i've read some threads about whining around 50 mph and a lot say its the transfercase...

when I'm in 5th gear cruising around 50mph at light loads around 2k rpm it'll make a bit of a whining noise. It's not annoying, but it is noticeable andI want to address it before something bad happens... is it fluids?

 

Is it very faint where most people wont notice but you notice it because its your car and you drive it daily? And it happens right around the 50-55 mph zone with just enough throttle to keep the car's cruising speed..

I have the same issue for close to 3 years now. I originally thought it was the transmission so I got a shep Street strip trans. Well I also had a 5th gear grind to that I wanted addressed. However it was not the transmission. Later on I found that it is actually the rear diff. Damn problem with the evo is the chassis makes everything sound like its coming from the middle or front of the car. But its the rear diff and it started way back when I did a launch with 700 lbs of driver+passengers in the car and the damp road caused a lot of wheel hop.

I dont know what it is exactly, maybe a slightly chipped tooth or cracked tooth, or can a damaged shim cause it? No out of the ordinary shavings in the oil either. I've been using either OEM fluid or amsoil and no other issues for 3 years (25k miles added) daily driver.

 

Yeah it's just like how you described it! Nobody notices... but since it's my car I notice lol

I haven't launched the car yet but I'm sure the previous owner did, I bought it used with about 50k

 

yeah i get a lot of rear diff whining, that could be it too - something with the harmonics makes mine come up around 40mph though - and then REALLY whines at 75mph

 

bump

anyone know if this is a problem to be concerned with?

 

I would need to hear it but I think it may be normal. If Im on the highway cruising and feathering the throttle I hear the rear diff gears "floating" and causing a rattling humming type noise. That would be normal to me

 

It seems like you just recently got this car. You'll realize over time that Evos make a bunch of little weird sounds. Mostly because the chassis is really stiff and the drivetrain is really beefy. your diff sound seems normal. The bad whine from the T-case is noticeable to passengers and will get higher with speed.