What could the possible reasons be for a low tone oscilating noise coming from the rear end? I can hear it pretty well any time I'm going over about 35mph.

I had thought that it might be the wheel bearing on the passenger side, but I have not had the time to dig into that to rule it out yet.

I'm wondering if it might be the differential itself?

If anyone has any clue, please help me out.

Thanks,
BrianHeston

 

I had a similar sound once on my 80. Turned out to be the nuts at the driveshaft to pinion flange were loose. I tightened them and it went away. May also wanna check to make sure your lugstuds are tight. I have seen another case of noise back there be nothing more than loose lugstuds.

Good luck and hope it isn't bearings,
James

 

when the drive shaft bolts are loose it usaly sounds like a THUMP when ever u take off. and i know all about loose lug nuts

and with the diff, usaly that noise starts off loud and the faster u get the less noise it makes, untill u start slowing down and it starts up agian..

if it sounds like a dry scraping sounds then im guessing it is ur bearing

 

Mine never went clunk. Just a low pitched vibration. As far as loose lugnuts, the 79 I bought was sold to me with the owner thinking the diff was going out due to the sounds it was making. Again, a vibration though only on decelleration or at cruise. I never said that this was the answer to his problem, just told him to check those things to make sure so back at you.

 

sorry didnt wana make it sound like i was having a go at u.. just what ive noticed from my personal experince..
and like u said, go around the rear of the car and tighten everybolt. it ight very well be only a lose bolt.

 

maybe a ceased uni joint, i have just replaced one of mine but at certain speeds it caused the whole car to shake.

 

The wierd thing about it is that there doesn't seem to be any vibration, just the noise. I'll do my best to check for loose nuts & bolts in the next day or two.

Thanks for the quick responses guys. I'll keep you posted.

BrianHeston

 

I know this might sound a little funny, but have you checked the gear oil in it recently? If its low, the diff will whine at cruise speeds.

 

My rear end started making a high pitched droan sound every once in a while from the rear end.... chaecked the rear diff fluid and it as low...... filled it up and it went away...

 

I haven't check the diff fluid yet. That is definately on the list. Just gotta find time in the middle of packing for my move. I really want to figure out if I can fix this before I move so that I can decide whether to sell it or not. I afraid to tow it with that noise, and don't know if I can afford to trailer it.

Thanks for the input guys, as always, it's been quick, and sounds right on the mark.

I'll let you guys know.
BrianHeston

 

Well, I checked the diff fluid, and to my amazement, not only was it totally full, but it was super clean as well. While I was under there I decided to check the tranny also, and it too was very clean. The tranny was a little low however, and now with maybe a half quart more fluid in it, she shifts so much smoother.

Unfortunately, what this all means as far as the mystery noise goes, is that I'm probably going to have to change out those bearings.

Thanks for the help guys,
BrianHeston

 

http://mazdatrix.com/g2.htm
Transmission / Differential Trouble Shooting

have fun!

 

Hmmm. I wonder if a guy should add some MMO to the transmission? Would it smooth shifting, or would it defeat the synchros by reducing sync friction?

B

 

The diff is full of gear lube...is it synthetic and changed recently? If it was... the howling/oscilating noise is probably telling you that the diff bearings are going bye bye.

 

go to hell james, you rat bastard.

 

Go outside and double check the lugnuts on your S5. I don't have the money to buy it should its diff start going out!!