Conditioner for rear end

**cruzincamaro** · 05-13-2012, 04:15 PM

Had a prob with a rattle up front. With the help of the forum, narrowed it down to frt. sway bar end links. Changed them, no sound up frt, but the frt rattle covered up the rattle in back. Changed rear end links, sound still there. Happens when making slow turns. Asked a friend who also runs a repair shop, about it. He seems to think its the rear end ltd slip unit. He claims, changing the oil and adding GM rear end conditioner will clear it up. Any thoughts from anyone?????

**pajeff02** · 05-13-2012, 06:08 PM

Rattles out back can be the heat shields or the exhaust where it goes over top of the rear axle.

There is a bulletin for Torsen rears that states that a "rusty screw" noise may sometimes occur and that the fix is to use limited slip additive in the rear. Not sure why it would work as it is a gear type posi, however, that is what it states.

**INMY01TA** · 05-13-2012, 06:53 PM

The rear end noise is normal. There's a TSB out calling for changing the fluid however it did nothing to help mine. It's called the can of marbles or marbles in a box noise. Good info here.

**2002ssslp** · 05-13-2012, 07:24 PM

Originally Posted by INMY01TA

The rear end noise is normal. There's a TSB out calling for changing the fluid however it did nothing to help mine. It's called the can of marbles or marbles in a box noise. Good info here.

rear end noise (marbles in a box) - LS1TECH

Good stuff. Nice to know that is a normal sound. It should save alot of people alot of money on repairs that do not need to be done.

**INMY01TA** · 05-13-2012, 07:33 PM

Ya notice that thread started back in 2003 I think. Was kind of an issue back then but most have swapped the stock rear out by now.

**pajeff02** · 05-14-2012, 03:21 AM

Had to go and find this from a prior thread.

Here is the quote from Torsen's website: GM issued a technical bulletin adding modifier to the rear axle oil. This was done to quiet what we call a "Rusty Screw" noise that we heard in a very small percentage of vehicles. This does not happen in all cases, however to address owner's concerns we asked that the modifier be used in all instances to insure that the driver would not get this noise. When replacing the fluid it is at the owner's discretion whether or not to add the modifier. Elimination of the modifier does not affect durability of the differential.