Traction control malfunction?
 

wondering if my traction control is working properly. For some time now when I do short pulls from start the car wants to go hard left. Tires have ample tread and are usually warm, but I notice there is usually only one distinct tread mark on pavement. This incident, see video, I was just moderately accelerating and car broke loose, surprising to say the least. Since it was in the mid 50's and tires had about 5 miles to warm up I don't think it's a tire issue I was under the impression that traction control was supposed to keep the car going straight if losing traction. Am I expecting too much or do I have a problem? Also, other than doing "burn outs" in the parking lot can a technician ascertain a problem via the computer. Thanks for any advice.

When the C5s came out people complained because they had a very restrictive traction control which would shut down the engine at the hint of both wheels spinning. They relaxed it to some degree so people could hit the throttle get a little wheel spin so the engine wouldn't bog and let them accelerate at a high rate. The stock eLSD will distribute power to both rear wheels and they will slip about the same amount at the same time. You might get a little more rear tire mark out of one tire than the other because the diff tries to distribute the power to the tire that has more grip but it doesn't necessarily stop the tire with less grip from spinning some amount. So TC will let the tires spin because they need that to some extent and with the eLSD you will get movement from side to side since spinning tires have no lateral grip.

In your video you open the throttle suddenly and apply a ton of torque to the rear wheels. The Z06 has more torque at those low rpms than most other cars have at their peak torque rpm level. On top of that the transmission downshifts to help multiply all that torque. That means it is easy to shock the tire/pavement interface and over load it. By the way, good tread just means you have less grip available. You mention the ambient temperature was in the 50s but if you were just regular driving there was no way you got the tires up to temperature. On a 90 degree day it is hard to get them up to temperature putt putting around on streets and highways. The tire needs to be about 190 degrees to have good grip. When trying to heat cycle new tires before going to the track I found it was impossible to get them up to temp driving on streets and highways. Even hitting 80 mph, using the brakes hard and pushing through corners I could only get the tires up to 135 degrees.

Each one of those tread grooves is nothing but air and does nothing to provide grip. Tread works on pavement that is wet since it gives the water under the rubber block some place to go and lets it touch the pavement instead of riding on top of the water. On dry pavement it is useless. That is why race cars use slicks.

The video shows you are on the right side of the crown and when both rear wheels start slipping the rear of the car moves to the right because spinning tires do not have lateral grip thus gravity does its thing and sucks the rear of the car to the right. In your case all TC can do is reduce throttle to let the rear wheels regain traction.

Bill

Ha! You hit every point I was thinking of Bill! Except for at VIR where I was able to hit 110+ at Charity Laps at least twice or 3 times every lap and got to use the tires a bit, was the first time I saw the pressures indicate high enough in the tires that they were at a good temp (MPSS). None of the other drives have added more than about 2 psi. On the drive home after break in was the first time I got it loose....and with 50 miles of straight driving and most of it without stopping (but also without corners), 2nd gear getting on it....I got it loose! At 50+ mph! Great fun! 5 miles of slow driving hasn't done anything for your tire temp....not even really enough to warm up the engine. As mentioned, crown or road angle will also start directing which way the car goes. Sounds normal to me.

Thanks for the reply Bill. According to your analysis all is normal. Also a good reminder for us all to respect the power these cars have. especially in traffic areas.

1. ABS- is designed to prevent the tires from skidding.
2. Traction Control- is designed to prevent the tires from “spinning”.
3. StabiliTrak- is designed to prevent the vehicle from going out-of-control… https://www.gmfleet.com/technology/stabilitrak.html.

There is only 1 flashing dash light when either TC or StabiliTrak is intervening. It would be a little more informative to have one flashing light for each system. Apparently, GM didn’t want to have 2 different flashing lights for some reason.

My suspicion (incorrect as it may be) is that cars are engineered to break loose to the right side. Has anyone ever tested this… by finding a good, safe spot to do the exact same comparative “maneuver” on the right, AND, left sides of the road?

Most all roads are crowned left to right to facilitate drainage. Once the tires start spinning you have no lateral grip and the crown of the road takes the car to the right. Even drag strips have so gradient built in for the same reason.

It has been posted & confirmed by semi-pro racers on here & vendors who set these cars up for 1/4 mile/road courses, that PROPER alignment has a HUGE influence on how car tracks when spinning tires. PS: ABS is for preventing tires from locking up under FULL braking stops (trying to push the pedal thru the floor). Would have nothing to do with car sliding under acceleration. S/C HELPS keep car from yawing (going off center from steering input) which SHOULD help if you car begins to fishtail left/right under acceleration. Keep in mind the "nannies" are not fail safe & can easily be over-whelmed by STUPIDITY!:D Just for info, I had 4 tires replaced with same OE MPSS & then a full alignment, including rear caster, due to frt. tire inside edges wearing out prematurely. It made a tremendous difference. My car will now go dead straight under FULL acceleration in 1st then into 2nd (NLS). Before, it too wanted to get SIDEWAYS. It always lays down two perfect acceleration marks (cause I like it TOO MUCH)!:rock:

Don't overlook the obvious. The tires might be warmed up and the air temp might be 55 but the road surface may be 15 degrees colder, especially if it's earlier in the am like the conditions we get this time of the year in the south. That cold surface negates a lot of the warmth and grip in the tires. My '16 acts like two different vehicles between a 55 degree day in the spring or fall and a 75 degree one in the summer.

cold tires,lots of torque,its normal.tthis is why you have to learn how to drive and control this beast before you beat on it or it will kill you simple.

:iagree:

I feel (at least) partly correct. Tadge says that C7s are designed to have the rear-passenger-side tire break loose before the driver side. Truth be known, I'm unsure which way the car will fishtail with only that characteristic.

I guess there are other factors too... the road being "crowned", differences in weight, the alignment on the car, and, the (e)LSD.

https://cimg1.ibsrv.net/gimg/www.cor...5128ec5237.jpg

also have the alignment checked. Mine settled down a bit once I had the alignment which was way out of whack from the factory set to a street specification.

My issue with traction control is the time it takes with the tires spinning before it finally kicks in, up to 1/2 second or so. That combined with the MPSS tires that seem to have little grip when spinning (which may be part of the reason the traction control takes so long to become enabled).