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Discussion Starter · #1 ·
The topic of the Corvette’s Z-51 E-Differential has interested me since I first heard of it being added into the powertrain of the Z-51. What is an electronically controlled diff? Here is a generic explanation :HowStuffWorks "Electronic Limited Slip Differentials "

The GM unit is a bit different in so far as it uses hydraulic pressure in a stand- alone system within the rear diff. unit to micro adjust pressures to the diff’s clutch pack to suit the drivers demands on the vehicle. Tadge Juechter speaks to the Z-51 E-Diff here on the Autoline Afterhours interview from last week.
Autoline After Hours (His comments about the system starts @ 1:01:08 into the interview)

What I am interested in finding out is: Exactly how the system works and if required, how is it serviced? My intention in starting this thread is for us to add to our knowledge of this sub-system and in time figure out exactly how it works, what it requires in the way of maintenance? I am also interested in finding out how reliable this system is, and how well it performs? Another aspect of this topic is: Does the cooling vent identified as the one for the “E-Diff” on the rear flank of the Z-51 actually one that cools the hydraulic fluid that drives this system? Where is the pump for this system? If you can add insight to its operation and performance please do.
 

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Good questions Chip, and I sure don't know the answers to most of them. What I know:

The eLSD (Chevy's official name for it) works through a hydraulic reservoir with fluid separate from the diff fluid. The differential and eLSD system interact via a clutch package that minutely adjusts the power differential to the two rear half shafts, and miraculously doing it 83 times per second. The eLSD has its own computer module, which communicates with, at least: the ECU, the ABS sensors, the traction control system, the steering wheel position sensor, a transmission gear selection sensor, throttle position sensor and more. When Jim Mero, Mike Bailey and their Corvette development team colleagues were fine tuning the computer controls for eLSD, they were able, with a single computer "bit" or "byte," to fine tune the operation of the system to within 0.1% inputs, changing the car from over steering to under steering (at a given speed and inputs) then back to under steering again. That is how finely tuned the system is. This lengthy (72 minutes) video provides more info (though also on many other chassis system attributes/components):

 

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Agreed that getting this checked by the dealer ASAP is important! Heard it was not a "recall," but a TSB (technical service bulletin), but that is just a matter of words, for getting it looked at is critical in view of several eLSD failures already -- including one where the car, going down the road at 40 MPH, had total wheel lock up.
 

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Just checked the official government "recall web site" and no recalls of any kind on the 2014 Corvette. And above, I posted that it was a TSB; yet, at least some of Chevy's dealers are using this word:

 

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Just got word that evey StingRay VIN lower than 2266 is being or has been recalled due to the differential not being filled with enough fluid. This is consistent with picture above of a recall notice for VIN # 1985. Those with VIN's lower than 2266 should call your dealer immediately! Sure wouldn't be taking any longer than a short drive with those VIN's to your service department, until they have checked it out. However, as some dealership's have been doing this as part of their PDI's, a phone call is suggested first.
 

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hey I took my 2lt z51 in for some issues when I found out that I was 2oz low on diff oil. When I was at dealership I told the tech that my car had severe wheel hop and he said" that's normal" ok... After I picked the car up, (Friday)I noticed that the "wheel hop" was completely gone, apparently it was a diff issue that when I turned hard ,a ruff shaking would occur felt like I had a flat tire.. cant be good.... if you have a z51 get your diff fluid checked... PS didn't want to start a tread on this because this is in same ball park....
 

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Discussion Starter · #10 ·
Thanks for this! There is a tech. reason pertaining to the Ackerman Angle principal that causes the corvette to have wheel hop, but perhaps low lube levels make it worse? From what I understand you can call your dealer and give them your VIN # and they will tell you if your car needs to checked or not. I think it might be a good idea though to get you Z-51 diff fluid level checked regardless just for the peace of mind that will give you. Just one less thing to worry about.
 

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Not a funny story
The yellow recall order above is from my dealership.
I sent it to my salesman. He got back and told me that this recall was for the 2013 corvette.
Very scary!


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Actually, that is the recall notice I was sent (my VIN is 1985). Car is currently at the dealer getting checked. That along with some other issues. PTM not working and apparently "losing communication" error codes. Boo.
 

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Discussion Starter · #13 ·
Not a funny story
The yellow recall order above is from my dealership.
I sent it to my salesman. He got back and told me that this recall was for the 2013 corvette.
Very scary!
I am not sure what you are saying... It's scary because the salesman is wrong? He is wrong, the recall is for the 2014 C-7.
 

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Just got word that evey StingRay VIN lower than 2266 is being or has been recalled due to the differential not being filled with enough fluid. This is consistent with picture above of a recall notice for VIN # 1985. Those with VIN's lower than 2266 should call your dealer immediately! Sure wouldn't be taking any longer than a short drive with those VIN's to your service department, until they have checked it out. However, as some dealership's have been doing this as part of their PDI's, a phone call is suggested first.
Having followed the advice here ...off to the dealer this AM. They were not aware of any recall but after pulling up the vehicle in the warranty system sure enough there was a recall for this issue. Went to the shop and they added 8oz of fluid to the eLSD and did a road test and now all is well. My VIN is #1020. The recall was issued on 11/7/13 however the "MyChevrolet Portal" does not list any recall for my Vette. I have also experienced the wheel chatter and it may still be there. More noticeable when tires are cold.
 

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I would like to know if there is a definitive RECALL that GM has notified NHTSA about and people are getting a letter. I think we are seeing dealers classify this as a recall to incite fear and get you to come in and possibly buy other things. I have seen no website that is official signify this as a true recall...does anyone have a factual hard data?

Talon?

this is the official website - there are no vette items issued:


just hate when dealers lie....
 

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Obvious salespeople in general care only about selling a car.
Even if there is a possibility of a recall shouldn't a sales manager email these recalls.
Maybe during a sales meeting mention it?
What bothers me is this was from my dealer. What happens if there is a real problem.

They have already delivered 3 corvettes. Do the owners of these cars know there is a possible problem?

Just sayin



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By the way
My sales person did day there was a recall


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I would like to know if there is a definitive RECALL that GM has notified NHTSA about and people are getting a letter. I think we are seeing dealers classify this as a recall to incite fear and get you to come in and possibly buy other things. I have seen no website that is official signify this as a true recall...does anyone have a factual hard data?

Talon?

this is the official website - there are no vette items issued:


just hate when dealers lie....
Well when I went to the Dealer I said I thought there was a Technical Bulletin or a Service Advisory concerning the eLSD fluid level. First they were not aware of any issue but when they pulled up my VIN in the warranty system I was told yes there is a RECALL for specific VIN's and mine was included. I also got a copy of the document which does not use the word RECALL in any section. It is as stated elsewhere as: "#13384: Customer Satisfaction - Low Rear Differential Fluid Level - (Nov 7, 2013)" and dealers are to inspect and add fluid if necessary and if fluid is added then a road test for any bearing noise. If any rear end noise is heard then to replace the the differential assembly.
 

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Discussion Starter · #19 ·
Well I guess we need to be careful about the language we use, but regardless of whether it is a "recall" or a "bulletin"; If you have a E-Diff in your car you should check with your dealer about getting the fluid level checked. Better safe than sorry!
 

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Well I guess we need to be careful about the language we use, but regardless of whether it is a "recall" or a "bulletin"; If you have a E-Diff in your car you should check with your dealer about getting the fluid level checked. Better safe than sorry!
absolutely...the diff is the word recall implies safety major concerns and "run , don't walk to your dealer"... and a bulletin/service action does not....in the public arena and how they think of C7's, , one is immeasurably worse....
 
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