Romano

Hey guys i put in 3.73's in the 07'. Im getting gear whine... or more like a slight gear hummmm. Its really not that bad, buti guess its not good. My question is if i leave it alone, am i going to run into trouble. Im not getting any chatter and it feels good. I tossed in a shim kit and bearing kit along with the purple stuff. Lemme know i dont wanna f*** up the car. [&:]

CrazyHorse0217

I don't think I would settle for that. What kind of gears? None of them should whine with a good install, but Motives are a mother to install.

Romano

frp

modular81

When you say purple stuff are you meaning royal purple synthetic gear lube. If so i've heard that you need to put in motorcraft's friction modifier as well because rp doesn't have enough in it. I'm not speaking from my own experience this i just what i've read on different forums. Maybe some else can chime in on the subject.

zx9rpilot

Yes, gotta use the friction modifier in the rear end. My Motives have made noise since day #1. Have pulles the cover and checked the pattern twice and it's fine. Have changed the fluid three times with no visible metal.

I have heard that the Ford Racing gears are almost silent, FYI.

mustangman02232

all helical cut gears are silent

bad install

Romano

Yeah royal purple..... Whats up with the friction modifier? Whats the brand, where do i get it and how much of it do i use?

Daniel60

My stock gears whined a little bit. FFFFFFFFFFForgetaaaaaaaaaaaboutittttttttttt.

Blair

My stock gears whined too. I bought a set of FRP 3.73s and had them installed by a "reputable" Ford shop and they whined like crazy... very loud at certain speeds. I bought a second set and did my homework about installers and went to a recommended 4x4 and offroad shop. Offroad shops do a lot of differential work and gear swaps. The service guys definately knew what they were doing. They showed me the pattern and the measurements were all in spec... and these new gears whine just exactly the same as the stock ones did... Go figure. I am also currently using Royal Purple gear oil which is on the light side. I am thinking about trying some Red Line Shockproof gear oil asI read on here that it helped reducegear whine.

Romano

I called up redline and spoke with some tech guy. He said not to use the shockproof and stick with the 75w 140... although people keep saying use the shock proof.....