My RX-8 seems to have developed axle whine over the past 6 months. It never exhibited this problem during the first 12 months or so of ownership. It seems to be much more pronounced during cold and wet road conditions, though I have no idea why since the diff case is sealed.

The problem seems to be the worst at 40-50 mph under under light to moderate throttle application. The whine is not very audible during coastdown and disappears altogether when in neutral coastdown. The problem is not very reproducable except in the cold and wet conditions I described, so demonstrating it to the dealer would be difficult.

I want to know if anyone else feels that his/her RX-8 exhibits objectionable axle whine. If you're unsure what axle whine is, it is a "whiny" sound that seems to emanate from the rear of the vehicle (differential) and should be most noticeable when there is a load on the driveline (light to moderate throttle, or coastdown while in gear). The pitch of the whine should increase or decrease proportionally with vehicle speed, and should disappear with clutch pedal fully depressed or transmission in neutral while coasting down. Don't confuse this with transmission gear whine which should sound like it is originating in the transmission.

 

I had a Miata that had the same problem, mine whined in the 30's . I brought it to a dealership and they said it was normal. I had a friend of mine look at it and he said the rear end was not properly broken in and that was causing the whine, he said normally it was caused from high speed cruising at the same speed for a prolonged time (ie cruise control). I noticed it after about 15K miles.

 

I am pretty sure its your tires. My winter tires on this car and all other cars that I have had make a similar tpe of whine, especially in the rain and snow.

I wouldn't worry too much. If it was your differential I think you would not only hear it but feel all the time.

 

I would also suggest that you consider the tires as the source of the noise. However, It wouldn't hurt to change your diff and tranny oils to a synthetic like Red Line. May not eliminate the noise, but then again, it might, but your diff and tranny will appreciate it in either case.

 

Since the whine is gone with the clutch dis-engaged, that eliminates the tires being the potential culprit

 

I have a whine in the rear end that started with 500 miles on the car. I think it was caused by cold weather conditions. I immediately changed to Red Line lubricants but the whine did not change in the slightest. The intensity of the whine is outside temperature dependent and has not increased in two months. I have written it off as a minor annoyance.
My whine is at the frequency of a dental drill and seems to occur when in 6th gear and 65 mph. The sounds seems to come from the rear and not from the transmission.

 

Yeah it's definitely not the tires--I'm an NVH engineer I know what the source of axle whine is. I'm just wondering how common it is in this car. You won't feel axle whine--the frequency is too high. Basically the whine is the result of individual gear teeth meshing together. If there are X number of teeth on the offending gear and the gear is turning at 600 rpm, you'll get a fundamental frequency of 60X Hz. So for 20 teeth, that's 1200 Hz, which is far outside the range of tactile vibration.

 

OK! Can't argue with your credentials!

 

Mine does it really bad on the coastside, don't hear it on the powerside. I'm going to try some high quality sinthetic gear oils for the diff and tranny... I've heard this can help.