Liter of cola

My failure was pretty much identical to the carguy11 video. Revved up dropped the clutch and bang, no wheel spin but the engine revved up freely.

The dealership so far confirmed the diff is blown i been waiting to hear back from the tech who diagnosed it to find out how bad it got scrambled. Im hoping its the spider gears alone so i can just swap em out with c6 parts.

Also waiting on gm to either confirm or deny my warranty (pretty sure i know which way thats gonna go) but im crossing my fingers.

Dealership quoted the repair at $3400 for a new diff and $1400 labor so if gm denys warranty i'll have to take it somewhere else cuz thats way too steep.

Smh i wish someone told me about the week spider gears on these damn things i woulda done something about it before romping on it

According to chevy.com the grand sport m7 has the same 3.42 ratio elsd as the z06 m7. So its kinda unfair if they blame my power mods and tune cuz im not making nearly as much power as the z06. Only z51s and grand sports with A8's have a 2.73 rear ends, A8 stingrays and z06s have 2.41 rears.

All M7 cars have 3.42 rear ends. I blew a 3.42 rear end.

JoesC5

The gear ratio doesn't have a major part in determining the strength of the differential.

For example you could take the 3.42:1 differential from a base 2005 C6 and replace the 3.42:1 differential in a C7 Z06, and it would last 1 second in a clutch dump. Even though they both(base C6 and C7 Z06) have the same gear ratio, the diameter of the ring gear is larger on the Z06, thus is much stronger. 9" diameter on the Z06 vs 8.25" diameter on the base C6 even though they both are 3.42:1 ratio.

You could take a complete 3.42:1 differential out of a C6 ZR1 and replace the 3.42:1 differential in a base C6(that's assuming that they both would bolt up the same), and you would end up with a much stronger differential even though they were both a 3.42:1 ratio.

I also bet that the 3.42:1 differential from a C6 ZR1 would hold up better than the 3.42:1 differential that is in the C7 Z06.

thill444

For the people berating the OP it's not like he modded his car and tried to hide it or cover it up. This forum can be so condescending sometimes.

OP, this sucks that it happened, and you are going about it the right way. And your right there is no sense in having GM install it since the replacement would not be under warranty as long as your car is modded. Well, at least likely You never know maybe they will work with you since this has happened to stock cars too.

Liter of cola

Nope, they denied me.

Anyone know if the z06 3.42 rear will fit my car? Im looking at a 3.42 on ebay for $1800 but i dont think its for my car i need the one with the coolers.

Dealer wants $4400 for the parts + labor.

Where else can i buy the diff other than dealerships?

thill444

Try these guys for new parts. I am sure used will be the way to go if you can find a good one:
http://www.trunkmonkeyparts.com/

Liter of cola

Found it but they dont say have parts for 2017 grand sport, looking at the parts for the 2016 z06 i cant tell which one if any would work with my car.

Hopper12

Hey Liter, really sorry this happened. Here's a link where I've purchased some stuff. I know it's not the diff you need, but they list several. You might contact them and see if they have what you need? I think they're a forum vendor (might be affiliated with trunk monkey??) but, if not, my post will self destruct in 30 seconds. Good luck!

http://www.gmpartsdirect.com/oe-gm/24255986

Liter of cola

So all the dealer did was take a fuid sample from the rear they havnt opened it up, what do you guys think? Open it up to see exactly what gears broke and then rebuild it or just buy a whole new rear diff?

Liter of cola

Can anyone tell me if i can use a z06 diff? A friend of mine has one he got from a crashed Z.

djnice

Sorry I don't know, but I would assume you can. I am commenting to bump your thread. I love how lots of people can tell you what your doing wrong, but can't actually help you out.

TGO

lol wut?


I could understand if you were using drag slicks but run flats have poor traction in comparison and didn't break your car.

Liter of cola

Yeah thats funny aint it.

Maxie2U

Yup, just like the OP's C7.

\Boost Monkey/

Why did they deny the claim?

They can prove one or more of you mods directly contributed to the failure?

That's bullshit.

Red Mist Rulz

One thing to remember is that the stock tunes on Corvettes implement what GM calls Torque Management. This programming includes a number of things to limit shock to the drivetrain. For example, it limits throttle imput in lower gears below 3,000 or 3,500 rpm, even if you mash the throttle to the floor. You simply can't get full true full throttle in first gear from a standing start. If the tune eliminates that, the drivetrain can experience far more stress than it would with a stock engine tune.

thill444

And the OP can't prove it did not.

Not trying to pile on the OP but when you significantly modify the car you can't expect GM to cover anything related to the powertrain.

The Moss-Mag act was never intended for that and I doubt anyone would win such a case in court.

This type of thing is why I am happy with a stock car and a warranty. If I needed more power I would buy a Z06.

NSC5

All they have to do is prove the engine tuning was modified. M-M doesn't actually say what a lot of people think it says (or would like it to say).

For the OP probably the best source of fit information is to go to your dealership when the parts counter isn't terribly busy and the parts guys can look up the part numbers for your rear end assembly and compare those to the part numbers for the Z06 (make sure to use the same year because part numbers can change even though the part itself is still identical). Since it is cost effective to share parts when possible the likelihood is high that your GS has the same assembly as the Z06 but make sure to either compare part numbers for the entire assemblies. Don't make the mistake of just comparing case part numbers because sometimes the same case is used with slightly different internals for some powertrain parts (like the A8 is configured slightly differently for different power levels) so the safest comparison is to make sure that the entire assembly uses the same part number for both models.

\Boost Monkey/

I missed the part where he said he was tuned...?

Although with those mods he should be tuned, is he? That would be an easy void for GM.

While I agree he's dancing with devil modding out a car under warranty, the mods would still have to contribute, in any way, to the failure.

Liter of cola

My mods are in the op

They simply said denied because of non gm calibration

I didnt know about this i will talk to my tuner about it

Unfortunatley my friend's diff was from an A8 car so i cant use it. According to the stealerships i've talked to so far aparently the 2017 rear diff for my car has a differant part number than the 15-16 ones. Meaning there may have been some kind of change. None of them will order me the part unless i bring them the car and have them do the work. One dealer even tried to make it sound like my car is a spaceship and that any parts and work will be very expensive lol, they hung up on me when they realized i knew what i was talking about, service manager said "since you voided your warranty we dont want to work with your car" and hung up. The 2017 diff's are not available yet anywhere else other than through dealers as a special order. Anyone know a good dealer than can get me the part without trying to rob me?

Foosh

You say above your mods are in the OP, where you did not mention a tune. Yet in the post above, you also say you need to "talk to your tuner."

Did you have your ECU reflashed or not? If you did, that would be a "non-gm calibration" and result in an automatic warranty block on anything powertrain related.