[spotswood]

I have had my ZL1 1LE for a month or so now and I keep the computer traction control disengaged most of the time.
I have found the launching in first gear at normal driving sensitive in that I need to have 1500 rpm and release the clutch moderately in speed to prevent bogging it down or it stalling which happened twice to me in the first week. Otherwise I have not experienced any problems. When I want throttle its there and can break the wheels loose as I don't use traction control.
I absolutely do not understand the wheel slip gauge that I can have on the display. It will show a % of wheel slip and I know there is no wheel slip happening.

[travislambert]

Originally Posted by spotswood

I have had my ZL1 1LE for a month or so now and I keep the computer traction control disengaged most of the time.
I have found the launching in first gear at normal driving sensitive in that I need to have 1500 rpm and release the clutch moderately in speed to prevent bogging it down or it stalling which happened twice to me in the first week. Otherwise I have not experienced any problems. When I want throttle its there and can break the wheels loose as I don't use traction control.
I absolutely do not understand the wheel slip gauge that I can have on the display. It will show a % of wheel slip and I know there is no wheel slip happening.

Keep in mind that the '18s have software driveability fixes that the '17s do not.

The answer to your Wheel Slip % gauge question is explained in the attachment in post #97. In a nutshell, it's a small amount of error in the sensors, tire circumference, etc. that leads the computer to believe the back tires are spinning faster than the fronts. Since it's a percentage, it doesn't take much error to generate a big spike on the gauge. Imagine the tires moving at a rate of 0.1 MPH, and a sensor error on the rear tires of +0.1 MPH. That would show as a 100% slip even though it's only 0.1 MPH off from actual.

This is why the gauge appears to going crazy at really low speed. It's simply giving visibility into the sensor error that's negligible any other time.

[Rooster OG]

I haven't read this thread, but on the Corvette side Tadge and an engineer explain the elsd and the display. I have no idea if this will help or not, maybe some of you will find it interesting.

https://www.corvetteforum.com/forums...d-display.html

[Infern0]

Originally Posted by Rooster OG

I haven't read this thread, but on the Corvette side Tadge and an engineer explain the elsd and the display. I have no idea if this will help or not, maybe some of you will find it interesting.

https://www.corvetteforum.com/forums...d-display.html

That's fantastic. Seemed to almost certainly confirm some theories (so maybe they were more than theories to begin with).

[ELS1]

Originally Posted by Infern0

That's fantastic. Seemed to almost certainly confirm some theories (so maybe they were more than theories to begin with).

“Generally speaking, we try to calibrate our chassis controls so that they are virtually invisible to the driver. The idea is to integrate our electronic and mechanical systems to the point where the Corvette just feels like a naturally great handling car - intuitive and benign without unwanted interventions that take the fun out of driving.”.


“When we calibrate eLSD, we work in units of torque. 100% corresponds to 2000 Newton-meters (1475 ft-lbs) of break-away torque (every 1% is 20 Nm (14.75 ft-lbs)). Said another way, while holding one wheel stationary it would take 2000 Nm of torque on the other wheel to make the clutch between the two wheels slip if the display read 100%. For reference a C6 mechanical differential clutch pack was roughly 120 Nm (88 ft-lbs). The actuator is very quick to respond and is able to change from open to locked (0 to 100%) 150 ms (.15 sec) in order to respond to any dynamic situation.“


“Bleed events. The actuator needs to bleed small amounts air out of the hydraulics every few keys cycles to keep things operating consistently. As a driver you may see a couple of spikes to 100% at very low speeds while going straight. This is totally normal and can only happen in a relatively small range of steering on-center so you won't feel it in tight parking lot maneuvers.”


“Wheel Slip percentage on the bottom of the display:
The important thing to know here is that this slip display is not directly connected to the eLSD software. This wheel slip display has its own calculation and it's showing the average rear wheel slip compared to the average front wheel slip. It's not showing how much slip is occurring across the eLSD clutch (between the two rear wheels), even though I can see how a driver could make that connection. ` Think about this as showing how much rear wheel spin you're getting at the drag strip in a burn-out box, for example.”


https://www.corvetteforum.com/forums...d-display.html


Great, informative read that was answered a few days ago! Awesome find.

[BaylorCamaro]

For those interested about eLSD and what it's displaying Tadge (engineer for Corvette) answered that question last week on the Corvette Forums. I'm sure the eLSD display is very similar in both the Corvette and Camaro.

https://www.corvetteforum.com/forums...d-display.html

Originally Posted by jcthorne Asked

Can you tell us what the information in the eLSD display screen means and how one might make use of it or understand what its trying to tell us.

Originally Posted by Tadge Answered

Good question, jcthorne. Many people have asked about that display. Electronic limited slip differentials (eLSD) have only been introduced relatively recently, so many are unfamiliar with the details of their operation. The Corvette is a very sophisticated machine and we try to provide instrumentation that is accurate, readable and informative about the hardware. When we first decided to add eLSD to the 7th generation Corvette, we started thinking about how we would inform drivers about its operation and decided an added display might be interesting to some customers.

Generally speaking, we try to calibrate our chassis controls so that they are virtually invisible to the driver. The idea is to integrate our electronic and mechanical systems to the point where the Corvette just feels like a naturally great handling car - intuitive and benign without unwanted interventions that take the fun out of driving.

Normally I write answers on the forum myself and check in with appropriate experts for additions or suggestions. I can't take any credit this time. Our eLSD integration engineer, Jason Kolk, provided a detailed answer below. He is one of several chassis controls engineers who calibrate the chassis controls to great effect on the Corvette.

Also, I would be remiss if I didn't remind everyone that the eLSD does some of its most important work in some pretty aggressive maneuvers. That is not the time to be looking at the display.... First priority is to keep eyes on the road!

Originally Posted by Jason Kolk Answered

eLSD is standard on all Stingray Z51, GrandSport, and Z06 models. The eLSD display (the bottom page in the Performance display group) was added in the 2015 model year to Corvettes equipped with eLSD. There are two pieces of information on the display, eLSD clutch coupling percentage value on top in yellow, and the slip percentage of the rear wheels on the bottom in white shown in the bar graph.

eLSD Percentage in the top/middle:
In the center there is an image of the car, two wheels and the differential. The differential lights up as the eLSD coupling increases. The value shown is a percentage of the full locking coupling capability, and it is the actual value reported by the actuator. When we calibrate eLSD, we work in units of torque. 100% corresponds to 2000 Newton-meters (1475 ft-lbs) of break-away torque (every 1% is 20 Nm (14.75 ft-lbs)). Said another way, while holding one wheel stationary it would take 2000 Nm of torque on the other wheel to make the clutch between the two wheels slip if the display read 100%. For reference a C6 mechanical differential clutch pack was roughly 120 Nm (88 ft-lbs). The actuator is very quick to respond and is able to change from open to locked (0 to 100%) 150 ms (.15 sec) in order to respond to any dynamic situation.

There is a lot going on behind the scenes in the software to come up with the eLSD coupling that you're seeing here. There are a number of algorithms that are running at the same time to collectively decide how much coupling is needed for the different vehicle dynamics situations that they each monitor and control. We have some logic to decide which one of them wins out or which ones add together to deliver the final command that you see on the display and feel in the car.

At the most basic level, the eLSD can have a subtle but profound effect on the handling of the car. We really consider it to be a 'base chassis' component. It's something that plays a big part in setting up the character of the car.
Off-throttle, more eLSD coupling adds stability, but too much can be a bad thing. The eLSD is connecting the two wheels so in a turn it's trying to slow down the outside wheel and speed up the inside wheel. In other words the eLSD clutch coupling is trying to oppose the direction that the car is turning, so setting this off-throttle level is pretty important to keeping the car feeling agile. In a steady turn this can help tune the amount of understeer the car has. In highly dynamic maneuvers, this results in something that we call yaw damping where it will reduce the rotation rate of the car.
When the driver is on-throttle, the eLSD clutch can shift torque from the inside wheel to the outside wheel. This has the combined effect of minimizing or eliminating inside wheel spin, but it also controls how much it feels like the car turns with the throttle. More torque on the outside and less on the inside will help the car turn - to a point, but that's the balance we're constantly searching for while we tune the software.

Each package is tuned individually so a Z06 won't have the same values as a Stingray Z51, for example. Automatic and Manual transmissions have different calibrations, and even suspension and tire packages like FE3 and FE4, FE6 and FE7 do differ from each other.

eLSD is fully integrated with the stability control and Performance Traction Management (PTM) systems.

Note that changing from Tour to Sport to Track has no effect on eLSD mode. eLSD mode does change automatically when the Traction Control button is pressed. No unique input from the driver is required.
eLSD Mode 1 is the standard mode when the vehicle is started. It is optimized for how torque is delivered with Traction Control active and off-power there is an emphasis on vehicle stability. Mode 1 is also used in Performance Traction Management Wet mode.
eLSD Mode 2 is engaged when both Traction Control and Electronic Stability Control are turned off. This calibration provides more nimble corner turn-in, and is optimized for traction out of corners.
eLSD Mode 3 is engaged when Performance Traction Management is in Dry, Sport 1 & 2, and Race modes. Off power this is a nimble calibration with similar functionality as eLSD Mode 2, however, it is integrated to work with Performance Traction Management when the driver is on power.
eLSD Mode 4 is engaged when Traction Control is selected off, but stability control remains on. Vehicle stability is still the priority, while allowing for optimized traction out of corners.
Here are some examples of what you may see if you watch this screen. I'll talk generally, so the numbers may not match exactly what you see, but the trends should be there:
Bleed events. The actuator needs to bleed small amounts air out of the hydraulics every few keys cycles to keep things operating consistently. As a driver you may see a couple of spikes to 100% at very low speeds while going straight. This is totally normal and can only happen in a relatively small range of steering on-center so you won't feel it in tight parking lot maneuvers.
Driving straight down the road, we have some speed based preload to add stability and on-center feel. This is going to be relatively small and you will only see a small amount around 10-15% at highway speeds. You'll notice that when you do steering inputs and simple lane changes that it drops down slightly and then pops back up when you are going straight again. This strategy is to improve steering feel and agility. We can be more open at low speeds than previous fixed clutch packs (C6 was fixed at 120 Nm (88 ft-lbs)), and then add more at very high speeds to add stability.
On larger throttle applies you will see eLSD clutch torque grow, and these could be the largest amounts of eLSD coupling that you'll see under normal circumstances. On track this could go as high as 40-50%. The goal of this algorithm is to maximize rear traction while cornering and tune the feel of how much the car is turning while you're on power.
The largest eLSD coupling will happen under very extreme lane changes and slaloms where we can nearly lock the eLSD clutch to add stability at just the right moments, but open back up to allow the car to steer through double lane changes at just the right times.
If you were to drive your car in the winter and start with one wheel on ice and the other on bare pavement, you may see clutch torque build in response the wheel on ice slipping to keep it under control and to maintain smooth acceleration.

Wheel Slip percentage on the bottom of the display:
The important thing to know here is that this slip display is not directly connected to the eLSD software. This wheel slip display has its own calculation and it's showing the average rear wheel slip compared to the average front wheel slip. It's not showing how much slip is occurring across the eLSD clutch (between the two rear wheels), even though I can see how a driver could make that connection. ` Think about this as showing how much rear wheel spin you're getting at the drag strip in a burn-out box, for example.

There may be rare instances where you see this display flicker when you first start to move or when you come to a stop. Don't be alarmed by that, it's function of the math behind the display when the numbers get really small.

[travislambert]

The control tec device was installed in my car this morning. I captured a few events by taking off slowly in a paved parking lot with some very fine gravel (to trigger a small amount of wheel slip). The car nearly stalled a couple times, so hopefully that'll be some good data for the engineers.

Tomorrow it's supposed to rain in my area. I don't like to drive my car in the rain, but I might take it out for a short trip because the problem is very easily reproduced with a little water on the road.

The control tec is scheduled to be removed Friday morning (September 1st). Hopefully, we'll hear back from GM within a couple weeks.

[Infern0]

Originally Posted by travislambert

The control tec device was installed in my car this morning. I captured a few events by taking off slowly in a paved parking lot with some very fine gravel (to trigger a small amount of wheel slip). The car nearly stalled a couple times, so hopefully that'll be some good data for the engineers.

Tomorrow it's supposed to rain in my area. I don't like to drive my car in the rain, but I might take it out for a short trip because the problem is very easily reproduced with a little water on the road.

The control tec is scheduled to be removed Friday morning (September 1st). Hopefully, we'll hear back from GM within a couple weeks.

Maybe do some aggressive launches to replicate the nose dive too? Launch control too perhaps?

[travislambert]

Originally Posted by Infern0

Maybe do some aggressive launches to replicate the nose dive too? Launch control too perhaps?

I took it out this evening and did my best to capture a few launches. I captured two launches that felt like good representations of the problem.

[Diggitydog]

Originally Posted by travislambert

I took it out this evening and did my best to capture a few launches. I captured two launches that felt like good representations of the problem.

Super glad you are working on this. Definitely hoping for a factory solution to keep warranty intact.

[Sooner Cole]

Originally Posted by travislambert

I took it out this evening and did my best to capture a few launches. I captured two launches that felt like good representations of the problem.

Thanks for working on this. As the data is captured, it is transmitted to the GM Engineers in real time. They should already have the data. The more times you push the "capture button", the more data they will have to look for common anomalies. It is just a matter of them going over it and reaching a conclusion. Hopefully the drivability and launches are both related and a simple software update will fix the issue.

[KyleL]

Forgive the conspiracy theory-esque wording of what I'm about to say but I have a question for all.

Does anyone think this was done not to save the clutch or driveline parts more so than it was to make the a10 look that much better on paper? And that in an effort to do this, compromised safety/driveability aspects in addition to performance?

A c6 zr1, c6z and 5th gen zl1 all allow for up to 4K rpms on their launch control too but when the clutch is disengaged, it seems as though the car doesn't fall down as hard. Rpms fall to about 2500-3000 and power is cut to counter wheelspin obviously.

A quick glance at the fast list shows the a8 is .2 quicker in the 1/4 so far than the m6, with one member pointing out that the fastest m6 passes were in +da and the 11 sec a8 passes were in -da. But let's just assume everything were equal and there really is a .2 difference, why would there be a greater contrast between the ss times and zl1 times? It seems as though the ss tq management is less invasive. Could that be bc the a8 wasn't quite as hyped up as the a10 was? As a consumer, it was only when I really started to look at trading my my c6 on an ss did I see this new 8 speed and looked specifically into it. I knew dodge had them and I wasn't even in the market for one of those at that time. Perhaps that's just the differences in marketing strategies between the two. I also understand that the a8 and a10 are different transmissions but the m6 in the zl1 is also different than the ss variant with closer ratios. So if the difference lies solely with the a8 to a10 transition, we could assume then that when a10 ss camaros (if that ever happens) hit the streets, they'll be seeing some 11.6-11.7 times under similar conditions and the average pass would be a high 11.

Just a thought. What do you guys think?

[17CamaroZL1]

I think it all boils down to the higher first gear ratio in the M6 ZL1 and trying to protect the clutch because of that and the added power of the LT4. If Chevy was solely trying to make the A10 look better on paper, they would've claimed a faster 1/4 ET, such as the 11.1 that Al O. told us about at Camarofest. He said they had managed an 11.1 with it, but chose the 11.4 because it would be something the owners could more easily achieve.

[KyleL]

Originally Posted by 17CamaroZL1

I think it all boils down to the higher first gear ratio in the M6 ZL1 and trying to protect the clutch because of that and the added power of the LT4. If Chevy was solely trying to make the A10 look better on paper, they would've claimed a faster 1/4 ET, such as the 11.1 that Al O. told us about at Camarofest. He said they had managed an 11.1 with it, but chose the 11.4 because it would be something the owners could more easily achieve.

I certainly believe them when they say they're doing it to protect the clutch, but it's not as invasive as the c6 zr1 which also had a tr6060, and very similar power, and I assume an equally strong clutch. I find it hard to think they would have put a substantially weaker clutch in a newer version of a product enough to put that much protection of it in the ecu when both engines produce similar power. I don't fully buy into the long first gear claim, bc my m6 c6 would run to 55 in first and the c6z would do 60-62 I believe, both didn't bog down near as bad on the initial launch. I'm not sure about the last gen gt500 or vipers, but they could all reach 60 or close to it in first gear as well

That's also a very good point too as far as et's but, like you said, they're trying to be more realistic with their times. I've read where GM claims their times on corvettes and camaros on unprepped surfaces....which would tie into your point of a realistic time. So you could say they'd do the same for the m6 too, which still wouldn't matter since if they could knock off .3 just by running on a prepped surface in the auto, you could also do it with the manual, which cal has almost already demonstrated exactly with his m6 zl1, knocking .2 off what GM claims.