Rear Differential Chatter/Howl-Problem Solved
 

Anyone who can change their oil can and should do this. Took my ZL1 to the dealer to check the rear diff noise and they said they planned to change the seals and diff fluid. 3 hr job to tear out the half shafts and replace seals and use the new fluid. But what they didn't know is the ZL1 already has the new fluid and compatible seals. And I wasn't thrilled at the idea of them tearing it down. So I went out and got some good quality Valvoline Synthetic 75W-90 and did it my self. No more noise, much smoother. Didn't see the sense in dealer putting the same stuff in that was making noise already after 4000 miles. Anyone who tracks should change the fluid regularly. I did one track day since I bought my car in May and just got around to changing the fluid.

Pulled it on ramps on the incline of the driveway so the fluid in the cooler would run to the back when drained.

Both the plugs are magnetic and will have a little debris on them.

Note the top fill plug has a paint mark I assume to keep you from over tightening.

BTW it holds about 2 1/2 quarts. And I took it out for a drive first to warm up the fluid first and it drains very quickly that way.

I thought the rear end now use auto transmission fluid, so only the manual trans uses automatic trans fluid?

if it starts making noise when it is cold on slow turns, go to the dealer and get the additive or LS gear oil that has the additive in it already. I tried Royal Purple but it started howling and chattering after a few days when it was cold. Switched back to GM LS gear oil and it was all quiet again.

incorrect info here

No, manual calls for 75W-90 gear oil. The oil I used doesn't require any additional additive. And actually the manual calls for additive in the SS but not the ZL1. The GM LS gear oil 88862624 that is recommended for the ZL1 in the manual doesn't require additive.

Copied from owners manual

Rear Axle (V6 Engine with Manual
Transmission)
Rear Differential Fluid 75W-90 Limited Slip (GM Part No. 89021677 and
Friction Modifier 1052358, in Canada 89021678 and
Friction Modifier 992694).
Rear Axle (SS)
Rear Differential Fluid 75W-90 Limited Slip (GM Part No. 89021677 and
Friction Modifier 1052358, in Canada 89021678 and
Friction Modifier 992694).
Rear Axle (ZL1)
Rear Differential Fluid 75W-90 Limited Slip (GM Part No. 88862624, in
Canada 88862625).


The TSB for the rear diff noise has the dealer replace the oil in the diffs of the SS cars with 88862624. Already in the ZL1!

Heres the TSB you mentioned for non-ZL1's


http://gsi.xw.gm.com/newsi/images/gmLogoFlat.gif Service Information
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2012 Chevrolet Camaro | Camaro VIN F Service Manual | Document ID: 2740658
#PI0137C: Rear Axle Chatter Type Noise on Low Speed Turns (Excluding ZL1) - (May 11, 2012)


This PI is being revised to add an Attention statement and update the Recommendation/Instructions. Please discard PI0137B.The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern


Some customers may comment on a chatter-type noise from the rear of the vehicle while making low speed turns.
This condition may be caused by a slip/stick of the posi-traction clutch plates. As the plates slip and stick, a jumping or jerking feel occurs, accompanied by a chatter noise.

Recommendation/Instructions

Caution: The rear axle seals must be replaced. The original seals are not compatible with the new fluid.

Replace both rear axle shaft seals with GM P/N 22798805 and drain/refill the rear differential with new fluid, GM P/N 88862624 (in Canada, use P/N 88862625). Refer to the Rear Axle Shaft Seal and Differential Oil Replacement procedures in SI. This fluid includes a limited-slip additive (friction modifier) already added. DO NOT add any limited-slip additive (friction modifier).
Important: Please advise the customer that once the differential fluid has been changed, it may take as long as 805 km (500 miles) for the lubricant to fully penetrate the limited slip clutch plates. During this period some chatter may still be felt on initial startup while making slow turns until the rear differential fluid warms up.

Note: DO NOT re-use the wheel drive shaft nut. Replace with NEW only.

Parts Information

Part Number



Description



Qty



22798805


Seal, Rear Axle Shaft


2


11611687


Nut, Rear Wheel Drive Shaft


2


88862624 (US -1 qt)

88862625 (Canada -1 L)


Fluid, Manual Transmission (Dexron LS Gear Oil 75W-90 MTF)


1

Warranty Information


For vehicles repaired under warranty, use:

Labor Operation



Description



Labor Time



F9739*


Replace Both Rear Axle Shaft Seals and Drain/Refill Rear Axle Fluid


3.1 hrs


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

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.

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Thats a "quality control" mark if you will,it means the diff. has been filled and the plug tightened at the assembly plant.

Great info, thanks for posting

The transmission fluid mentioned is only for the diff cooler. I had a Valvoline lube place change mine while I watched using the GM recommended fluid. They said their fluid met the GM spec, but I elected to use the GM fluid instead. It's only about $40 to have them do it versus $100+ for the dealer.

That's right, the ATF is circulated the length of the car not the diff fluid. I had looked at it before but forgot how it was plumbed. So really was no need to lift car and keep it level to drain. Just the rear up in the air would have been fine.

...was it leaking...why did they have to replace the seals as you stated?

No leaks. The TSB for the SS cars tells them to replace the seals with new part # to be compatible with the new fluid. The ZL1 already has the new seals.

Love to read threads like this one. I'm always learning and when the time comes I can always refer back to it. Thanks for posting.

Be careful with the synthetic fluids. Not all of them hav ehte additive included. I know that Mobile 1 doesn't.

The Mobil 1 LS 75W-90 gear oil does have the additive already. I looked at that one too.

http://www.mobiloil.com/USA-English/..._75W-90LS.aspx

Mobil 1 Synthetic Gear Lube LS 75W-90 does not have enough LS additive to meet GM spec #88862624. This is why I went back wit the GM fluid. I didn't want to use more additive, nor add more than necessary. I think Valvolines synthetic gear lube meets this spec.

To the o.p. The owner's manual specifically says to change your diff fluid after every track day. If you tracked it a while ago...and just now got around to changing your fluid...that's what could have caused the chatter.

I had the chatter in my SS, but I got my techs at work to upgrade me to the LS gear oil with new seals and all is well!:thumbsup:

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So how is everyone's diff doing now?
Does the valvoline fluid work fine over the lung run wihout needing to use the LS additive?

The original poster added some extra addative to the valvoline oil eventually.

here is my .02 on this topic take it for what it is worth. buy some good fluid. IE the gm fluid, good aftermaket synthetic. Now if the fluid has addative don't run any extra up front. If you buy fluid without the additive use the recomnended GM addtive right out the gate.

after you fill the diff do some figure eight driving in a parking lot to cycle the diff clutches. I think the GM TSB specifies how many to do

Now if you still get some chatter go get more of the GM addative that is recomended at add say 2 ounces at a time then go repeat the figure 8's until the chatter is elimitnated.

the friction modifer material is not a more is better type thing you need the right amount.

my fresh gm fluid will be here this week I will do the change and if I get a bit of chatter I will do just what I posted. I am positive it will work because it worked on my Z06.

my chatter is very minimal on my car right now and only when cold but I want it 100% gone. sometimes I think with these tires having such piss poor grip in the cold it magnifies the issue.

I tried the Mobile 1 in my car. Definitely not enough additive in it. When the car is cold, the differential makes more noise than when it had the GM fluid. I'm gonna try Valvoline next.

Unfortunately, Mobil One doesn't meet the spec. The GM/DELCO fluid was expensive but worked well.

There is now a bulletin out on this, it calls for the dealer to flush and fill three times along with some figure 8s, etc. I had mine done and it silenced the howling.

I think my ZL1 has this problem. I just didn't know what the hell it was.

Don't know when the bulletin came out or whether my dealer did all that, but they pulled it apart to check it last year and refilled it and mine has been fine since. Basically what this guy said.

I just came back from my dealer and cant believe they were going to put the wrong fluid in the car. The tech looked at me like "who the hell is this guy" I told him that this car uses a fluid from gm with the additive already in the car. He went to parts and came back with the right stuff.

When filling he used 2 bottles/quarts of the fluid and pumped it in then I reminded him that in needs 2.1 and he again went and got another bottle and pumped in about 1/2. Some fluid came out and we watched it drain from the fill plug and closed it up when it started to drip.

Makes me thank this forum and its memebers for the insight and info. I pray this guy torqed the bolts right.

Now that I think about it i hope he cant overfill the thing........

I wish the dealer would change mine. Since the TSB says not for ZL1 they wont. guess I will guy buy the stuff and do it myself soon.

There is a new one specifically for the ZL1. Anyone have it?

my dealer said the same but next oil change ill try again

so, what is the correct oil to use

GM LS gear oil is the correct gear oil for the rear. http://www.gmpartsdirect.com/results...umber=88862624

additive already in bottle.

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my diff isn't making any noise as of yet. although my car only has 1500 miles so we'll see what happens.

Mine already started whining :facepalm:

Ahmad

Dealer drove mine and the write up says it is normal. It whines at 65mph when rolling between slight throttle, coasting, and off throttle.

It mainly does it in slow turns, more so in colder weather.

Dumb question so here goes. How does changing the rear end fluid fix this issue? I would think that GM used the same fluid that we can buy from the dealership to do it ourselves.

Does the fluid magically wear out or something that quickly?

My understanding (through three visits to the dealer) is that some of the lashing compound is remaining in there and causing the noise, By flushing it and refilling 3 times along with some figure 8's etc. removes any remnants of the compound. Maybe someone can find the bulletin and publish it here.

Edit: I am trying to get a copy and will post it here.

TSB # #PIP-5097

I thought someone posted this somewhere but cant find it. Ayone have a copy?

EDIT: found it http://www.camaro5.com/forums/showth...light=PIP-5097