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Discussion Starter · #4 ·
okay, new to posting....l heard the transfer case working while switching from 2WD to Auto/4WD/4WL last night before l drove it (the vehicle is at my GF's house now) l put it into 4WD and it engaged (as l had to give it a little more gas) once l got a few blocks away it started that noise and when l slowed down it seemed to want to grab. I switched back to 2WD and no noises...nada :/
 

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2004 chevy trailblazer_ls_ext
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#1: Do not use auto 4WD, or A4WD as it's labeled on your selector switch. That's really hard on the clutch packs in your transfer case. Leave it in 2WD and switch to 4HI or 4LO as conditions warrant, then back to 2WD.

Can you describe WHERE you think the noise is coming from? If it's coming from the passenger side I would suspect the front axle disconnect. That's the part that the CV axle goes into on the oil pan.
Here's some info on it:
Front Axle 4WD Disconnect Rebuild | offroadTB.com

Jack up the right front tire and spin it. If you hear gravely crunchy noises from that part, you've found the culprit.
 

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Discussion Starter · #6 ·
#1: Do not use auto 4WD, or A4WD as it's labeled on your selector switch. That's really hard on the clutch packs in your transfer case. Leave it in 2WD and switch to 4HI or 4LO as conditions warrant, then back to 2WD.

Can you describe WHERE you think the noise is coming from? If it's coming from the passenger side I would suspect the front axle disconnect. That's the part that the CV axle goes into on the oil pan.
Here's some info on it:
Front Axle 4WD Disconnect Rebuild | offroadTB.com

Jack up the right front tire and spin it. If you hear gravely crunchy noises from that part, you've found the culprit.
It does sound like, what you just described AND it seems to be coming from the passenger side, what l can't figure out it don't make any noise while driving in just 2WD.
I don't hear the noise while driving in 2WD. I will check it for sure and post later.
thanks
 

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2004 chevy trailblazer_ls_ext
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It could be that something in there is only getting loaded up in 4WD and making the noise then. If you do decide to replace it RockAuto has the Dorman (yes, Dorman) unit at a decent price. The Dorman unit uses a forged aluminum shift fork instead of cast like OEM, and it has 3 contact points instead of 2. It's what I used when I replaced mine last fall.
 

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'05 TB 4.2 EXT
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It could be that something in there is only getting loaded up in 4WD and making the noise then. If you do decide to replace it RockAuto has the Dorman (yes, Dorman) unit at a decent price. The Dorman unit uses a forged aluminum shift fork instead of cast like OEM, and it has 3 contact points instead of 2. It's what I used when I replaced mine last fall.
Sadly --- if the A4WD clutches are wiped out and too thin from abuse - or even actually USING them - you won't get a firm front wheel drive --- those clutches need to be locked into position to get to front axle activation.
The other problem is that the clutches can be so worn out that the cam goes over-center and the motor cannot pull it back out oif driving the front axle - even less than normally.​

That Dorman fork is super good --- I know.

Two Rules Here --->

#1 ---- NEVER DISCONNECT THE BATTERY
#2 ---- NEVER USE A4WD - NEVER.
 

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Discussion Starter · #9 ·
Sadly --- if the A4WD clutches are wiped out and too thin from abuse - or even actually USING them - you won't get a firm front wheel drive --- those clutches need to be locked into position to get to front axle activation.
The other problem is that the clutches can be so worn out that the cam goes over-center and the motor cannot pull it back out oif driving the front axle - even less than normally.​

That Dorman fork is super good --- I know.

Two Rules Here --->

#1 ---- NEVER DISCONNECT THE BATTERY
#2 ---- NEVER USE A4WD - NEVER.
Sounds like l have my work cut out for me 🤨
Ohh l know all about the battery issues, the biggest pain in the *ss was that vent flow actuator 😡
 

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2002 chevy trailblazer_lt
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Have a look at the right side CV shaft where it enters the splined disconnect/intermediate shaft bearing assembly. If it wobbles around a bunch like this one or worse it is shot.

 

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Discussion Starter · #11 ·
Have a look at the right side CV shaft where it enters the splined disconnect/intermediate shaft bearing assembly. If it wobbles around a bunch like this one or worse it is shot.

thanks
I am picking up her vehicle and will bring it to the house and take a look at that. Thanks again
 

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'05 TB 4.2 EXT
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Ya know --- a down-n-dirty test of that axle connector assembly --- is to shift into 4WD/High at around 25 MPH.

If it grinds then there's trouble in that axle lock assembly.

The left front axle must always spin at the same rate as the rear axles ... and the right front axel up to the sleeve lock ring, is spinning too.

The wheels fall off (bad choice there, sorry) and the lock sleeve doesn't get into position and actually lock itself to the differential stub output shaft --- there cannot be any clashing or grinding at all.

If there is noise at a low speed, then that axel-slider-sleeve-lock thingy is not working correctly.
I say: "low speed" so you don't get scared of a small yield nuclear explosion --- which won't happen.
 

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The left front axle must always spin at the same rate as the rear axles ... and the right front axel up to the sleeve lock ring, is spinning too.

That right side intermediate shaft and gear is likely to be spinning "backwards" as well !! I've known mine to be spinning at about 400 rpm in the opposite direction as the right side CV shaft and associated gear in that disconnect.
 

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Discussion Starter · #14 ·
#1: Do not use auto 4WD, or A4WD as it's labeled on your selector switch. That's really hard on the clutch packs in your transfer case. Leave it in 2WD and switch to 4HI or 4LO as conditions warrant, then back to 2WD.

Can you describe WHERE you think the noise is coming from? If it's coming from the passenger side I would suspect the front axle disconnect. That's the part that the CV axle goes into on the oil pan.
Here's some info on it:
Front Axle 4WD Disconnect Rebuild | offroadTB.com

Jack up the right front tire and spin it. If you hear gravely crunchy noises from that part, you've found the culprit.
Well l raised the vehicle up and spun the wheel, no grinding/gravely noise. I did hear a clunk coming from the hub when l would spin the CV axle coming from the differential back and forth, but the clunk is not that gravely noise...ughhh
 

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2003 chevy trailblazer_ltz
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I've had a whine/whirr noise only in 4WD or A4WD on my '03. Gone completely in 2WD.

Bearing in the axle disconnect had destroyed the "gear" it supports.

Coin Currency Money Camera accessory Nickel


Replaced the "gear", the bearing using a wider unit, and the shift fork. Fresh grease, new seals. Good as new.

As far as I know, the Dorman shift fork is not "forged", but it does have the third contact pad.
 

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Discussion Starter · #16 ·
Ya know --- a down-n-dirty test of that axle connector assembly --- is to shift into 4WD/High at around 25 MPH.

If it grinds then there's trouble in that axle lock assembly.

The left front axle must always spin at the same rate as the rear axles ... and the right front axel up to the sleeve lock ring, is spinning too.

The wheels fall off (bad choice there, sorry) and the lock sleeve doesn't get into position and actually lock itself to the differential stub output shaft --- there cannot be any clashing or grinding at all.

If there is noise at a low speed, then that axel-slider-sleeve-lock thingy is not working correctly.
I say: "low speed" so you don't get scared of a small yield nuclear explosion --- which won't happen.
So the left side don't have the same thing as the right? I guess i'll try the low speed test maybe tomorrow, l watch a few videos to remove it and seems it could be a pain getting the axle back in...IDK
thanks
 

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Discussion Starter · #17 ·
I've had a whine/whirr noise only in 4WD or A4WD on my '03. Gone completely in 2WD.

Bearing in the axle disconnect had destroyed the "gear" it supports.

View attachment 60902

Replaced the "gear", the bearing using a wider unit, and the shift fork. Fresh grease, new seals. Good as new.
OMG hope it's not the fork, is it inside the differential or the lock assembly where the actuator is?
 

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Discussion Starter · #19 ·
clanking
#1: Do not use auto 4WD, or A4WD as it's labeled on your selector switch. That's really hard on the clutch packs in your transfer case. Leave it in 2WD and switch to 4HI or 4LO as conditions warrant, then back to 2WD.

Can you describe WHERE you think the noise is coming from? If it's coming from the passenger side I would suspect the front axle disconnect. That's the part that the CV axle goes into on the oil pan.
Here's some info on it:
Front Axle 4WD Disconnect Rebuild | offroadTB.com

Jack up the right front tire and spin it. If you hear gravely crunchy noises from that part, you've found the culprit.
Well l raised the vehicle up and spun the wheel, no grinding/gravely noise. I did hear a clunk coming from the hub when l would spin the CV axle coming from the differential back and forth, but the clunk is not that gravely noise...ughhh
l am trying to figure out how to upload a video of the clanking which is not the gravely sound, it doesn’t sound good
 
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