07 Tahoe - occasional Bucking feel when in AWD in Snow

George B

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Thinking out loud...
Almost seems to me like the locker in the real axle is locking and then unlocking if this has RPO G80. Is the thump occurring shortly after a turn where you may have spun a rear tire? Does it also do it in 2wd in the snow of is this an unknown?
 

okfoz

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It does not do it in a turn, It has always happened on the highway at a constant speed, anywhere between 45 and 65 mph. I have not noticed it at a lower speed. It has never done it in 2WD mode, more or less, while in the snow it is almost always in AUTO or 4WD, I have driven it in 2WD in the snow, but not often, and it has never done the jerk in 2WD.

Now I think about it, I believe the issue started after I had the rear axle bearings replaced because I was getting a Waa --- Waa --- Waa noise.
 

George B

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It does not do it in a turn, It has always happened on the highway at a constant speed, anywhere between 45 and 65 mph. I have not noticed it at a lower speed. It has never done it in 2WD mode, more or less, while in the snow it is almost always in AUTO or 4WD, I have driven it in 2WD in the snow, but not often, and it has never done the jerk in 2WD.

Now I think about it, I believe the issue started after I had the rear axle bearings replaced because I was getting a Waa --- Waa --- Waa noise.
Thanks, then we can take that off the table.

Next I wonder if the slip yolk in the rear of the T case for the read drive shaft is binding. Just looking at previously touched parts. That is related to rear axle work.
 

okfoz

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Thanks, then we can take that off the table.

Next I wonder if the slip yolk in the rear of the T case for the read drive shaft is binding. Just looking at previously touched parts. That is related to rear axle work.
The rear axle might be the culprit. Today I was in 2WD, I had to wait for a semi to turn down the road I was on, and I was stopped on some ice. once the Semi was out of my way I accelerated and I felt the rear slip a little, and I got the same clunk sound and a jerk forward.
I almost wonder if it is as simple as changing the diff fluid.
 

George B

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The rear axle might be the culprit. Today I was in 2WD, I had to wait for a semi to turn down the road I was on, and I was stopped on some ice. once the Semi was out of my way I accelerated and I felt the rear slip a little, and I got the same clunk sound and a jerk forward.
I almost wonder if it is as simple as changing the diff fluid.
Worth a shot. Do you see RPO G80 on the sticker in the glove box?
 

Bill 1960

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If you slipped on ice, and the G80 clunked and locked, that is normal.

It’s a red herring IMO; nothing about cruising straight at highway speeds will cause the diff to lock.
 

George B

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The rear axle might be the culprit. Today I was in 2WD, I had to wait for a semi to turn down the road I was on, and I was stopped on some ice. once the Semi was out of my way I accelerated and I felt the rear slip a little, and I got the same clunk sound and a jerk forward.
I almost wonder if it is as simple as changing the diff fluid.

Worth a shot. Do you see RPO G80 on the sticker in the glove box?

Indeed it does have G80...
What You might have felt was the rear locker engaging when you spun on the ice. I asked because I have had my locker engage and then remain locked only to disengage later. The scenario doesn’t match your at speed clunk but these lockers are supposed to disengage at a certain MPH. I was postulating that in the snow and in 4hi or 4auto you would spun a front and rear and then the rear axle would lock. Then remain locked until you reached the unlock speed.

It’s a guess.
 

okfoz

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Ok, if I understand, the low speed clunk I experienced today is probably not related... Hmm.

I was really hoping that someone could say, "My truck was doing this and it was part x."
 

MikeW

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My 02 with 350K (and 6.0L) started doing this "bucking" 2 weeks ago..... took it to a transmission place and found out it was not the trans but rear differential gears were tore up/wiped - in some places worn very smooth... ended up getting replacement from junk yard (with on 100K) was half the cost than rebuilding.....
 

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