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Noise in rear end when turning at low speed

11K views 26 replies 9 participants last post by  pb3 
#1 ·
I've got a 2000 AWD Safari, about a month ago the rear end (limited slip)started making noise when turning at slow speed. Like rubbing or grinding. If you are going maybe 10 or 15 MPH the problem disappears.
I stopped in at a dealer and they said to replace the fluid with their special Grape scented synthetic GM fluid, and if that doesn't work the first time, do it again. They also said $35 per Quart. I went to the Auto parts store and bought 2 Quarts of Valvoline full synthetic 75/90 for $10 a quart, drove the van for a few hundred miles, no significant improvement. Went to another dealer, and got the same recommendation, in fact they said sometimes it takes 3 times before it works.
They say they are familiar with this problem.....
Anyone here know about this?
 
#2 ·
I new to Astro/safari posi but I have dealt with the rest of the rear wheel drive GM line with posi.When you add fluid there a posi additive you put in as well or it will slip to much and burn clutches.ASSUMEing all else being same.I am sure there is supposed to be additive tho.For the noise I would check the bearings for wear.If I not in the know about something somebody be along soon with that info
 
#4 ·
What dealers are telling you to change the fluid repeatedly? We could not get away with that up here!

Sometimes, the clutches will get dry because of centrifugal(sp) force, esp after driving for extended periods on the highway, and will make noise.
The no-dollar fix is to find a big empty parking lot, and drive in tight circles(steering in full lock) to the left and then to the right. About a dozen circles each way. This will work the gear oil into the clutches.
It may not fix your problem, but the price is right!
 
#5 ·
I also had this problem when I clicked 30,000 miles. It was random at first, and then became near regular at low speeds. Mine was more of a thud like it was shifting gears around the 10-15 mph mark. Once accelerated over 15 mph, van ran smooth as butter with absolutely no noise.

Again, my noise was a deep thud and didn't hear any grinding. Sounded more like a broken down CV joint on a front wheel drive car.

I took the van to the local Chevrolet dealership to get their take. They concluded that the transfer case between the tranny & rear differential needed the oil flushed out. And that oil was a high cost item along with the procedure. I believe they flushed it 2X. I don't recall them saying it was the "Grape" scented type.

The outcome was that iIT DID fix my noise issue, although I had serious doubts the flushes would fix it. I paid around around $150 for some type of deductible with warranty work. Now sitting around 66K, I've hear the thudding noise once, and that was last week during fluctuating temperature drops. If the noise starts to become regular, I'll probably suck up the costs and let them do it--as much as I don't like anyone else working on my van.

You stated you heard grinding, so your issue may not be the same as mine. Does the dealership know that? Maybe they can have their mechanic to test ride your van to suggest what the problem may be and isolate the transfer case or differential as the problem area.

I may still have my receipt that details the work they did if you're interested. It should the type off oil used, labor fees, etc. Let me know.
 
#6 ·
I'm in Connecticut, two different dealers said the same thing. GTKane, what you said makes sense. You drain it and put 3.6 pints or whatever including the additive, what's going to happen to that fluid? Does it go bad, or get contaminated?
I figured it's got to get in to the clutch plates. I didn't know that they can get dry, but that makes sense. It drags and moans pretty good when you turn the wheel. I've tried driving faster on curvy roads, hoping the lube will get in there, but I've been trying not to push my luck- lots of three point turns when parking.

Rags-The fluid for the transfer case is Auto Trak II, and it solves a lot of problems. Its blue in color but not scented that I've noticed. It's about $10 a quart. The Grape thing is just for the rear end. Mine doesn't thud, it almost sounds and feels like the tire is rubbing on something as you turn.

Maybe I'll spring for the GM fluids and then try the parking lot maneuver GTKane recommended.
Thanks for the posts!
 
#7 ·
Does anyone have a part number for the grape scented additive? I would like to look into this more , years ago the additive was a deep red color and made from whale oil , but I have heard that they don't use that anymore , i 'm curious what the new additive is , is it synthetic or what?
 
#8 ·
2HB, where in CT are you from? I'm from CT and have an AWD safari myself.
 
#9 ·
The Grape stuff is Synthetic Gear Oil. The additive is unscented as far as I know. When I get some I can post the #'s
Philly- I'm in Hartford. I see you are in Bridgeport. I used to drive through there all the time, but not so much these days.
 
#10 ·
2 H.B. said:
The Grape stuff is Synthetic Gear Oil. The additive is unscented as far as I know. When I get some I can post the #'s
Philly- I'm in Hartford. I see you are in Bridgeport. I used to drive through there all the time, but not so much these days.
And I'm from West Simsbury. I only get back up there about once a year, though.
 
#12 ·
Thanks for the replies, I took the weekend off! West Simsbury...is that where Tulmeadow Farms is? That's a pretty nice area, still a lot of woods and wildlife.
As for the van, it is supposed to push both wheels, that is true, but it never grunted and groaned before, put it that way. It sounds really nasty. The description of the clutch plates drying out seems to fit, but driving in tight circles hasn't fixed it, unfortunately.
I put in the GM synthetic kool-aid and additive, and I've put about 300 miles on it since.
I almost want to change the fluid to some super low viscosity oil- no limited slip additive- just to get something to penetrate and lube things up. I think I'd rather have it slipping, and then go back to the recommended stuff to fix that.
On the other hand,Is there some way to manually get at the plates with the cover off, without taking all the gears out?
 
#13 ·
2 H.B. said:
Thanks for the replies, I took the weekend off! West Simsbury...is that where Tulmeadow Farms is? That's a pretty nice area, still a lot of woods and wildlife.
Yup. I grew up playing in their pastures...winter and summer. They make THE BEST ice cream around - fruit is all from their orchard, cream from their cows....it's awesome.

For a pic of my Bravada's limited slip diff, 3.73 gears, with the cover off, if that helps:

 
#15 ·
The insides interchange, but the offset is different. The Astro's offset is one-of-a-kind.

My Astro does not have a G80 but is also 3.73. I haven't pulled the cover to look at that one yet.
 
#18 ·
I didn't disassemble it any further since I didn't need to, so I'm not sure about getting fluids into the clutches directly. If no one else answers in the meantime, I'll find the applicable pages in the service manual when I can get to them.
 
#19 ·
Thanks so much, I guess you're talking about a GM manual. The Haynes doesn't really get into it.
I took a walk out in those fields with my wife about a month ago, and I noticed 2 or 3 Astros or Safaris here and there, I forgot about that until just now, but I remember thinking they have good taste in vans at Tulmeadow Farms.
 
#20 ·
Well, for a while it wasn't getting any worse, but I'm not sure that's true anymore. It just seems to be locked now at slow speeds, so it's hopping and jerking around, and I'm sure it puts a lot of stress on the rest of the drivetrain.
Is there a way to just disable the clutch mechanism that anyone knows of? It still works fine as long as I'm over 15 MPH.
Thanks
 
#21 ·
Ok, I'm no expert, but Heres what I have been thinking, And I had a g80 Grenade that made noise and then eventually locked like you, and then eventually after I got stuck in a snowy nightmare, It wouldnt lock at all anymore.
It still drives fine, but has no LS at all, I've pulled it outta the van for spare parts now.

Anyways, in my reading, I heard that the weakest link in these G80 is a small pin. I saw pix of the pin, but dont have the link anymore.
If I recal, it might have the pivoting thing on it, or it might have been some other pin, it was a long time ago. Anyways, they work out of their hole, and eventually wear or break and the thing fails.
During the wearing out period, you'll hear noises from the diff and it wont corner slowly well at all, I guess cuz the pivoting locking thingamabobber isnt doing as it should.
I remember the picture from that thread showing a pin with a knurled end that had wiggled out of its hole just a bit.
Heyfound a quik pic for ya, I think its #11.

Maybe your problem? maybe not, but my :2:
 
#22 ·
There's a thing that's visible in LeeAnn's photo, that looks like the #11 in the diagram. I remember when I had the cover off I could move it to the right and it had a spring that pushed it back to the left. It's like a 1" cylinder with a cutaway so you can see the spring etc inside it. Kind of in the middle of the photo, just a little higher than center. Is that it?
It sounds like yours just lost the LS and kept working otherwise? That would work for me! Mine will probably blow up instead. Was yours AWD?
The snow here has helped me out, It makes the problem go away, pretty much.
 
#23 ·
That G80 of mine was not witn an awd.
The one in my awd never ever gave me any grief.

Ya the thing on the pin, pivots and makes the diff lock.
Seems that pin can bend, come loose or break.
Loose or bent will make it sticky and not work well.
Broken, well, thats just broken,end of story.

Speaking of broken, dont spin your tire is you get a bit stuck in the sno, it could mean the end of your G80, just like mine.
 
#26 ·
Here's am update, if anyone's interested.
I talked to a guy in a local tranny shop, and he said get the stuff from the dealer and do it repeatedly if necessary.

Anyway, what I did after about 1000 miles of no improvement with the GM fluid, was tip the van a little to the left and put a little extra fluid in, since I had about 8 ounces or so left over. I just couldn't bring myself to spend another $80 on fluid, and I figured the extra might help as long as I stayed off the highway. Amazingly enough, it seems to have made a difference, even though the problem isn't gone, it's definitely getting better, now I'm looking for sharp low speed turns instead of avoiding them.

Fortunately, I don't have any highway driving I need to do right now, I'll let it drain on a flat spot to get the level right before I go on any trips.

Thanks for all the help!
 
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