ronb01ws6

iTrader: (3)

To my understanding the whine from the rear diff comes from the pinion and bearing. I was looking around and found a new regular cts diff that has 3.73's in it. It looks just like our diff and has the round driveshaft flange. Would it be advisable to purchase this diff and just pull the 6 or 8 screws holding in the pinion housing and install it on my diff? Looks like it should match right up. Im just looking to get rid of this whine which seems to be getting louder on the cheap. Has anyone tried this or will this work? Part number on the diff is 21992547.

Hostile03SVT

These are the Diffs that work in the V. this was posted in another thread by a member here.

Difference between 04/05 and 06/07 rear ends: http://www.cadillacforums.com/forums...erentials.html
1st Gen ---- 10368780
2nd Gen ---- 12378261
3rd Gen ----- 15793756
4th Gen----- 25873498

ronb01ws6

iTrader: (3)

I know the numbers of the diff for our cars Im just trying to swap out the pinion section to get rid of the whine noise and was wondering if this would work. Instead of shelling out $900 on a used diff or $1600 on a new one if I can spend $250 and get this new one and just swap out the pinion section and get rid of the noise that would be great.

Hostile03SVT

I wish I had that answer for ya bud. Is there anyway maybe you can call a dealer and see if they have a part number just for that pinion and see if it is the same number? I will tell you though your whining noise can also be the spider gears. If you do the pinion you will need to do the ring. You cant do one and not the other. The wear of the metals interchanged would cause a whine if not worse then before. Have you tried the cheaper way and going with maybe a heavier weight gear oil and add the friction modifier?

ronb01ws6

iTrader: (3)

I didnt go with a heavier weight, I just changed over to royal purple and put in the posi additive.

ronb01ws6

iTrader: (3)

And I only hear the whine on decel. If I am giving it any throttle at all the noise disappears. Thats why I figured it was the gears

Hostile03SVT

My rear does the same. But for some reason it is also shooting oil out of the vent tube. So I have a new 4th gen. diff I am installing soon. I didnt wanna get stuck with a broken rear one day or night. It might just pay to not risk the time and labor of changing the pinion, at that point your just doing guess work and putting a band aid on a boo boo, lol..

BudRacing

iTrader: (3)

Is the differential just as noisy when cold? Heat was a factor with my diff noise. I swapped the fluid to amsoil 75w90 with modifier and wrapped the exhaust pipes around it and the noise is now hardly noticeable.

lollygagger8

iTrader: (7)

It might help......for a little while. Then after a few good torque sessions (or spirited driving) the gears will distort again and the whine will come back. Sounds like a waste of time to me. If you want to get rid of the whine, get a 9" or 8.8".

These rear ends were designed for Pontiac Soltices, and should've never been even close to the same room as the V.

punishmentcycle

iTrader: (6)

the more you abuse these diffs the more the case distorts..whats actually causing the whine is the backlash becomes bigger and bigger as the case expands. my last gen 4 was getting worse and worse and when in finally broke another CV it cracked the case. i pulled the side cover ad checked the backlash for haha's and its almost .20..which is crazy

punishmentcycle

iTrader: (6)

just for the record..im not sure of the factory set backlash but on an 8.8 its supooed to be .06-.08 backlash

z28C4maro82z

iTrader: (33)

Almost every rear in these cars whine. It's part of owning a CTS-V. I've had 2 of them, and both whine

Cadzilla

iTrader: (3)

I'm not worried about my rear breaking seeing as only 80 hp makes it to the f7cking wheels.