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Oscillating grinding noise under truck

42K views 12 replies 9 participants last post by  iamtammi 
#1 ·
I have a 1997 K1500 Z71, it has 92,000 on it. I have a grinding/rubbing noise that seems to be coming from the front passage side. The sound oscillates like a warped brake rotor. It does not do it all the time. If the truck is cold, it will start at approximately 25mph and will speed up with the increase in vehicle speed. After the truck has been driven for approximately 10-15 miles at highway speeds, when I get in town, it will do it when I hit bumps. I have changed the following parts on both sides in the front: axles(CV), brake rotors, calipers, brake pads, and hub assembly. It shifts in and out of 4HI, 4LO, and 2HI fine. Any help would be greatly appreciated.
 
#2 ·
Only rotating part that you haven't checked or changed is the right hhand output shaft of the front axle assembly. there is a bearing in the end of the tube that the shaft journal rides on, and it may be worn, or the shaft journal itself. best way to check is to unbolt halfshaft flange from the output shaft flange, and then try to move output shaft up and down. Should have very little movement in shaft. If that is the problem, can be repaired by replacing bearing and seal on the tube.
 
#4 ·
I had that part go bad on my 2000 silverado. It was the drivers side though. When I went around a hard turn and there was a lot of load on the drivers side, it was quiet. When I went around a turn the other way, and it unloaded the drivers side, it would make a grinding noise. I jacked the front end up and could actually wiggle the wheel / tire, but it wasn't the tie rods or ball joints that were moving. It was the bearing that the end of the CV axel goes through before it passes through the hub. Easy fix.
 
#5 ·
I have the same problem on my '99 on the drivers side but it is not the hub bearing it is the differential end of the axle. I believe that is what the OP was describing on the passenger side.
I think, and I hope I am wrong, that you must disassemble the differential to service the bearing.
Some one please tell me I am wrong!
 
#6 ·
I also have this oscillating grinding noise under truck. It only occurs for me when in auto or 4hi and 4lo.
I put it on the stand and sounds like it is coming from Transfer Case. I replaced the fluid with the GM "liquid gold" (due to price $13.00 a quart!) Auto-Trak II T Case fluid and no change in noise. Noise eventually goes away when placed back in 2WD. Anyone else have this issue? Would sure like to know what it is and if it is a part that can be replaced or a new transfer case is in my immediate future?
 
#7 ·
I have a noise that is more of a knock that sounds like it's coming from the front left wheel area. When reversing it is more prominent, sort of knock knock knock as the wheel rotates. Doesn't seem so bad in forward but there is a rattle there when you go over bumps. Does this sound like the drive shaft too? Does the shaft turn when not in 4wd?
 
#8 ·
Time to play "stump the chumps!"

If this is doing this right after you hit a bump (and you changed most everything else that spins at wheel speed) perhaps you have a sticky shock tube. The suspension compresses on the bump, but doesn't return all the way and your tire may be rubbing.

Tell me, does the grinding go away after a short period of time?
 
#9 ·
like I said, it seems to be always there in reverse, almost sounds like something not meshing type of clunk clunk clunk, or even a drive shaft end flopping around as it spins.then when you go forward it sounds ok until you hit a bump but I can't be sure it is coming from exactly the same area. I will have to have a bit more of a look under the car I think. It's just that it's been raining so much here in Queensland Australia that trying to find a dry bit of lawn has been difficult.
 
#10 ·
Perhaps it's a loose tail pipe that occaisionally shifts position and rubs the drive shaft. Also check the shafts and u-joints for looseness. See if you can get a friend to run out along side to zero in on the noise.
 
#11 ·
I jacked up the front left first and rocked the wheel back and forth and there is a clunck transmitted to the front tail shaft. I jacked the right side and no noise. does this indicate that the bearing in the hub is grabing the front left drive shaft? There is no play in the shaft.
 
#12 ·
I have this same problem in my 03 Silverado. It makes a knocking noise whilr in reverse and turning the wheel to the left. There is a kind of grinding/whoping sound but only when turning the wheel to the left and only when the wheel is slightly turned to the left. It doesn't make the sound if the wheel is completely turned to the left but only when the wheel is turned slightly.
 
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