Notices
997 GT2/GT3 Forum 2005-2012
Sponsored by:
Sponsored by: Porsche North Houston

well, ABS Ice Mode finally got me...

Thread Tools
 
Search this Thread
 
Old 04-26-2011 | 03:19 PM
  #196  
997gt3north's Avatar
997gt3north
Thread Starter
Drifting
 
Joined: Nov 2006
Posts: 2,188
Likes: 5
From: Toronto
Default

Originally Posted by utkinpol
it contradicts with previous statements 'can be done on any street car with street ABS'. Also, I understood OP had it happened on his stock PASM GT3, or was it not stock? i also understand GT3 car comes stock with michelin cups r-comps which are 'stickier than street tires' in this thread terms.
My car has no modifications to the suspension or brakes. I can't tell you with 100% certainty if I was on the Firm or Regular suspension setting, but unless it is raining at Mosport, my default config at Mosport is 3 orange lights (suspension firm, sports mode, TC - off):
- Suspension Firm - it is a fairly smooth track
- Sports Mode - I like the increased throttle sensitivity
- TC off - Turn 5B at Mosport usually lifts the inside rear right tire so this saves the brake pads (there is a large drop off right after the apex where TC goes crazy - 45mph corner in 2nd gear - so no danger)

In the rain, I run with no Orange Lights (Soft, no Sports, TC on)

Again, as I have stated early in this post, given that I know it is now possible in this corner, I can drive around it - just brake earlier and more importantly, take a line mid track (not fully left) so that 'if' it happens again, I would have way more track to dis-engage the brakes and then re-apply them - you would blow the corner for sure, likely still go off, but at least you wouldn't leave the track having done almost no braking (this corner is taken at 1/2 the speed of your corner entry speed).


Using my knowledge of the car, and all the times I have experienced various ABS intervention, if I had to guess where the 'issue' in the program is, this would be my guess:
- when you start braking, if the surface incline, just at the exact point where the brakes engage CHANGES (in my case, lets say 5 degrees uphill to 2 degrees uphill), then you have potentially perfectly replicated, momentarily, the "I'm on black ice" friction surface
- if this happens at the instant the brakes are applied, given the rear engine / 50% rear braking bias of the gt3 (unlike any other production car), the ABS locks out all rear brakes until it is certain it is not on "Black Ice"
- since this 'extremely low friction' environment has now been triggered, additional priority / time is now allocated to determine what the actual surface friction level is (time is passing, you are not slowing) and you are stuck with only your initial brake pressure, which in the case that I described above, is basically zero rear brakes and maybe half the front brakes
- if you release the brakes, you get to start again, but as happened to a few people, sometimes there is no time / enough pavement to do this - unless you knew it might happen and you made sure there was

Again, from a programming logic perspective, the situation is easily fixable if you buy into the premise that the driver knows better than the Computer what is the more desirable outcome. If in the above situation, the braking pressure was slowly reduced from maximum to the black ice threshold as oppose to the opposite (built up from the black ice threshold) which the ABS module clearly does, then the outcome would be slightly flat spotted tires but a car that would have the speed reduction requested by the driver. I believe the easiest way to implement this would be to add another button to the dash (the ABS button) that would simply take this approach.

It is an obvious fix in my opinion and something very much in the spirit of the GT3 - i.e. a car that can be driven on the street and enjoyed during a Porsche DE.

Suspension (Regular, Firm)
TC / SC (ON, OFF)
ABS (Street, Track)
Old 04-26-2011 | 04:24 PM
  #197  
mooty's Avatar
mooty
GT3 player par excellence
Lifetime Rennlist
Member
 
Joined: Apr 2002
Posts: 43,564
Likes: 5,896
From: san francisco
Default

christ, the car is fine.
just drive it.
when you have ice mode, deal with it, tap, pump, eject.
Old 04-26-2011 | 05:25 PM
  #198  
997gt3north's Avatar
997gt3north
Thread Starter
Drifting
 
Joined: Nov 2006
Posts: 2,188
Likes: 5
From: Toronto
Default

Originally Posted by mooty
christ, the car is fine.
just drive it.
when you have ice mode, deal with it, tap, pump, eject.
I agree totally.
I actually deal with mini ice-mode every 2nd lap at Mosport on turn 5A if I don't release the brakes before the car slightly unloads so I'm fully comfortable with the situation - probably have maybe 300+ laps of dealing with it.

If you want to see where it happened, I found this video on youtube of a car following me (me = white gt3 with RS wing) - not from the day but at Mosport. At time index 1:06 at brake marker #2 with car almost fully left is where you start braking - you then carry brakes almost half way from that point to apex. As you can see, if you only get 20% of your brakes at marker #2, and the track goes fully right, and you are fully left, you run out of track in about 2/10ths of a second.

At time index 1:27, my car is hidden by his rear view mirror, is Turn 5A - it is steeply uphill. You ideally want to carry the brakes up the hill as far as you can and carry as much speed as possible to turn 5B (similar to Oak Tree at VIR), but with the 997gt3 if you have not fully released at the Apex the car's ABS will fully release the brakes and you will go straight off the track and miss 5B - I can replicate this every single lap. What you need to do is let 'ice-mode' hit, release the brakes fully and then re-apply - I basically do this every single lap. It is what it is - I deal with it - but at least in coming into 5A I have managed to scrub 85% of the speed off that is required before this happens.

http://www.youtube.com/watch?v=RiI8p...yer_detailpage
Old 04-26-2011 | 05:30 PM
  #199  
mooty's Avatar
mooty
GT3 player par excellence
Lifetime Rennlist
Member
 
Joined: Apr 2002
Posts: 43,564
Likes: 5,896
From: san francisco
Default

North, I hope you understood what I meant. no slight to you.
And it could be a dangerous situation but the thread is not myth, legend, fact, joke, debate….
Just be aware of the situation and react to it.
There are a WHOLE lot of other issues that makes this hobby deathly.
Abs ice mode… haha… my car almost blew up in fire last week…
The car in front of me may drop coolant due to the poor coolant pipe connection.
I think most of the long time posters like yourself get the drift.
Old 04-26-2011 | 11:12 PM
  #200  
Terry L's Avatar
Terry L
Rennlist Member
 
Joined: May 2003
Posts: 938
Likes: 1
From: PA
Default

Paul, tell the troops what you are using for tires and brake pads, and any other mods which may be relevant.
Old 04-26-2011 | 11:24 PM
  #201  
TRAKCAR's Avatar
TRAKCAR
Rennlist Member
 
Joined: Jan 2008
Posts: 29,449
Likes: 1,692
From: S. Florida
Default

Release, re-apply. Repeat if needed, keep car out of wall. Got it.
Old 05-01-2011 | 07:52 PM
  #202  
Izzone's Avatar
Izzone
Nordschleife Master
 
Joined: Dec 2008
Posts: 7,342
Likes: 294
From: Florida
Default

Another 997.2 rs rip.....

Ceramic brakes
Old 05-01-2011 | 07:58 PM
  #203  
Izzone's Avatar
Izzone
Nordschleife Master
 
Joined: Dec 2008
Posts: 7,342
Likes: 294
From: Florida
Default

Another 997.2 rs rip.....

Ceramic brakes
Old 05-01-2011 | 09:26 PM
  #204  
FTS's Avatar
FTS
Burning Brakes
 
Joined: Nov 2002
Posts: 901
Likes: 4
From: Maryland, USA
Default

At Sebring? T17 again?
Old 05-01-2011 | 09:26 PM
  #205  
jenk12m's Avatar
jenk12m
Banned
 
Joined: Dec 2006
Posts: 5,869
Likes: 0
From: new york
Default

do you know what brake pads and fluids they were using
Old 05-01-2011 | 10:03 PM
  #206  
Izzone's Avatar
Izzone
Nordschleife Master
 
Joined: Dec 2008
Posts: 7,342
Likes: 294
From: Florida
Default

Originally Posted by FlyingToaster
At Sebring? T17 again?
No comment, just wanted to state ice mode

I wouldn't want my details on net
Old 05-01-2011 | 10:49 PM
  #207  
superquant's Avatar
superquant
Rennlist Member
 
Joined: Mar 2010
Posts: 623
Likes: 59
From: CT
Default

Originally Posted by mooty
christ, the car is fine.
just drive it.
when you have ice mode, deal with it, tap, pump, eject.
Car is fine. Until it's in a wall. Then it's not.
Old 08-26-2011 | 02:51 AM
  #208  
Coleco's Avatar
Coleco
Instructor
 
Joined: Aug 2001
Posts: 205
Likes: 0
From: MA
Default

So how much is the motorsport race ABS modules?

I am guessing it's if I have to ask, it's too much...
Old 08-26-2011 | 04:33 AM
  #209  
Nordschleife's Avatar
Nordschleife
Drifting
 
Joined: Dec 2004
Posts: 2,722
Likes: 0
From: Munich
Default

Originally Posted by Coleco
So how much is the motorsport race ABS modules?

I am guessing it's if I have to ask, it's too much...

The hardware is very good value - for the right car.

The real cost is in finding the right engineers to develop the various non standard software options and all the logging equipment, and the time (its really boring work after a bit), to say nothing of the water bill, and all that shiny fake ice sheeting (or a trip to Scandia)......

Having said that, I do think there is a case for a very expensive properly integrated brake/suspension package to be offered

R+C

PS if you came up with a solution to wet leaves on the road surface in the Autumn/Fall - that would be heroic
Old 08-26-2011 | 09:47 AM
  #210  
deputydog95's Avatar
deputydog95
Rennlist Member
 
Joined: Mar 2004
Posts: 4,271
Likes: 30
From: Left Coast, Florida
Default

I didn't read all 14 pages, but I'm guessing this is still an issue then?


Quick Reply: well, ABS Ice Mode finally got me...



All times are GMT -3. The time now is 07:29 PM.