Crash postmortem; ABS didn't kick in

[Rusty67]

Well, I got in a car accident yesterday. I'm 95% sure my DD is totalled. I'm also 99% sure I am not at fault.

What I want to know is, why didn't my ABS kick in ? When I got on my brakes super hard, the wheels locked up and when I came to a stop all 4 of them were smoking hard from the skid.

I had the Bullitt front caliper upgrade and the Cobra rear brake upgrade. Stock rotors front and back, stock pads up front and a set of Cobra rear pads from Centric parts.

The only thing I can figure is that the larger bore in the MC caused the wheels to lock up and the ABS unit wasn't capable of dealing with the increased braking power ? That doesn't make any sence tho because the MC and ABS unit are matched. I know the Cobra/Bullitt/Machs come with a slightly smaller bore MC then the GT/V6 cars do but that really shouldn't make too much of a difference. The ABS system works off of the tone rings, if those aren't turning but I'm moving, isn't the ABS unit supposed to pulse ?

Maybe the car thought I was a 0mph when I was skidding and thats why the ABS didn't pulse ?

Anyone have any ideas as to why my wheels totally locked instead of the ABS pulsing ? There are some LONG skid marks near by my house now.... maybe 200+ feet.


Crash would have happened no matter what the ABS did as I wasn't using my brakes until after impact.... if I would have tried to use my brakes to get out of it, I would have hit him instead of him hiting me. I'm 100% sure of that.

 

[DKVL]

Hello Rusty67.

Sorry about what happened and sorry that I am not able to provide you with an input to your question. I am glad that you came out alright and wasn't seriously hurt. Do take care and make sure to seek medical attention for any discomforts as needed.

In my field, individuals involved in accidents don't usually feel the discomfort until days later. Some are serious and others are not, but in all cases, it is hard to tell unless the patients seeks medical attention. Just make sure if you feel any dizziness, tightness in the chest, or difficulty breathing that you go to the ER right away.

Due take care.

David

 

[Rusty67]

Thanks for the concern =)

I went to the ER last night and I'm going back in for xrays today.



Anyone got any idea why my ABS didn't do squat ?

 

[Mustang5L5]

Well the MC shouldn't matter. The sensors should detect the wheels locking and cause the ABS pump to begin to open and close to modulate the brakes.


I assume the ABS system was working properly before? No ABS light when driving around?

Only thing i can think of is that you locked all 4 wheels hard at the same time and the computer thought you had come to a stop? Even that would be a real tough stretch.

 

[whyask]

If you can salvage the computer take it to a dealer and see if they can pull something of a reason as to why the ABS didnt kick in.... Those little "black boxes" can come i handy sometimes !

 

[bhuff30]

The only reference for actual speed the computer has, is comparing the wheel speed of each individual wheel. Sounds like you got on the brakes hard enough and quickly enough to lock all 4 wheels, tricking the computer into thinking you are sitting still.
While ABS is helpful, it is still not a replacement for the driver. It certainly isn't instinct, but when the wheels lock, you have to let off the brakes to get back traction. Had you let off enough for one wheel to get some traction, the ABS would have likely kicked in.

 

[Brute03]

how are you using stock rotors with the bullitt calipers?

 

[CobraRed_96_GT]

how are you using stock rotors with the bullitt calipers?

Stock rotors for bullit calipers, i.e. brembo blanks.
Maybe there was air in the lines? ABS systems no likey air.

 

[Rusty67]

Ok, I forgot to mention that during the impact, my rear axle bent on the passenger side.

No ABS light on, I've had the ABS work recently.

No air in the system, I bleed every time I change brakes on my car. Fluid is still rather fresh.

I have the Bullitt front setup and the Cobra rear setup.

I got on those brakes harder then I've ever got on them in that car and I may have actually locked them all at the same time.

I thought the ABS system interfaced with the main computer to read the vehicle speed vs the rotation of the axles but I guess not. If I had known that I would have pumped the brakes, I've always been told to never pump brakes on an ABS system and thats why I didn't.

On another note, the x-rays came out clean today, its all just sore muscles from the blunt trama.

 

[Mustang5L5]

I thought the ABS system interfaced with the main computer to read the vehicle speed vs the rotation of the axles but I guess not. .

It does, however if you lock the wheels up, the tranny also stops it's movement as well.

You may have just tricked the car into thinking you went 35MPH to 0MPH instantly