Hum from the Differential

[jessrayo]

Originally Posted by Stephen12ZL1

I can almost guarantee they put the generic GM crap gear oil in the car and not the required GM dexron LS gear oil. Check the manual and show them what it says and it has a part #88862624. If they didn't use that gear oil it needs to be changed again ASAP! The clutch grabbing will go away...hum may continue.

You are probably right, I didn't even consider that they may have used the wrong fluid. But as you pointed out, this will not fix the hum you hear when on the throttle. I still would tell them to swap the entire unit.

[kaos_ss]

The paper from the dealer has Part # 88862624. Also says that they drained and filled differential 3 times as per doc#3331992.

I'm not sure what that doc number refers too. But now that I think about it, my car only had 9 extra miles when I picked it up from the dealer. So there is no way they drove the car as indicated on the TSB.

[OldScoolCamaro]

*, that may not be necessarily true. I have seen previous issues with with GM posi rears that when the rear diff is drained, and the proper lubricant is installed the issue goes away.

[Sven59]

9 miles definitely does not meet the tsb requirements, it is at least 40. Many dealers treat the ZL1 like any other Camaro and don't understand the differences. They probably put the wrong oil in to. I have had both the ring and pinion snapped and the tsb done the correct way.

Sent from a large hammer.

[jessrayo]

Originally Posted by kaos_ss

The paper from the dealer has Part # 88862624. Also says that they drained and filled differential 3 times as per doc#3331992.

I'm not sure what that doc number refers too. But now that I think about it, my car only had 9 extra miles when I picked it up from the dealer. So there is no way they drove the car as indicated on the TSB.

Okay, I searched a little but could not find the TSB on the ZL1. I found the TSB for a non-ZL1 but that is useless. If I remember correctly from the ZL1 TSB once the figure 8 driving is done if the differential is making noise you add friction modifier additive part number 1052358 (this part number is in the owners manual). You do this in increments just until the noise stops. Ask your dealer if they can show you a copy of the TSB and read it.

[oldchevyguy]

Originally Posted by jessrayo

Lol, you have got more than one problem. the first problem you described is not the fluid problem. Now that they changed the fluid you need more friction modifier because you have the fluid problem on top of the first problem. In my opinion you should let your dealership swap the entire differential. If you search the forums that is the most common fix at GM dealerships. Very few local dealerships have the expertise to work with the clutch system on this limited slip diff so GM keeps them in house. I would just tell my service manager to order the rear end and call when the parts are in so you can schedule. You know it was not right to begin with and what you described originally is not a common problem. Several guys have had their diff's swapped and that fixed the problems for them. Good luck to you.

Swapping the differential didn't fix mine, in fact now it whines constantly where it was only on decal before. The area rep drove mine and then one at a dealership in Salt Lake and said it made the same noise just not as loud as mine. In the end just expect to be told it's a common thing with the ZL1.

[Sven59]

Recommendation/Instructions

Note: Steps 2 – 9 MUST be performed two (2) times for a total drain and fill of three (3) times to have this procedure be effective.

1.*With original lube in axle, conduct Freeway Speeds for 10 miles to warm up lube.

2.*Immediately drain original lube and refill with fresh lube.

3.*In parking lot lock steering to the right, and then execute 5 Full Circles at (5-10 mph).

4.*In parking lot lock steering to the left, and then execute 5 Full Circles at (5-10 mph).

5.*Perform 4 Figure 8’s at (5-10 mph).

6.*Freeway Speeds for 20 miles until operating temperature is achieved.

7.*In parking lot lock steering to the right, and then execute 5 Full Circles at (5-10 mph).

8.*In parking lot lock steering to the left, and then execute 5 Full Circles at (5-10 mph).

9.*Perform 4 Figure 8’s at (5-10 mph).

10.*Immediately drain current lube in axle and refill with fresh lube.

11.*Perform Steps 3 thru 9 again.

12.*Immediately drain current lube in axle and refill with fresh lube.

This procedure is only to be used for the condition listed above. *During regular maintenance, the fluid only needs to be changed one time. *The maintenance schedule can be found in the owner’s manual on pages 11-5 and 11-7. *For regular service the fluid is changed at 45,000 miles or 72,000 Km and for severe service the fluid needs to be changed every 15,000 miles or 24,000 KM.

Oil Dextron LS Gear 75w90: *US - 88862624 2.43 Qt.; Canada - 88862625 2.3L

Warranty Information

For vehicles repaired under warranty use:

Labor Operation

Description

Labor Time

F9744*

*Road Test, Drain, and Refill Axle 3 Times

*2.6 Hours

* This is a unique labor operation for bulletin use only. It will not be published in the Labor Time Guide.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer".* They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle.* Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely.* If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition.* See your GM dealer for information on whether your vehicle may benefit from the information.



*

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

© 2013 General Motors.* All rights reserved.

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Sent from a large hammer.

[11B250]

Well that truly sucks....

Curious what the outcome of this will be. me being me, I will probably just accept it, which isn't the right thing to do.

[OldScoolCamaro]

...you got to break the sucker in...it's synthetic lube, like as in the engine oil. It's friction inhibiting and long life service to the max. There is a specific amount of time that seating and break in can occur upon. You miss the window, you miss the boat. Guys, seat the reciprocating and drive assemblies with gusto, they will break in and seat. Drive this car like a Sunday driver and you may incure issues down the road.

[kaos_ss]

Thanks for all the suggestions. I stopped by the dealer today and they said to take it back on Monday. They also said that the mechanic wants to replace clutches. I think I'm just going to ask if they can verify that the correct oil was used and if necessary to add the friction modifier suggested by jessrayo.

As for the car...when I drove to the shop...the noise was loud. But it's not really a moan anymore. Instead it is a "thumping" or "grinding" noise. Very hard to describe.

Thanks again everyone!!!

[OldScoolCamaro]

...it can only be a few things...There is a quality control issue with the assembly of the rear axle<doubtfull>, there are quality issues with the parts involved<possible> by the comment of the last post. Some of the complaints are driver perception versus reality issues. If the noise gets worse, or more pervasive over time, then it's a mechanical problem.

[kaos_ss]

I went out and bought Royal Purple Max Gear 75w-90 with friction modifier additive.

Is that one ok to use with the ZL1 differential? If so I'm going to replace the oil with the RP and then drive the car in the figure 8's as suggested.

If that doesn't work then I will take it back to the dealer and start looking at my options.

[Sven59]

Originally Posted by kaos_ss

I went out and bought Royal Purple Max Gear 75w-90 with friction modifier additive.

Is that one ok to use with the ZL1 differential? If so I'm going to replace the oil with the RP and then drive the car in the figure 8's as suggested.

If that doesn't work then I will take it back to the dealer and start looking at my options.

I am not sure if that is the right lube and additive, the ZL1 is very specific.

I have had both issues you talk about, The moan while turning in the cold is the second thing I had done because it was done prior to the release of the service bulletin. Be very careful, there are two bulletins for the Camaro's one excludes the ZL1 the other is the ZL1, the # for the ZL1 is #PIP-5097. The other issue you have is the one I would worry about. I had the same thing and it was the backlash, it was off and they swapped the ring and pinion. After that it was quiet for awhile as far as the slow turning in the cold moaning sound, and the decel sound was gone (backlash). Later, the slow speed turning noise came back. The TSB came out so I took it back to the dealer and they performed it. Mine has been quiet ever since and I have 25,000 miles, both proceedures were performed between 3,000 and 5,000 miles. I understand wanting to do the bulletin yourself and if capable why not other than the cost. I would just make very sure you are using the proper fluids because there is definitely a difference between the ZL1 and other Camaros. What I was told about the moaning slow speed noise is that leftover lashing compound gets into the clutch packs and makes the noise. The procedure removes the excess to eliminate the noise, so changing the clutch packs may not be necessary. I will find my work order and try to provide more info. The other problem may be the Dealer, very few really understand the differences in the ZL1. They will try to treat it like a normal Camaro and make mistakes. Good luck!

Found the work order, part # for the fluid was 88862624. I am not sure if the Royal Purple is the same as the GM 88862624 so it might be good to check that before you do it. There was no slip additive listed on my work order, I believe that is for other Camaros, unless it is contained in the 88862624 lube.

[580/556 ZL1]

Originally Posted by Sven59

I am not sure if that is the right lube and additive, the ZL1 is very specific.

I have had both issues you talk about, The moan while turning in the cold is the second thing I had done because it was done prior to the release of the service bulletin. Be very careful, there are two bulletins for the Camaro's one excludes the ZL1 the other is the ZL1, the # for the ZL1 is #PIP-5097. The other issue you have is the one I would worry about. I had the same thing and it was the backlash, it was off and they swapped the ring and pinion. After that it was quiet for awhile as far as the slow turning in the cold moaning sound, and the decel sound was gone (backlash). Later, the slow speed turning noise came back. The TSB came out so I took it back to the dealer and they performed it. Mine has been quiet ever since and I have 25,000 miles, both proceedures were performed between 3,000 and 5,000 miles. I understand wanting to do the bulletin yourself and if capable why not other than the cost. I would just make very sure you are using the proper fluids because there is definitely a difference between the ZL1 and other Camaros. What I was told about the moaning slow speed noise is that leftover lashing compound gets into the clutch packs and makes the noise. The procedure removes the excess to eliminate the noise, so changing the clutch packs may not be necessary. I will find my work order and try to provide more info. The other problem may be the Dealer, very few really understand the differences in the ZL1. They will try to treat it like a normal Camaro and make mistakes. Good luck!

Found the work order, part # for the fluid was 88862624. I am not sure if the Royal Purple is the same as the GM 88862624 so it might be good to check that before you do it. There was no slip additive listed on my work order, I believe that is for other Camaros, unless it is contained in the 88862624 lube.

see SVEN59 know's all about the issu on our differentiel.why does the Chevrelet Customer SVC can't teach there own dealer's about it...Why do we always have to fight with dealer's to get proper repair...i really hate GM dealer's they are just there for the money and don't give a Dam if you have a ZL1 or a Chevrolet cruze and they always have the famous answer...''Its a Normal sound for the Car ''or ''don't worry it's Normal'' and in there mine they all thinking .....''get the fk out a here !we won't repair Under warranty bc GM pays us Under what we would charge you if you wasn't on Warranty''..almost all ppl in there are working for the week-end and won't even look if the ZL1 is special compare to an SS
...almost all of them will say ....''oh i did an SS last week put that kind of oïl in the differentiel its all the same anyway'' like i said they all working for the week end!!!!! i hate them!!! I had to much Bad experience with them .Now my solution is i go in a Professional speed shop when the warranty is off and i can tell you they work with there heart in there and they knows alot compare to the GM mecanical worker's that working for the week-end....and that problem will last forever in GM dealer's