1996 tahoe Differential Problem?

1996 CHEVROLET TAHOE
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GILBERT011
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My vehicle recently started to make a loud thud when I stop and accelerate. Sometimes it does it real loud then sometimes if I am carefull with braking it does not do it. I took everything out of the tahoe to make it was not a tool inside rolling around in the truck. I checked my spare to see if it was secured on tight.
I noticed it started after I pulled a 16ft. trailer with only landscape debris. I checked the fluid in the differential. I have checked all the motor mounts and transmission mounts. The u-joint look okay, but do have a little bit of play when I put it in neutral and twist the shaft. I did notice that there was some play in the axle shaft when I check my brakes and tires. How much play should there be?

My transmissions shifts fine, and it does not make the thud noise when i put it in reverse. I have put the truck on a lift and had it running to see if I can see the transmission or motor shifting from bad mounts, but everything looks solid. The only thing I noticed on the tranny is area where the drive shaft inserts into the tranny is a bit wet, not to the point where it creates a puddle of oil. Any help Please.

Gilbert
Odessa,TX
Sep 21, 2007 at 10:19 AM
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WRENCH
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A lot of the time when you here a thud or clunk in the driveline its the u-joints since you said there was some play in the u-joints there should be none. There will be some play in the differential not a lot but some. You need to take a closer look at your u-joints since that sounds like it and is easy enough to get at.
Sep 21, 2007 at 10:49 AM
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GILBERT011
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Looks like the problem has been fixed. What ended up happening was I removed the drive shaft with yoke, I started to remove it when I realized I was short on time, so the only thing I could do was to give it a couple of hits with a pin and hammer and inspect the seal and boot where the yoke inserts into the tranny. Well I put everything back in its place and made sure everything was tight. Then I went for a test drive just to make sure I didn't goof anything up, and there it was, I don't know exactly what I did but I have no more thud noise and it stops fine, no shimmy or rattles. Weird!!

I am still going to take it to a mechanic so they can do a better inspection and still switch out the u-joints, and also the seal, since I noticed it was wet with tranny fluid. I was told that these u-joints were injected with some plastic from the factory, and they said they need to be heated up so the plastic can melt, then you can remove them and put the new u-joints in place.
I spoke with a GM parts specialist from a local dealer and they said that was right GM does do that.

I was just always used to the old school type like on the 79 and older chevy's.
Sep 24, 2007 at 8:45 AM
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8052ROYC
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I had the same problem on my 1999 Tahoe.
Cure:- Remove prop shafts, (front & rear) and grease the splines, replace them and it should be OK.
What happens is that the splines sticks, then when it releases it makes a loud clunck.
Nov 16, 2007 at 3:59 PM
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GILBERT011
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well this week the rear u-joint completly broke off my driveshaft. I don't know what exactly went wrong but it almost did a number on my trans. But fortunantly I only needed a new u-joint. I had a driveline company rebalance, and check everything make sure it was good, and installed a new u-joint. Then I took it to a transmission shop and they checked it out. They gave me the good news and said nothing was wrong, just low on fluid, they installed driveshaft and test drove. Gave the trans. a once over. And the total damage was 76.00 at the trans. shop, and 56.00 for the driveline place. I seriously thought I had done some major damage. Everything looks good so far. Thanks guys for all responses.
Nov 23, 2007 at 12:12 AM