Can somebody run down the differences of what both are in terms of normal driving, sporty driving, and track driving?

Also, what about wet conditions, gravel, dust, etc.

Just trying to figure out if I need the e-diff or not and what the pros/cons are.

Thanks.

 

I was wondering this also.

 

electrical vs mechanical

 

In automotive engineering the electronic differential is a form of differential, which provides the required torque for each driving wheel and allows different wheel speeds. It is used in place of the mechanical differential in multi-drive systems. When cornering, the inner and outer wheels rotate at different speeds, because the inner wheels describe a smaller turning radius. The electronic differential uses the steering wheel command signal and the motor speed signals to control the power to each wheel so that all wheels are supplied with the torque they need.

Functional description

The classical automobile drivetrain is composed by a single Internal combustion engine providing torque to one or more driving wheels. The most common solution is to use a mechanical device to distribute torque to the wheels. This mechanical differential allows different wheel speeds when cornering. With the emergence of electric vehicles new drive train configurations are possible. Multi-drive systems become easy to implement due to the large power density of electric motors. These systems, usually with one motor per driving wheel, need an additional top level controller which performs the same task as a mechanical differential.

The ED scheme has several advantages over a mechanical differential:[1]

• simplicity - it avoids additional mechanical parts such as a gearbox or clutch;
• independent torque for each wheel allows additional capabilities (e.g., traction control, stability control);
• reconfigurable - it is reprogrammable in order to include new features or tuned according to the driver’s preferences;
• allows distributed regenerative braking;
• the torque is not limited by the wheel with least traction, as it is with a mechanical differential.
• faster response times;
• accurate knowledge of traction torque per wheel.

your welcome

Not really needed unless your tracking the car. Base rear end is posi traction

 

So is the base non-Z51 differential a limited slip mechanical then?

I was looking for specific info that relates to the diffs on the C8 and not a general wiki entry which I already read. But thank you.

Trying to figure out what comes on the base C8 and exactly how does it differ from the Z51 diff.

 

No description yet on the C8 diff but here's the description of the C7's eLSD.

 

Electronic LSDs use feedback signals from the car to engage/disengage clutch packs to transfer torque. The variables that trigger torque transfer can be orders of magnitude more in quantity/sensitivity than mechanical LSDs
The Mechanical LSD would require some sort of mechanical feedback (e.g. minimum speed difference between left and right tire) before it starts to split/transfer torque.

 

Read this then. Page 2 and 3. C8 base differential is mechanical limited slip.
https://auto.howstuffworks.com/elsd1.htm

 

https://www.lsxmag.com/news/make-you...d-calibration/

 

Unless you track the car, the eLSD does not provide a huge benefit. Perhaps some tuning at the margins on low-traction conditions. The real benefit is digging out of corners in AutoX or Track. The C7 GS and Z06 with the eDiff were monsters at the limit. Unless that is your world, save your money. You won't miss it.

 

Some of the above answers about mechanical limited slip differentials are misleading because there are multiple types of mechanical limited slips. One of the best limited slip differentials is a torsen type.

Torsen differentials are excellent and some might argue that they are better than an electronic limited slip. They are expensive.

I do not know if non Z51 diff is a clutch type or a torsen type.

 

The biggest benefit of eLSD is that it's tied into PTM. PTM to me is way more important than eLSD.

 

You’ll have to get MSRC on your Z51 to unlock PTM, sure you realize that but others won’t.

 

Yes, good point. So $5K for Z51 + $1,895 for MSRC, so $6,895 to unlock PTM.

 

Speaking of the Diff, any of you guys ever wear a diff clutch pack out after all your track/autocross/motorsports events on a C7?

 

We have torSen diffs on my audi s5 and then also an e-diff (audi calls it a sportdiff) and the sport diff being programmable really allows you to almost specify how much the rear rotates out if the corner.

Ive had three audis without it and one with it. Its a neat feature.

Some folks say they will never buy another car without it. Im in thee i could take it or leave it camp.

I honestly like the rear to feel more planted so usually left the diff in its most conservative mode anyways when tracking. Just an fyi it happened to be a 5 thousand dollar part if people killed theirs although we find them used for a few hundred.

Mike

 

No, torque only. The greater traction on the one tire will produce an axial load on the spider gears attempting to unmesh. This unmeshing places pressure on the clutch pack splined to that axle.
The bevel on the spider gears determines the pressure. The clutch packs are preloaded with little springs. The ramp angles determine the amount of slip or torque split.
GM has been the best company in the world to refine a mechanical Salisbury type differentials since the 60s.
Another way of controlling torque split on a LS diff, is to have a split casing where the spider gear pins are incased. The torque split caused by spider gears coming out of mesh can further be fine tuned by widening the gap of the casing by an axial load caused by the pins forcing the gap to widen. The casing itself is kept together by little springs.
A good machine shop can alter the slots for both on and off throttle response and corresponding loading requirements.
When you build a car from scratch, one has to refine everything. My diff started opening thru wear and tear. I blasted thru my favorite 90 mph turn and I was able to get on the throttle much sooner than I would normally do. I never thought that a diff would make such a difference to performance. Too much torque to the outside tire will saturate the friction circle prematurely. I took just one degree out of the thrust ramps and reduced the torque and made the inside tire work a little harder. The trailing felt fine to me, so I didn't alter those ramps.
Now that was for a specific application. An ediff will adjust for most situations. A GM tuned mechanical diff will be as good as it can possibly can be in the C8.
One problem with an ediff. Heavy. DI, heavy. DCT, heavy. A C8 would be < 3000lbs without all that crap. Push rods lower the CG and they placed those coil overs way above the engine. Anyway, that's another story.
An ediff will optimize the torque split upon desired duties, which is mainly allowing for best traction on exit in addition to other handling duties.

Remember when C7s with M7s with ediffs spun out to the right during an upshift to second at max thrust???. The ediff opened upon throttle release. Max throttle after shift, there is a slight delay in hydraulic clutch engagement and together with poor caster adjustment, the car turned abruptly to the right. Not as serious in a mid engine car would be. Give me a well tuned mech LS diff. anytime.

 

The Torsen in my GT350 is amazing and Mustangs have typically not handled lateral transition well partially because the diff can't keep up. The T2 in the 350 does wonders. And yes, no clutches to go bad. Why doesn't Chevy use a Torsen in its cars? Because the eLSD is kinda their "thing?"

 

I had one in my Boss 302. Great for road racing but I don't think it can adjust lockup like the GM eLSD. Also, Torsens tend not to hold up to drag racing abuse.

 

Some quick questions:

Do Torsen Differentials (TBD) work during deceleration? (braking/trail braking)
What happens when cornering hard and the inside rear wheel goes up in the air?