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Discussion Starter · #1 ·
My 2015 is making a small click when starting to accelerate or decelerate. It's more pronounced in L than in D. I jacked up the front end and found that both sides make the same noise when the tires are rotated under light load. It appears to come from the drive unit, rather than the axles themselves. Is this normal? Is it something that I should have the dealership check out?
 

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"How much clicking is normal for CV axles?"
answer: NONE.
If they are starting to click at all they need to be replaced.
 

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They click due to wear and/or loss of lubrication due to damaged boots. It could be the inner ones or the outer ones. The outer ones usually click when turning and can actually sound quite bad. Inner ones more so as you describe but a mechanic will need to determine if it is one, two, three or all four. If the click is very slight, it could be slack in the drive gearing in the final drive line of the transmission setup and not the CV joints. Some have had click sounds from wheel bearings/hub assemblies too. Best to take it in and get diagnosed, especially if you still have warranty.
 

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My first experience with FWD was with my Dad's 1968 Austin America. The driver's side CV joint failed first and it was clickling loudly. You can read what makes up a CV joint and see why it clicks.

My previous FWD GM cars were a 1984 Olds Ciera and a 1995 Buick Regal, and none had a CV failure or "clicking". Newer FWD GM vehicles have improved designs and should never click!
 

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Need to replace nuts and washers. See "Click or Pop noise from front on Accel or Decel" page 10, on the forum.
I don't think so.He said it would click when jacked up. that means no torque on the axle nuts and washers. It sounds more to me like what he needs are new brake hardware kits, the click being slack being taken up as the brake pads shift position with the forward and reverse rotation of the wheel.
 

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Discussion Starter · #10 ·
I appreciate all the advice, but some of these things can be ruled out. I don't think it can be brake hardware, because it comes from the drive unit, inboard of the axles themselves. I shouldn't have even mentioned the CV axles, since it's not the axles themselves that are making the noise, but the unit that they are pressed into.

I know with manual transmissions that have CV axles, there's always some slack in the system from the differential gears engaging. Are you folks really saying that there is no slack whatsoever in a Volt drive unit, and that it's completely silent when engaging and disengaging drive?
 

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I know with manual transmissions that have CV axles, there's always some slack in the system from the differential gears engaging. Are you folks really saying that there is no slack whatsoever in a Volt drive unit, and that it's completely silent when engaging and disengaging drive?
It's a single geared system attached to electric motors. There isn't any "engage or disengage" the drive and there shouldn't be any play in it let alone enough to make a click or thunk. If you are getting clicks and/or thunks out of your drivetrain, something is worn or out of spec and you really need to get it checked and fixed.
 

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Discussion Starter · #13 ·
It's a single geared system attached to electric motors.
I don't understand. There are planetary gears, a multi-geared differential, and other moving components within the drive, as well as clutch packs. I don't think I've ever seen a differential with zero lash. What do you mean by a "single geared system?"
 

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And I say again "If you are getting clicks and/or thunks out of your drivetrain, something is worn or out of spec and you really need to get it checked and fixed." If that isn't clear enough for you then I can't help you any further.
 

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The differential gears are simple spur gears and it's common to feel the tooth to tooth action when rotating the tires with the front end in the air. This is normal. When you are driving, these gears don't normally turn unless you make a turn, and then they rotate very slowly.

https://www.youtube.com/watch?v=yYAw79386WI
Perfectly explained! It's amazing how the old didactic videos are so much easy to understand than most current, CGI-made "how it works" techno babble.
 

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Discussion Starter · #17 ·
And I say again "If you are getting clicks and/or thunks out of your drivetrain, something is worn or out of spec and you really need to get it checked and fixed." If that isn't clear enough for you then I can't help you any further.
Sorry--I know it sounds like I'm picking a fight here, but I'm anticipating a difficult time with the dealership and I need to be able to explain what's going on with the car. I anticipate their saying "that's normal." I'm hoping I can say, with authority, "No, it's not normal because...." and have a good answer. If I say "because it's a single geared system" they'll probably tell me that I'm wrong. If I'm able to explain exactly what normal should be, and what they're listening for in the test drive that's abnormal, I'll have an easier time convincing them to do the warranty work.

The sound is very subtle--something you wouldn't notice with an ICE running. Here's a video--not very clear, but you can figure it out.


https://youtu.be/680-SaU5T5A
 

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Hmm...doesn't sound like CV "click" to me. In my experience, CV clicking is higher frequency, a "tick...tick" sound rather than a knocking sound.

WAG here: motor mount?

Whatever it is, it is NOT normal, so don't except any "...they all do that..." argument from anyone.

Have you tried an independent FE shop?
 

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Mine doesn't do that either......but you do need to vacuum that carpet. ;)
 
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