: long pedal on full ABS stops



c4racer
03-01-06, 02:15 PM
I found a particularly distressing behavior of the ABS braking system on my car - in a panic, full ABS stop the pedal travel is quite long. To an experienced track driver like myself, this feels like a soft pedal from fade and my natural reaction is to let up on the pressure and pump the pedal a bit. I cannot unprogram this response from my body - it is much like countersteering going into a spin - my body reacts from pure instinct before I even think about what I am doing. I have owned several performance cars from GM (Camaros and Vettes) and from BMW and never have owned one that reacts in this way. It reminds me of the horrible ABS system on the GM trucks.

This seems like a classic case of GM platform engineering. They stick a normal car ABS box in the CTS and then use it in the V version of the car instead of adopting a performance ABS system from the vette. So we get awesome brakes, but a suck ABS system. Nice. Thanks GM. I will say that in a track situation the brakes work great - even when dipping into the ABS a bit - incredible feel, zero fade, and top notch performance. But in a routine panic stop on the freeway where you are just jamming the pedal fully into the ABS zone, you get this long pedal. I'm not impressed GM.........

Dreamin
03-01-06, 03:31 PM
My brakes dont behave that way... they are very linear from non-ABS zone, into ABS zone. And the pulsing isn't too bad either. Wonder if you have some air trapped somewhere. :hmm:

crowan
03-01-06, 06:42 PM
My brakes dont behave that way... they are very linear from non-ABS zone, into ABS zone. And the pulsing isn't too bad either. Wonder if you have some air trapped somewhere. :hmm:

Ditto.

CR

thebigjimsho
03-01-06, 07:52 PM
Ditto.

CRDitto x 2....


Did you just drive through a puddle or go through a car wash?

thefly
03-01-06, 08:39 PM
could it be the electronic brake distribution system...

Dreamin
03-01-06, 09:02 PM
could it be the electronic brake distribution system...

Wish that could be turned-off... i hate that feature... but it doesn't account for c4's symptoms.

Dennisscars
03-01-06, 10:48 PM
let up on the pressure and pump the pedal a bit. I cannot unprogram this response from my body - it is much like countersteering going into a spin -

I hear you, but this makes matters worse, the hydraulic pump is having to take up the slack to pressure up the system. Once it figures out that your out of it it takes control away from you and does what it wants.

I know it's easier said than done, but with 4W ABS stand on the brakes and let it do it's thing.

Mine will detach your retina's with race tires. After 5- 25 min. sessions the shoulder belt will dig into my shoulder. And I haven't tracked the brakes hard enough, as some have, to gold the calipers..:thepan:
I had an instructor once kept telling me to stop sooner because he thought it was a heavy car, until one time I put him up against the shoulder belt without going into abs.