Differential Whine (SOLVED)

[Whelan]

Would I like some whiiiiiine with my cheese? Why yes, thank you.My 2005 Matrix XR AWD with 126k on the clocker now has a symphany when driving. I get a nice whine from the back which can only mean the differential. It eminates through my car turning it into a tuning fork.Anyways, I'd like some thoughts on this. Could it be that it just needs a fluid change, hopefully?Saw the other posts, am dissapoint I have been holding out for the upcoming Focus ST. What are the issues with not doing anything?

[Salsa Guy]

Sorry to hear that. When did you last change the fluid? Or check the seals? I only ask these question out of research on my car.

[neebishis]

Whelan.....I cannot speak specifically to a Matrix rear end, but generally when a 3rd member gets to whining, its going to need much more than a fluid change. You've most likely got ring and pinion gear noise caused by a bad bearing which has thrown the mesh of these gears out of specs.....and only replacing or rebuilding will cure the noise. If its a high pitched, rapid whine, its most likely one of the pinion gear bearings gone bad......the pinion is turning close to 4 times faster than the ring gear bearings. Cause??...could easy have been run low on gear lube, or just a defective bearing.

[northvibe]

mmmm focus ST hmm ya check the oil first. have you ever changed it during the life? but what about wheel bearings?

[jimincalif]

If it is the rear end it probably is a bearing. Might as well try to change the lube, but don't get your hopes up.If you do nothing, the worn bearing and out of spec clearances can lead to a chipped tooth on the pinion gear. Then you need a new ring and pinion set, as well as bearings and a rebuild.

[Whelan]

I did a little more investigating yesterday. I got home and popped the rear up on the jack and spun the driver rear tire. I noticed two things while spinning as fast as I could.1) Tires spun in opposite direction = no LSD, I learned something new today.2) No sound noticeable.I went to the passenger rear and started spinning. Then I heard it, the wheel made a sound that was similar to a misaligned brake pad that rubs each rotation. As I spun faster (as fast as a person could), it was more noticeable.I then took it for a ride, rolled up the windows found a long road with no one around, sped up to about 50 and let off the gas. Leaning my ear to the drivers side back I could barely hear anything, but when I turned my listening to the passenger side. I could definitely tell it wasn't coming from the center where the differential is, it was the passenger side. I also listened carefully and it's not so much a whine anymore as it sounds like a grind (i.e. the brake pad noise happening rappidly as the wheel rotates). So I am pretty certain at this point that it's not the differential and most likely a wheel bearing from the passenger rear. Would you concur? I have to drive to work the rest of the week and am swinging by the shop today for them to check it out. Hopefully I can get it to them Saturday for a fix. I'd much rather pay for a bearing than a differential.

[Salsa Guy]

Hope that's is all it is.

[jimincalif]

Agree, that does sound more like a wheel bearing.

[808 Vibes]

Quote, originally posted by Whelan »I'd much rather pay for a bearing than a differential.Actually, they both get replaced.

[Whelan]

UPDATE:Car is going in this afternoon for a look. The noise has not gotten any worse thankfully, and I tried another home test. I drove it to about 40mph then let off the gas. I shifted it into Neutral and the noise was still there. Again helping to confirm that it is not anything with the drivetrain itself.

[Whelan]

After a good test drive and checking out, the conclusion is that nothing is wrong. It must be my own batty self. I used to have the cargo cover on which made the car much quieter, and since having it off, the typical little whine that comes from the car under normal circumstances just echos more than I must have been used too. She is still going in for brakes and a oil/differential fluid change (would do myself, but since it's in, they can handle it). I'm going to put the cargo cover back in this week too. He was actually amazed at how well the car was holding up for 126,000 miles. Shocks/struts were still mint, tranny was solid, engine was quiet. He noted how it by no means felt like it had mileage on it. Made me proud.

[Salsa Guy]

You may want to do a fluid upgrade and get the Transfer case while your at it.