MikeVistaBlue06

I hear just a smidge of whine with these gears. I looked up the part number at Ford and here is what they say:

http://www.fordracingparts.com/parts...tKeyField=5701

Replaces our popular M-4209-F373. New manufacturing technology utilizing a Face Hob Process which features a single pass pinion tooth machining operation compared to a conventional three pass process for machining. CNC cut and lapped gear teeth. Higher strength and better quality gears are produced with the Face Hob Process. NOTE: These new gears look a little different, the gear teeth are cut on a different angle and the ring gear has a bevel on the back of the gear.

I just wonder if these gear teeth cut at a different angle is the deal?

Just curious.

281GT

What ratio? I assume by the part numer that it's a 3.73? Numerically higher ratios have a tendancy to whine more so than numercially lower ratios. The gears might not be set up correctly and then you will get some noise fur sure. IF this is the case the gears also will not wear correctly and you will have bigger problems down the road.
Despite the fact that numerically higher ratios will tend to make a little noise, I have been able to get 3.73 and 4.11 ratios to be almost silent, so I would remove the cover and check the contact pattern. If the contact pattern looks ok you'll just have to live with the whine.

randy78045

I have a Moser assembled center section (I assume it's put together right) and got noise after changing the control arms. They claim that suspension changes can cause this. Don't know but I don't like it.... [sm=pimp.gif]

281GT

Oh God don't assume anything. Better safe than sorry. Remove the cover and check the pattern. Assuming that you didn't have the noise prior to changing control arms though, the diff is probably alright. The stiffer control arms will tend to transmit noise better, so it might have something to do with that. The noise was probably there all the time but it wasn't loud enough to hear before you swapped control arms. Now with the stiffer control arms, the sound is being transmitted to the body of the car. At any rate it's been my experience that some rear axles will whine a little with ratios numerically higher than 3.50 so you might just have to live with it.

351PONY

When I ordered my gears from BrenSpeed (4.10) he mentioned that the Ford Racing Parts gears are a bit noisy and suggested I go with the Motive Performance gears instead. So I suspect this 'new technology' is what's causing the slight whine you're hearing. As 281GT said, I'd just take the precaution of removing the cover and checking the contact pattern.

MikeVistaBlue06

Thanks for all the inputs. I am going to drive it a good bit today and see if the vibration in the driveshaft has gone away and also listen to the whine. Both seem to be worse when the car is at normal operating temperature.

It was raining yesterday and those 18" wheels sure make a lot of noise on wet pavement. Today it is nice and sunny so I can hear much better what the car is trying to tell me!

Thx,

Mike

RyanAcosta

Ive got FRPP 4:10's and did notice a very very quiet whine, I don't really notice it anymore but it could just be that I'm used to it, either way it's insignificant and doesn't pose a problem.