Hey all.

currently I've fitted a C7 bell housing, Torque Tube, TR6070 and E LSD into my C5.

My goal with the ELSD was to try and get it to work manually in my car. For example, putting it into steering wheel paddles and controlling it from 25%, 50%, 75%, or 100% on the fly. Or maybe just 25%-80%.

I can't find documents on exactly how the pump and solenoid function. iE, pump controls pressure and is variable speed or pump runs 100% and solenoid controls pressure to the diff.

ideally I would love to just figure out a away To tell the controller on the diff how how much to lock it up with my controller but if it's as simple as controlling voltage to the pump im sure I could make my own controller. I believe it's controlled by a serial data cable,
something passed me lol

any info or pointing me in the right direction would be great

thanks Jim

 

This is what's in the service manual. It's kinda thin on real details. The schematic for the motor just shows two signal wires and a ground. The scan tool parameters suggest that it's probably a PWM signal.

Getting this working is going to be a serious undertaking.

The rear differential clutch control modules function is to control the electronic limited slip differential. The rear differential control module receives a torque command signal from the chassis control module (CCM) according to the driving situation to achieve vehicle dynamics and traction.
The electronic limited slip differential system contains the following main components:

• The rear differential clutch control module
• The rear differential oil pressure/temperature sensor
• The differential clutch pump
• The rear differential clutch solenoid valve
• The rear differential oil temperature sensor

When the torque signal is received, the rear differential control module actuates the following components:

• Differential clutch pump (bi-directional rotary piston pump)
• Rear differential clutch solenoid valve (fail-safe pressure relief)

The electro-hydraulic piston actuation engages the limited slip clutch to allow active variable locking torque transfer to the left and right half shafts.
The rear differential clutch control module monitors voltage levels, hydraulic and clutch sump temperatures, over-current, and circuit failures.

 

thank you for taking the time to post that.

i googled PWM signal. Basically that's how the modular controls the speed of the pump?

 

PWM signals are used for pulsing things on and off extremely fast. Hundreds or thousands of times per second. It's how they adjust brightness in LED lights for example. That's also why you get that flicker when you see them in some videos. The frame rate of the camera is out of sync from the lights, so you manage to see some of the brief periods where it's off.

Pumps work the same way. If you pulse 12 volts to it, it'll run at a slower speed than if you just run constant 12v power to it. Change the pulse, and you change the speed the pump runs at. It helps with temperature control too. If you just throw a constant 12v at the pump you might overheat it. So that's something else to consider.

It can also shift torque from the inside wheel to the outside wheel in a turn. That's probably why the pump has two wires. It can run in both directions.

That's just the super basic function to make the pump run. The logic for when it should run, and at what speed, is a whole other huge topic. I don't know enough about the topic to say what kind of effect it would have on the car's stability to just lock it at 25% via a switch like you're talking about. Do it at the wrong time and it could spin you into a wall.

EDIT

This is mostly about the eLSD display on the dash, but it's got some good background info on how the diff itself works.

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

 

This is all but going to be impossible to get to work. The e-LSD doesnt work on a percentage, it is variable depending on the data input. As you go into the corner the e-LSD controller pushes the power to the outside tire to help and aid in getting through the corner. It is always varying how much power it is sending to the appropriate tire depending on the data input. There is nothing I know of that is going to allow you to run a C7 or even a 6th gen Camaro e-LSD controller in a C5 and also allow it to work.

 

i think I found a solution. I found a PMW controller that will adjust the speed and can be reversed. The pressure and temp sensor both run of 5v so I should be able to hook them up to the imputs on my Holley to monitor them.

The idea wouldn't be to use it as Intended but just as a simple controller for the diff clutches. If I knew the PSI range of the system it would help greatly.

with a scan tool you can run the controller threw its paces from 0-100%. Ideally it would be nice to simply power the controller and send that signal to adjust the % as need be for the situation.

Im going to run the motor with the controller and try to T in a mechanical PSI gauge to see how the controller and motor set and hold the PSI. Basicly all I really need to do is control the PSI pushing on the clutches for each driving condition.

i could also just adapt a holly oil pressure sensor to the system and may still do that

 

I dont think you understand how or what the e-LSD diff is used for or how it works. It is used for a road race situation, the controller literally locks and unlocks the outside wheel to apply power and help the car turn in faster, it isnt designed or intended as a drag racing differential. If you are intending to use it for drag racing you would be much better off just using the standard LSD diff since they will lock up on launch.

Even if you intend to use it for road racing, it isnt as simple as using a PWM controller and setting up a 25/50/75/100 lock ratio. The e-LSD works just like the mag ride system does, it takes thousands of samples a second and varies the lock ratio to keep the outside wheel powered up during the turn and help with turn in.

Here are some articles to help you understand better the e-LSD. There is much more integration involved them just using a PWM controller, I dont think you are going to be able to achieve that you are trying to do personally.


Here is the explanation from the Ask Tadge thread:

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


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.

You Tube

You Tube

 

I understand perfectly how it works.

It's literally just a limited slip differential that adjusts on the fly. That's it .

i think when they say it's sending torque to different wheels it's confusing people.

most cars have open diffs for easy turns and gas millage. Performance cars have limited slip differentials with springs pressing against the clutch pack to keep both wheels spinning in a straight line then allowing them to break away during a turn, drag, most drift cars have a spool to keep the wheels constantly locked together.

the E diff is just like your clutched diff but instal of springs pressing the clutch pack together it's using hydraulic pressure. This whole system can be simplified to hydraulic pressure and that's it.


The system basically taking all that data on the fly and adjusting it. If I were to take a C7 to the strip and launch the module would apply full lock to both wheels. The car would drag just fine.


so, again, I know I can't utilize the computer or the adjustments per second.

This doesn't mean I can't use the system to my own advantage.

I was using drag racing and auto cross as examples.

i could adjust the pressure to make the car an amazing auto cross machine and then take it to the track or drift and lock it up on the turn of a ****.


if you are a serious weekend drag racing but loved the street you would have the diff shimmed to keep the slip down. Your car would want to over steer if you took it to an auto cross event.

if you had an auto cross car you would want to have less spring pressure in your diff allowing more slip and keeping the car more agile and stable at auto cross but when you took it to the drag strip you run the risk of slipping it to much and doing a one wheel peel while burning up the clutch.

so, instead of dropping the diff, shimming your LsD for events and racing styles you could simply turn up or down the hydraulic pressure in your diff up or down with the turn of a ****. Not as great as the tuned E diff but for someone who wants to tune there LSD on the fly a great advantage over constantly shimming a normal LSD

 

The scan tool command may have control restrictions on it. The module probably won't execute the command if the car is moving or in gear, for example.

The module may not do anything if it doesn't see a few dozen other CAN messages on the bus that convince it it's in a fully operational car.

You're probably better off with your original idea of trying to drive the pump directly.

 

yeah, I'm thinking that's a bust. Would have to be able to program it. It's to bad the Chassis control Module didn't just send it a voltage to adjust from.

i read the entire service manual and should be getting the PMW controller today. Ordered one for 12v, 60amp for a brushed motor that also swaps direction.

also will need to control the solenoid, I believe that is controlled by voltage as the test procedure calls for 1v @ 10%..

One thing i still need it the max pressure the system can take.

I can add a holly pressure sensor to the system that will monitor the system on my LCD dash.

can also as a relay to it, if the pressure gets over the voltage I can have it cut power witch will open the valve as a fail safe.

From there I can Control the solenoid and pump. Likly keep the solenoid 20% open abs adjust the RPM on the pump to get the desired pressure.



searching the interwebs for that, only other thing I can think of is some Math, Jason said it had 1200nm of pressure, perhaps if I calculate the amount of surface area on all the pistons I can calculate the PSI needed then make my Max PSI just under that. Or, run a pressure gauge while monitoring the the voltage on the factory pressure switch and when it gets to the voltage required to set a DTC read my gauge and call that max pressure.

it would be simpler if they just wrote it down somewhere lol

 

One thing I really wish GM would do is publish more 'theory' documents. Audi has excellent docs that explain how and why their systems work. The diagrams are gorgeous. They're separate from the service manuals that explain how to repair those systems.

Let me know if you need any data from a car. I've got a 17 GS I can get info from. I don't want to pull any of the hydraulic system apart, but anything I can get from the factory scan tool or CAN logging I'll do. I've also got a messed up diff control module from a 2014 that I can hook up on my bench to see if I can coax any useful info out of. It's just the bare control module though. No pump assembly.

 

that would be great!! If the scan tells you the psi it would save me alot of work.

a few people have told me to worry about pump
life but from what I've read the pump seems to be working alot while your driving

 

I suspect the pump is cycling on and off a lot during normal driving. Running it at a constant pressure for long periods might not be good for it.

It looks like pump pressure and electrical current are both available in the scan tool. I might be able to check it out tonight. Worst case it'll be this weekend. It really depends on whether I can do it with the car stationary on the ground, or if I have to jack it up and have the wheels turning.

 

thank you that would be great

 

I think you will be able to control the eLSD with the method you outlined. GM might PWM the pump power, and/or PWM the solenoid, to regulate the clutch pressure.
Or, perhaps the solenoid valve is to quickly dump the clutch pressure, to release the locking quickly.

 

The scan tool data list mentions a duty cycle for the solenoid. Somewhere in my reading I also saw that it can run the pump in reverse to lower pressure in the system. So that's a potential factor too.

 

they outlined that it's only for a fail safe, but then in the diagnostics they say it can be run at different percents so I'm assuming they use it in conjunction with with pump. I tried to find out if it's PWM powered but didn't see anything how ever it said to use a Volt meter to check for voltage going to the solenoid we're as the Pump they said to use a
tesr light and see if the light gets brighter when you increase it with the scan tool .

wondering if that sounds like the pump uses PMW but the solenoid regulates with voltage

 

i did see that also. Im guessing the reverse it more needed for the speed. I mean when you actually sit there and think about it it's amazing.

I've seen fast robotics and CNC machines but it's crazy to think how many times a second the pump is making or taking pressure from the clutch pack.

I'm hoping I don't need to use reverse but the controller coming can reverse.

if the solenoid has a duty cycle would that determine the way it's controlled?

im
limited on this

 

Somebody needs to put a two channel oscilloscope on the pump motor and solenoid, then drive the car. That would then show if the Pump is PWMed, if the pump polarity is reversed, and if the solenoid is PWMed, or just full ON and OFF.

 

i had to google that, it would tell us for sure.

i talked to someone about an hour ago and he was 80 % sure That if both have a Duty cycle they are both PMW. Just sat down to do some googling lol