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Discussion Starter #1
A few months ago, I would take off and my driveshaft would spin but the truck wouldn't move. And then after a few seconds, it would lock in and really jerk forward. I recently changed the rear end oil hoping that would solve it.

Well, it helped until yesterday.

I was cruising on the highway 65-70 mph and had to slow down for a traffic light. I came to a stop at the light, but there was this horrible loud noise eventhough I was stopped. It did this for about 5 seconds, and then all of a sudden the rear end locked in and made a loud noise and jerked the truck forward and I initially thought the car behind me tapped me.

A little later, I was in the median turning left and I hit the gas but the shaft just spun again and then it locked in after about 2 seconds and jerked me forward.

I'm fixing to take it in to the dealer and see if they can figure it out.

Can anyone give me any ideas?


The dealer drove it and couldn't feel or hear anything. Well no ****, I told them that it doesn't do this but maybe once a week.

Most mechanics I've talked to say if it were broken gears, you would feel it and hear it more often. They mentioned some kind of plates in the posi-trac that aren't working right and that I should try to change the rear oil again with oil from the dealer and add an additive called E-oil or something like that.

Does anyone think it could be related to a bad u-joint or yoke?

I've also been hearing a clicking noise sometimes but thought that was just a rock in my tire.

I've also heard howling but thought that was just my mud grip tires.

I plan on taking the rear end cover off soon.
 

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This almost seems like a transmission issue not a differential/rear-end issue. Have you checked your fluid level in the transmission? When was the last time you serviced the transmission? I guess it could be your limited-slip unit, but if that was screwed up you would still just be driving normal. Well, without being there I can't accurately diagnose any problem, but look at your transmission as a suspect as well.
 

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I miss you little guy
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If the driveshaft were spinning that would mean the transmission is working though.....maybe something is coming loose on the inside and is getting thrown back into place once you get the momentum of the drivetrain up.
 

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Do you have the Gov-Lock(RPO code g80)? They can act funny when they are on their way out. I would pull the diff cover and see if your fluid has metal shavings and whatnot in it.
:read: Its just a gasket away to know if its the rear.
 

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I would be willing to bet its going to be a transmission problem. For one if it were in the diff it would be an issue way more often, and probably occuring all the time. know are you sure the driveshaft was spinning (how odd), please keep us informed on whats going on.
 

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Discussion Starter #7
Update....forget the part where I said the driveshaft was spinning cuz I don't know that for sure, it must've been something in the transfer case spinning that I heard.

Driving home from work Friday, my truck quit on me 3 times but I was able to make it home. Then Saturday morning as I was taking it in to the dealer, it gave out for good and had to be towed in.

You can give it gas and the engine will rev but the truck won't go forward and I can hear a noise under the cab. It almost sounds like a loose chain that is just rattling inside a housing, so if the transfer case is chain driven, then that could be it.
 

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Discussion Starter #8
Update...

Dealer called and found bits of metal in the transmission pan and recommends replacing tranny for $3400 with 3 year warranty or repairing it for an estimated $2400 with 1 year warranty.

Ridiculous...I'm calling Chevrolet customer service to tell them that there is no way a transmission goes out with only 49,000 miles on it.
 
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