Z51 differential noise when cold
Thread Starter
3rd Gear
Joined: Nov 2014
Posts: 3
Likes: 0
From: Washington Michigan
Z51 differential noise when cold
I have a loud grunting or ratcheting noise from what seems to be my differential when my C7 Z51 is cold and when turning. I hear it when I back out from the drive and turn into the street. After driving to the corner one hundred feet further there is no noise when turning onto the next street. The dealer warned me when I took delivery that I may hear this so I have not persued this issue with them. Do other C7 owners experience this noise as well?
Also, a new problem I just started experiencing. Sometimes while cruising at relaxed speeds in 5th gear, the shifter pops out of gear. Have other owners experienced this?
Also, a new problem I just started experiencing. Sometimes while cruising at relaxed speeds in 5th gear, the shifter pops out of gear. Have other owners experienced this?
Thread Starter
3rd Gear
Joined: Nov 2014
Posts: 3
Likes: 0
From: Washington Michigan
C7 Differential noise
Thanks for your response. The noise I have is quite alarming to passengers that are expecting a high level of refinement. I fill their ears with praise and technical jargon for the C7 and then let them experience a large grunting within seconds of backing out. Do you expect mine is no worse than most?
Race Director
Joined: Jan 2014
Posts: 10,709
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From: Fulshear, TX
Mine makes all sorts of noise backing out of the garage each morning, especially when turning on an incline (I have a sharp driveway apron)...the colder it is, the louder it gets. These are performance cars, not Lexus'...just remind your passengers of that 
If you really want to hear a loud/mechanical sports car, take a ride in a GT-R, those things sound like a 4x4 pickup locked in 4-Low during slow speed maneuvers.
If you really want to hear a loud/mechanical sports car, take a ride in a GT-R, those things sound like a 4x4 pickup locked in 4-Low during slow speed maneuvers.
Last edited by Kracka; Nov 28, 2014 at 10:18 AM.
Thread Starter
3rd Gear
Joined: Nov 2014
Posts: 3
Likes: 0
From: Washington Michigan
C7 Differential Noise
Mine makes all sorts of noise backing out of the garage each morning, especially when turning on an incline (I have a sharp driveway apron)...the colder it is, the louder it gets. These are performance cars, not Lexus'...just remind your passengers of that
If you really want to hear a loud/mechanical sports car, take a ride in a GT-R, those things sound like a 4x4 pickup locked in 4-Low during slow speed maneuvers.
If you really want to hear a loud/mechanical sports car, take a ride in a GT-R, those things sound like a 4x4 pickup locked in 4-Low during slow speed maneuvers.
Supporting Vendor
Joined: Nov 2010
Posts: 3,893
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From: Houston, TX
Might want to have someone check rear end fluid or just take back to dealer. Many C7s were shipped with low gear oil. Should be a recall for it. Dealers should know about issue.
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Pro
Joined: Nov 2014
Posts: 687
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From: Fort Worth Texas
I have this same "noise" when backing out of my driveway when turning in reverse. The colder it is outside, the more noticeable the sound. Our 2013 Nissan 370z did the same thing.. Not sure if its related but we had our 370z rims powder coated and instead of adding nitrogen "air" back into the tires, we just used normal compressed air at a local tire shop. The "noise" was much louder when it was cold and we sort of freaked out.. Took our 370z to the Nissan dealer and was able to do an air for nitrogen swap. The sound was still there when we backed out of our driveway but it wasn't nearly as loud.. Still scratching my head why "air" in my tires made the noise louder?? Do our C7 tires come with nitrogen?
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Racer
Joined: Oct 2014
Posts: 346
Likes: 70
There was an issue where a differential o-ring would fail to seal fluid when below some freezing temperature. (which caused the low fluid level issues in the rear differential)
I would check the fluid and/or for evidence of a leak
Edit: https://www.corvetteforum.com/forums...uid-check.html
I couldnt find where I read about the o-ring though (just remember reading it someplace, could be wrong)
I would check the fluid and/or for evidence of a leak
Edit: https://www.corvetteforum.com/forums...uid-check.html
I couldnt find where I read about the o-ring though (just remember reading it someplace, could be wrong)
Last edited by awright2009; Dec 7, 2014 at 01:42 PM.
Racer
Joined: Mar 2009
Posts: 361
Likes: 4
From: Chandler AZ
Rear end noise is normal, but popping out of great is not! Corvettes have made a popping noise when it is cold since I owned my 1967 Stingray in 1972! My wife's C6 Grand sport, my c-6 Z06 and now both of our C7's make the noise, so I would suggest not taking it in for service for that problem! I definitely would take it in for the popping out of gear issue!
Team Owner
Joined: Sep 1999
Posts: 41,732
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From: Springfield MO
rear end noise is not normal. I don't have rear end noise in my RWD Mercedes, I don't rear end noise in my 1956 Corvette, I don't have rear end noise in my 1964 Corvette. I don't have rear end noise in my C6 Z06 Corvette.
The C7 has the same design rear end as my Z06 except the posi in my '64 and my Z06(and in the base C7 )has springs to maintain a clamping force on the clutch discs where the Z51 has a hydraulic cylinder to provide a clamping force on the clutch discs.
That hydraulic force is provided by a pump driven by an electric motor based on signals from various sensors on the car. The hydraulic pressure is variable thus the clamping force on the clutch is variable.
First thing I would do is have the dealer change out the fluid in the differential. If that doesn't get rid of the noise, then the dealer needs to troubleshoot the operation of the eLSD.
The C7 has the same design rear end as my Z06 except the posi in my '64 and my Z06(and in the base C7 )has springs to maintain a clamping force on the clutch discs where the Z51 has a hydraulic cylinder to provide a clamping force on the clutch discs.
That hydraulic force is provided by a pump driven by an electric motor based on signals from various sensors on the car. The hydraulic pressure is variable thus the clamping force on the clutch is variable.
First thing I would do is have the dealer change out the fluid in the differential. If that doesn't get rid of the noise, then the dealer needs to troubleshoot the operation of the eLSD.
Last edited by JoesC5; Dec 7, 2014 at 06:28 PM.
Safety Car
Joined: Nov 2002
Posts: 4,168
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From: FLL Florida
[QUOTE=JoesC5;1588431830
The C7 has the same design rear end as my Z06 except the posi in my '64 and my Z06(and in the base C7 )has springs to maintain a clamping force on the clutch discs where the Z51 has a hydraulic cylinder to provide a clamping force on the clutch discs.
[/QUOTE]
That's not how the clamping force is generated on your older Vettes.
The C7 has the same design rear end as my Z06 except the posi in my '64 and my Z06(and in the base C7 )has springs to maintain a clamping force on the clutch discs where the Z51 has a hydraulic cylinder to provide a clamping force on the clutch discs.
[/QUOTE]
That's not how the clamping force is generated on your older Vettes.
Team Owner
Joined: Sep 1999
Posts: 41,732
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From: Springfield MO
Then how is the clamping force generated in the C1 and C2 Corvettes?
What do you think is the function of those blue thingies that look like coil springs in this C2 positraction unit?
What do think item #36 is?
PS- the C1's used Belleville springs instead of coil springs.
What do you think is the function of those blue thingies that look like coil springs in this C2 positraction unit?
What do think item #36 is?
PS- the C1's used Belleville springs instead of coil springs.
Last edited by JoesC5; Dec 11, 2014 at 02:42 PM.
Safety Car
Joined: Nov 2002
Posts: 4,168
Likes: 1,336
From: FLL Florida
Then how is the clamping force generated in the C1 and C2 Corvettes?
What do you think is the function of those blue thingies that look like coil springs in this C2 positraction unit?
What do think item #36 is?
PS- the C1's used Belleville springs instead of coil springs.
What do you think is the function of those blue thingies that look like coil springs in this C2 positraction unit?
What do think item #36 is?
PS- the C1's used Belleville springs instead of coil springs.
Team Owner
Joined: Sep 1999
Posts: 41,732
Likes: 1,718
From: Springfield MO
You don't know the function of the springs...plain and simple. Are you going to now tell me how the airflow around the canopy of a P-51 Mustang when flying inverted 50 feet above the ground is the reason a U6a can take off in 300 feet and because off that short takeoff the B-29 can carry more bombs than a Piper Cub when pulling 5g's in vertical flight, and that's why the springs aren't for providing a clamping force on the positraction's clutch packs. Of course you will use a bunch of big words to make people think you know what you're talking about.