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2002 gmc envoy_slt
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Discussion Starter · #1 ·
I don't know if this is the right place to post this. I've tried to search and research but haven't found what I'm looking for.

My wife is the primary driver of our Envoy, and for the past several weeks she's been trying to get me to look into a noise it's making. It's not really a grinding, but it's a kind of vibratey noise (not a vibration that you can feel, just one you can hear) that pulses and the pulses get faster and closer together as wheel speed increases.

I thought it was coming from the rear end so my cousin and I pulled each wheel off and ran it up on a lift. With no weight on the wheels there is no noise. We pulled the drive shaft and turned the wheels and the pinion. There is some roughness in the pinion. It has the G80 locker.

Does the pinion bearing seem like a likely culprit?

My next question will be: How difficult is that to work on? We have access to every kind of tool we could need, but we've never had a G80 rear end open before. Is it different from working on a standard open diff?
 

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2006 chevy trailblazer_lt
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Just some thoughts--I haven't had a G80 apart, though there are pics in other threads: Search for G80 and G80 locker.

Anyway, I had a pinion bearing go bad on my 03 Envoy. It started with a whine in the rear end that got progressively louder and louder. When I finally investigated, you could actually move the differential yoke up and down a bit, but still no leaking fluid!!

If you can feel roughness, then I strongly suspect that is the culprit. On front hub bearings, they will make noise with weight on them, but when you take them out, you usually can't feel any roughness in them. Now, the pinion bearing isn't loaded like the hub bearing, so you won't get the same noise or the same feel. Like I said, I would strongly suspect the pinion bearing. There should not be any roughness.

Finally, no reason not to remove the rear cover. You won't hurt anything, and you can peer in and look around and poke around (with clean tools). You will see that except for the locker mechanism, it looks very much like an open differential.

You might also look at the magnet on the cover (I believe it has one) to see how much metal it has caught. That will be another indication that metal somewhere has worn to the point of causing noise.

If all else fails, drive if a few months more. If it ain't broke enough to find, it ain't broke enough to fix!
 

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2002 gmc envoy_slt
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Discussion Starter · #3 ·
OK, I took it down to a shop to get a second opinion. We put it up on a hoist and with it in 4wd I ran it while he listened to all the wheel bearings with a stethiscope. He said it sounded like the front wheel bearings were both going out. He's a friend of mine so I trust him and he had no reason to mislead me because he knew I wasn't going to have him fix it.

So now I guess I'll buy new wheel hub assemblies for the front. Any recomendations for good brands? At one site I looked at to order them they had one Dorman hub assembly for like $68 and another of the same brand for $215. Any ideas why the difference in price?
 

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2006 chevy trailblazer_lt
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I put an AC Delco obtained from Rock Auto in my '03 Envoy.

Others have had good success with Timken bearings, which are a bit cheaper.

General consensus is to avoid the cheap bearings found on eBay, as they are typically made overseas and the quality is suspect, as some who have installed them did not get good life from them. Others had no problem.

For the amount of work involved, I'd spend the extra hundred bucks or so and buy and install an American made bearing.

Just my :m2:
 

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Discussion Starter · #5 ·
I ended up ordering 2 Dorman wheel hub assemblies online from autopartswarehouse.com

Anybody have any experiance with that brand? It seemed like a hella good deal. The were listing the original price as like $3XX (don't remember exactly) and I bought them for $68 (free shipping) and they had another set of Dormans on there for like $4XX. For the orignal price it seems like they ought to be good quality. I hope I didn't just get scammed.
 

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2004 chevy trailblazer_lt
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Hi I was wondering how the Dorman wheel hubs worked out on the Envoy? My 2004 TB needs the passenger side replaced asap and I want to do both sides before long. I want to buy American but they are twice the price of the Dormans and that is a little tough 3 weeks before Xmas! I did install a Dorman fan clutch and it is working well. Any insight would be appreciated, thanks guys for a great forum! :tiphat
 
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