I know this is a simple question, but the owner's manual and a search of these forums didn't reveal an answer.

Once I set the car to Track Mode, how do I select the PTM mode? I know I press the traction button twice quickly to get the selection window, but once I rotate the **** to select Dry, for example, do I press the traction button again to select it or just drive away with the little PTM window up?

Thanks for your patience.

 

After you select which PTM mode you want you have 2 primary options:
do nothing- the message window will convert back to previous information after about 10 seconds.
press OK with the right thumb button on the steering wheel. this just expedites returning to previous information.

if you decide to switch ptm modes, just rotate the mode ****.

pushing the traction button again will cancel PTM mode and return you back to Tr.

 

I'll jump in here since it't PTM. Just returned from SM school & forgot to ask this. First all instructors recommend 2 things-Never drive in TRACK on streets unless you have perfect roads or don't mind the occasional replacement wheel due to being bent hitting the unexpected pothole-also don't drive with all nannies off. If feeling froggy get into one of the PTM modes. (Consensus was Sport 1). Now (finally) my question I forgot to ask. Is the straight TRACK mode in the normal selections the same as TRACK mode in the PTM pertaining only to the SUSPENSION of the car (stiffness/rebound)?

 

madrob, SM is great but they are not giving complete information on PTM/street compliance. PTM Wet actually uses touring suspension. Further, Tadge just answered a question about PTM, stating that any mode is fine for the street - the bent wheel problem is due to the runflat sidewall stiffness. Subscribe at your own risk.

I'm not sure I follow your question fully, however each PTM mode calibrates several parameters such as throttle sensitivity, mag shocks, eLSD, active handling, traction control, etc. There's a nice spreadsheet on here somewhere with the differences.

Running in Tr without PTM submodes - the car is constantly calculating(guessing?) what road conditions you are in, whereas a driver selecting a PTM mode declares to the car what your road conditions are.

 

It is in the owners manual/ driving and operating section/driver mode control.
2015 manual page 9-41

 

https://www.corvetteforum.com/forums...rack-mode.html

 

Thanks! But I was asking about whether being in normal TRACK mode versus PTM TRACK mode was the same suspension setup. Thanks to the posts from Jaden61 & lrobe22, I could compare the 2 charts (normal versus PTM) & see that TRACK is TRACK (at least in PTM Sport 1/Sport 2/Race, all the time in normal mode TRACK), regardless.

 

Tadge sort of answered your question as part of his explanation detailing the PTM system...

Tadge answered:
Although we have talked publicly many times and published quite a bit of documentation about PTM (and other chassis controls), there continues to be additional questions. Assuming this section of the forum attracts a very tech-savvy audience, we are going to give a more technical description than our usual public statements. At the risk of helping our competitors, I have asked Alex Macdonald, our lead Corvette development engineer and expert in chassis controls to provide the definitive treatise on PTM. So, thanks for asking….

Performance Traction Management was first brought to the market on C6 with the 2010 ZR1 and was available on C6 Z06’s with MR from 2011-2013. It has evolved with each new model of Corvette since then but still retains the same functions and philosophy as when it was introduced. All of this discussion applies to any Corvette with PTM, not just the C7. For C7 any Z51 with MR dampers and all Z06’s are equipped with PTM.

The first important part of PTM is the traction control function. This is the core of PTM. Later I will describe the other adjustments it makes to the chassis but the fundamental change in each mode is the logic and calibration of the traction control.

It will help to understand how the standard TCS system works when not in PTM. See Fig 1 for an example of a C7 Z06 turning left at 25mph and approximately 0.8G lateral acceleration (a spirited left turn). The driver steps to 100% throttle (point #1) which causes the rear wheels to start spinning. Prior to spinning up the tires, the TCS system doesn’t know much about the road surface conditions. It could be wet, dry, gravel, coarse concrete, smooth asphalt, etc. To determine the surface condition the engine torque is allowed to increase until the wheels start slipping a certain amount (point #2). They would continue to slip at this torque level so torque is quickly reduced to stop the slipping (point #3). The initial engine torque that caused the wheels to slip along with how much torque needed to be removed to reduce the wheel spin are used by the TCS to calculate the type of surface the car is on. Once the surface grip is known the torque is added back in to maintain an amount of slip that’s appropriate for that surface (point #5).





The drawback to this method is that the wheels have to over-slip past the ideal target at the start. This disturbs the cornering of the vehicle and requires the driver to adjust the steering angle. Further, bringing the wheels back down from the initial over-slip with a torque reduction dramatically reduces acceleration in order to regain stability.

The use of the PTM switch tells the car that it is definitely on dry asphalt (or wet asphalt in in mode 1) and that the driver is prepared for some amount of wheel slip. Since the surface is known the PTM system can make a good approximation of the maximum possible engine torque that will not over-slip the tires based on how hard the car is cornering and how fast it’s going. This torque estimate is used as a starting point (since no new information about the surface is needed in PTM) and then depending on the amount of slip that results more fine adjustments can be made. As the driver unwinds the steering wheel the tires gain grip and torque will be fed back in due to the lower slip. See Fig2 for the same maneuver described above but using PTM mode 2 this time.





As you look at these two examples one thing to note is how much more gradually steering and lateral acceleration can be reduced on corner exit in PTM vs normal TCS (Red and Tan lines). The initial over-slip in normal TCS is what prompts the driver to make this abrupt steering adjustment.

Each of the Traction Control modes in PTM are differentiated in two ways. First, the target slip levels are lower in the lower modes as you would expect. Second, the estimate we make for the starting torque is lower. In DRY we err on the low side with our estimation and may have to increase torque to reach the target slip. In RACE we err on the high side and the driver may have to use more steering correction to manage the extra slip in the rear until the target slip can be recovered.

Along with the traction control, the other chassis subsystems are modified for the conditions expected in each mode. The following is a chart of the status of each subsystem for each PTM mode:





Mode uses:
WET: This mode is intended for any driver who is on a wet track. The track should be wet enough to be glossy, not just damp. A damp or drying track will require the driver to decide between WET and DRY modes to get the best performance. Standing water is not recommended as hydroplaning is possible and no TCS system can accurately control a tire that is hydroplaning.

The slip targets are very low, lower than in standard TCS. The MR is in tour mode to maximize mechanical grip since the lower cornering forces don’t require the extra control offered in Sport or Track. ESC is on and uses the normal calibration, not the competitive calibration.

DRY: This mode is for a novice driver on any track or an experienced driver learning a brand new track. I also use it to warm up the tires or run the mold release off of new tires, especially if it’s cold out.

Slip targets here are very similar to normal TCS but will feel very different due to the entry prediction. MR is in Sport to compliment the usage we expect in this mode. ESC is on but uses the competitive calibration.

SPORT 1: This mode is for any driver who is ready to run very competitive lap times while still having stability control on in the background. I use this mode whenever I have a passenger, possible distractions such as data collection, or as I am continuing to become more familiar with a new track.

Slip targets are higher here than in normal TCS. MR is in track mode and ESC is on using the competitive calibration.

SPORT 2: This mode uses the exact same traction control settings as SPORT 1 but turns off ESC completely. This mode is designed as a way to turn off ESC while maintaining a fairly stable TCS calibration. I use it very often. Basically any time where tenths of a second are not critical to my testing or when the tires are getting too hot or wearing out. After 10 to 15 consecutive laps it is likely that your fastest times will be achieved in SPORT 2 rather than RACE.

Slip targets here are the same as SPORT 1. MR is still in track mode and ESC is turned OFF.

RACE: This one is pretty self-explanatory, it’s as fast as we know how to make the car go. This mode is for a well prepared car on relatively new tires with an advanced driver that is completely familiar with the track. The track should be somewhat warm and the tires should be up to temperature.

Slip targets are 100% optimized for forward acceleration, any small variances in the track or tires can result in momentary overslip that will have to be managed by the driver.

A few notes about RACE mode: I approach this mode as a tool to go faster meaning that I think specifically about it when I go to WOT and I try to change or optimize my throttle application point and steering to help the computer do its job. It can do the job better than me but only if I give it good information. A specific example is how I unwind the steering wheel mid corner and as the corner opens up. When learning to drive on track it is good practice to automatically unwind the steering wheel as you apply throttle regardless of the vehicle response (a string tied from throttle toe to steering wheel is the analogy used by some instructors). The problem in RACE PTM is that by doing that you are telling the car you are ready to go straight. It will add power and drive you to a wider line. The best results are found by holding the wheel as steady as you can and pointing the car to corner exit only when it’s time. Obviously you have to be ready to correct for overslip but as you gain trust you will find this is required less often than it feels at first. It is very useful to practice using PTM in the lower modes where you can focus on letting the car go where you point it and not correcting your steering too early.

We find that the calibration settings that achieve the fastest lap times often result in expert drivers feeling like they are being held back slightly on corner exit. Most of the time that extra little bit of slip that an expert driver wants is over the traction peak of the tire and may feel good but is wasting forward acceleration. The restrictive feeling is not there as a safety net, rather, it’s as close as we can operate to the peak capability of the tire in a robust way.

Other notes: The eLSD “PTM mode” is only a slight alteration of its normal track mode. This alteration is required since it is likely to see engine torque values that would not occur without PTM. However, the philosophy of what it’s trying to do and how it’s controlling vehicle dynamics does not change between PTM and TCS/ESC OFF mode.

As for the nannies, that term is a big gray area. I would personally call TCS, PTM, ESC and active rev match nannies but would not call the eLSD or MR dampers nannies. ABS is very gray. ABS, TCS, PTM, ESC and active rev match are trying to do a better job of something you normally do as a driver, steering, throttle, brake or shifting. However, no driver ever controls a differential directly or a shock absorber directly. They are part of the base chassis tuning and can be thought of as a calibration component like a spring or anti roll bar.
ABS is more of a gray area but it is not allowed to be shut off because the capability of the vehicle is so limited without it. You may need 200 bar of brake pressure to get max decel from a wheel that’s on the outside of a corner but the inside wheel would be totally locked at 50 bar. Unless you want a lot of flat spotted tires you need ABS in that situation. Also, somewhat like eLSD and MR, individual wheel brake pressure is something even the best driver can’t physically control without the electronics.

That’s a long way of saying you can shut off TCS, PTM, ESC and active rev match but you can’t shut off MR, eLSD or ABS.

 

So according to this chart, when you are in sport 2, traction control is in sport mode, so it is still somewhat active, more so then race, which shows "race" under that mode for traction control.

Anyone please feel free to comment on this... When I'm in track/sport 2, and shift too quick, the car will bog, feels like traction control kicking in, COMMENTS???

 

Each setting in PTM lessens the amount of T/C & S/C until you get to Sport 2 & Race with no S/C but still a touch of T/C. Just returned yesterday from Spring Mountain & this is what instructors told us. PTM decreases the "NANNIE" intrusion as you move up thru the setting to Race. Go back & read what Tadge says in the above post, but don't worry about the charts, just the explanation for each PTM setting. As to you bogging with a fast shift it would have to be T/C. At first I thought maybe S/C felt the car begin to move laterally, but then I re-read the Tadge part & see S/C is off in Sport 2 & Race.

 

I prefer to not get into the PTM modes but I am in the minority. I just run all off or 1 touch off TC while in Track Mode.

 

Thank you very much, yes, it feels like TC kicking in when I shift too quick, even in track/sport 2. So the TC effect would be less in track/race, but I would still have some nannies in effect...

 

Yea jbsblownc5, as you are well aware I imagine, these beasts cannot just be quick shifted or banged into 2nd gear w/o getting back onto WOT slower than 'RAYS. I had '14 Z51 & you could absolutely no lift shift going straight on descent road surface but not these. I have a favorite 1/2 mile long bridge I go over when going to town & I like to be in 2nd when I round the corner coming to it. If there is no oncoming traffic, I always punch it in 2nd at 40mph & in Sport 1 the tires break loose a tiny bit-yeehah! Again I'm in a M7, the A8s seem not to have this problem with different gearing than us (I've read on here).

 

So PTM any mode is ok for the street?! I have never use it until yesterday where the roads are pretty new!! And you just plant your foot on the gas and it felt soooo good, no spin and so easy!!!

Never used it because I read few threads saying that it's so hard it will damage the suspension, rims and the MR is real expensive to replace!

So it's fine to use any PTM modes on the street huh? at worst it will just damage the rim but not suspension or other parts? man wish I had read this thread earlier! PTM is so much more fun on the street.

 

I am well versed in PTM at the track and have NEVER used it on the street nor can I imagine a practical application for it on the street.

And by the measures above, Positraction is a mechanical nanny. Use them all to get to the finish line faster with fewer excuses! I see no heroics in buying a new car and driving it old fashioned, going slower, and deriving pride from that. Now if you could do it faster, then I'd listen!

Also, when you see stuff in threads about PTM modes damaging wheels, just roll your eyes and enjoy the drive. Bent wheels seem to follow particular drivers, not modes. I've never bent one and I use Tr on the street. Others have been multiples sets of wheels and never use Tr or PTM on the street.

 

The only reason to use PTM on the street or while cruising with friends, is the cool Machine Gun sound it makes while you keep your foot planted around turns. Yes, it sounds good.

 

Is anyone really familiar with WET track mode? Why do the TC & Active handling lights come on? I figure those lights would not illuminate since all the nannies are on.

 

Because the TC and AH are being controlled differently than in Weather/Eco/Touring/Sport Modes. The driving mode is track mode and TC will behave like PTM. I have novice students drive a few laps in WET Mode on a dry track so they can understand what PTM sounds and feels like without having to push the car hard. Once they have heard the power to the rear wheels being modulated and feel how the car pulls out of a corner a few times I have them move to Sport 1. In Weather mode, you don't have any PTM actions, and TC & AH perform similarly to all other cars with occasional bogs on acceleration. In PTM you don't have any bogs in acceleration as power is limited to the grip available at the tire having the most grip instead of just being cut.

Post # 8 explains it better than I can since it is a copy of one of Tadge's Answers. As he said you get the overspin with standard TC followed by a cut in power (the bog). PTM doesn't do that when you roll onto the throttle the system is working very fast to maintain the torque at the rear wheels at the maximum point for the grip available. That is the cause of the engine blatting sound that is so loud when powering off a corner. As the steering wheel straightens and the rear tires gain more grip the car accelerates faster than when normal TC is used.

Bill

 

Great information Bill !
Does regular track mode equate to dry or sport 1 or something in between? Is there a formal explanation by Corvette ?

 

Track Mode includes Wet, Dry, Sport 1, Sport 2, and Race. To get those modes you need to turn the dial until you see Track in the DIC and then push the center button twice. After you push the center button twice you should see WET displayed in the DIC. Once you see that you turn the **** to get Dry, Sport 1, Sport 2, or Race. If you don't push the button twice you are in an undefined mode. Per the C7 Corvette New Owner school at Spring Mountain the best overall selection for track duty is Sport 1. The OM has explanations of the modes but the best place to look is in the Tadge Answers section. He provided a nice engineering explanation of the modes.

Are you interested in using a C7 on a road course? I have a story to how much the PTM modes improve lap times. When I took my C7 Z to its first HPDE I had just returned from my Spring Mountain course. At the HPDE I parked next to another C7Z owner. While talking to him I found out he had purchased a used car and didn't have the OM or any knowledge of what the drive mode settings were. We were at VIR and he was complaining he couldn't get his lap times below the mid 2:03s because stability control was interfering too much. Mid 2:03 laps are fantastic lap times at VIR especially on a car with street tires and not set up for the track.

I showed him how to select Sport 1 and we went out for a track session. When we got back to the paddock he was smiling and proclaimed his best lap during the session was in mid 2:01 for a drop of two seconds just due to choosing Sport 1. He dropped his lap time another second before the end of the day.

Bill