[cab33]

Are StabiliTrak and ESC the same thing(stability / yaw control)?

What do you think the reasoning behind disabling stability control in Sport 2 and Race modes?

[TrackClub]

Originally Posted by cab33

Are StabiliTrak and ESC the same thing(stability / yaw control)?

What do you think the reasoning behind disabling stability control in Sport 2 and Race modes?

Yes, Stabilitrak is a brand name for GM ESC.

The reasoning behind Sport2 and Race not offering Stabilitrak would be to allow for faster rotation, assuming driver can effectively manage yaw level by applying either proper steering corrections, throttle, or brakes to permit higher yaw yet stay in control of rotation and not spin out.

This is also true for managing any understeer btw in case the car goes wider vs what the initial steering angle would suggest.

In short, if a car oversteers, or understeers, in theory a skilled driver should be able to correct the excessive yaw thru controls and lose less speed vs when Stabilitrak kicks in to assist the recovery by applying individal brakes (which will slow the forward progress of a car some).

To what extend one is faster vs slower is very much dependent on driver skill and ability to feel traction level at both ends of the car also combining proper vision to understand a directional attitude of the car in a given corner phase. And of course not spinning out.

Hence there is a fundamental difference how the car will feel in PTM Sport2 or Race vs Competitive Mode as these systems work under different (and almost opposing) principles:

While Comp Mode does not offer TC to manage tire slip and the car may feel faster on exits because of it, Stabilitrak is always present. With the 2 PTM modes there is no Stabilitrak hence allowing for faster rotations but TC will try to provide maximum exit speed by not allowing excessive tire slip which would otherwise slow forward progress. The important part here is that in this case PTM only manages tire slip and not yaw angles, hence requiring proper driver skill to manage the latter.

Hope this helps. I am not a technical expert here and these thoughts are only based on my actual driving experience and information i have gathered thru different sources re individual settings. But by and large i believe them to be correct. Ciao!

[cab33]

Good explanation, Thanks.

[TrackClub]

Originally Posted by cab33

Good explanation, Thanks.

Thank you. Heres another angle to look at it:

PTM up to and including Sport1:
The system manages any over or understeer and excessive tire slip on exits

PTM Sport 2 and Race:
The driver manages any over or understeer and the system manages excessive tire slip on exits

Note: Race mode will permit higher tire slip hence potentially increasing yaw level (and hence increasing driver involvement some)

Competitive Mode:
The system manges any over or understeer and the driver manages excessive tire slip

Note: if a driver over does the tire slip to an extend that yaw increases excessively on exit, the Stabilitrak will engage albeit it can likely be easily overpowered by torque.

Final note: if one were to drive like a hooligan any ESC can be overpowered. Hence it is not a fail safe system to save a car under all situations. Just my opinion here to indicate that all such systems have their limits.

[cab33]

So how different is Track Mode from PTM Sport 1?

[TrackClub]

Originally Posted by cab33

So how different is Track Mode from PTM Sport 1?

E-LSD will have a much more conservative calibration in Track mode without engaging PTM with stability as priority. Per my OP the GM engineer equates it to PTM in Wet mode and it seems that torque levels might be reduced as well.

[cab33]

When you choose sport 1 ptm, is it suppose to show the no tc and no stability control lights on the dash? Even though both should be on in Sport 1.

[Boost Creep]

Originally Posted by cab33

When you choose sport 1 ptm, is it suppose to show the no tc and no stability control lights on the dash? Even though both should be on in Sport 1.

From messing with the PTM modes a little last week, it seemed anytime you are in any PTM mode, both stability and traction lights are on.
Similarly, in competitive mode, both are lit but you still retain some stability control.

[SpazmXylam]

So, silly me I thought just hitting traction button in track mode automatically picked PTM and went through several track days not knowing any better.


Long story short, just got back from an auto cross event today using the PTM in "Dry" mode for the first time. Its almost freakish how much the behavior of the car changes. Just point the car where you want it and mash the noise maker. Poof! you are teleported where you were wanting to go.



I cant wait to give it a go on a proper track day.



Huge thumbs up for PTM.


Also, yes while in PTM mode both traction and stability lights are on. Likely as a redundancy to indicate you changed the behavior regardless of the mode selected.

[TRZ06]

Originally Posted by SpazmXylam

So, silly me I thought just hitting traction button in track mode automatically picked PTM and went through several track days not knowing any better.


Long story short, just got back from an auto cross event today using the PTM in "Dry" mode for the first time. Its almost freakish how much the behavior of the car changes. Just point the car where you want it and mash the noise maker. Poof! you are teleported where you were wanting to go.



I cant wait to give it a go on a proper track day.



Huge thumbs up for PTM.


Also, yes while in PTM mode both traction and stability lights are on. Likely as a redundancy to indicate you changed the behavior regardless of the mode selected.

Dry mode is good, Sport 1 mode is even better.

[Uncle Sam]

Here are three (inexpert) observations about modes from my last track day:

1. "Dry" has quite a lot of intervention especially in controlling power down on exit. Big cut in power, you can actually hear it cut if you are too hard on the pedal.

2. "PTM 1" Much better as far as intervention in cutting power from engine but still noticeably less power. Braking very stable, no yaw noticed.

3. "PTM 2" Definitely more power especially with car straight. Can move the car with the throttle with fine adjustments at the pedal. This is what you expect with a torquey V-8. In a long steady state series of esses I could move the nose into the next corner more by moving the rear end out with slip angle at the rear. Definite yaw in braking, slight rear end sway under heavy braking. You need to manage braking but the car will "manage" throttle off in a corner within reason.

If you have been track driving for some time PTM 2 seems the best to me. I have not turned everything off, however. Maybe next time.

[TrackClub]

Good observations. Did you also try PTM Race, or stoppped short of it? Cheers

[Uncle Sam]

Originally Posted by TrackClub

Good observations. Did you also try PTM Race, or stoppped short of it? Cheers

I didn't but will the next time depending on track conditions. I probably will never regularly run with "everything off" as I want the safety net. My opinion is that if you know what your doing as a driver (I have had many years of car and motorcycle racing in my past), PTM 2 is where you should be at least. The car does too much in taking control until you reach PTM 2.

[TrackClub]

Originally Posted by Uncle Sam

I didn't but will the next time depending on track conditions. I probably will never regularly run with "everything off" as I want the safety net. My opinion is that if you know what your doing as a driver (I have had many years of car and motorcycle racing in my past), PTM 2 is where you should be at least. The car does too much in taking control until you reach PTM 2.

Makes sense. Note that the car may feel very different (especially to a high skill driver) as up to PTM sport1 both Stabilitrak and TC are present. At PTM sport2 and Race only TC is present and naturally may only engage on exits. So entry and mid corner are completely up to a driver to manage.
The only difference between Sport2 and Race is that TC is in its lowest engagement mode in the latter permitting the most tire slip vs any other setting.
I like it especially on any uneven pavement and such as it aids in maintaining forward progress. And i find it very unobtrusive and neat.