View Full Version : 2010 Sierra. Rear diff is done at 46,000 km - 28,000 miles

12-12-10, 10:04 PM
My dad's '03 Sierra. Bought used, 249,000kms on it. LSD (G80 optioned) didn't work since we had it. Spider gears started to grind the night I bought my dog, Bandit, last January. Replaced with a nice Eaton LSD - much stronger unit. No problems since, and very nice lock-up action when you need it.

I got stuck in the snow today, threw it in 4x and carefully spun my way out. Now it's making clunking noises from the rear end area driving forward.

I've always loved GM products but are their 1/2 ton rear axles weak? I'm not one of those guys that goes burning rubber around corners or spins on ice and then hits pavement- I know how bad that is for driveline components. But seriously, with this mileage on the odometer?

I guess I'll be calling GM in the morning to get this fixed- I hope warranty covers this, if not, I'll be swapping in another Eaton LSD -

12-12-10, 10:06 PM
Anyone else had experiences like this with their Chevy's or GMC's?

12-12-10, 10:13 PM
Haven't seen nor heard of anything. I've done a few u-joints on the '99+'s, but never had to actually open up/replace the rear end.

12-12-10, 11:25 PM
That is very weird. Like Drew said, U-Joints aren't uncommon on these, but the whole differential isn't a part that gets worn out on these newer ones.

12-12-10, 11:27 PM
I find that rear ends on vehicles in general are an oft ignored weak-point. Maybe ignored isn't even the right word as you aren't expected to do anything to a diff that early. More like poor assembly to start with. I have replaced a rear end on a 2001 BMW 330i at around 35k, a 2003 Lincoln Navigator at around 55k, both for howling at the moon. Numerous Jeeps with various grinding and other fun noises at various mileages. And so on and so forth. Someone here along time ago who had a GMT800 Escalade, I forgot the guy's name but but he's a big Zaino distributor, found that the fluid level in the rear end was about a quart low FROM THE FACTORY. He apparently changes Diff fluid as soon as 3k after buying a new vehicle. The front diff on the 2002-2003 Escalade AWDs is notorious for going south, in 2004 they changed the front diff to Synthetic fluid and mostly solved the issue.

The precision involved in a rear end is pretty crazy, and it only takes a small degree out of tolerance for them to start wearing down and making noise. Differentials are probably the one thing I've had less luck with than N* engines.

12-12-10, 11:37 PM
A 4WD 1/2ton pickup with a snow plow won't last one winter around here. It's the transmission, the transfer case, or a differential every winter. 3/4 ton is minimum if you're going to be doing anything beside hauling a few bags of groceries.

12-13-10, 02:34 AM
I've had problems on my old 1999 Z28, automatic, LS1, notoriously weak 7.5" 10 bolt rear. Yeah its the same rear end they use on 2wd S10 trucks, for some reason 4wd S10 trucks get a bigger rear than an LS1 car with 340hp stock.

That thing made a slight clunk when turning left at low speeds. Did it the whole time I owned it from 40k-120k, never got better or worse, posi always worked. I was prepared for the rear end to grenade at any time when I owned that car, never did oddly enough, and I gave it many reasons to blow up. Ended up blowing the tranny though.

Also, just a little rant here, but WTF was with Cadillac not offering a posi rear end on any of their RWD models??? I spun out two times today going up a hill, had to turn around and try it again, and it snowed about 3" inches. I mean you could get a posi in a Chevy or Buick, but not a Cadillac.:ripped:

12-13-10, 07:38 AM
G80 not an option in the old RWD Cadillacs? :(

I'll be calling my selling dealer soon to see what they can do about this. Also yesterday when I had it in reverse, it would not take the gear (first time ever) and the whole time I've owned the truck, under WOT acceleration, every now and then it will get stuck in 3rd gear and I'll have to feather the throttle to get it to upshift. I've mentioned that to them but it's only every now and then, and with my luck, dealership will test drive, and it'll work fine-

I love the truck otherwise - no complaints - the 5.3 has plenty of towing power, (6000 lbs is what I usually tow), decent fuel economy even though it's not near what they stated, but the active fuel management isn't worth a darn. The only time it's in 4 cylinder mode is going down a hill. Not even straight highway at 55MPH will it be in 4 cyl mode-

12-13-10, 09:17 AM
Honestly I would've bought a 3/4 or 1 ton truck if you're towing 6000lbs. The 4l60e is a damn shitty transmission IMO, most LS1 fbody guys end up destroying it with normal "fbody" use(ie brake torquing, burnouts, etc). Same thing with truck use, IMO, I really wouldn't buy a 1/2 ton truck if I planned to tow more than 3000lbs. The 4l80e in the 3/4 and 1 ton gas models is just a 100x more durable transmission, plus you get a much bigger 12 bolt rear end.

EDIT: And yeah, G80, or positrack rear end is not an option on ANY RWD Cadillac from 1990-1996. That shit really pisses me off, because a limited slip rear end makes a world of difference in snowy/icy conditions. Although I will say that there was a sheet of ice under that 2-3" of snow we got last night. I swear traction was a lot better when we got 6" of snow last year in January, there wasn't that polished sheet of ice on the road last year.

12-13-10, 10:58 AM
My Sierra has a 9,900 lb towing capacity and I expect it to live up to that on occasion :) This truck does not have the 4L60, it's the 6L?? (six speed). Most 1/2 ton 4x4's that I've owned in the past had a 4L80 anyways-

I honestly believe that a 1/2 ton should handle 6,000 lbs- I've towed 4,000 lbs behind old mid 80's GM B-bodys and never had a problem - but still, if the cost didn't jump so much I would have gotten a 3500 Duramax Dually -

My Parisienne had the 200-4R and that eventually lost partial use of 2nd gear (it would slip out under WOT) because I figured, if I'm going to replace my worn tires anyway, I may as well ensure they're completely bald first :D But that was a stock 200-4R behind a 403 Olds -

12-13-10, 06:18 PM
To clarify, the G80 RPO in RWD cars is completely different than G80 in GM trucks. G80 in trucks is a Gov-Lock unit. Open, until one wheel spins, then it locks. Nickname: Gov-Bomb, cause they like to explode from the shock of the sudden lockup. I didn't make up the name, google it and you will find lots of stories. I actually bought one once, but luckily learned about it before bothering to install it.

Here's what they look like:

And, here's why they get the nickname:

12-13-10, 06:23 PM
^ That picture belongs in the fail thread.

12-13-10, 06:24 PM
I'll be calling my selling dealer soon to see what they can do about this.

What? What do you mean "what they can do about this"? At 28,000 miles they damn well better fix it!

12-14-10, 07:49 AM
Well I took the truck into the dealer to have it diagnosed. The service manager drove it a bit and says it's completely normal- the sound of the governer engaging. It did not make the clunking sounds that it did the night before- and I'm not 100% convinced it's ok -

so I asked the dealer to do a front and rear diff fluid change (good to do anyways, with 28000 miles everything should be nicely broken in (or broken?))- and I asked the service manager to take the rear cover off (apparently it has a drain plug, didn't know that) and make a quick inspection of the gears and check for excessive wear or broken parts. Apparently all checks out.

I did not like the clunk sounds I heard the other night. The more I hear about this gov-bomb diff, makes me want to void my warranty and throw an Eaton LSD in place.... worked like a charm in my dad's '03 Sierra - and locks both rear wheels very quickly. I couldn't be happier with that setup.

I hope I can trust this truck right now. I have to be in a certain place at a certain time and if this new truck lets me down I'll be in deep ________. I have faith in GM but some sounds are warning signs -

12-14-10, 01:42 PM
Around here both Lock-Right and Detroit Locker differentials are very popular. Both make loud clicking noises when turning at low speeds but this just means they are doing their job.