Anyone have a groan in the rear when backing out in the morning?

I noticed it a few days ago. When cold, I get a groan when backing out of the driveway in the morning and going from R to D. I got it last night too after leaving from a golf outing and backing out of the parking space.

My first step is to get the dealer to change the rear fluid and see if that helps. 9k miles on the clock by the way.

Anyone else notice or hear this at all?

Have the dealer use Dexron LS synthetic lube. If it's the rear end plates making noise, this should fix it.

I have a TBSS that has a TSB with this new lube as a fix. I had it done due to the rear end becoming very noisy at 2000 miles and it is now totally quiet. Also, you don't have to use limited slip additive (actually it's not recommended) with this fluid.

Another plus, you don't have to worry about the dealer voiding your powertrain warranty for not using GM fluid.

Kadonny,

I had the same issue and I took it in and the dealer flushed it out and filled the rear end with fresh fluid and additive under warranty. The problem is gone and has not returned.

The fluid in your rear end is most likely low or isn't doing it's job of lubricating any longer. I would take it in as soon as possible to minimize any damage to your rear gears.

SG

Wonder if it will generate a TSB like in the Getrags of the older V series ?

Thanks SG, gonna call them today and get it in early next week.

Kadonny,

You are welcome! That's what makes this forum priceless! We all have something to contribute.

SG

I did a rear diff service last week and it quieted down. The fluid level was low.

Did it at 5200 miles

I heard it within my first 100 miles. I had the diff changed at like 500 and than 2k.

What is the factory fill lube for the rear end? Is it this Dexron LS synthetic lube mentioned above or some other fluid (as is this other one synthetic as well)?

What is the factory fill lube for the rear end? Is it this Dexron LS synthetic lube mentioned above or some other fluid (as is this other one synthetic as well)?

For the 2009 CTS-V, I believe you will need GM's rear axle gear lubricant 80w90 and the GM LSA to eliminate chatter, grinding and groaning. Check your owner's manual for exactly what fluids you need and I would recommend sticking with the GM factory fluids for the rear end.

SG

They wanted it asap. Taking it in this afternoon. No noise this morning (of course) but I am going to insist on changing the fluid, not just topping off.

Again, thanks. Will report back.

Have the dealer use Dexron LS synthetic lube. If it's the rear end plates making noise, this should fix it.

I have a TBSS that has a TSB with this new lube as a fix. I had it done due to the rear end becoming very noisy at 2000 miles and it is now totally quiet. Also, you don't have to use limited slip additive (actually it's not recommended) with this fluid.

Another plus, you don't have to worry about the dealer voiding your powertrain warranty for not using GM fluid.


Are we talking about a 2009 V here? I have a whine in mine and over the phone the dealer said he see's nothing concerning the 09 V models. They are going to check it out in the morning. 2000 miles seems you're talking 09, do you have a TSB number for the new lube fix? TIA, Roger.

RogersV, got it drained and filled yesterday. Have your dealer look it up. I was told that a TSB is coming out shortly regarding the problem, so it is well known....and yes it's an 09 V2.

Here is my write up:

Confirmed condition. Limited slip clutch plates making noise. Drained fluid and inspected. Found no foreign matter in fluid. Refilled differential with 2.3 ounces of limited slip additive and 1.37 qts of gear lube. Road tested, noise gone.

Noise is gone.

I doubt the rear end is going to be EVER considered crap in this car. I have put mine thru 10,000 times more abuse than the V1 rear and i havent had a problem yet. I could break a stock v1 rear on one launch at the drag strip. I gave up counting how many my 09 has done.... :D

Fluids, are another thing. We just need to make sure all the bolts are tight in the rear, and we need to make sure that the diff is filled to the right spot. Then all is good!

Man, this brings back memories. The '05 Vettes suffered from this same problem with the added kick that the plates would stick and the rear sounded like it was snapping, very scary. Same service bulletin as V2, drain and change fluids, except we had to also change out the clutch pack but problem was solved.

RogersV, got it drained and filled yesterday. Have your dealer look it up. I was told that a TSB is coming out shortly regarding the problem, so it is well known....and yes it's an 09 V2.

Here is my write up:

Confirmed condition. Limited slip clutch plates making noise. Drained fluid and inspected. Found no foreign matter in fluid. Refilled differential with 2.3 ounces of limited slip additive and 1.37 qts of gear lube. Road tested, noise gone. Noise is gone.

Kadonny: Thanks for the info. I just returned from the dealer and they performed the same fix as you described. While the whine seems to have gone and since I'm starting a 4000 mile trip on the 24th, I'll have more of a chance to evaluate it.

4000 mile trip? Wow!!! Where are you going.. Europe? LOL!

Man, this brings back memories. The '05 Vettes suffered from this same problem with the added kick that the plates would stick and the rear sounded like it was snapping, very scary. Same service bulletin as V2, drain and change fluids, except we had to also change out the clutch pack but problem was solved.

I was wondering if this was the same issue as on my 07 vette, with the same solution.

Sounds like I may need to get double the fluids and do both at once.

Kadonny: Thanks for the info. I just returned from the dealer and they performed the same fix as you described. While the whine seems to have gone and since I'm starting a 4000 mile trip on the 24th, I'll have more of a chance to evaluate it.

Well I guess the little whine I reported must not have liked the new lube that was put in yesterday. I was taking a one day trip across our state, when 80 miles from home that little whine became a big loud whine. GPS said Caddy dealer in 2.5 miles. Took it in, rearend fluid was full, said it sounded like a pinion bearing going south in a hurry. Hearing this I headed for home and will bring it in Monday to have it taken care of :ill:............. P.S. nynd: That 4000 mi. is round trip.

* Kidding... enjoy your trip!! Nothing like a V on the open road!

Wonder how he knew it was full.....

Wonder how he knew it was full.....

He put the V on a thing called a "lift" and then raised it up. He then removed the fill plug and checked the level. That's how he knew it was full. :rolleyes:

He put the V on a thing called a "lift" and then raised it up. He then removed the fill plug and checked the level. That's how he knew it was full. :rolleyes:


I'd like to know how he "checked" the level, not like there is a dip stick. The fill plug is a little up there so you can't like wedge your head up in there and look in... unless he had a tiny head :want:

The fill plug is horizontal not vertical like the transmission fill plug, you can see if the fluid touches the plug on the tranny. On the diff the only other way I can think of is use a piece of paper and dip it in to see how far below the hole the fluid is. Or if he pulled the plug and some fluid flowed out..... :bigroll:

I'd like to know how he "checked" the level, not like there is a dip stick. The fill plug is a little up there so you can't like stick your head and look in... :want:

The fill plug is horizontal not vertical like the transmission fill plug, you can see if the fluid touches the plug on the tranny. On the diff the only other way I can think of is use a piece of paper and dip it in to see how far below the hole the fluid is. Or if he pulled the plug and some fluid flowed out..... :bigroll:

Sounds like the same configuration as in the old T-10 transmissions or any old GM rear axle. You just remove the fill plug from the side, stick your finger in and bend it down just a hair to see if it finds fluid.

Would the same work on a CTS-V rear?

I would guess so.... I just drained, found it ~30% low by measurement, was a little over a quart drained. refilled with 4oz additive ~1.5 qts AMSoil about 3 days before HPDE class.

Well I guess the little whine I reported must not have liked the new lube that was put in yesterday. I was taking a one day trip across our state, when 80 miles from home that little whine became a big loud whine. GPS said Caddy dealer in 2.5 miles. Took it in, rearend fluid was full, said it sounded like a pinion bearing going south in a hurry. Hearing this I headed for home and will bring it in Monday to have it taken care of :ill:............. P.S. nynd: That 4000 mi. is round trip.

My dealer checked with Cadillac as to why no part numbers are listed for the rearend. The reason is because they want the entire diff changed out, not rebuilt. It's being shipped Overnight Delivery.

I would venture they would just change it out, the diff is fairly small in comparison to a diff from a live axle. I was scratching my head when I got the V on a lift to change the diff fluid.... I was thinking in my head...wow that's a small rear diff. Can't pull a cover etc etc... must just be a replaceable unit. I should have realized that when it only takes ~1.5 qts to fill up.

Dealer replaced my rear diff fluid under warranty at 9500 miles. They were able to repeat the noise in the mornings. They added 2 bottles of limited slip additive.

Hans.

I can't find the lube spec anywhere in my 2010 Owner's Manual. Does anyone know the recommended weight fluid per Cadillac?

I can't find the lube spec anywhere in my 2010 Owner's Manual. Does anyone know the recommended weight fluid per Cadillac?

Go to a dealer and buy Dexron LS fluid. Part number is 88862624.

I can't find the lube spec anywhere in my 2010 Owner's Manual. Does anyone know the recommended weight fluid per Cadillac?

75W90 - Synthetic Part#12378261

My dealer checked with Cadillac as to why no part numbers are listed for the rearend. The reason is because they want the entire diff changed out, not rebuilt. It's being shipped Overnight Delivery.

All went well, they assessed the problem and ordered the diff on 9/21, received it the 22nd and I had the V back on the 23rd. This is from a dealer whom I did not buy the car from. Some times things go smooth.

Go to a dealer and buy Dexron LS fluid. Part number is 88862624.
This is the fluid that is going in this weekend. My car has 500 miles on it and will change it again at 2000 miles and then I should be good to go. I had to buy a case to get the per quart price down. It is 75W90 and is GM's latest and greatest synthetic gear lube and does not require any limited slip additive. I'll let you know how it goes.

This is the fluid that is going in this weekend. My car has 500 miles on it and will change it again at 2000 miles and then I should be good to go. I had to buy a case to get the per quart price down. It is 75W90 and is GM's latest and greatest synthetic gear lube and does not require any limited slip additive. I'll let you know how it goes.

Do you have a cost on it and whether it is readily available? Supposedly, it is not available in Canada so I'll need to make a trip to some US dealer to track it down. The Canadian dealer looked it up and it came up as OEM USE.. he couldn't figure out what that meant.

Do you have a cost on it and whether it is readily available? Supposedly, it is not available in Canada so I'll need to make a trip to some US dealer to track it down. The Canadian dealer looked it up and it came up as OEM USE.. he couldn't figure out what that meant.
Canada Part Number is 88862625 if that helps. Got mine from GM Parts Direct.com

That helps... and that they have. So, no LS additive required with that? Was there a TSB and does anyone have it?

Updated...

No worried about TSB: Found some reference on a C6 site.. should be similar.. here was the write up:

IMPORTANT: Read the latest GM TSB regarding rear axle chatter to determine which GM gear oil / additive and amounts you should be using. This info has changed over the years and is subject to further periodic change. The latest axle TSB (as well as previous axle TSBs) can be found at the bottom of this page

As of January 2008, the oil specified for use in the Corvette differential is Dextron LS Gear Oil 75W-90, part #88862624 (#88862625 in Canada). No additive is required or recommended – just add straight Dextron LS 75W-90 only.

Your C6 differential requires roughly 2 quarts (check manual and/or TSB for exact specs for your year / model). But be sure to have at least 3 quarts of oil handy since it is almost impossible to squeeze all the oil out of the bottles into the axle, plus you’ll likely spill some anyway.

Since you will not be able to get the oil bottles higher than the fill hole, you must pump or squeeze the oil up into the hole.

The GM oil bottles come with extra pointed nozzle caps and a short piece of clear tubing. I found this set up to be too short and too small a diameter, plus after a while the nozzle gets oily and the hose starts slipping off the nozzle no matter what you do. One solution is to buy an aftermarket fill tube at the local auto store. The product I found (at Pep Boys) is made by Hopkins Manufacturing, called a “FloTool”… it threads right onto the GM oil bottles and has a 12” long section of clear tubing attached… twice as long and larger diameter than what you get with the GM oil bottle. This FloTool fit really nice and made the oil fill a breeze.

I just took mine to get serviced. I'm at about 10,000 miles on my V2. The rear end noise happened in the morning when the car is cold. Right before I took it to the dealership, the noise was pretty bad. The worst I've heard. Almost felt like the diff was binding up. Took it to the dealership and told them to change the fluids.

They ended up keeping the car overnight so they can hear the noise for themselves, and got a call today, saying they are ordering a whole new diff to replace the old one. I guess that is better than trying to sugarcoat the problem with a better fluid trying to reduce the friction.

So far kudos to my dealership. They replaced two of my driver side tires under the tire protection warranty program (due to some bruises in the side walls of the tires), and now the differential is next to get worked on.

I just took mine to get serviced. I'm at about 10,000 miles on my V2. The rear end noise happened in the morning when the car is cold. Right before I took it to the dealership, the noise was pretty bad. The worst I've heard.

They ended up keeping the car overnight so they can hear the noise for themselves, and got a call today, saying they are ordering a whole new diff to replace the old one. I guess that is better than trying to sugarcoat the problem with a better fluid trying to reduce the friction. .

I had the same problem and the same result, a new Diff. See post 33

I had the same problem and the same result, a new Diff. See post 33

I didn't catch that. I hope that fixes my problem also. Bad thing I guess is the wait on the shipping of the Diff, they said about a week. So we will see.