Humming Noise when Coasting. Update 9/6/23

[Usterzai]

Hi All,

Sorry if this is a repeat thread but I read through 10-12 threads related to 100 series and a couple of 80 series threads. All of them were related to wheel bearings or front diff. Except this one 80 series thread which pointed to T-case and their noise went away after replacing T-case.

The noise I have is only during coasting, and goes away when accelerating. It is present at all speeds and very loud when I let go of gas. At highway speeds and when driving around the neighborhood the noise is same. I removed the front DS and it is still present. When coasting w/o the front DS if I shift transmission in Neutral noise remains but as soon as I shift the T-case in neutral it completely goes away. Does this indicate the t-case outer bearing is bad ? It also seems like the noise is coming from the t-case shifter area.

No noticeable play in DS shafts. Greasing the u joints does not make any difference. No driveline vibrations either just the noise when coasting.

Maintenance I have done in past 10k miles. All Toyota parts

• New Wheel bearings and spindle bearings
• New Rotors and pads front and rear
• New CVs and hub flanges
• Oil changed in all diffs and T-case, no shaving or excessive sludge. Oil mostly clear. Also just daily driving this right now has not seen the dirt or been off-road yet.
• Front and rear, upper and lower control arms.

I probably can tackle the t-case bearing replacement myself but I just don't want to throw parts at it.

 

[Usterzai]

Last couple of seconds its very clear and this is while the LC was coasting. It goes away as soon as I shift into N. Forgot to mention Tires are new as well. Michelin defenders stock size.

 

[excessive]

proably either pinion bearing in front or rear diff or driveshaft itself. Try removing the driveshafts one at a time (use the center diff lock) drive around with just the front driveshaft and see how it affects the noise.

 

[Usterzai]

proably either pinion bearing in front or rear diff or driveshaft itself. Try removing the driveshafts one at a time (use the center diff lock) drive around with just the front driveshaft and see how it affects the noise.

Same noise when rear drive shaft was out. Changed the T-Case oil no metal shavings but a lot of metallic color sludge. The only thing that makes the noise go away is when I put the t-case in neutral while de accelerating.

 

[Usterzai]

Update and a question.

I am now an expert in taking the transfer case in and out within 2-3 hours

1st replacement T-Case from ebay had one of the bolt holes broken but I only saw it after I had removed my T-Case. Lesson learned, thoroughly inspect the parts before starting the work. Got my money back but lost a whole day and some $ as I had rented a bay to do the work.

I decided to order a new. Pricey but at this point I am way too tired to deal with another ebay or junk yard T-Case. No time to pick one in person either.

While I wait for the new one I decided to take my old T-Case apart. There was alot of damage/pitting in one of the bearing. The case was full of glitter especially around the corners where oil was not circulating. Not sure what would cause this. Hopefully the new T-Case solves the humming noise I was getting when de accelerating.

My question: Is the transmission case bearing in the picture replaceable? Is that something I should do while things are apart or leave it alone.

 

[LEXCRUISER]

Check U joint, especially the forward driveshaft U joint

 

[Usterzai]

Update number 20 new transfer case and new drive shafts but now I have vibrations on acceleration. At this point I am completely lost, the old t-case and driveshaft with 260k were smooth only symptom was the noise.

 

[zgfiredude]

Did you make sure that both shafts are "in phase"? The orientation of the u-joints needs to match at each end of the shaft.

 

[Usterzai]

.

 

[Usterzai]

Did you make sure that both shafts are "in phase"? The orientation of the u-joints needs to match at each end of the shaft.

Yes I checked that, I thought maybe the new rear shaft is bad so I installed the old one. It does the excat same thing.

 

[zgfiredude]

Were the new shafts balanced? Sure seems confusing....

 

[Usterzai]

Were the new shafts balanced? Sure seems confusing....

They are toyota OEM and I picked them up locally. It is very confusing at this point.

 

[Dirt J]

Did you remove the cross member or TC mount? Could those be loose?

 

[Usterzai]

Did you remove the cross member or TC mount? Could those be loose?

I can check those, but I did not remove the cross member.

 

[Dirt J]

What kind of vibrations? Steering wheel or body?

Have you tried all the functions of your TC (h-N-L and lock) to see if they are acting right?

Also, have you tried alternating removing each of the new driveshafts to see if it goes away?

 

[Usterzai]

What kind of vibrations? Steering wheel or body?

Have you tried all the functions of your TC (h-N-L and lock) to see if they are acting right?

Also, have you tried alternating removing each of the new driveshafts to see if it goes away?

Body vibrations most notable when accelerating around 50, and then 65 to 70.

All functions on the T-Case work, shifts in H-N-L, center lock working as well.

Last night I drove in 2wd and with the rear shaft out it smooths out by 75%.

 

[elhombre]

Man, I'm sorry this is happening to you. I have been down this path with my 80 also. I too have an extra T case on my shelf in the garage along with rear axles and such. I still have a vibration around 60 mph but have learned to live with it. It can be maddening to keep looking and not find the single one part that is causing the problem. First, go with your successes. You found metal shavings in the T case oil which led to finding a ruined bearing. One problem fixed. Now, your problem has changed. If it is in a differential, then you will see the same sign as the T case. Look at the magnetic plug for metal. Then, look at the diff oil in the sun light and see if it glitters. It will also show shiny metal by putting a few drops on a paper towel and looking at it in the sun. If you find nothing sparklely, then the bearings inside are doing OK. Next I would remove each drive shaft and make sure the U-joints are moving freely in all directions. And I mean Freely. No direction should be tighter than the other. If all 4 joints check out, and I see that you have tried driving around with each drive shaft removed, then did you put too much grease in the slip joint? I'm going to guess "No", but it can cause a noise if the slip joint is completely full of grease.

If you can't find any sign of a bearing going bad in the T case. The U-joints are all good. The diff is not imploding. The wheel bearings are all tight with no play at 12:00 and 6:00. Then I believe you will have to drive it until what ever part is the problem finally wears out enough to become obvious.

My 80 has had the harmonic vibration around 60 mph for 100k miles now. My 2004 did it a little when I bought it used at 125k miles and does it a little more now that I have lifted it, and put bigger tires on it. I of course don't know how bad your truck is, but I thought my story may help a little. I still love diving both of them. Just like the interior of both cars show age due to being 20+ years old, I had to realize and accept they arn't going to drive like new and perfect anymore. We still look way better cruising around in our heavy ass 4x4 pieces of metal than most of the rest of the world driving in their battery powered tin foil crap boxes.

 

[Usterzai]

Man, I'm sorry this is happening to you. I have been down this path with my 80 also. I too have an extra T case on my shelf in the garage along with rear axles and such. I still have a vibration around 60 mph but have learned to live with it. It can be maddening to keep looking and not find the single one part that is causing the problem. First, go with your successes. You found metal shavings in the T case oil which led to finding a ruined bearing. One problem fixed. Now, your problem has changed. If it is in a differential, then you will see the same sign as the T case. Look at the magnetic plug for metal. Then, look at the diff oil in the sun light and see if it glitters. It will also show shiny metal by putting a few drops on a paper towel and looking at it in the sun. If you find nothing sparklely, then the bearings inside are doing OK. Next I would remove each drive shaft and make sure the U-joints are moving freely in all directions. And I mean Freely. No direction should be tighter than the other. If all 4 joints check out, and I see that you have tried driving around with each drive shaft removed, then did you put too much grease in the slip joint? I'm going to guess "No", but it can cause a noise if the slip joint is completely full of grease.

If you can't find any sign of a bearing going bad in the T case. The U-joints are all good. The diff is not imploding. The wheel bearings are all tight with no play at 12:00 and 6:00. Then I believe you will have to drive it until what ever part is the problem finally wears out enough to become obvious.

My 80 has had the harmonic vibration around 60 mph for 100k miles now. My 2004 did it a little when I bought it used at 125k miles and does it a little more now that I have lifted it, and put bigger tires on it. I of course don't know how bad your truck is, but I thought my story may help a little. I still love diving both of them. Just like the interior of both cars show age due to being 20+ years old, I had to realize and accept they arn't going to drive like new and perfect anymore. We still look way better cruising around in our heavy ass 4x4 pieces of metal than most of the rest of the world driving in their battery powered tin foil crap boxes.

Thanks for the kind words! I Absolutely love my trusty 20-year-old 100! It's been a blast for my family and me.
Checked the T-Case oil, driveshaft, and rear control arms - all seem fine. Yet, the vibes are getting worse, and I can't risk a breakdown. It is my daily driver and I feel like instead one problem I might end up with more if there is catastrophic failure.

Scheduled an appointment for Tuesday with a Toyota Specialist; fingers crossed they spot the issue and help me fix it.

 

[Usterzai]

Got the LC back from the shop, inconclusive diagnosis. Rear DS was noted to have some slop, however w/o the rear DS LC now has developed the same symptoms with the front driveshaft. The shaking seems to increasing as I drive more. Seems like I have to wait for something to go bad. Hopefully not the T-Case as that was expensive.

Side note the T-Case was damaged a little in shipping, they seem to think it was minor and it should not be the reason. The transmission out shaft must be bad, not sure what do next.

 

[Usterzai]

Update: After 15k miles, the vibration in my truck has been increasing gradually. I recently acquired another used transfer case to eliminate it as the source of the issue, confirming it's the new T-case was not the culprit. Despite replacing two rear drive shafts the issue does not seem to go away. However, if I rotate the driveshaft at the T-case of rear differential it will change the speed I get the vibration at. Driving without the rear drive shaft reduced the audible vibration significantly, but the truck still shakes at specific speeds (45, 55, 60, and around 70 mph).

Next step is to source a rear diff to rule out problems with rear diff. Absolutely baffled! Can anyone explain why changing the transfer case would cause the rear differential to go out? I've been troubleshooting my truck's vibration issue for past couple of months. Any insights or advice would be greatly appreciated!