Driveline noise

gcook · July 1, 2005

I have a 2002 Z71 short wheel base Chevy pickup that makes a noise that sounds like worn out brake shoes while I am moving at speed. The noise is definately coming from the front differential. 2 dealers have heard the noise and they both say it is a normal noise, don't worry about it. I can hear this noise with the windows down when I'm traveling by buildings or guard rails or whatever. Can't hear it with the windows up. Since they say it is normal I was thinking of trying sythetic gear lube in the front differential. Does anyone think this would help to reduce the noise somewhat? I know synthetic helps my motorcycle shift much better, but I don't know about the synthetic gear lube. Any ideas?

thanks

shiden_kai · July 1, 2005

I have a 2002 Z71 short wheel base Chevy pickup that makes a noise that sounds like worn out brake shoes while I am moving at speed. The noise is definately coming from the front differential. 2 dealers have heard the noise and they both say it is a normal noise, don't worry about it. I can hear this noise with the windows down when I'm traveling by buildings or guard rails or whatever. Can't hear it with the windows up. Since they say it is normal I was thinking of trying sythetic gear lube in the front differential. Does anyone think this would help to reduce the noise somewhat? I know synthetic helps my motorcycle shift much better, but I don't know about the synthetic gear lube. Any ideas?

thanks

<{POST_SNAPBACK}>

Is the noise present in 2hi, 4hi....?

Ian

gcook · July 2, 2005

I have a 2002 Z71 short wheel base Chevy pickup that makes a noise that sounds like worn out brake shoes while I am moving at speed. The noise is definately coming from the front differential. 2 dealers have heard the noise and they both say it is a normal noise, don't worry about it. I can hear this noise with the windows down when I'm traveling by buildings or guard rails or whatever. Can't hear it with the windows up. Since they say it is normal I was thinking of trying sythetic gear lube in the front differential. Does anyone think this would help to reduce the noise somewhat? I know synthetic helps my motorcycle shift much better, but I don't know about the synthetic gear lube. Any ideas?

thanks

<{POST_SNAPBACK}>

Is the noise present in 2hi, 4hi....?

Ian

<{POST_SNAPBACK}>

gcook · July 2, 2005

I have a 2002 Z71 short wheel base Chevy pickup that makes a noise that sounds like worn out brake shoes while I am moving at speed. The noise is definately coming from the front differential. 2 dealers have heard the noise and they both say it is a normal noise, don't worry about it. I can hear this noise with the windows down when I'm traveling by buildings or guard rails or whatever. Can't hear it with the windows up. Since they say it is normal I was thinking of trying sythetic gear lube in the front differential. Does anyone think this would help to reduce the noise somewhat? I know synthetic helps my motorcycle shift much better, but I don't know about the synthetic gear lube. Any ideas?

thanks

<{POST_SNAPBACK}>

Is the noise present in 2hi, 4hi....?

Ian

<{POST_SNAPBACK}>

Ian, the dif makes the noise all the time you are moving in 2 or 4 wheel drive. Since this truck has push button 4WD, the front diff is turning all the time whether in 2 or 4WD. Sounds like metal on metal rub, but GM says it's normal. Technician said since the housing is aluminum, and the gears are cast, and the bearings are steel, these units will make this noise. I think that is a bunch of crap, but GM won't budge. Just thought I might try synthetic gear to see if it will help to quiet it down a bit.

gcook · July 2, 2005

I have a 2002 Z71 short wheel base Chevy pickup that makes a noise that sounds like worn out brake shoes while I am moving at speed. The noise is definately coming from the front differential. 2 dealers have heard the noise and they both say it is a normal noise, don't worry about it. I can hear this noise with the windows down when I'm traveling by buildings or guard rails or whatever. Can't hear it with the windows up. Since they say it is normal I was thinking of trying sythetic gear lube in the front differential. Does anyone think this would help to reduce the noise somewhat? I know synthetic helps my motorcycle shift much better, but I don't know about the synthetic gear lube. Any ideas?

thanks

<{POST_SNAPBACK}>

Is the noise present in 2hi, 4hi....?

Ian

<{POST_SNAPBACK}>

Ian, the dif makes the noise all the time you are moving in 2 or 4 wheel drive. Since this truck has push button 4WD, the front diff is turning all the time whether in 2 or 4WD. Sounds like metal on metal rub, but GM says it's normal. Technician said since the housing is aluminum, and the gears are cast, and the bearings are steel, these units will make this noise. I think that is a bunch of crap, but GM won't budge. Just thought I might try synthetic gear to see if it will help to quiet it down a bit.

shiden_kai · July 2, 2005

Ian, the dif makes the noise all the time you are moving in 2 or 4 wheel drive. Since this truck has push button 4WD, the front diff is turning all the time whether in 2 or 4WD. Sounds like metal on metal rub, but GM says it's normal. Technician said since the housing is aluminum, and the gears are cast, and the bearings are steel, these units will make this noise. I think that is a bunch of crap, but GM won't budge. Just thought I might try synthetic gear to see if it will help to quiet it down a bit.

<{POST_SNAPBACK}>

Even though the front diff is turning, it's not "engaged" in 2hi. Often you will

hear no noise in 2hi, but plenty once it's in 4hi. In any case, side bearing

failure is almost an epidemic on these trucks. Here is what I would do, pull

the front diff drain plug, it has a magnet on it. Take a look at the magnet,

if it has a ton of metal fuzz or actual metal pieces, you can be fairly sure

that a side bearing has gone south.

We overhaul these front diffs on a regular basis at our dealership.

But, I will say that some growling noise from the front diff/t/case can

be heard from trucks with perfectly good running gear. Most of the

time, this would occur in 4hi only.

Ian

JRW68 · July 2, 2005

Im not discrediting anyones judgment but are we sure its not the calipers not retracting the small amount that they should or warped rotors? I agree that diffs generally growl and if its an outer bearing, they tend to leak fluid soon there after.

Just my thoughts, good luck.

gcook · July 5, 2005

Im not discrediting anyones judgment but are we sure its not the calipers not retracting the small amount that they should or warped rotors? I agree that diffs generally growl and if its an outer bearing, they tend to leak fluid soon there after.

Just my thoughts, good luck.

<{POST_SNAPBACK}>

The noise is not brakes as I raised the rear wheels and ran the truck in 2 HI with the front wheels on the ground not turning. I have yet to drain the fluid and check for metal and was thinking of using synthetic fluid in the front diff. I really don't expect the synthetic fluid to make any difference, but I thought I might give it a try. GM is not going to do anything about it, so I guess I'll have to live with it or trade. I've read about some failures in these units and I'm just afraid that I may have one that will fail at an inconvenient time or place.

thanks

garyandtricia · October 23, 2005

Im not discrediting anyones judgment but are we sure its not the calipers not retracting the small amount that they should or warped rotors? I agree that diffs generally growl and if its an outer bearing, they tend to leak fluid soon there after.

Just my thoughts, good luck.

<{POST_SNAPBACK}>

The noise is not brakes as I raised the rear wheels and ran the truck in 2 HI with the front wheels on the ground not turning. I have yet to drain the fluid and check for metal and was thinking of using synthetic fluid in the front diff. I really don't expect the synthetic fluid to make any difference, but I thought I might give it a try. GM is not going to do anything about it, so I guess I'll have to live with it or trade. I've read about some failures in these units and I'm just afraid that I may have one that will fail at an inconvenient time or place.

thanks

<{POST_SNAPBACK}>

There is a problem wuth the transfer case causing the front diff bearings to wear. I have had three front diff replacements before they suppoesedly found that the transfer case was set up too tight. These trnsfer cases have clutch packs that are set up wrong, causing front pinion bearings to wear.

gcook · October 25, 2005

I'd like to know more about this transfer case clutch pack problem. My dealer says there is no problem with the truck. Some front differentials are just noisier than others. Mine is plenty noisy, sounds like metal rubbing metal that can be heard when passing buildings and such. Anyway I'd like to know more about this. GM did give me extended warrantee to comver driveline problem, but I'd just like to have the truck fixed before it lets me down somewhere.

thanks

gss036 · October 31, 2005

I wonder if that is my problem. See earlier post on noise from under truck. Noise from undercarrige http://www.gm-trucks.com/forums/index.php?showtopic=45175