Weird humming sound.

[inerta]

Hi I have a 2020 ST and last night I finally had time to install MBR exhaust. Double checked and made sure I installed it correctly. It sounds go when idling and accelerating but when I let go of the gas and slow down there's a humming sound. Humming sound only comes when slowing down. Im just wondering if thats normal. Sorry if its a dumb question, only other car I owned was a 2008 Altima. Thanks in advance P.S. also added the steeda diff brace dont know if that matters

 

[Cdubya]

Maybe from your rear diff if you stiffened it well. Decelleration whine/hum could be a symptom your rear diff pinion bearings are shot.

You mentioned the Steeda brace... do you also have JXB inserts?

 

[inerta]

Maybe from your rear diff if you stiffened it well. Decelleration whine/hum could be a symptom your rear diff pinion bearings are shot.

You mentioned the Steeda brace... do you also have JXB inserts?

Yes I installed those too yesterday. Could that be the humming?

 

[2020FordRaptor]

Most likely is the NVH gained from those two differential support units.

 

[Cdubya]

Yes I installed those too yesterday. Could that be the humming?

It's the JXB inserts and like I said, potentially your pinion bearings. Some have the JXB inserts and have no noise on a MY2020. Mine did but I have over 100k miles. I ended up removing the passenger side insert and the noise is gone... it was getting on my nerves.

 

[inerta]

Its probably the JXB inserts cause it didn't have this humming til I installed them. Any way to fix it besides removing them (JXB inserts)? Thanks for help really appreciate it.

 

[Cdubya]

For me, the passenger side insert is what is causing the noise. The inserts really don't work by filling the gap in the rubber bushing--the back plate of the insert engages the collar of the mount and limits movement. This is much more true for the passenger side because the JXB insert sits further in than the driver's side. I would recommend removing the passenger side insert if you do not want the noise... but i have no clue what effect using only one of the inserts would have.

 

[inerta]

Yea I was thinking of removing both JXB inserts and see if the humming continues. Ill post my results. Thanks for the info guys, really appreciate it.