2004-2007 Cadillac CTS-V General Discussion Discussion, Rubbing, Scraping Noise from Rear End??? in Cadillac CTS-V Series Forum - 2004 - 2007; V is at the dealer (again) because of a rubbing, scraping noise I get when I turn the wheel--especially at ...
V is at the dealer (again) because of a rubbing, scraping noise I get when I turn the wheel--especially at low speeds and it's most noticeable when I first drive the car in the morning.
The dealer now says that it thinks its the rear differential. Didn't sound like it was coming from there (I thought it was from the front). But it could make sense since the first time I noticed this was when I got my car back from having the differential replaced by the dealer.
Did they put the limited slip additive in the new diff? If not (or not enough) it will make a noise like you are describing. In an empty parking lot, do some figure 8s - it'll make a ton of noise if it needs additive.
I have the same thoughts as Stealth. I had my rear end diff fluid changed, the mechanic forgot to put in the additive and after a 200 mile round trip to the Jersey shore, my rear had all the same symptom's you are describing.
Some believe you can just throw in some more additive and it should be OK, but mine did not. They changed the diff fluid again, put in the additive and the car got progressivly worse. Thats when the dealer ordered a new rear...
Someone did establish that once the rear is run without the additive, for some period of time, damage does occur.
Anyway, I got a new rear and all noise, grinding problems went away...
I had a similar experience when the service department forgot the additive. The noise during slow turns was the same as you describe and after about 200 miles they ended up having to replace the rear differential.
If the V doesn't have the limited slip additive, the clutches inside the differential basically grind themselves to pieces. That in itself isn't the end of the world as it would just cause the classic "one-wheel-wonder" during a burnout. The downside is all the extremely hard carbon clutch material is floating around in the differential lube, eating away the gears and bearings.