Rear end problem

[DW5.0L]

I had my rear end rebuilt and added a 3.73 ford gear set. I have 650 miles on axle now. It doesn't make any noise while under load, but when you let off the accelerator to change gears or come to a stop, there is noticeable whine type noise from the rear end. It doesn't do it if you are under 25 mph. It even does it in neutral while coasting along.

The mechanic asked me if I was going to go to the track with the car, I replied occasionally. He said he set it up loose. When I asked him about it he said the noise was normal.

Does it take a while for the gears to break in so to speak and is this normal?

 

[SVT32VDOHC]

First of all I hope that he checked the back lash of the gears. That's where the pinion meshes with the ring gear.
Second of all...all Ford rear axles with Traction-Loc, posi..etc.....need friction modifier used along with the gear lube. Friction modifier is only 5-7 bucks a bottle and you only need one bottle per rear end. I think the bottles are like 4-5 ounces.

 

[DW5.0L]

I recently changed the oil and added the 4 oz of modifier. That didn't help.
Sounds like I need to take back to have everything checked out before the rear end goes out.

 

[chobracobra]

I think 3:73 spin faster than stock gears for a given rpm so whine is normal. I'm sure 4:11's whine even more. This is my guess

 

[dragnazz5.0]

you dont set it up loose for drag racing you just set it up differently. you want the wear pattern to be more towards the heel because the pinion pushes on the ring gear during hard acceleration and will actually move more with the instant force that is associated with drag racing

 

[Grn92LX]

Backlash is off or the pinion bearing preload is too loose.

Properly set up gears should NOT whine or make any noise. My 4.30's are nice ad quiet

 

[DW5.0L]

Thanks, I'll have those areas checked out. It doesn't seem normal to me.

 

[srothfuss]

My FRPP 3.73's are very quiet in all conditions of driving also

 

[90lxcoupe]

do you have stock bushings in your lower control arms? i have solid bushings in myne and that causes road noise to resonate into the interior, which could be mistaken for the gear whine. dunno if this applies to you but in my car its not very loud and i cant hear it over my exhaust

 

[SVT32VDOHC]

Backlash is off or the pinion bearing preload is too loose.

Properly set up gears should NOT whine or make any noise. My 4.30's are nice ad quiet

RIGHT!!!

 

[RYC CUKR]

I think 3:73 spin faster than stock gears for a given rpm so whine is normal. I'm sure 4:11's whine even more. This is my guess

My 4.10s are quiet as a church mouse. Whine is not normal and indicates that either backlash is off or they didn't preload the pinion correctly.