has anyone followed up with fixing the ABS problem?? I have had similar issues with mine to the point that it has created some really unsafe conditions, usually from hard acceleration to hard braking. I also think its a cause of insufficient vacuum and was wondering if anyone has tried the reserve cannister mentioned. I am currently running with the ABS disabled but the braking really isnt as efficient as it should be due to improper balance.

 

no not really. I had to change my driving around to get past it. Braking sooner with less pressure helped, and as long as you can get on the gas soon enough you should be fine. Plus holding down the VSA button till mostly everything is off helps a bit.

 

ya I've found stabbing the brakes to quickly is no good in these cars.

 

exactly lol

 

Disabling ABS will not have any effect on vaccuum. You need to figure out if you're running out of vaccuum or having an ABS problem.

I haven't autocrossed my SS, but have had zero problems at track days. 20 minute sessions with repeated braking from 110 to 30 (fastest straight leading into slowest hairpin).

 

I'd be curious to see some of the specific conditions that people are having this problem. If it was a vacuum issue I'd expect to have a noticeably harder pedal. The only time I've noted odd ABS behavior has usually been when I suspect a rear wheel has lifted or bump in mid-corner braking.

If it does feel like a vacuum issue due to left foot braking I'd be curious to look at the service manual and see if GM used an ejector fitting on the brake boost vacuum line. This can be common on factory forced induction vehicles that don't have an electric vacuum pumps. It is basically a tee that bleeds off a small amount of boost back into the intake trace and uses a Venturi effect in the tee to create vacuum on the third fitting that's used to provide vacuum to things like vacuum motors for mechanical cruise control on older cars as well as to the brake booster.

 

well one time when it happend to me the breaking zone was a bit rough were the suspention was moving quite a bit, perhaps losing some traction. The time it did happend in that corner i broke way late and fast from gag to break. But still you would think a wheel off the ground for a split second should cause the ABS to be frozen.

 

Most ABS systems can't tell if a wheel is off the ground or on solid ice, so when it comes off the ground and immediately locks because you're braking the ABS is going to kick in. Some cars are worse such as older models with three-channel ABS that modulate the front wheels independently but to save money used one solenoid pack to control both rear wheels together on the same circuit.

The Cobalt does have a pretty advanced four-channel system (which should be the ATE (Continental Teves) Mk25e that is also used on many other cars) so it should be less of an issue as it can control all four wheels independently (required for stability control to be able to brake individual wheels to rotate the car). A single rear wheel is still going to activate the system and the programming may start modulating the other brakes slightly.

The only time I've had an issue with the system feeling like it wasn't braking has been at the end of courses where they use a 2x4 or out in the real world and hitting a sharp upward edge in pavement that causes both wheels to lose contact with the road surface under heavier braking. As expected the wheels should stop rotating the instant that happens if you're already braking with moderate pressure, the ABS controller sees them lock up, activates the anti-lock function, but when the tires immediately drop down and start rolling again it may be taking a second for it to modulate them correctly.

It's usually during this split second of time I've noted the "no brake" feeling but it isn't as bad as on some other cars (for example there was a recall over the Prius recently because of issues where one of the rear wheels goes into anti-lock on certain rough pavement the controller would get confused and braking would diminish for a moment as it released braking pressure to other wheels as well). With the ABS being partially an electrical system that has to read the wheel speed sensors and then mechanically modulate solenoids to hold or release pressure in the ABS module and to the wheels it may just be normal limitations of the system needing time to operate and change between modes. If that's the case there may not be much that can be done except to tune the suspension so the wheels remain in contact with the pavement better (if possible).

 

Found that out today as well at our local autocross. As someone mentioned earlier, it's way to sensitive. Coming off of straights and going to straight hitting the brakes, the ABS goes "OMFG WTF are you doing?!?!?"

 

this has finally become a serious issue for me. My local autox club runs a night series and the course stays the same all year, wednesday night was the first race of this series and there is a long straight and a kink that can be taken flatout that while going through goes from level to off camber about 40ft. before the braking zone. I dont know what is is about this turn but if I dont coast that whole final section the ABS FREAKS out on me and will not stop! I can usually drive around this issue by braking slightly sooner and smoother but I am loosing some serious time in this on particular part.

I'm chasing a previous national winner ST civic (car won not the driver) for the pax indexed Pro class win and coasting for 60ft through a flat out section is costing some SERIOUS time!

How are you guys over riding the ABS, pulling a fuse or something?

pax results link to see said civic kick my ass --> Pax Time Results, #1 - HSCC Nite Series #1 - Wed 04-20-2011
still 3rd out of 90 not to bad 6th of 90 raw time.

 

If you pull the ABS fuse you would also disable the electronic brake force distribution (EBD) that the ABS system performs in place of a conventional mechanical proportioning valve. I'd probably try disconnecting a rear wheel ABS sensor which on most Teves ABS controllers will disable ABS but leave EBD active.

 

thanks man, will that be right where it plugs in near the hub somewhere?

 

hmm I am trying to think what I changed with my driving when I 1st had this happen. I know I did what you said at 1st but then I started getting more agressive with it. My 1st event was last weekend and I was on Rcomps and i feel like that helped a lot, I could feel it start to kick in but I let off a slight ammount so that the car was still braking but allowed the abs pressure to catch up, then get back on them hard... If you get what I am saying lol.

 

well this weekend was bad for this issue with me. Still ran a fast run but the one run that was perfect up untill the icemode was fast lol. It didnt help that the section this happened on twice yesterday was a fast section into a hair pin turn with a hard braking zone that was less than smooth. The issue I had this weekend wasnt going to the brake to fast cause initial bite was great, but as the car went into the rough section and with the car pitching as much as it did i bet a wheel came off or the car lost traction and the ABS system froze up.

Its tough when you are chasing Pro drivers on index but the car and the braking zones dont give you much confidence lol

 

Have you had a chance to try disabling the ABS via one of the sensors and see how the car behaves? Outside of ATE/Continental I doubt you're going to be able to find anyone with the ability to alter the programming of the ABS' HCU (hydraulic control unit). It might be a long shot, but if you know anyone inside GM that was working on the various Cobalt racing programs you might see if they have any suggestions or have that ability or can direct you to someone else at ATE, but it wouldn't surprise me if they had pulled the ABS system.

That would technically be another option if your series allowed it as you could cannibalize a system off an non-ABS Cobalt or possibly Epsilon car (G6, etc.) but it might be tricky finding the correct size master cylinder and getting a manual proportioning valve set up to work with the giant front Brembos. Other than that, suspension changes might be the only other way to try to keep the rear inside wheel in better contact with the pavement.

 

havent tried pulling any fuses yet, maybe next event this weekend. We will see how it all goes.

 

Don't pull the fuse for the ABS or you'll lose brake proportioning and the rear wheels may lock up prematurely. You might be able to work around that if needed by altering to a less aggressive pad compound out back, but it should be easier to just unplug and make sure one of the rear wheel ABS speed sensors (should be on the center, back side of the hub) is disconnected and secured. On other ATE/Continental Teves systems that have integral EBD (electronic brake force distribution) this will usually disable ABS, stability, and traction control but leave EBD active.

 

it might work, the only issue then is I cant unplug anything for nationals, when I comes down to it ill have to drive around it lol

 

Funny thing is I live 7 miles from the Continental Teves plant, been thinking about getting a job there. I don't think they do any development there though

 

that is probably best styled as "misinformation" and should be labeled 'driver mod"

 

ps, koni continental balts did not use the teves system or brembos, grand am would not allow brembos, and the abs race cals were on the older delphi system.

learn to drive around it is the best advice i can give you. it is possible...

 

yeah, i did when I was using street tires last season but Rcomps are a different animal. I was just posting cause I had the same issue again... Just gota work around it cause the car itself is stallar lol

Few picks of my Ice mode lol

 

haha nice pics, love the wheels. The only way I can drive around it in my situation is coasing through a flat-out section of track. Not the best option when your on the heals of a national level spec civic in out pax indexed pro class.

 

when you guys go really fast the ps will start to fail. abs wont bother then....

 

lol thanks for giving us something to look forward to.