Abs question...

[DaveLC2]

Tonight I was kinda of goofing off at work and was probably going about 35-40mph and went to stop quick and I guess the sprinklers had been on earlier so my abs activated as the pedal started to pulsate. I decided to just hold it steady to check out the performance of the abs. I know you're supposed to pump on non-abs braking systems and just hold firm and let the computer sort out the mess with abs systems. There was a bump in my braking which might have played a roll in the extremly poor response. There was nothing in my way but had there been a car in front of me I would have not been able to stop in time. It felt like it took an extra 10-15 feet to stop. Kind of scary :shock: Like I said I wasn't in danger of hitting anything. During the pedal modulation the kept rolling pretty good and it almost felt like the brakes were hardly being applied. I know it was damp and there was a good size bump right in the peak of my braking. Just wondering if anyone else has experience this? I am glad I found this out by just goofing off and not in a real situation on the street and in traffic. My brakes have always been bang on the money. Another thing I just thought of is that I just came off of heavy throttle (no vacuum) and then hard on the brakes. The vacuum canister for the master cylinder may have been a little low too.

Dave

[EVO GRIM]

The abs system has sensors on each wheel, but if its slippery enough like on the first rain of the year, they can only do so much.

[vtluu]

I've had the ABS go into something like ice mode when braking over extremely uneven and bumpy surfaces; I noticed this when bedding in new brake pads on an industrial road near where I live. Basically I hit the brakes, then hit the bumpy patch and braking force was drastically reduced (basically felt like I was on ice) even after I cleared the bumps. I released and reapplied the brakes and got good braking again.

[DaveLC2]

I've had the ABS go into something like ice mode when braking over extremely uneven and bumpy surfaces; I noticed this when bedding in new brake pads on an industrial road near where I live. Basically I hit the brakes, then hit the bumpy patch and braking force was drastically reduced (basically felt like I was on ice) even after I cleared the bumps. I released and reapplied the brakes and got good braking again.

That's exactly what it felt like. I thought about releasing and then reapplying before the lock up point but I wanted to see what it would do. The wet surface was mostly on the left side only. I must say the car did stay straight as an arrow. Thanks for the input guys.

Dave

[MarkSAE]

I've had the ABS go into something like ice mode when braking over extremely uneven and bumpy surfaces; I noticed this when bedding in new brake pads on an industrial road near where I live. Basically I hit the brakes, then hit the bumpy patch and braking force was drastically reduced (basically felt like I was on ice) even after I cleared the bumps. I released and reapplied the brakes and got good braking again.

Yeah, I've noticed that too under similar braking conditions. Do you think that's due to our quaifes? I never really tried braking under the same conditions w/ the stocker.

[chrisw]

I've had the ABS go into something like ice mode when braking over extremely uneven and bumpy surfaces; I noticed this when bedding in new brake pads on an industrial road near where I live. Basically I hit the brakes, then hit the bumpy patch and braking force was drastically reduced (basically felt like I was on ice) even after I cleared the bumps. I released and reapplied the brakes and got good braking again.

Yeah, I've noticed that too under similar braking conditions. Do you think that's due to our quaifes? I never really tried braking under the same conditions w/ the stocker.

I am not too sure what is happening...

I get the same "ice mode" every now and then. It seems that if we reach a certain amount of loading to the front wheels, then the ABS does not know how to compensate.

This ABS problem only happens when I jump off the trottle and onto the brakes hard enough to activate the ABS, I can feel it pulse. If I gradually back off the throttle and onto the brakes then the problem does not occur.

So far I have not noticed no decrease in braking performance, despite what my pucker factor is from the calibrated butt-O-meter....

[DaveLC2]

I've had the ABS go into something like ice mode when braking over extremely uneven and bumpy surfaces; I noticed this when bedding in new brake pads on an industrial road near where I live. Basically I hit the brakes, then hit the bumpy patch and braking force was drastically reduced (basically felt like I was on ice) even after I cleared the bumps. I released and reapplied the brakes and got good braking again.

Yeah, I've noticed that too under similar braking conditions. Do you think that's due to our quaifes? I never really tried braking under the same conditions w/ the stocker.

I am not too sure what is happening...

I get the same "ice mode" every now and then. It seems that if we reach a certain amount of loading to the front wheels, then the ABS does not know how to compensate.

This ABS problem only happens when I jump off the trottle and onto the brakes hard enough to activate the ABS, I can feel it pulse. If I gradually back off the throttle and onto the brakes then the problem does not occur.

So far I have not noticed no decrease in braking performance, despite what my pucker factor is from the calibrated butt-O-meter....

On one of my other turbo cars with a vacuum brake conversion I would get a hard pedal if I was on boost and then needed brakes right after due to the engine not producing any vacuum for the power assist while under boost. The was only an issue when you're doing a burn out and are using the brakes to stay in place (brake stand) and then you'd get the stiff pedal. I was thinking something like this might be happening. Hard on the throttle, off throttle, hard on the brakes decent braking power (lack of vacuum in canister) and then after the engine is making vacuum for for a moment it increases the power assist even though your pedal postion has not changed therefore activating the abs. Just a theory. This was the first time I ever had done this to my Evo since I've owned it.

Dave

[vtluu]

Yeah, I've noticed that too under similar braking conditions. Do you think that's due to our quaifes? I never really tried braking under the same conditions w/ the stocker.
The front diff would only make a difference under acceleration. I think Mike@RRE got asked about zillion times about ABS + Quaife... Eventually his answer become something like what my sig says. :lol:

[chrisw]

On one of my other turbo cars with a vacuum brake conversion I would get a hard pedal if I was on boost and then needed brakes right after due to the engine not producing any vacuum for the power assist while under boost.

It's not a hard pedel, I know what that feels like. That happened a lot in my WRX or if I try left foot braking. In fact, I expect it to happen when I am LFB...

This is distinctly different, the ABS definately cycles and pulses the brakes and it started after my Quaife install.

[ZK]

This is my first car with ABS and I've felt the pulsating as well. It does seem to come on when you brake hard.. whether you want it to or not. I'm thinking of disabling it because it really messes you up, no matter how hard you push it feels like the car won't stop!

[earlyapex]

This is distinctly different, the ABS definately cycles and pulses the brakes and it started after my Quaife install.

That sounds like ABS doing it's job. You still need to threshold brake, even with ABS, I have rarely felt ABS pulse on the track.

[jaymzz]

I have something similar happening with my Evo. Pedal pulses, ABS light comes on, and then no brakes. I wrecked my Evo last year from this. I have had this happen to me three times since December. Mitsu told me it is a normal ABS characteristics, but I dont like it. I am trying to figure out how to disable mine. Isnt the ABS tied into the ACD? If anyone knows of a way to turn off the ABS, please let me know.

[dohcvtec]

Damn, how are you driving your car to kick on ABS like that? Mine has only come on a few times, but I expected it.

[turbotiger]

I've had the same experience when braking fairly hard and hit a bump on one side. But it wasn't as bad since I wasn't going too fast, and I had a bit more braking force left since stepping on the brake pedal slowed me down a bit more.

[jaymzz]

It happend again today. Turning into a store parking lot. About ten mph, brakes pulsed and released. My 03 Evo never did anything like this. I am getting frustrated about it. I dont really trust my brakes at all. I wasnt on the throttle, because I was turning into a parking lot when this happened. I have asked everyone I know, and no one seems to know what is going on. Any ideas?

[dohcvtec]

Faulty sensor maybe? Take it back to the dealer.

[jaymzz]

Thanks. Would that show up when they scan my abs computer? Or does the Evo not have that cabability?

[MitsuMan]

well durring abs braking theres only one way to drive and that is the SSS method stomp, stay, and steer abs only allows you to control the car in a panic brake application. I think that was a normal feeling to have