: Differential issues, going to dealer tomorrow. Need pep talk.

10-08-08, 07:20 PM
Alright, the car is a CPO 05 V with 32k on it(bought at 18k 6 months ago). At 80mph I can't even hear my own thoughts because at anything more then 5% throttle, the howl is unbearable. I am betting the ring/pinion have shifted inside the dif and is creating a not so favorable mateing.

Since I have an 05 and I hear the 06 was upgraded with better parts/dif. I am going to push for them to do the swap now, so I don't get stranded later. (I put anywhere from 15-25k on my cars a year.)

Here is the catch. I live in a city/state where the speed limit is 55-60. You don't hear it till 80. I am not gonna feel comfortable having a tech driving my car "wreckless" to test for the noise. Granted i know its not wreckless to drive at that speed but the cop that nabs him will...

How would you handle this? Dumb question but interested in hearing how others get it handled. Never really had to "fight" a dealer for a parts replacement before.

I also have another thread where i talk about a bad clunk I get when pushing in the clutch. not sure if I should bring it up this time or wait to see if it goes away if I get the new dif put in.

10-08-08, 07:26 PM
The clunk is related to the front diff bushing, which would get replaced with a new diff.

You don't hear any whine until 80 mph? Does it happen regardless of what gear you're in?

10-08-08, 07:46 PM
My own experience, as well as most of the differential whine-related posts I have seen on this forum, involved parital throttle at 40-50 mph speeds. I suspect that if you are hearing it at 80 mph it also exists at 40-50 mph but you may be accustomed to it. I suggest you try testing it with the center of the rear seat in both the up and folded-down positions. It should be more audible with the center folded down.

10-08-08, 07:47 PM
You don't hear any whine until 80 mph? Does it happen regardless of what gear you're in?

I'll bet he doesn't get it at 80 mph in 1st or 2nd!!! :hide:

10-08-08, 08:46 PM
Ya know, my last car was a subaru that I converted into "the ultimate sleeper". Stripped, no deadening, clutch pack differentials, metal to metal bushings, race triple plate clutch, A1000 fuel pump, fuel cell and lexan side windows(low 4 second 0-60, trapped in the mid 120s on 93 oct). So my ears are fairly deaf to the hum in the cadillac at lower speeds. I really only hear it "pronounced" at 80mph at very little throttle input. Thanks for the info though.

10-08-08, 09:17 PM
If you dont like what you hear, take it to another dealership. Just for the record 14k miles in 6 months?

10-08-08, 11:39 PM
Which dealer you taking it to? I took mine into Heritage Cadillac in Lombard a few months ago when I was livin in the Chi. I had some nice whine going on then and they told me it was "normal drivetrain noise". I get down here to sunny FL and a very nice dealer down here swapped me out for a fresh, whine free diff.

I talked to a service tech once and he told me that the tech has to hear the whine over climate control fans and normal conversation/radio, for it to be deemed "bad". I don't know that is the true test, but mine got to that point.

What drove me to try and get it replaced again was that recently my diff started to whine at speeds above 75 (sounds like your prob). Whining at that speed scared me as I wouldn't want a grenade at that speed. When I went in I just told the service advisor what was going on, whine with light throttle between 35-45 and that it started to whine at that high speed. I suggest that since you don't want them to be driving your car at that speed, just tell them the whining at high speeds feels unsafe.

Not sure if you will be able to read all this before you take it in, but good luck with the visit. I haven't ever had any problems with this new dealer, they are great. Just find a good dealer and you'll be fine.

Seattle CTS-V
10-09-08, 01:24 AM
If you dont like what you hear, take it to another dealership. Just for the record 14k miles in 6 months?

He meant that he purchased it for $18k, not at 18k miles...at least I hope so cuz that's a lot of driving and you'll get bed-sores (on your ass).

10-09-08, 02:02 AM
Hey, I wasn't lieing about putting anywhere from 15-25k a year on my cars. Bought it with 18k on the ODO this spring. Just rolled 32.3k today. I drive a lot for work. :burn:

Going to leave who I take my car too off the forums till things get settled. Never know what can happen or be taken out of context. But I have had good luck with my dealership with covering other issues I have had.

Thanks for the input guys. Hopefully I will report back saying I have a sweet new 06+ style rear end in the car along with no more whine.

10-09-08, 02:53 PM
Mine had the whine at 80 and beyond as well. Just more prominent then because you aren't revving through the gears or shifting often. ***Just remember to turn off your radio and all accessories when you drop it off. Once in a high gear at low speeds with light throttle...and she will hum. As 510 said the new diff comes with the new front bushing. helps alot with the clunk but doesnt eliminate it completely

10-09-08, 02:58 PM
My original '04 diff didn't make a peep...until it grenaded. The '06 model whined like crazy until I changed the fluid out to RedLine 75w90. Change out the fluid when you get it home, you won't even need additive (since it's in the RedLine already)

The diff bushing will help with the "clunk" for a little bit.....then it will slowly come back. I'm holding my breath for UUC to get their diff bushing into production....I'm turning blue!!:suspense:

10-10-08, 10:00 AM
I've got an 07 with 30k on it, had the front pinion seal taken care of earlier this year.. and my rear is whining like crazy anywhere between 30-80 at partial throttle... if i'm coasting at 40 in 4th, let off the gas... no whine... then barely put the gas on and it starts howling.... i've also got a bit of clunk when i push the clutch in at low speeds... probably time to visit Lindsay eh?

10-10-08, 03:29 PM
Well I am currently pimping a 3.6 09 CTS.
I gotta say, its response to steering input in way better then the V. The brakes (not surprising) suck. Overall, its a quieter car then the V but I hate where everything is placed in the car. The window controls are very low and out of the way. The arm rest on the door is slightly lower then I am used to on the V. I would say the only plus is, it seems more roomier then my V. All and all, if this is what the new V is like. I am going to keep my V1 and mod it till its faster then a v2. My V seems more comfortable then the new CTS.

10-16-08, 10:53 AM
update: The differential has been replaced!

Part numbers:
25873498: Carrier 5.505
15852707: Vent 5.387
11517996 Nut 8.917
11589264 Stud 8.981

10-16-08, 11:16 AM
update: The differential has been replaced!

Part numbers:
25873498: Carrier 5.505
15852707: Vent 5.387
11517996 Nut 8.917
11589264 Stud 8.981

ewill/luke: are these the part numbers you are using for replacements?

10-16-08, 11:19 AM
I got mine swapped couple weeks ago, but my list is different.

25873498 Carrier 5.505
15852707 Vent 5.387
89021677 Gear 8.800
1052358 Additive 8.800

My list has the fluid in it, but no nut and stud. What those be?

10-16-08, 12:04 PM
I'm willing to bet the tech broke them and needed to replace those parts.
I wonder why Gear and Additive is not in my list though. Hmm. Should I give him a ring?
What is SUPPOSED to be replaced? Did I get short ended?

10-16-08, 01:00 PM
I doubt they forgot to put fluid in yours, but I have read a few threads that stated that the additive was forgotten.

10-16-08, 08:59 PM
The "carrier" is the diff, Luke would have to verify the part number.

The new diff comes with no vent, thus the vent...
The "gear" is the gear oil, the 75W-90 synth lube for the diff.
The additive is a bottle of the friction modifier, that looks like a good list of parts to me.

Not sure what the "stud" and "Nut" thing is about... they must have broken a wheel stud or something.

10-23-08, 02:42 PM
Just an update.
Had to bring the car back in for service. Found a leak when peaking under the car while waiting for the woman to come out of the record store. Brought it in, an axle was improperly installed and was leaking a little fluid. They put a new seal in, new fluids and off I went. Launched as hard as I could a few blocks from the shop, to ensure proper installation... Besides massive wheel spin then transferring to wheel hop. Everything is back to normal.