: How much is acceptable rear gear whine?



Slithering_Joe
11-01-08, 11:44 PM
I just bought my '05 V last week (Oct 25) with 24,800 miles on it and it has the balance of the factory warranty that runs out at Sept '09 or 50,000 miles. All this talk here about the vulnerability of the '04/'05 differentials has made my ears more prone to sounds. I know there are some acceptable levels of sound from a hypoid gear set but I don't remember ever paying so much attention to a rear axle before or the sounds they may make. While inside the vehicle, I'm experiencing an ever-so-slight "hum" that comes from the rear area that changes with road speed. It only hums if there is a load on the axle and the frequency is dependent on road speed. It doesn't hum when coasting and it is independent to what gear the transmission is in. The volume or loudness of the hum does not change no matter how much of a load is on the rear. In fact, it is hard to hear the hum once you get to a certain RPM since the engine sound overcomes the hum. Because of this I don't think there may be a problem but since it being a Cadillac, I would expect more and I shouldn't really hear anything. I never really noticed how much noise a "normal" rear makes.

Does this sound normal to you? Should it be a concern? I know if I take it to a dealership, they won't hear anything.
Those of you that have had catastophic failures of their differentials, what kinds of early warnings did you get?

Thanks for any advice, comments and/or tips given.

mgscustomtune
11-02-08, 01:52 AM
It is amazing the talk about the rear ends. There should be a total recall to pull rear ends out of the 04,05,06 and be replaced with an 07 differentials. It does more damage than good in the long run for Caddilac to have this problem out there. Joe take your car in have them replace the rear end with a 07. Or you will fall into what so many here have that is GM does a patch to gets the car by until its out of warranty then you are screwed $$$$$.. If Cadillac had some people with balls rather than golf balls come to our web site read the problems they would turn the corner and start gaining sales from back from there competitors. I have $1500.00 sitting just waiting to do my differential when it fails talk about seeing the future.

rand49er
11-02-08, 07:25 AM
Doesn't sound too bad to me. Do you know for sure that it hasn't ever been changed out before?

Slithering_Joe
11-02-08, 08:08 AM
mgscustomtune, have you noticed that your diff 'hums' and that is why you are putting money aside?



Doesn't sound too bad to me. Do you know for sure that it hasn't ever been changed out before?

The only GM warranty service history that was printed when I bought it was:
- Reprogramming of the PCM (curious what that was all about)
- Resurfacing the rotors (great, couldn't replacement them huh?)

I'll be going to the dealership soon to pick up a new chrome hood trim since the chrome is blistering. While I am there, I will see what they can do for me about replacing the navi/radio buttons and knobs, and the memory switch. Those parts have the label paint chipping/flaking off and looks like crap. I'll also have them look at the differential. On a good note, there's no signs of leaks.

Anybody else have any comments about my differential 'experience?'

mgscustomtune
11-02-08, 09:44 AM
Yes that is exact reason l have the money set aside never mind the all the complaints l read on the site.

YoshiV
11-02-08, 09:53 AM
It sounds okay to me. The original diff in my 05 has 43K on it and sounds just like yours, hums a little under load but don't they all. I run Royal Purple gear lube in mine to keep it in good shape. I did have the front pinion seal replaced because it was leaking...there is a national recall for that so you don't even have to worry about warranty.

NormV
11-02-08, 09:54 AM
The dealership will do nothing but flush the fluid, which I would recommend if you do not know the history. Other than that you can add sound deadening, turn up the radio, or run 75w140/84w140(instead of 75w90 stock stuff) weight in the diff. There is no measurable effect on gas mileage.

Norm

YoshiV
11-02-08, 10:00 AM
I'm still running 75W90 in mine.

rb1
11-02-08, 10:02 AM
Mine has the origional diff with almost 80,000 miles. I.ve been listening to the diff like crazy ever since I bought it. It hums - sometimes under load - sometimes when I let off. I wouldn't say it's a whine though. Pinion seal was replaced in May. Thinking about the heavier weight oil now though.

Izzmeister
11-04-08, 04:49 PM
I have an 07 34k miles and my rear is definitely humming louder than when I bought it. I had the seal replaced already, it hums loudly when i cut the wheel all the way and turn the car in circles slowly. I think my tranny is a little noisy too...

BeastMaster
11-04-08, 05:47 PM
When I had to get mine replaced ( 5 times). I always waited until the whine was loud enough to hear over a normal volume (for a 50+ year old) on the radio, or it was dificult to hold a conversation. I believe it was always the worst between 30 and 50 mph under a light load.

Good Luck

Slithering_Joe
11-07-08, 12:13 PM
Over the last week I stacked on about 300 miles. While on the turnpike with the cruise control on I could hear this 'ring' or whine over a normal volume level on the radio. It was driving me nuts. This morning I went down to the dealership to address the chrome pealing off of the hood trim, the flaking off of the radio/GPS buttons and the "1-2" memory select button. I brought up the rear whine sound and they took it for a ride Well their response in short form was: "The bearings are bad and it's going to need a new differential assembly. We placed an order to get one." Hopefully, the replacement diffs are available and not on backorder. I asked him if the diff was the newer spec'ed ones and he said yes. On another positive note, they replaced the chrome hood trim and will be replacing the buttons when the diff comes in.

I hate taking my car in for service. There is always a new scratch or new ding that occurs. Thankfully, this recent visit was no problem.

DansCTSV
11-07-08, 01:00 PM
It seems that the dealerships are more willing to replace the diff's lately. Not sure why, maybe they need the work. See my recent thread. My diff was just replaced for whine but they didn't add the limited slip additive. So you can save yourself a trip by reminding them to put it in.

Also I had my car back in 2 days, so the diffs seem to be in stock. Unless I got the last one...

Slithering_Joe
11-07-08, 03:08 PM
The problem with telling a service writer or the mechanic on how to do the job makes me feel like a "know it-all" and they really don't pay attention anyway. Even if you remind them to pour in the LSD additive, they can always say they did it when they didn't. Taking my car in to the shop makes me crazy.

Another thing I noticed in my car is when you would make slow, underload, full-lock turn the rear would rumble noticeably. A sure sign of a worn or bad differential clutch pack. I've had to deal with that in the Ford 8.8" rears and they were easily fixed with a $60 kit.

lollygagger8
11-07-08, 03:29 PM
Bottomline: NOBODY cares about your car as much as you do.

Change out the diff fluid with RedLine, Amsoil, Mobil 1, RP (your choice) and it should quiet down. I used 75w90 Redline and it shut the hell up. Make sure if you use a particular brand, it has the LSD added in it already. If not, buy the additive, and pour it in BEFORE the regular diff fluid. That way you make sure you use the entire bottle of LSD.

Use anything but the crappy/loud/expensive/wanna be grape smelling GM fluid.

FactoryFast
11-08-08, 12:47 AM
Ive been driving my car for two weeks now (1K) and the drive train is noisy. I hear the trans and the diff whine. The car has 27K on it right now. If this is normal operation after a few different dealership opinions then im going to look into the aftermarket. Sometimes thats the only logical solution.

Cowan480
11-08-08, 12:55 AM
I have the same wine or humm coming from mine.. Never had a problem with my diff.. plus all my mods since June08...

Do I need to change the fluid in the rear end? if so, whats the best fluid??

Slithering_Joe
11-15-08, 04:15 PM
Had my rear diff replaced under warranty. Much much quieter than before. No more rumble either.

Kurlee Daddee
11-17-08, 10:30 AM
Another thing I noticed in my car is when you would make slow, underload, full-lock turn the rear would rumble noticeably. A sure sign of a worn or bad differential clutch pack. I've had to deal with that in the Ford 8.8" rears and they were easily fixed with a $60 kit.


I don't hear that loud of a whine in the rear all that much, but I think I hear something similar every morning. When I take a 180 degree turn off the offramp of the freeway onto the main road on my way to work, it feels like the diff doesn't want to unlock when the car is eventually straight. Does the V have a LSD in the rear diff? The reason I ask is I put a locking diff in my Toyota 4x4, and when I go around the same turn, it feels the same like it is not dis-engaging.

Vee
11-17-08, 11:17 AM
Besides, as I understand it, any '04's, '05's, or '06's will get an '07 rear if replaced automatically.

Slithering_Joe
11-17-08, 01:07 PM
I don't hear that loud of a whine in the rear all that much, but I think I hear something similar every morning. When I take a 180 degree turn off the offramp of the freeway onto the main road on my way to work, it feels like the diff doesn't want to unlock when the car is eventually straight. Does the V have a LSD in the rear diff? The reason I ask is I put a locking diff in my Toyota 4x4, and when I go around the same turn, it feels the same like it is not dis-engaging.


clutch style limited-slip.