Mercutio

Recently my 05 V started making a grinding noise that sounds as if it's coming from the rear wheels. It only happens while turning fairly tightly, and it only happens while going forward, not reverse. There's nothing obviously loose or rubbing that I could see.

The car has 65,000 miles on it. I really hope it's not the diff, but it seems like a possibility. Any other ideas? Wheel bearings?

raven154

iTrader: (14)

Have you changed the fluid in the diff lately?

Mercutio

Yes, perhaps 2,000 miles ago.

raven154

iTrader: (14)

Did you put any limited slip additive with the new fluid? That is most likely the cause. Even if you put some in that already had it, you should add another 8 oz of gm additive or similar. For some reason the V diff doesn't really like the additive that comes in most HD gear oils for LSD's.

nikon

iTrader: (2)

Does if feels as though the diff is binding at all? If so ravens right.

Mercutio

The dealer is actually the one who changed the fluid, so I can't be sure what they actually did...I'd like to think they put in the additive, but who knows.

raven154

iTrader: (14)

I wouldn't bet on the dealer to add it. They aren't uses to working on V's.

Mercutio

I guess I'll try draining and replacing the fluid and adding friction modifier. What's the proper weight gear oil? 75-90?

z28poweredlt1

iTrader: (1)

Most of the RWD cars that they work on require a diff additive, I used to work at a dealer and I highly doubt that they forgot it.

But then again, you never know!

raven154

iTrader: (14)

Most CTS's don't have LSD's in them and the service manual fails to mention the addition of limited slip additive for the V so most likely, they left it out. Especially since this just started after a fluid change of the rear end.

z28poweredlt1

iTrader: (1)

Hence why I said RWD cars, I think they'd notice that there werent working on the normal FWD CTS.

raven154

iTrader: (14)

All CTS's are rwd. Yes even the regular ol V6 cars are rwd.

z28poweredlt1

iTrader: (1)

Ahh for some reason I thought the base model was a FWD. Mabad. Did they have an 4wd model or something? Could have sworn there was an option or something.

raven154

iTrader: (14)

I know thay make a 2nd gen AWD CTS but cant recall if they made one out of the first gen.

Mercutio

What's the proper weight gear oil?

raven154

iTrader: (14)

75 90

1actsv

I have had the same issue for a couple of months. Thanks for the information.

Mercutio

Those who suggested friction modifier were right. I replaced the fluid and added the LSD additive and the grinding is gone. Thank you for your help.

Score: LS1tech 1; Caddy dealer, 0.

z28poweredlt1

iTrader: (1)

Very nice!

Dakota Kemp

when I take off from a stop it almost sounds like a grinding sound from the read end. But it goes away after second gear. I haven’t had to on lift and tore down yet. But I hoping it’s not a transmission.