Odd metal noise when letting off the gas at 1900 RPM. What should I do?

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Evening everyone,

Was hoping my first post back from deployment would be a lot nicer, but unfortunately, ran into an issue. Cruiser was ran this morning and was completely fine. I started going at highway speeds and noticed as I left off the gas, this weird metal noise comes it at 1900 RPM. It sounds like it’s from the front of the cruiser. I had tranny work done a year ago and has never been an issue, but I also haven’t driven this baby in 9 months. When accelerating, no issue. when letting off the gas, this issue occurs. Will post video momentarily

NOTE: It makes this nice at any RPM above 1900 when letting off the gas.
 

LandLocked93

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Are you sure the tranny shop put your front shaft back in correctly, orientation and phase?
Had the same issue when I got my truck back from tranny shop.
 
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Are you sure the tranny shop put your front shaft back in correctly, orientation and phase?
Had the same issue when I got my truck back from tranny shop.
Pretty sure, drove it for about 12,000 miles on the new tranny. Forgot to mention it was from the mechanic shop on my way home when I heard these noises. I got a knucle rebuild, the front diff removed, a lift, these were the big things.
 
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I'm not sure about this exact noise, but I had an intermittent similar noise after a knuckle rebuild due to the brass spindle on the driver side not getting grease. Does it sound from the exact area of the front driveshaft?
 
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I'm not sure about this exact noise, but I had an intermittent similar noise after a knuckle rebuild due to the brass spindle on the driver side not getting grease. Does it sound from the exact area of the front driveshaft?
It does sound like the front where the knuckle rebuild was, the front drive shaft, the only thing that concerns me is that its that engaging noise, I dont know if you can hear it in the video.
 

LandLocked93

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Forgot to mention it was from the mechanic shop on my way home when I heard these noises. I got a knucle rebuild, the front diff removed, a lift, these were the big things.
Are you sure the last mechanic who performed work in the areas of those which you mention put your front shaft back in correctly, orientation and phase?

lol
 
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So you mentioned that you lifted the LC? The U joints in your front drive line are probably the issue. I would get yourself a grease gun and grease the slip joint and the u joints on the front drive line.
Will definitely look into it, gonna have to do it first thing in the Am, thank you for your input
 
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Will definitely look into it, gonna have to do it first thing in the Am, thank you for your input
People are talking about phase of the drive line. Toyota shipped LC with the drive line out of phase on certain vehicles for a reason. People have said the LC front drive shaft should be set up in "phase" but if Toyota shipped them out of phase for a reason then leave it. Make sure the slip joint of your front drive line is attached to the 3rd member, if it is attached to the transfer case it has been installed wrong.

1661912796939.png


Toyota shipped the LC with the front driveline like the one in the bottom of the picture for a reason. I was told by Kevin @Tools R Us a member that has passed to change the phase of the drive line to what is in the top of the picture, I just never got around to it.

Your drive line sat at one angle for years and wore the needle bearing ones way. Once you installed the lift it changed where the needle bearings ride so you might be getting a growl from the unhappy bearings.
 
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I can't hear the noise for sure in your video. Mine makes a kind of grinding or growling sounds when I let off the gas, mostly noticable at speeds 50mph and under. Have not been able to track it down but it was there before I lifted the truck and is still doing it. It's been that way for the 7 years I have owned it though and does not seem to be getting worse. I've also rebuilt the front axel and replaced all the Ujoints.
 

CPACruiser

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I can't hear the noise for sure in your video. Mine makes a kind of grinding or growling sounds when I let off the gas, mostly noticable at speeds 50mph and under. Have not been able to track it down but it was there before I lifted the truck and is still doing it. It's been that way for the 7 years I have owned it though and does not seem to be getting worse. I've also rebuilt the front axel and replaced all the Ujoints.
I have the same decel noise that I can only describe as a "rotational hum."

I have tried new u-joints, thicker yoke grease (the Mercedes gray stuff), new diff fluid, repacking bearings and resetting preload, sound still remains, been that way for over a year, I've also learned to live with it...but also have this mild concern every time I hear it. 🤷🏻
 
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People are talking about phase of the drive line. Toyota shipped LC with the drive line out of phase on certain vehicles for a reason. People have said the LC front drive shaft should be set up in "phase" but if Toyota shipped them out of phase for a reason then leave it. Make sure the slip joint of your front drive line is attached to the 3rd member, if it is attached to the transfer case it has been installed wrong.

View attachment 3101851

Toyota shipped the LC with the front driveline like the one in the bottom of the picture for a reason. I was told by Kevin @Tools R Us a member that has passed to change the phase of the drive line to what is in the top of the picture, I just never got around to it.

Your drive line sat at one angle for years and wore the needle bearing ones way. Once you installed the lift it changed where the needle bearings ride so you might be getting a growl from the unhappy bearings.
Apologies for the late reply. Took it to the cruiser shop that did the lift. They found the issue, pretty much the front drive shaft as you said, they worked on it free of charge! No more noise, cruiser sounds like a dream now!!


Thank you and everyone else who helped identify the issue!
 
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This is not an uncommon thing if it's what I think it is. Others have responded above that they have a similar noise on decel. I have had that same noise on my truck for the 7 years I've owned the truck. I've replaced ujoints, I've replaced the brash spindle bushing in the knuckle, changed the bushing to the roller style. I've come to the conclusion it is likely a worn bearing in the transfer case, probably the output bearing. Since very few of us are modifying or doing maintenance on the transfer case other than changing fluid and since many 80 are well over 200K miles I think it would be reasonable that a bearing could be the issue. Replacing the bearings and upgrading to lower tcase gears is in my plans sometime hopefully soon.
 
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I have the same decel noise that I can only describe as a "rotational hum."

I have tried new u-joints, thicker yoke grease (the Mercedes gray stuff), new diff fluid, repacking bearings and resetting preload, sound still remains, been that way for over a year, I've also learned to live with it...but also have this mild concern every time I hear it. 🤷🏻
I have this too. Hate it, but it seems harmless and I haven't been able to track it down. I think I have it narrowed to rear t-case output but haven't looked into it much further.
 
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This is not an uncommon thing if it's what I think it is. Others have responded above that they have a similar noise on decel. I have had that same noise on my truck for the 7 years I've owned the truck. I've replaced ujoints, I've replaced the brash spindle bushing in the knuckle, changed the bushing to the roller style. I've come to the conclusion it is likely a worn bearing in the transfer case, probably the output bearing. Since very few of us are modifying or doing maintenance on the transfer case other than changing fluid and since many 80 are well over 200K miles I think it would be reasonable that a bearing could be the issue. Replacing the bearings and upgrading to lower tcase gears is in my plans sometime hopefully soon.
Yeah my thinking was T case of viscous coupler. I have an over haul of the T case on my list, not sure if I will do the lower gear set or not. Be interested to hear if your bearings and gear upgrade has any effect on the noise.
 

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