Brakes and Shocks

FTS · #1 05-31-2011, 09:55 AM

Two things I did not note on the other thread about our Barber day thinking they deserve their own thread:

1- Brakes, specifically ice mode.

This has been discussed in length in many forums and even here. While using PSDS cars, I tried my best to induce ice mode on the Turbos and GT3s, four different cars, by slamming on the initial application of brakes, which is also what the instructors were asking us to do, gradually ease off them. I just could not even get close to anything that might be described as "ice mode." The cars were stock; tires, pads, fluid, etc., except one of the GT3s had ceramics with PS2s on it. The Turbos exhibited very long pedal travel, but kept the same braking performance through all sessions, a bit longer stopping distances than the GT3s.

2- Shocks

I think we are either at 3rd or 4th generation PASM on the 997.2 GT3s, and I thought they are pretty good both for daily driving and track. After driving the Cup car though, I am better able to relate why the Excellence Magazine is so critical of PASM on the GT3s. In stock configuration, there are several areas on the tracks I visit in which the rear loses traction for a fraction of time, especially on bumpy sections, elevation change points, etc. The car takes a split second more to settle on its tires at full speed, and generally engages traction control. It is a momentary loss of traction that I can live with for my purposes.

However, after driving the GT3 and Cup back to back, the problem was much more amplified for me. The Cup car never loses traction, always planted, always full power to the rear, very smooth. Although it is a lighter, much more rigid and stiffly setup car, the ride over the track surface and curbs were noticeably smoother than that of the GT3. Granted some of it is due to aerodynamics, but at the cornering speeds we were traveling, I doubt the downforce on the Cup car had significant effect. As shocking as this may sound, I would hope Festina can collaborate my observations.

I think the issue is over-dampened rebound of PASM, which is a compromise of course between street and track driving. But in this case, with back to back driving, the issue was annoying to me.

Festina Lente · #2 05-31-2011, 12:44 PM

If the Cup Car had a traction control light to show that it too was loosing traction going up over Turn 4 and the Tunnel would you be as annoyed?

Physics is physics...and some of your issues are above my pay grade.

But, if you notice your Coach was having you short shift at the bottom of turn 4, even in the Cup..have you thought about why? I think it is because it too gets LIGHT at the top and with all that power, a wrong input (like too much steering) would have terrible consequences at the top and no opportunity for recovery.

RE ice mode, then only place to possibly experience it would be going downhill into 5 (imo) if you left the braking too late... but like you I have never encountered it and I think when the experience happens it is more to do with the driver inputs than the car's flaws...but again this is a base position until I see/experience proof since it too is above my pay grade.

FTS · #3 05-31-2011, 01:15 PM

Quote:

Originally Posted by Festina Lente

If the Cup Car had a traction control light to show that it too was loosing traction going up over Turn 4 and the Tunnel would you be as annoyed?

Physics is physics...and some of your issues are above my pay grade.

But, if you notice your Coach was having you short shift at the bottom of turn 4, even in the Cup..have you thought about why? I think it is because it too gets LIGHT at the top and with all that power, a wrong input (like too much steering) would have terrible consequences at the top and no opportunity for recovery.

I am not annoyed of the light flashing on the dash, most of the time I don't even see it, but I do feel the traction loss with slight unloading and the gain back when the rear loads back. But I am not certain if short-shifting in the Cup had anything to do with it; were we on 3rd or 4th gear in the GT3 through T4, I cannot remember?

There was also another place in which this was happening in the GT3, but I don't remember which section that was, a little more subtle, but was there still.

I guess my point is, somehow the PASM, with the short suspension travel in the GT3 compared to other Porsche road cars, leave me wanting a little in the shocks department. I may of course be exaggerating a little, especially after driving the Cup

ToddB · #4 05-31-2011, 07:49 PM

Quote:

Originally Posted by FTS

I guess my point is, somehow the PASM, with the short suspension travel in the GT3 compared to other Porsche road cars, leave me wanting a little in the shocks department. I may of course be exaggerating a little, especially after driving the Cup

You know the sin you committed was driving the cup... It's going to haunt you, and soon you will think the 3 is a POS

FTS · #5 05-31-2011, 10:37 PM

LOL, I actually made that comment to someone, too funny.

Today I got into my 3 first time in a week, the clutch was too soft, the throttle was late in response, the car did not feel like itself... I think it was me than the car

Festina Lente · #6 05-31-2011, 10:54 PM

Just wait until you get into an "electric" motor car (MB-SLS E car), they make n/a engines feel like they have a case of 70s turbo lag! It adds perspective to the carping about existing turbo lag versus n/a engines.

FTS · #7 05-31-2011, 11:02 PM

I don't doubt it, that is going to be special one way or another. I wish you had written something about it, I am sure it was a special experience.

Festina Lente · #8 05-31-2011, 11:32 PM

^
Not compared to the Cup Car experience...I am still on a high!

Back to brakes and shocks... I need to go back to do more analysis.

amaist · #9 05-31-2011, 11:48 PM

Was the Cup car on slicks and the GT3 on PS2's?

Then it's all in the tires. Slicks are like heroin. One good shot gets you hooked and all those r-comps feel like junk. Stuff like PS2 is just for driving on the street to the mechanic.

Locally a 997.2 RS was known to be driven within 4 seconds of a recent (997) Cup car's laptime (mid 1:40s). It was on slicks. It's all about the tires.

landjet · #10 06-01-2011, 12:34 AM

Fatih, the turbo's longer stopping distance was because of the extra 500lbs that it carries.

I have experienced ice mode in my car when I am trying to brake hard at higher speed when turning. Not trail braking as such but rather as a control measure in a sweeper. The rear end is unloaded in a lateral fashion and the PSM is trying to compensate to maintain control. Last time it happened was at NJMP going into that sweeper before you get to the octopus. In my owners manual it says that you can press the brake pedal even in this condition{doesn't call it ice mode} to apply more brakes. I have done it and pressed through the ice mode. It is very unnerving the first time it happens.

Doesn't the cup car have 4 way adjustable shocks? I'm sure the drivers and mechanics had them dialed in ahead of time and that would account for the superior damping and feel.

FTS · #11 06-01-2011, 12:44 AM

Quote:

Originally Posted by amaist

Was the Cup car on slicks and the GT3 on PS2's?

Then it's all in the tires. Slicks are like heroin. One good shot gets you hooked and all those r-comps feel like junk. Stuff like PS2 is just for driving on the street to the mechanic.

Locally a 997.2 RS was known to be driven within 4 seconds of a recent (997) Cup car's laptime (mid 1:40s). It was on slicks. It's all about the tires.

One of the GT3s were on PS2s, the other on Sport Cups, the Cup car was on Michelin slicks. I think Trakcar had lap times of 1:41-42 in March in his RS on RA1s. The instructor's were doing 1:33-1:36 in the Cup, my best was 1:46.

Details are here: http://www.gt2gt3cup.org/showthread.php?t=231

Quote:

Originally Posted by landjet

Fatih, the turbo's longer stopping distance was because of the extra 500lbs that it carries.

Doesn't the cup car have 4 way adjustable shocks? I'm sure the drivers and mechanics had them dialed in ahead of time and that would account for the superior damping and feel.

Yes the weight difference was very apparent between the Turbos and GT3s, but the Turbo was so very fast still.

And yes, the Cup car has 4-way Sachs units and the whole car was setup before hand by its crew

That is my point about this post, I think the shock setup can be improved on the GT3/RS, but I am not sure if it would be worth the hassle at this time. I really do not like modifying the car.

lightweight · #12 06-01-2011, 10:21 PM

FTS, if you haven't already done so, it may be worth speaking with Mike Levitas at TPC about their Stage 3 suspension.

FTS · #13 06-01-2011, 10:48 PM

I speak to him relatively frequently, he is only ~25 mi. from me, but not on car setup

Not a bad idea, but I really do not intend to modify the car, was just stating my observations to see what others think. Thank you for the suggestion though.

Festina Lente · #14 06-01-2011, 11:18 PM

Thinking about 'dem brakes on the Cup Car, I am smitten with the pedal feel. It never varied in feedback through your foot, or pedal travel; yet the harder you pressed the quicker you stopped (very linear). Oh my! better than... I mean, I never experienced better brakes.

mooty · #15 06-01-2011, 11:18 PM

"I think we are either at 3rd or 4th generation PASM on the 997.2 GT3s, and I thought they are pretty good both for daily driving and track. After driving the Cup car though, I am better able to relate why the Excellence Magazine is so critical of PASM on the GT3s. In stock configuration, there are several areas on the tracks I visit in which the rear loses traction for a fraction of time, especially on bumpy sections, elevation change points, etc. The car takes a split second more to settle on its tires at full speed, and generally engages traction control. It is a momentary loss of traction that I can live with for my purposes.

However, after driving the GT3 and Cup back to back, the problem was much more amplified for me. The Cup car never loses traction, always planted, always full power to the rear, very smooth. Although it is a lighter, much more rigid and stiffly setup car, the ride over the track surface and curbs were noticeably smoother than that of the GT3. Granted some of it is due to aerodynamics, but at the cornering speeds we were traveling, I doubt the downforce on the Cup car had significant effect. As shocking as this may sound, I would hope Festina can collaborate my observations."

===> that's what i have always been saying about pasm. usually 90% of the time they are great. but they aren't the same as moton, jrz, penske, ohlins. but for what it's designed for. you can't ask for more.

after driving the stripper, i already think all street cars are POS ;-)

with regard to ice mode. i have driven cayman, gt3, c2, lotus, m3 on track from street tires, RA1, nittos, R6 to slicks. i have never experienced it except on the lotus. i am VERY abrupt on brakes.

slicks are great, but that alone will not solve suspension problem.

festina and fatih, you should stop talking about cups... or else i see a 28' trailer and F350 somewhere near where all the 997.1RS gathered for dinner few years back.... wife will not be happy.