ABS engaging during hard braking
 

During hard braking, from about 80 mph on a straight flat road, the right front wheel's ABS in engaging. I am trying to brake as hard as I can, but I don't just use the brake pedal as an on off switch. I get on the brakes and after the weight is transfered to the front, I really mash the pedal and thats when the ABS engages. Very good tires, pressures correct, pads/rotors all in good shape.

Maybe I'm just reaching the limits of my brakes?

That is...
 

... very normal.
Happy Boxstering,
Pedro

You're not reaching the limits of your brakes. You're reaching the limit of your tires. This is how it is supposed to work.

Everyone should try this under safe conditions to become familar with the braking characteristics of their car and what it feels like to get into the ABS. This is usually the first exercise in a defensive driving school.

Stabbing the brakes and turning at the same time to avoid a simulated emergency situation is a great fundimental exercise.

I'm not sure why you see this as a problem. If you COULDN'T brake hard enough to make the ABS fire, you'd have a problem.

Sometimes my starter engages when I turn the key... any idea what might be wrong? :p

That is the second skill taught! :cheers:

Interesting topic... I think I have the reverse of the TS....

At high speeds if I brake hard, on my front brakes, the abs actually sometimes allows the tires to skid (???!!!) slightly, usually just one sound then no skidding but no abs as well. If I step any harder, the ABS will kick in. The skid usually last a split second to at most a second.

I've changed abs sensors on all 4 brakes and even changed the front brakes to the S brakes, but it still behaves the same.

It's as though I've got "lazy" abs that is pretty slow in engaging.

My mechanic says its normal as "Porsche determined this way you get the most effective braking". Don't know whether to believe him or not ?? I've never had a car with abs that allowed any skidding !

My front tires are PS3 and the rears are N specs PS2, if that makes a difference.

Any thoughts ? I hope it's not the abs unit... those things are expensive !

An every so slight skid; whining of the tires is where you want to be for the best stopping distance. Getting right into the ABS is less effective.

Should you not have ABS, you will have to come off the brakes to "break and avoid" an obstacle or you will slide into said obstacle

I'm not sure if I would describe mine as "slight skid" or "whining of the tires" - its a loud loud skid. But its not a sustained skid. As I mentioned, 99.99% of the time, the abs doesn't come on after that (if no increase in brake pedal pressure).

It's embarrasingly loud.

I did have a sustained skid once with the tail swinging out, but since changing the abs sensors and the engine mount (that seem to affect stability quite alot), haven't happened again. That time was on an emergency emergency stop at lower speeds even...

Would the climate/pavement type influence ABS at all? Silly question I know (don't flame me!) but I have the same loud tyre skid noise thing happening to me durring hot summer days. However durring mild-cold winter days, the ABS seems to be kicking in normally.

That would explain alot for me if weather did affect the abs.... it's hot here all year round !

When you panic stop, you may initially hear a single chirp. Since the Boxster is so nicely balanced, the front wheel(s) momentarily break free in a panic stop. All that load you're piling onto the front suspension while decelerating pushes the tires more firmly into the pavement, causing the skid to stop. This is why you try on the track to load your brakes progressively instead of stabbing at the brake pedal - you want to shift load to the front suspension before threshold braking.

There's a spot on my way home where I love to chirp the front brakes during threshold braking. I had not realized until today that this is cause for embarrassment. :D