Feels like its in the rear end only happens when taking off from a stop - I just bought a 04 Silverado Z71 it has 120000 miles on it. It ...

I just bought a 04 Silverado Z71 it has 120000 miles on it. It is in great shape, but I have noticed this noise coming from what sounds like and feels like the rear end area. It only happens when I am takin off from a stop. If I take off real slow it wont happen or if i take off fast its not as bad. It kinda feels like I can feel somthing moving. I have felt for play in the u joints, and they are tight, but doesnt mean that they are dryed and stuck. Any sugestion for the new owner?

Thanks for reading
Ryan

Have you checked to see if the rear end gears have excessive play? Sometimes a sticking slip yoke could cause similar symptoms. They had a TSB that replaced the slip yoke with a nickle lined on for that year truck I believe.

I had a problem close to this and what it ended up being is that i needed to grease the spline shaft on my drive shaft. When stoping some of these trucks torque a little and when you go to take off it almost feels like someone tapped your rear end, im not sure what the specific grease it is because the stealership did it for free under warranty. I have found a few post online outlineing the problem. Just drop your rear drive shaft pull it out and grease that puppy up ... worst comes to worst that part wont rust .... best case you dont have anything broken and can spend your money on better things

^^^^ that's the cheap fix for a sticking slip yoke. It will usually correct the problem for a while. Just make sure you do not use a lot of grease and are sure to coat all the way around the shaft.

Note-You should not use grease on the slip joint on 4x4 vehicles, only use ATF.

There is no seal in the transfer case that will prevent the greases from migrating into the transfer case and mixing with the special AutoTrac II fluid. The seal is only to keep fluid out, not out. If grease gets to the transfer case clutches it can problems.

I have the same clunking noise but when I tracked the noise down it's coming from inside the rear end. I took the back cover off and noticed a lot of play and the clunking noise in the area of the spider gears. How much play should be in the spider gears and are there supposed to be any shims on them? I checked the play in the ring and pinion ans it's good.

There should not be much play in the spider gears at all. The spider gears that have the pin going through them usually have a shim behind them. They are not offered in different sizes, like a preload shim though. Spider gears are pretty east to install. There is not adjustment to them, just pull out the old ones and put in the new ones. I guess someone could have left the shims out I mentioned and that would cause excess play. Any time I have replaced spider gears, the new ones came with the shims that go behind them.

Thanks Aste25,
I did notice that it still has the shims installed but the spider gears have way to much play in them. They must just be worn out with 180,000 miles on them. Would I need to remove the carrier Assembly to remove them or can they be removed while still in the housing? This is a Z71 with limited slip diff.

Thanks

I just read the post below from the web site of east Coast Gear Supply, Anyone here have an opinion on this?

GM 10 Bolt 8.6 Spider Gears, Spider Gear Kit
**G80 Code indicates Factory Positraction, Spider gear replacement for G80 Gov Lock are not available and should not be replaced, The Gov Lock is a ticking time bomb and needs to be replaced with either an open carrier or a quality positraction**
**1999 and Up GM, Chevy Ten bolts do not have 10 bolt 8.5 rear-ends, rather they have GM 10 Bolt 8.6 There are 2 Spider gear Options for the 8.6. In 99 and early 2000 some carriers had 2 large windows, where as the 2000 and Up Carriers have one small window and one Large window** **See picture to determine your carrier**

Fyi

All Trucks
G80 Differential, heavy-duty automatic locking rear

All Cars
G80 Differential, limited slip (aka Posi)


If you are jumping on the gas a lot or taking corners fast and furious then the G80 locker is going to make a "banging" noise because it is mechanically activated when the difference in speed between the 2 rear wheels exceed 100 rpm. Its a fact that drivers who have never had a G80 prior will be concerned about the noise, which in most instances is normal.