Rear end howl on decel

[IDEALG]

Just took delivery of my 2015 ZL1 Thursday night wasn't 40 miles before it started making decel noise. I'm still deciding what to do. does it mostly around 40mph and 60 mph. No noise while on the gas soon as i let off the gas it whines.

Bad news for me is there are at least 5 dealers near me and none of them are worthy of doing the task, I wouldn't let their mechanics fix a Spark nor trust them driving my car.

The dealer i bought the car from even said not to bring it in for service because their service department is horrible.

Since i own my own shop and work on these cars regularly i'm seriously thinking about fixing it myself.

After having nothing but problems with the trans and rear in my previous 2011 Camaro SS you can't even imagine how pissed i am with having this happen to me again.

[ValZL1]

I took mine in for a howl around corners at low speeds when not really hot. Got a TSB service'd for rear end (3x drain and fill with figure 8's) and seems to have fixed it.

[ZMEnow]

There is a problem with the ZL1 lash and GM knows it.. I have driven a few friends who's do not whine in the typical 65 to 71 mph. Although mine does and started around 3600 miles. I expect unlike the Supercharger that had history with the caddies and was known to fail, I doubt GM will make a move on the lash issue as it probably won't come apart but will prematurely wear the ring and pinion out a lot sooner than it would have. For a car that is really for the majority a summer use car, you will just have to listen to the sound for the lifespan of ownership. Not something GM should be proud of..

[IDEALG]

The decel noise on mine is not too bad, I purchased a shim kit and new fluid. Pulling it out Saturday to check the backlash with a dial indicator and hopefully fixing the problem. I'll post up the results

[djnice]

Originally Posted by IDEALG

The decel noise on mine is not too bad, I purchased a shim kit and new fluid. Pulling it out Saturday to check the backlash with a dial indicator and hopefully fixing the problem. I'll post up the results

Are there good instructions online somewhere for doing this job? How many miles of running with backlash out until you need to replace the ring and pinion? Thanks.

[IDEALG]

Originally Posted by djnice

Are there good instructions online somewhere for doing this job? How many miles of running with backlash out until you need to replace the ring and pinion? Thanks.

Not that i know of, I'm using GM service information through shop software and it's scattered all over the place on different pages.

Basically you drop the Diff, remove the cover, using a dial indicator measure the backlash ( The amount of play in between the ring and pinion by rotating it back and forth ) My information says it should be between .006" -.010"

It says adding .002" of shim gives you .001" closer or further away backlash depending on which side your adding shims.

[djnice]

Well, I will be interested in hearing how it goes and if you can get improvement.

[IDEALG]

Originally Posted by djnice

Well, I will be interested in hearing how it goes and if you can get improvement.

If the parts get here before Saturday i will do it this weekend and post my results.

[IDEALG]

I haven't received the parts yet so it won't be until sometime next week till i get to try this.

[Emvici]

what is decel noise? sorry to hear the 2015 is having an issue, and I am actually surprised as it seems like they got all the bugs out on the 2014 model. So did Gm do something new to the 2015? to make this happen, or is it just a factory mistake?.

[IDEALG]

Originally Posted by Emvici

what is decel noise? sorry to hear the 2015 is having an issue, and I am actually surprised as it seems like they got all the bugs out on the 2014 model. So did Gm do something new to the 2015? to make this happen, or is it just a factory mistake?.

same rear just who ever is setting them up isn't doing them right i guess. Decel whine/noise/whirring ect is when you take your foot off the gas pedal and the car is coasting you hear a humming noise.

[IDEALG]

Finally had a chance to pull the rear out. It's showing a backlash of .005" but take a look at the pinion picture, i don't like the way the wear looks on it but i don't build rears either so i'm not exactly sure what's right and what isn't. definitely doesn't look right to me though looks like it's chattering??? only 130 miles on it

3 pics one is the pinion and the other 2 are the ring gear, i would say the noise is coming from the pinion by the looks of it but i'm no expert.

[IDEALG]

so i ran some gear compound through it to see the pattern. looks dead on to me, i may just leave it alone and forget the little coast whine.

[ZO6 Bryan]

Did you load it when you did the pattern? You should put the e-brake on one or two clicks to create some load then put a wrench on the pinion and crank it clockwise. That will give a better indication of what the pattern really is. But so far it looks fine. Why don't you just let GM put a new diff in it under warranty since its a brand new car?