Rear Diff Whine While Coasting

[Aonarch]

My rear diff is whining while coasting at 65 mph or higher.

I can't hear it any slower. It does it in any gear so it shouldn't be the transmission.

Does anyone else have this problem? I noticed it after installing the Steeda Ultimate Handling Kit, so I am thinking this is one of the causes.

Fluid level is good, fluid is clean, car only has 3k miles.

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[NHMach1]

Mine did that for about the first 5000 miles. All stock suspension at that point. Same as yours, coasting at about the same speed. Then it went away. Very slight whine. Just turned over 10000 miles and haven’t heard it since.

 

[Aonarch]

Mine did that for about the first 5000 miles. All stock suspension at that point. Same as yours, coasting at about the same speed. Then it went away. Very slight whine. Just turned over 10000 miles and haven’t heard it since.

Good to know!

 

[shogun32]

I noticed it after installing the Steeda Ultimate Handling Kit

that's what that kit does. The only way to not have diff whine is use Whiteline bushings.

 

[Oakley]

its the diff bushing inserts installed near the snout of the diff where the pinion gear rides.
my cobra did this and I had poly bushings front and back.

current mustang doesn't and I have kelltec inserts with big bertha bolts ONLY in rear (stock setup at snouth) ZERO whine.

 

[Aonarch]

For the record I am still on the factory diff bushings. I do have the Steeda ones sitting in a box though. Just too lazy right now to install.

 

[Racer5973]

My rear diff is whining while coasting at 65 mph or higher.

I can't hear it any slower. It does it in any gear so it shouldn't be the transmission.

Does anyone else have this problem? I noticed it after installing the Steeda Ultimate Handling Kit, so I am thinking this is one of the causes.

Fluid level is good, fluid is clean, car only has 3k miles.

Yeah I heard mine after changing driveshaft and doing all the rear suspension work. Took all those mushy bushings out that absorbed all the harmonics.

 

[23GreenGremlin]

Mine has done the same thing starting at about 70 MPH. I only noticed it after installing the Steeda ultimate handling kit but who knows, I may just have not noticed it before that but I suspect the inserts are transmitting a bit. Annoying but easy to fix with a slight adjustment of the stereo knob.

 

[Aonarch]

Mine has done the same thing starting at about 70 MPH. I only noticed it after installing the Steeda ultimate handling kit but who knows, I may just have not noticed it before that but I suspect the inserts are transmitting a bit. Annoying but easy to fix with a slight adjustment of the stereo knob.

Funny they emphatically state zero added NVH.

 

[murick]

Funny they emphatically state zero added NVH.

Technically they say "little to no"

Product Benefits:

• Eliminate wheel hop with little to no increase in NVH

 

[shogun32]

Funny they emphatically state zero added NVH.

I suspect the Steeda guys are A) hard of hearing B) never let off the gas. So the answer is simple, never coast.

 

[hot rod]

A quick google search: Whine/howl while coasting is often too little pinion preload.
Honestly i can‘t imagine that the pinion nut come loose neither the crush sleave looses it tension. And bearing wear after so little milleage….i don‘t know
Maybe some mechanics can explain.

 

[murick]

Since we are resurrecting this thread, I might as well add some observations. I had some Steeda parts added before the season - ultimate stop the hop kit and diff bushings (red ones).
Since then I have:

a) an audible "clunk" when shifting in low speeds/velocities. E.g. shifting from 1st gear to 2nd, or when coasting in 4th gear at low RPM and going to 3rd, etc.

b) an audible "whine" as if driving on the road markings, when coasting at the high speeds and higher gears (from 4th gear up, and from 60 mph up). It is most pronounced in the 6th gear.
The whine (and mostly the clunk) is there only when there is no hard pull on drivetrain though, it needs just enough throttle to maintain the speed (on a flat or descending road).

The guy who put the Steeda parts on my car told me that there is too much of a leeway in my diff (whatever that means), that he had never heard this so much pronounced on other Mustangs he had been working on.
I believe I heard it before the mods too, but only faintly (and was actually looking for diagnosing it better), but after the mods, it is as clear as it gets.

The behavior suggests that indeed something is loose somewhere (and probably was since the start), now it is just better to catch.

I had a privilege to drive @Esset car, which has basically same mods, which does not do this.
The other possibility that something went wrong during the install is hard to justify too.

I plan to take it to the dealer to have a look on, but I am not sure how they will deal with it with all those addons.

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