Loud, low pitched hum at 70+

[BuckeyeBOSS]

My 05 GT has a loud, low pitched hum at 70+ mph and a very slight vibration, but the vibration is barely noticeable. Not sure what it is. I had the tires checked out and rebalanced this weekend, but it's still there. Maybe low on rearend fluid or a driveshaft issue? Anyone had this or have any ideas? Thanks.

 

[05sc281]

sounds like its in the differential. can be low on fluid or the gears ...

 

[08gt4u]

mines is not loud but is noticible with the radio and ac off on a quiet night.mines have been doing it for a year now and i have had the oil from the diff replace,gears check,drive shaft rotated in every possible way and is still there.i have learn to live with it but has not affect in performance one bit.

 

[kevinatfms]

install the axle weights from the tsb, it will remove unwanted axle whine/groan/hum at crusing and decel speeds...once installed if you have anymore noise then it will be bad pinion bearings
also you can check by turning sharply left to right and see if it changes pitch, if it changes pitch you have axle bearings going bad

and finally if you are more mechanically inclined, jack the car up and secure firmly
run the rear wheels up to 70mph and use a stethoscope to pin poin which bearing exactly is going bad

 

[BuckeyeBOSS]

install the axle weights from the tsb, it will remove unwanted axle whine/groan/hum at crusing and decel speeds...once installed if you have anymore noise then it will be bad pinion bearings
also you can check by turning sharply left to right and see if it changes pitch, if it changes pitch you have axle bearings going bad

and finally if you are more mechanically inclined, jack the car up and secure firmly
run the rear wheels up to 70mph and use a stethoscope to pin poin which bearing exactly is going bad

Awesome, thanks man. Does the dealership have to install these weights for free or not? I hope it's not the bearings, the car only has 22k miles.

 

[Dread53]

Do you have a 1 piece DS? Mine does something similar at speed. No noise, but a cyclic low vibration. I've never tried re-indexing the shaft because it isn't that bad. Lots of people have had driveshaft balance issues, especially with the 1 piece.

 

[kevinatfms]

your car is out of warranty, you will have to pay for it, if you buy the parts you can install them yourself...ill pm you tomorrow with the part number if someone doesnt do it on here before then

 

[BuckeyeBOSS]

your car is out of warranty, you will have to pay for it, if you buy the parts you can install them yourself...ill pm you tomorrow with the part number if someone doesnt do it on here before then

Cool, thanks man.

 

[gzmo]

Maybe the type of tires you have? Every tire is different and omits different road noises. I would take a look at some reviews to see what people say about them and if they complain about noises at high speeds.

 

[kevinatfms]

part number is: 5R3Z-3C246-A
and to install is just tightening them down with a 15mm socket and wrench
takes all of about 10 min to do

 

[BuckeyeBOSS]

Maybe the type of tires you have? Every tire is different and omits different road noises. I would take a look at some reviews to see what people say about them and if they complain about noises at high speeds.

Stock tires

part number is: 5R3Z-3C246-A
and to install is just tightening them down with a 15mm socket and wrench
takes all of about 10 min to do

Thanks man, I'll give it a shot

 

[1FastS197]

i have tore the rear end down three times now try'n to find the hum (also a '05 GT)... i have come to the conclusion of "FUCK IT"... i will fix it when it breaks... gears look great, bearings are fine, no metal shavings, no slack in the diff, etc... i'm just gonna cut the radio up...

 

[BuckeyeBOSS]

i have tore the rear end down three times now try'n to find the hum (also a '05 GT)... i have come to the conclusion of "FUCK IT"... i will fix it when it breaks... gears look great, bearings are fine, no metal shavings, no slack in the diff, etc... i'm just gonna cut the radio up...

Have you tried these axle weights?

 

[1FastS197]

Have you tried these axle weights?

naw, i haven't tried them but its not gonna be long before i change the gears and axles so i'm gonna see how that does...

 

[BuckeyeBOSS]

part number is: 5R3Z-3C246-A
and to install is just tightening them down with a 15mm socket and wrench
takes all of about 10 min to do

Well, I got this axle weight kit and went to install. They "appear" to be exactly the same weights already on the axle, minus some rust. Are they different in anyway?

 

[MikeVistaBlue06]

Do you have a 1 piece DS? Mine does something similar at speed. No noise, but a cyclic low vibration. I've never tried re-indexing the shaft because it isn't that bad. Lots of people have had driveshaft balance issues, especially with the 1 piece.

I too had vibe problems with my single piece driveshaft at about 65mph. I had it removed and rebalanced. It was way the fuck off balance. After it was balanced, I have no more vibe at any speed!

If you have a single piece driveshaft, you may want to have it yanked and balanced.

HTH

Mike

 

[BuckeyeBOSS]

I too had vibe problems with my single piece driveshaft at about 65mph. I had it removed and rebalanced. It was way the fuck off balance. After it was balanced, I have no more vibe at any speed!

If you have a single piece driveshaft, you may want to have it yanked and balanced.

HTH

Mike

Thanks guys, I'll look into this next.

 

[smoken1986]

I too have the vib at 70-80, mine will disapear if I drop into 4th gear though. Is your car a stick? You might want to try that. I read somewhere that a bad bushing in the trans causes it, but I have not pulled mine apart to check yet.

 

[BuckeyeBOSS]

I too have the vib at 70-80, mine will disapear if I drop into 4th gear though. Is your car a stick? You might want to try that. I read somewhere that a bad bushing in the trans causes it, but I have not pulled mine apart to check yet.

Mine's an auto, I took it off OD and let it downshift at 70, made no difference.

 

[smoken1986]

Sounds like a bearing issue or driveshaft then. Not to ask you to drive crazy or anything but does it change pitch if you change lanes fast or move the weight of the car back and forth. If it does it could be a axle bearing or axle, if not I would say pinion bearing or driveshaft. Do you still have the stock 2 pc shaft? Just throwing some things out there for ya