OneFasTT997

So this weekend at Sebring my ABS and Traction Control kept erroring out so I just ran without and it was actually fine.

Now I'm contemplating just getting rid of both and I'm not sure the best way to do that. Should I just pull the fuse?

I noticed that without ABS I wore the pads less. I'm not sure if that is because I was braking with less pressure because of the ABS or if the ABS and Traction Control eat pads. Anyone else have any experience with this?

Bill Dearborn

I doubt the pads wore less due to the lack of ABS. The rear pads could wear more due to TC since TC will apply the brakes when the engine can't reduce torque enough to keep the rear wheels from spinning excessively. AH will cause the rear brake pads to wear more since it applies the inside rear brake to correct understeer in a corner. It can also cause the front pads to wear faster if it is trying to prevent the car from oversteering as you come out of a corner.


Bill

OneFasTT997

Thanks Bill.

So AH does not interact with the front brakes? Also, if I wanted to bypass ABS and AH should I take out the fuse for abs? Will that cut it completely?

fatbillybob

Timely topic. We just lost another C5Z trackcar going straight line with ABS traction control going haywire. Guy was doing nothing and car pitched and rolled. I lost a set of near new hoosiers at the start of a braking zone flying off track sideways into the dirt. Others have has similar problems. I think there are unpredictable times where the TC/ABS just looses it mind. If you are unlucky it can be at a bad time. Threshold braking is rarely needed in these cars where people cheat and manage with ABS. I am seriously considering pulling the fuse on this system too if the bias stays the same after hearing of my friends loss of his Z.

mgarfias

Bias doesn't stay the same on the 01+ cars.

OneFasTT997

What does the bias become without ABS?

crimlwC6

I unplugged mine near the front of the motor and then ziptied the plug.

RedLS1GTO

Add me to the list... luckily I had a big runoff area at VIR and didn't hit anything. This was my first time into T1 after the out lap. I shut the car off in the pits for an oil cleanup and when I fired it back up, I forgot to turn off AH. It looks like I just blew the braking zone but that is not at all the case. I was on them WAY earlier than usual. Fortunately, I was still getting things in order and wasn't pushing yet. I was a good 10mph slow down the straight and started braking about 100ft earlier than I do on a hot lap. If I had been pushing, I'm not sure I would have gotten it slowed up before the tires with the wet grass that I was on.

This played a big big part in deciding to go with a purpose built car instead of building the C5.

mgarfias

rearward. i've had some excitement when my ebcm was offline.

andy3101

I had issues with abs/TC. Car pitched and rolled and drove left even though my input was a straight line brake zone. Pulled it all out of the car. Went with a rear brake bias adjuster attached by the master cylinder.

RX-Ben

On my '01, I always locked only the front when I was having intermittent ABS issues (as in, the ABS was intermittently shutting off while due to a bad sensor wire).
When I ran w/o ABS, I would still lock the fronts only - such as when I was on a flyer and a competitor decided to come to a stop near the apex of a turn b/c a car was stopped, well off-track, 200 ft away. A huge plume of tire smoke resulted, but the car stopped in a straight line.
You can get the rears to lock if you trailbrake too much, but you will not go immediately spinning if your ABS stops functioning.
This is all possibly countered by Scott M's spin at WGI, where ABS stopped working due to damage to a sensor wire. I don't know if all four wheels locked, though if so, it would certainly be easier to get into a spin.

These reports of malfunctioning are a bit different. Any more info on what happened? Was TC and/or AH on during these incidents?
I have never had an issue, other due to broken sensor wires, with only ABS on (ie TC/AH switched off).

andy3101

On my incident, I turned off TC/AH. Still had abs in car. Dropped left side wheels in grass, TC/AH activated itself. While driving I pressed button again to turn off, 15 seconds or so after it's off, the dash shows TC/AH activated again, shut if off one more time and drive down main straight, hit brakes, car turns left and spins. No lockup marks, just tire marks from when the car was sideways. Have video of my steering wheel straight when applying brakes... I had some sort of malfunction of the factory system, so I took it all out.

RX-Ben

Were the yaw sensor and steering wheel position sensors still hooked up?

andy3101

I do believe the yaw sensor was but not 100% sure on the steering wheel sensor.

RX-Ben

My guess is that not having either hooked up may be safer as they will be providing a null value to the EBCM. In my experience, when a sensor gives a null value, the operation "branch" is voided --- so when my wheel sensors went out, ABS shut off.
I am not sure how this would work with the AH "branch" - but I would think the fail safe (i.e., in a situation with null inputs) would be for the EBCM not to take any actions it would otherwise attempt if AH was on, and I'm not sure what actions the EBCM could take if it was not receiving any data to feed the algorithms.

fatbillybob

What does that mean? So perhaps if you just pull ABS fuse the AH or other stuff might still work? So if you unplug the wheel speed sensors nothing can work because there is no input? i.e. this is a better solution?

There was a guy really good with C5 electronics. Anyone know him? His name was curlee or something?

RX-Ben

More specifically, in the modified system that I am suggesting (yaw sensor and steering position sensors not connected to EBCM) -- ABS would still work b/c those sensors are sending info. My hunch/hope is that the AH/TC "branches" would not and could not work b/c they are not receiving any info from the sensors that those "branches" rely on.
Given the large impact that AH could have on a vehicle, I would think the fail safe for a null sensor situation would have to be shutting down that "branch."

Bill Curlee, but I don't think he can receive PMs. This question is a bit in the nether regions of functioning - not sure if anyone has info on the EBCM fail safe logic. But if anyone would, he might. Or if anyone has any friends at GM/Delphi that worked on the C5, they might.

OneFasTT997

How did you take it all out?

andy3101

Basically I took out the ABS module and ran brake line direct from master cylinder to calipers. (With a rear bias adjuster by the master). Setting this can be a treat as too much rear and you tend to spin under braking, easily fixed by adjusting after each spin.. Ha. Or the smarter idea was I went and got a brake pressure tester to hook up to get braking pressures near what I need and can adjust from that starting point. As far as the AH/TC. All sensors etc were unplugged. Don't have to hit the TC/AH button anymore. Just get in car and drive it now. The DIC will come on and say service active handling but I just hit clear and ignore because nothing is hooked up.

2002 z06 -

Bill Dearborn

Yes, it does use the front brakes. The front brakes are used in an oversteer situation where the outside front brake is applied to keep the backend from sliding out. The reason the rear brakes wear more is most people enter a corner too fast and get into an understeer situation as they enter the turn. C5s also have a rear stability mode that is used on corner entry which can increase rear pad wear. From the Service Manual:

Rear Stability Control
When the vehicle performs a high speed turn or curve, the EBCM will enter rear stability control mode. The vehicle speed is greater than 48 km/h (30 mph) and the vehicle lateral acceleration is greater than 0.6 g. The vehicle will exit rear stability control when the vehicle speed is less than 40 km/h (25 mph) or the vehicle lateral acceleration is less than 0.4 g.

During a rear stability control event, the EBCM performs a pressure increase on the outside rear brake and a pressure hold on the inside rear brake. The driver may hear the pump motor run and may feel a vibration in the brake pedal.

Bill