Question regarding LSD
Melting Slicks
Joined: Nov 2014
Posts: 2,204
Likes: 17
From: Fayetteville North Carolina
St. Jude Donor '15
I don't quite understand why the assumption is that it's working normally. This is one of the situations that the limited slip is supposed to prevent.
If the clutch pack is allowing that much slip, then you might as well
be driving a car with an open differential. With that situation, you'll have all kinds of trouble getting power to the ground on launch and corner exit.
I would make them prove to me that it's working correctly.
If the clutch pack is allowing that much slip, then you might as well
be driving a car with an open differential. With that situation, you'll have all kinds of trouble getting power to the ground on launch and corner exit.
I would make them prove to me that it's working correctly.
Le Mans Master
Joined: Jun 2014
Posts: 7,474
Likes: 116
From: Over there
Le Mans Master
Joined: Jun 2014
Posts: 7,474
Likes: 116
From: Over there
I didn't mean that it actually failed. GM recommends that you don't drive in extreme cold on summer tires, it doesn't say anything about not driving in extreme cold with a differential. So if it did fail, the fact that GM recommends not using summer tires is irrelevant, because that's not what caused it to fail (theoretically. Once again, I am not saying that it did fail).
Melting Slicks
Joined: Nov 2014
Posts: 2,204
Likes: 17
From: Fayetteville North Carolina
St. Jude Donor '15
I didn't mean that it actually failed. GM recommends that you don't drive in extreme cold on summer tires, it doesn't say anything about not driving in extreme cold with a differential. So if it did fail, the fact that GM recommends not using summer tires is irrelevant, because that's not what caused it to fail (theoretically. Once again, I am not saying that it did fail).
Le Mans Master
Joined: Jun 2014
Posts: 7,474
Likes: 116
From: Over there
If you're driving in extreme cold and the tires crack, GM can deny a claim you make because they warned you about it. If you're driving in extreme cold and your radio fails, GM can't deny your claim because there is no warning about the radio not working at low temperatures. The same thing goes for the diff. There is no warning for the diff failing at low temperatures, so if a diff fails at extremely cold temperatures, GM can't deny a claim.
I'm not saying that his diff did fail. What I'm saying is that if it did, the fact that the tires aren't rated to operate at low temperatures doesn't matter. Are you suggesting that because the tires aren't rated for sub 40F weather, then the entire car isn't rated for that low temperature, and if anything on it breaks it's your fault for driving it in the cold? What happens if you put snow tires on the car then?
Last edited by Crabbers; Mar 4, 2015 at 02:06 PM.
Melting Slicks
Joined: Nov 2014
Posts: 2,204
Likes: 17
From: Fayetteville North Carolina
St. Jude Donor '15
You -------------------------------------------> The point
If you're driving in extreme cold and the tires crack, GM can deny a claim you make because they warned you about it. If you're driving in extreme cold and your radio fails, GM can't deny your claim because there is no warning about the radio not working at low temperatures. The same thing goes for the diff. There is no warning for the diff failing at low temperatures, so if a diff fails at extremely cold temperatures, GM can't deny a claim.
I'm not saying that his diff did fail. What I'm saying is that if it did, the fact that the tires aren't rated to operate at low temperatures doesn't matter. Are you suggesting that because the tires aren't rated for sub 40F weather, then the entire car isn't rated for that low temperature, and if anything on it breaks it's your fault for driving it in the cold? What happens if you put snow tires on the car then?
If you're driving in extreme cold and the tires crack, GM can deny a claim you make because they warned you about it. If you're driving in extreme cold and your radio fails, GM can't deny your claim because there is no warning about the radio not working at low temperatures. The same thing goes for the diff. There is no warning for the diff failing at low temperatures, so if a diff fails at extremely cold temperatures, GM can't deny a claim.
I'm not saying that his diff did fail. What I'm saying is that if it did, the fact that the tires aren't rated to operate at low temperatures doesn't matter. Are you suggesting that because the tires aren't rated for sub 40F weather, then the entire car isn't rated for that low temperature, and if anything on it breaks it's your fault for driving it in the cold? What happens if you put snow tires on the car then?
Changing the tires to something non-OEM doesn't mean GM has to warranty the vehicle with aftermarket parts.
Team Owner
Joined: Mar 2012
Posts: 49,198
Likes: 3,889
From: Best Island in the U.S.
St. Jude Donor '12 thru '17
Is there something somewhere that says what kind of LSD (thanks for that cat graphic!
) is in the C7? Without knowing that it's impossible to answer the OP's question.
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Melting Slicks
Joined: Nov 2014
Posts: 2,204
Likes: 17
From: Fayetteville North Carolina
St. Jude Donor '15
WTF are you talking about? Where does it say that a C7 doesn't belong on ice or that it's not designed to be driven on ice?
Is there something somewhere that says what kind of LSD (thanks for that cat graphic! ) is in the C7? Without knowing that it's impossible to answer the OP's question.
Is there something somewhere that says what kind of LSD (thanks for that cat graphic!
) is in the C7? Without knowing that it's impossible to answer the OP's question.The tires are not recommended for use under 40 degrees. Ice happens at and under 32 degrees. DERP They don't recommend the tires for use on ice BY DEFINITION. They are also called "summer tires" for a reason.
Good luck making them prove how the diff is supposed to work on ice when they won't rate the tires for it. Switching to non-OEM parts (tires) isn't going to help.
Le Mans Master
Joined: Jun 2014
Posts: 7,474
Likes: 116
From: Over there
Melting Slicks
Joined: Nov 2014
Posts: 2,204
Likes: 17
From: Fayetteville North Carolina
St. Jude Donor '15
Le Mans Master
Joined: Jun 2014
Posts: 7,474
Likes: 116
From: Over there
Snow tires will not void your warranty. Are you really suggesting that driving your car in under 40F weather will void your warranty and if you put snow tires on it to drive in under 40F weather, that will also void your warranty?
Melting Slicks
Joined: Nov 2014
Posts: 2,204
Likes: 17
From: Fayetteville North Carolina
St. Jude Donor '15
I can explain it to you but I can't understand it for you.
Le Mans Master
Joined: Jun 2014
Posts: 7,474
Likes: 116
From: Over there
Oh, and before you say it, I agree that GM doesn't have to prove it is working, he has to prove it isn't. And I don't think it is broken.
Last edited by Crabbers; Mar 4, 2015 at 03:30 PM.
Instructor
Joined: Feb 2015
Posts: 115
Likes: 2
Are there any engineers on board this thread?
BINGO. Both tires on ice would be a 'corner case' for operation of a mechanical LSD, which is only designed to work when there is some minimum amount of traction available.
In an older car you would see both wheels spin helplessly, until the rear drifted sideways a little bit and suddenly caught some traction, spinning your car violently into the guy parked next to you.
But this is the age of electronic integration, and the C7 has some of the most advanced control software of any car. So it's not just the diff at work in this case, even with traction control turned off I bet the car is actually braking one wheel so that they don't both spin. Note it would never brake both rear wheels simultaneously instead it would cut engine torque, but it's not going to cut that to zero either.
If you want to test the diff is working properly you've got to do it in dry or only slightly wet conditions. And thats the only way the dealer is going to test it.
Good luck!
In an older car you would see both wheels spin helplessly, until the rear drifted sideways a little bit and suddenly caught some traction, spinning your car violently into the guy parked next to you.
But this is the age of electronic integration, and the C7 has some of the most advanced control software of any car. So it's not just the diff at work in this case, even with traction control turned off I bet the car is actually braking one wheel so that they don't both spin. Note it would never brake both rear wheels simultaneously instead it would cut engine torque, but it's not going to cut that to zero either.
If you want to test the diff is working properly you've got to do it in dry or only slightly wet conditions. And thats the only way the dealer is going to test it.
Good luck!
Melting Slicks
Joined: Nov 2014
Posts: 2,204
Likes: 17
From: Fayetteville North Carolina
St. Jude Donor '15
BINGO. Both tires on ice would be a 'corner case' for operation of a mechanical LSD, which is only designed to work when there is some minimum amount of traction available.
In an older car you would see both wheels spin helplessly, until the rear drifted sideways a little bit and suddenly caught some traction, spinning your car violently into the guy parked next to you.
But this is the age of electronic integration, and the C7 has some of the most advanced control software of any car. So it's not just the diff at work in this case, even with traction control turned off I bet the car is actually braking one wheel so that they don't both spin. Note it would never brake both rear wheels simultaneously instead it would cut engine torque, but it's not going to cut that to zero either.
If you want to test the diff is working properly you've got to do it in dry or only slightly wet conditions. And thats the only way the dealer is going to test it.
Good luck!
In an older car you would see both wheels spin helplessly, until the rear drifted sideways a little bit and suddenly caught some traction, spinning your car violently into the guy parked next to you.
But this is the age of electronic integration, and the C7 has some of the most advanced control software of any car. So it's not just the diff at work in this case, even with traction control turned off I bet the car is actually braking one wheel so that they don't both spin. Note it would never brake both rear wheels simultaneously instead it would cut engine torque, but it's not going to cut that to zero either.
If you want to test the diff is working properly you've got to do it in dry or only slightly wet conditions. And thats the only way the dealer is going to test it.
Good luck!
Instructor
Joined: Mar 2014
Posts: 239
Likes: 29
I'm going to guess that you didn't apply enough throttle to get any lock-up/clutch pack grab. It remains open at low throttle/ramp. If you want to test it, just put one wheel on the road and one on ice or dirt and apply heavy and quick throttle -- make sure you know how to control the car.
Team Owner
Joined: Sep 1999
Posts: 41,732
Likes: 1,718
From: Springfield MO
I don't quite understand why the assumption is that it's working normally. This is one of the situations that the limited slip is supposed to prevent.
If the clutch pack is allowing that much slip, then you might as well
be driving a car with an open differential. With that situation, you'll have all kinds of trouble getting power to the ground on launch and corner exit.
I would make them prove to me that it's working correctly.
If the clutch pack is allowing that much slip, then you might as well
be driving a car with an open differential. With that situation, you'll have all kinds of trouble getting power to the ground on launch and corner exit.
I would make them prove to me that it's working correctly.