Help! Hum/grinding sound when applying gas at highway speeds

[mgmyota]

So this has been an ongoing issue and I’m honestly stumped at this point. I only notice it at highway speeds between 50-80. Basically I’ll be going along and I’ll come off the gas and coast, but right when I start to apply the gas again I’ll hear and feel a slight hum and almost light grind sound from what seems like right under me. Sounds almost like two gears trying to mesh together again. And I can manipulate the sound repeatedly by playing with the gas pedal in and out. It doesn’t happen every time I apply the gas but it happens quit often. I am regeared and just had the rear diff rebuilt again and the sound is still present and exactly the same. Changed the fluid after break in and the fluid looked normal. I almost don’t think it’s a diff problem. I saw the gear pattern from this build and it looked solid. Thinking it’s something with the driveshaft maybe? The angle of the driveshaft/pinion doesn’t seem crazy and I measured the angles and they look to be within spec if i did it right lol (first time learning how to do that). If anyone has any ideas or has had a similar experience I’m all ears.

 

[ct__tacoma]

I get something similar when I decel through the mid to low 60’s sometimes. I believe mine comes from the fact that I tend to have my leaf packs under loaded which causes the rear driveshaft angle to be off by a degree or two. When I have some weight in the bed it goes away. Not sure if that’s applicable for you but sounds similar to my problem. I was going to say the needle bearing but yours is already swapped.

 

[mgmyota]

I get something similar when I decel through the mid to low 60’s sometimes. I believe mine comes from the fact that I tend to have my leaf packs under loaded which causes the rear driveshaft angle to be off by a degree or two. When I have some weight in the bed it goes away. Not sure if that’s applicable for you but sounds similar to my problem. I was going to say the needle bearing but yours is already swapped.

Guess I could try loading the bed up with weight for shits and giggles. Also thought about bringing it to a dedicated drivetrain shop to see what they say

 

[ct__tacoma]

Guess I could try loading the bed up with weight for shits and giggles. Also thought about bringing it to a dedicated drivetrain shop to see what they say

Couldn’t hurt. Driveshaft angles make sense in the videos then the second the angle finder goes on the truck I’m lost again.

 

[mgmyota]

Anyone else with any ideas before I get it into a shop? Could the wear pattern on the gears change drastically after breakin? Enough to cause issues?

 

[bonifacio]

It's not the exhaust hocking a loogie? Maybe your truck has bad allergies.

 

[mgmyota]

It's not the exhaust hocking a loogie? Maybe your truck has bad allergies.

I wish it was something that dumb lol. I’m just hoping it’s not something transmission or diff wise lol

 

[New Holland Overland]

I wish it was something that dumb lol. I’m just hoping it’s not something transmission or diff wise lol

I have a similar sound at the moment, but mine occurs when the truck is coasting at speed. Im guessing its more than likely a loose bolt or bad bearing

Let us know what you find out!

 

[mgmyota]

I have a similar sound at the moment, but mine occurs when the truck is coasting at speed. Im guessing its more than likely a loose bolt or bad bearing

Let us know what you find out!

You might be able to figure yours out by putting it on a lift and in drive and hunt the sound down that way. Could just be a u joint or carrier bearing. Hopefully something simple lol

 

[Reddirtnaps]

Mine does the same thing and gets louder the faster I go over 70. I could've sworn it was the from under the hood for the longest time like the intake or something. Once I removed the plastic cubbies behind the back seat for more storage it was very apparent it was the rear diff. Im also regeared and ECGS has on their website a howl is not uncommon. Sound deadening, putting the plastic back, and turning up the radio fixed it for me.

 

[StormRnr]

Try greasing the u joints. Check for wear. My OME lift came with drive line drop so I'm not getting any noise. Might try that as it's cheap and easy to install.

-M

 

[mgmyota]

Mine does the same thing and gets louder the faster I go over 70. I could've sworn it was the from under the hood for the longest time like the intake or something. Once I removed the plastic cubbies behind the back seat for more storage it was very apparent it was the rear diff. Im also regeared and ECGS has on their website a howl is not uncommon. Sound deadening, putting the plastic back, and turning up the radio fixed it for me.

I have the 40% delete so I’m used to some extra noise. And I understand gears make a whining or humming kind of sound to an extend. This sound doesn’t sound like a regular gear whine. I think I can feel it with my foot more than I can hear it as well. Not saying it couldn’t still be the rear diff though.

Try greasing the u joints. Check for wear. My OME lift came with drive line drop so I'm not getting any noise. Might try that as it's cheap and easy to install.

-M

My rear drive shaft doesn’t have greasable ujoints. Only the front shaft does. And I just greased those. I also checked for play in the joints and carrier bearing. I have thought about trying a carrier bearing drop. But I think I would rather take it to a drive shaft shop first and have them measure the drive shaft angle and pinion angle and make sure everything is aligned properly. If it’s off then I can go from there with a drop or axle shims. I’m thinking it’s something more mechanical than that though

 

[Battle Born Offroad]

Check the carrier bearing for play.

 

[mgmyota]

Check the carrier bearing for play.

I set the truck in neutral and tried checking the drive shaft for play but felt nothing around any u joints or the carrier bearing. I could unbolt the carrier I guess and see if I feel anything then. The carrier bearing was replaced about 15k miles ago though so I can’t imagine it’s already bad