Rich W

RSAErick,

You and I have the same car. I've never turned the ABS off, and have usually managed to stay out of trouble.

That being said, I've never been in a race, so there might be some advantage to not having ABS. However, none springs to mind. I'll let others more learned on this topic continue the discussion.

Just my measly $0.02.

Greg Fishman

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Robert Henriksen:
<strong>Hm. About the only relevant experience I've got is threshold braking to stay just OUT of the ABS. I've read that *straight-line*, dry surface braking distances are longer w. ABS than without. Perhaps this is just the older systems? At any rate, my heavy braking is all in a straight line, with some light trail braking at the end. When I'm heavy on the brakes in a straight line, I'm able to flutter just on the edge of ABS. I *think* this is the right thing to do for maximum deceleration; am I wrong here?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">That is what I do. There are places on some tracks that I do get into the ABS and it does seem to lengthen the stopping distance and I make an adjustment on the next lap.

DJ

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Danno:
<strong>The latest incarnation, PSM is the most sophisticated yet and if anything, prevents spinning no matter how hard you try.
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">LOL! That's not true at all. PSM equipped cars spin on the brakes all the time. Yes, PSM is good, but no combination of hardware and software can overcome the laws of physics.

DJ

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Greg Fishman:
<strong> </font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Robert Henriksen:
<strong>Hm. About the only relevant experience I've got is threshold braking to stay just OUT of the ABS. I've read that *straight-line*, dry surface braking distances are longer w. ABS than without. Perhaps this is just the older systems? At any rate, my heavy braking is all in a straight line, with some light trail braking at the end. When I'm heavy on the brakes in a straight line, I'm able to flutter just on the edge of ABS. I *think* this is the right thing to do for maximum deceleration; am I wrong here?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">That is what I do. There are places on some tracks that I do get into the ABS and it does seem to lengthen the stopping distance and I make an adjustment on the next lap.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Agreed. I find that getting into the ABS always lengthens the stop. I like ABS, but not for a reason that anyone here has mentioned yet: flatspotting tires. This is probably the single biggest benefit to ABS (at least for me). Sure, when you screw up, and go too deep into a corner and get into the ABS it lengthens your braking a little, but you still make the corner, and your tires are none the worse, except for a little wear. Do the same thing in a car without ABS, and you're likely to be replacing a tire or two. A few weeks ago, I wrecked a set of front (sticker) tires after one lap because of a lock-up. Sure, I know that you're supposed to get back out of the brakes when they lock, and I did, but when you're already too deep, it's pretty tough to get off the brakes when you see that wall coming right at you. The skid marks showed that the wheels were only locked for about 50 feet (at 140 mph). It still ruined the tires though. With ABS, that doesn't happen.

Z-man

DJ: you bring up an excellent point about ABS & not flatspotting your tires! I agree: unless I'm going sideways, I'll never have an issue with flatspotting a tire due to braking!!!

Regarding PSM: while my car isn't equipped with it, Charlie, a friend of mine in the red-run group (for DE) in a Boxster S I know does the following:
1. In the dry, he turns PSM off, but leaves the ABD (?-that brake induced LSD-type) system on.
2. In the wet, he keeps both PSM and ABD on, and finds he can go deeper into corners knowing the safety net of PSM will be there if he needs it.

Charlie is an exceptional driver, BTW.

-Z-man.

NetManiac

So if I understand it correctly the difference between racing ABS and street ABS is the modulation interval. Is that right? If that is the case is it possible to upgrade street ABS to racing ABS by replacing/upgrading the software which controls the modulation? I presume racing ABS would be fine for street use as well, so "upgrading" a street-track car wouldn't cause issues?

924RACR

ABD = Automatic Brake Differential. Think of as traction control without engine torque reduction; won't cut power, more or less just applies brakes to make sure that the drive wheels are turning close to the same speed.

NetManiac

I don't have PSM on my Boxster. Does ABD come with PSM or is/was that a separate option?

Cupcar#12

The Racing Abs system in my car is a little different from the stock system namely it uses shorter "pulses" to modulate the lock/un-lock of the wheels. it's about 2x as fast as the street system (don't quote me on that) and it has a larger Master cylinder (nessecary for the larger brakes) of 25.4mm vs 20.64mm of a standard C2 964. I get into Abs when going deep into corners and then it is only until the turn in point- releaseing and trail braking out (usually while getting back on the Gas, left foot braking).I am not an expert by any means, just trying to keep the car neutral to exit. For the wet i am going to investigate a version of traction control which cut's pulses to the injectors instead of Porsche's PSM system (brakes selective wheels). Rember if your out of traction there is not much PSM, traction Control, or ABS is going to do for you.
Both Feet in and Hope you regain some traction so you can steer yourself out of trouble.

Ed Newman

It all depends on the ABS system. My car the ABS SUCKS!!! I want the parts back from my 99. Worked SOOOOO much better for racing.

SimonK

Just got lost in this thread...

Is it not true that the whole point of racing is skill driven?

Every idiot can step on ABS full blast and stop better quicker and steer the car at the same time. That's great for the street and ordinary people. Where did the skill which makes one driver better than the other go? ABS - I hope they take it out of the F1 - I am getting bored watching it.

Autopilots and hud displays soon?

M758

F1 Does not have ABS.. You must have been sleeping through the various lock ups and tire smoke

This discussion was about the safety of ABS on the track. From what has been exchanged ABS is safe on a track and can lead to better braking performance on the track. There is local and well respected club racer that tell you how good ABS is. Infact he installed ABS on his 86 944 Turbo to make he car faster.

Personaly I like to run without ABS in my race car since it requires ME to modulate the pedal for better braking. To ME it is better for learning the finer points of racing. Leave the ABS on in DE in most cases unless you specificly want to practice threashold braking and pedal modulation.

Ed Newman

Update on my ABS issues... I changed from the MPCS to Hoosiers (like my 99 had) and there are no more ABS issues. I am not sure if the ABS had a problem with the MPCS's diameters or if the Hoosiers are that much stickier, but during my most recent excursions at the Glen and Pocono Full, I never had ABS come on with the Hoosiers. Problem solved? or problem found?

SimonK

M758, Sorry you are right F1's do not have ABS.

They had it and they don't have it anymore.

I hope they take traction control out asap too!

But that's my point it should be about driving skill not about driver aid's - safety or non safety - after all it is racing.

The way to make tracks safe is to make huge run off areas then stop restricting everything and let it rip!

And you are right I used to watch every single F1 race and I still do but by the lap 8 I am fast asleep.

pjgo

I attended a Skip Barber racing school last month, and we drove open-wheel Barber Dodge formula cars without ABS. Practicing threshold braking was definitely fun, especially because we could see the wheels lock up!

Before we went on track, the instructors explicitly told us to lock up the brakes when in a spin. Their rationale: locking up the brakes will most likely keep the car on the track and away from the walls.

During the last session of the day, I had the chance to put their advice to good use. I screwed up turn 11 either by not slowing down enough or by applying power to early or abruptly. The car spun and shot backwards towards the inside wall. I locked up the brakes as instructed and managed to stop the car a few feet from the concrete wall.

I obviously do not know what would have happened if the car was equipped with ABS. If ABS had extended the braking distance by even a few feet, I would have hit the wall.

pj