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Rear differential locking?

DocWinter

Full Member
Joined
Jan 21, 2016
Messages
36
Location
Southern Colorado
2007.5 Chevy Avalanche 5.3 4wd 160k miles,                        SPI says G80 Diff.

The problems started about a week and a half ago when I noticed that when I started my truck and pulled out of my parking spot ( a good sharp 90-degree turn ) my rear diff would act as if they were locked and kind of skirt or chirp my wheels and after either straightening out or continuing to turn there would be a noticeable pop or bang. Well, it didn't take long for that issue to worry my and I read online that bad gear oil can sometimes cause it to lock up.

So that day I went out, bought a gasket, gasket sealant, a pump, 3.QT's of gear oil and some lock stop/diff additive and replaced the oil. No smoking guns really. Oil looked as you would expect from a 160k miles truck, no metal shavings stuck to the magnet. ( side note: remove, and replace the fill plug BEFORE removal, it was ON THERE TIGHT) It took about 2.1 QT of gear oil before it started to come out of the fill hole. I take it for a spin real quick to see if there are instant results and from what I can tell it improved.

Used Lucas Gear Oil 75w-90 and a Bottle of differential additive

Well, a few days have gone by and I honestly, don't see an improvement. its still doing it and maybe its just me but my truck feels kind of slugish too.

As usual, any and all advice is wanted. thank you in advance.


EDIT:  :B: :B: Thank you for all the advice. My diff exploded the next day, currently being replaced  :B: :B:
 
You aren't supposed to add the additive with these diffs.
 
Might have broken G80 locker parts inside differential
 
ygmn said:
Might have broken G80 locker parts inside differential


Yea that's what it sounds like. The G80 good for traction at low speeds but can't take a lot of abuse so if any high revving is done they can break/strip the locking gear and mechanism. Not saying he abused it..


Should have pulled the cover when you drained it for an inspection..
 
How about a front axle that is staying locked in. That will do what you say and is much more likely.

Jack up (just) the right front wheel off the ground and make sure you can easily spin it with the engine started and trans in park.
 
2004Slickside said:
How about a front axle that is staying locked in. That will do what you say and is much more likely.

Jack up (just) the right front wheel off the ground and make sure you can easily spin it with the engine started and trans in park.
Randy said:
Yea that's what it sounds like. The G80 good for traction at low speeds but can't take a lot of abuse so if any high revving is done they can break/strip the locking gear and mechanism. Not saying he abused it..


Should have pulled the cover when you drained it for an inspection..
ygmn said:
Might have broken G80 locker parts inside differential
enoniam said:
You aren't supposed to add the additive with these diffs.

I want to thank everyone who posted but it's unfortunately too late. At approx. 0452 driving straight down my road to work, I heard a bang, and a grind and what sounded like my pinion gear slipping... my diff is no more. It's sitting at the dealership right now waiting for an insurance inspector to tell me I'm f#*%$!ed out of three grand. Insurance or not ill pay it. and ill keep paying it. whatever it take to get my baby back on the road. It's like a knife to the chest. Just like when my tranny went (Gear slippage, metal shavings like a machine shop in the pan). Just like when my engine went (lifter valve somehow came apart and just f#*%$!ed the whole crank). I know it looks bad like I abuse my truck when nothing could be further from the truth. Just a take a shot for the diff. that was, for me. I definitely feel like poop.

https://drive.google.com/open?id=0B8rPVh4E_HY6OEFPbEtoRHhUTm8

https://drive.google.com/open?id=0B8rPVh4E_HY6OE1teXVuUVJYbGc

https://drive.google.com/open?id=0B8rPVh4E_HY6V1JYaExUdWdtTTA

Thanks,
 
I know a lot of folks opt for a tru-track instead of replacing it with another G80.  Something to consider.
 
The Eaton Detroit Truetrac Locker is a lot stronger than the G80 AKA grenade at 80k


I guess I should explain a little better, the G80 has weights that spring out to lock the diff( at speed)

The truetrac locks gradually.

When mine locks it sounds like a gunshot, you hear a big thud and start to look around thinking WTF was that.
 

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I knew MS03 2500 would chime in.  He's the best at explaining these things.  (y)
 
MS03 2500 said:
The Eaton Detroit Truetrac Locker is a lot stronger than the G80 AKA grenade at 80k


I guess I should explain a little better, the G80 has weights that spring out to lock the diff( at speed)

The truetrac locks gradually.

When mine locks it sounds like a gunshot, you hear a big thud and start to look around thinking WTF was that.

Ha, my G80 used to sound like that too. I will definitely look into this, thanks!
 
I spoke with the Eaton folks at their booth at the Hot Rod Power Tour a few years ago where they had cut-out display models of their various diffs on display.  The Tru-track is definitely their top of the line for street performance, and does pretty well off-road too.  I told them I had just replaced the G80 in my truck after about 200k miles - they were surprised it had lasted that long!  I've been very happy with it in snow and on the dragstrip.
 
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