveway but no problems until Sunday. I'm going to change the diff oil soon. Any thoughts on why it made the noise and reccomendations on diff oil? I'll probably use synthetic gear oil. Thanks
 
Last edited:
Sometimes the 80 does that it could have been partially engaged for some reason when you parked the truck then when u backed up it released, I've had that happen with mine.
 
I didn't think the G80 was a locker; I thought it was a clutched limited slip differential. If the fluid has never been changed, it'd probably be smart to change it, ensuring that you use the proper additive or use a fluid that's designed for that use.
 
The G80 is an actual locker, but works a little differently. It's basically an open diff until one wheel starts spinning. Then, a pin pops out once it spins about one revolution, locking the axles.
 
GM recommends their rear axle fluid, 75W-90 synthetic, P/N 12378261 that comes with the proper additives in it already. Other have reported using other brands with separate additives and getting chatter from the rear. I change mine every other year. The only downside to the GM lube is that it's $32/qt.
shocked.gif
 
Last edited:
I have heard what I would call a "knock" from my Silverado's G80 rear, especially when the traction control kicks in. I've had Amsoil SVG 75w-90 in it for about 60,000 miles now with no different or unusual noises compared to the stock GM grape-scented oil.
 
Last edited:
Mine has the G80 and it will make popping noises when the locker is engaging and disingaging. Nothing to worry about. I am running Amsoil Severe Gear 75w90 in mine with no additives.
 
Originally Posted By: xxch4osxx
Mine has the G80 and it will make popping noises when the locker is engaging and disingaging. Nothing to worry about. I am running Amsoil Severe Gear 75w90 in mine with no additives.


Same here. I think it's just the nature of the G80 design to make noise when engaging. I have had Amsoil Severe Gear 75W90 in the rear axle of my 2014 Sierra for about 10,000 mils now and it has been working just fine.

Here is a video show how the G80 works: https://www.youtube.com/watch?v=tTGZOJQQBeE
 
I have the G80 on my Trailblazer. It marginally makes noise when engaging but nothing serious. They dont spec (at least mine) for any friction modifiers, but many fluids already come with them and it doesnt hurt. I run Amsoil 75w90 in mine and it is no different then with the FF.
 
Status
Not open for further replies.
Back
Top