Warp Factor

I don't know. Like I said earlier, my C7Z doesn't do it. With traction control off, it behaves about the same as my C5 did when I spin up the tires, which had the conventional positraction clutch pack.

Couple of wild guesses:

If one is accustomed to a solid rear axle, the independent rear will behave somewhat differently. The solid rear will apply a lot more weight to one rear tire than the other, making the traction unequal between the two. When I first started driving an independent rear, I found that I was automatically still compensating for that offset thrust from a solid rear, and had to learn to stop doing it.

Stepping out the rear on a short wheelbase car is more treacherous than on a longer wheelbase car. Step the rear out 3 feet on a short wheelbase car, and the car will be angled 45 degrees. Step the rear out 3 feet on a school bus, and the bus may only be angled about 15 degrees.

I haven't experimented much spinning the tires with the traction control on, but remember a few times when it cut power so quickly that the jerk as the car went straight again was pretty violent. It didn't allow me to modulate that with the throttle, or time it to happen when I was expecting it.

MontanaBob

Warp Factor,

. . . but my previous Corvettes and all of the race cars, were equipped with independent suspension on all corners.

I totally agree with your wheelbase hypothesis.

As for trying hard acceleration with and without traction control, I have not done that, fearing that the result will be a wreck. Secondly, from what we are being told, the electronic control of the differential cannot be shut off, so, the way that I see it, those of us with production vehicles cannot compare the two situations.

There has to be something going on--or not going on--with the electronic controls. That is why I would like to see the results of the back-to-back, old technology vs. new technology, testing on identical Z06s, under identical circumstances, at the same time. I sincerely doubt that we'll ever see that test, sooooooo this thread wil go on and on and . . . .

Just my humble opinion.

Montana Bob

Warp Factor

The E-diff can't be shut off, but the "traction control" can, and I found the car (at least my own car) to be quite normal and predictable with it shut off. Maybe our cars are different? Find a wide open space and see what you think.

MontanaBob

Warp Factor,

Traction Control can be shut off in my car (a 2018 Z06/Z07) also, by virtue of depressing the "T/C" button in the center of the "Mode" rotary control ****. As our weather is still quite cold here in Montana, I am not even driving the car. Secondly, finding a suitable, large parking lot, sans numerous light posts, is a stretch here in Montana. In the meantime, I'll be on the lookout for a suitable, more importantly, a safe testing location.

Lastly, I thank you for your measured, thoughtful and, most importantly, experienced responses.

Respectfully,

Montana Bob

ronsc1985

Did you miss post 474?

djnice

MontanaBob, thanks for posting about this. I don't have the driving experience you have, but have decent experience driving hard. I always enjoy spinning up and drifting whatever I am running whether two or four wheels. Sport bikes are tricky to step out while avoiding the high side, which is similar to the snap situation I have noticed in the Z06.

Here are my observations. In addition to the Z06 I have a 13 ZL1 that only has 580 hp and is heavier, but it has the similar traction control, stability control, and 5 PTM modes as the Z06 except it is the mechanical differential. I have two sets of wheels/tires for the cars so I experiment with hard summer/track rubber and all season. Even with hard rubber the ZL1 is not snappy and much more predictable when launching and stepping out the rear whether on the street or track. Prior to the Z06 I had the 17 GS and it had the same snap tendency as the Z06 both when launching and drifting just less pronounced. BTW, the GS and ZL1 are similar in quickness.

I have experimented with all three of these cars with TC on/off, etc. They have similar results except the ZL1 is more predictable and doesn't snap as quickly even with TC on. I have also run them in cold wet/light snow conditions with PTM-wet on, and put the pedal on the floor up to 100 or so. Pretty interesting to see how they behave and how the torque management intervenes. You need more than a parking lot to experiment with these things. I know you have good wide nearly empty back roads in MT to test on.

On the track the ZL1 has nice feel when you want a bit of oversteer to help get it turned. I don't have as much confidence doing this in the Z06 yet. This could be due to the added HP/TQ and lightness of the Z06. Maybe I just need better throttle control, but I do want to try the alignment recommended by DSC to see if it helps. I have had some time with GS on the track and it does feel more balanced for some reason, but there are always various factors and hard to compare unless you spend a ton of time running back to back tests.

I don't know if I have a conclusion other than there are a variety of variables that contribute to the situation. BTW, with the ediff (eLSD), the right side is the drive wheel and the left is by the electronics telling the hydraulic pump to put pressure on the clutch plates. If you tuned it off, you would only get power to the right side.

Bill Dearborn

With power to the right side only the snap over steer problem disappears as one side of the car will still have lateral grip.

Bill

MontanaBob

DJNice,

I thank you for your thoughtful response, quite obviously based on a ton of experience, far, far more than have I with today's high performance vehicles. Unfortunately, I do not find myself with the resources to perform the testing as you have done, particularly with multiple vehicles with varying technology! Secondly, the years have taken their toll on my reaction time, so the limited testing that I will perform, once the weather warms up, will be limited to low speed.

I notice that you reside in eastern Washington. Depending on whether you are in the north or the south, you may also still be experiencing cold weather and maybe even "spitting" a little snow, as am I. Yesterday morning, we actually woke up to about two inches of new snow!

Yes, there are some roads with little traffic, but they tend to be narrow, (I'm in western Montana), with either deep barrow pits (ditches) or adjacent to canyons with rock walls or steep drop-offs, less than ten feet from the road edge, certainly not in an area that I want to flirt with loss-of-control situations.

You have answered several of my questions. Most interesting was the revelation of how the eDiff functions, revealing why it cannot be disabled. My guess is that, should the electronics fail, the diff would be in a full-lockup condition. Without full lockup, at high speed, and with all power being directed to the right hand wheel, the failure would result in doing some wild counter-clockwise loop de loops, causing the rapid emptying of one's bowels!

I just had a new set of MPSSs installed, along with the requisite alignment. Upon arriving home, I reviewed the before and after alignment specs. Although the changes were minor, there are no rear caster settings. I have a call into the dealer questioning that, but, as yet, no response.

Anyway, your post provides me with some "homework" which I will perform once we get into the seventies and eighties, unfortunately, two or three months down the road.

Once again, my sincere thanks for your enlightening post!

Now, I've got to get outside to buck some firewood. Yup, we heat our place with wood. D____d good exercise for this old fart!

Montana Bob

djnice

I am up north and yesterday I took the Z06 out in 50F and light rain. I have MPSS tires on. I used PTM-wet and PTM-dry just to see how it behaved. I normally use Sport with TC off. You should try PTM-wet it works better than Wet mode.

If the "e" part of the diff fails it acts as an open diff. It will power both tires equally until there is slip. If slip occurs the tire with the least traction will get all of the power. This is actually more stable, and when spinning one tire the car will go straight and not jerk to one side violently. As Bill notes the non-spinning tire provides lateral stability. I have had the "e" on my Z06 fail (long story) so I know how it drives as an open diff.

I am fortunate to have gas heat, but I suspect the wood splitting is good for one's health. I would like to add a wood stove for comfort and during outages.

lupicon

All--this has been very interesting reading. I'm new to the Z06 and have about 10 miles experience driving my Z07 equipped car to date (weather has been horrible and picked her up in late December--so straight from dealer to garage). Toronto is under a sheet of ice as I speak.

When it warms up I would like to find some open space to better understand how the car handles so reading this has certainly provided perspective and insight as to what I may expect. I'm strongly considering a trip to Spring Mountain to better understand the limits of the car and my own abilities. I'm coming from a Boss 302 and several Mustangs and the Z is clearly more to handle.

Based on reading this and several other threads, I'm strongly considering an alignment.

I won't be tracking this car and I have two objectives:
-extend tire life of SC2's
-optimized street handling/safety.

I found a reputable alignment shop that deals exclusively with high performance cars for street and track.

Can someone reco some of the key markers I should be looking for based on the setup I am after?

pkincy

Searching for the term: "alignment" likely will return to many choices. Try searching for threads or posts mentioning "rear caster" as those will also discuss alignment but will have more of the key information you need.

lupicon

I've hit the point of information overload/confusion
Understand everyone's opinion is different, and I'll be relying on the expertise of the shop in conjunction with what I read here, but looking for advice before I go in. I seem to keep reading rear caster at 0, and the rest becomes blurry. Apologies as far less technical than most replying to these threads...

pkincy

First problem is finding a shop that is able to measure and set rear caster as an alignment machine will not measure rear caster. So first find a shop with the appropriate angle guage and a tech that can use it. Once you do that use the stock alignment and get the rear caster set to +0.5 to +0.8 on both sides.

djnice

Try this link for recommended alignment and they even list the part number for the caster tool. A shop needs to have the caster tool or equal to do the alignment.
http://www.dscsport.com/wp-content/u...ent-sheets.pdf

lupicon

Much appreciated djnice.

Mr. Gizmo

siglite

LOL, I took mine to the strip. It spun perfectly straight down to about the 1/8th mark. I couldn't hook up for nuthin'. Best I got out of it was low 12s, but it definitely stayed in a straight line while it spun. A lot.

lupicon

Good to hear Gizmo. Did you go in with numbers or did they calibrate to the manual specs? Did they provide a print out?

Mr. Gizmo

pkincy

What did they set the rear caster to?