Tahoe Shark

I did some searching but could not come up with any info on the lateral G's an S4 could pull on a skid pad. Does anyone have that info. It would also be helpful if some of the road guys might share their data logging info on the loads in turns. If you could also include a brief description of the tire and suspension mods done to your cars.
Thanks in advance.

AO

http://members.rennlist.com/pirtle/reviews.htm

Look half way down the page.

Tahoe Shark

Thanks Andrew,
Great articles in addition.

Vilhuer

With latest modern rubber stock S4 could probably go well above 0.87g it did with period tires when it was new.

IcemanG17

Tim
This is a VERY good point.....sure 928's pulled mid to upper .8g back in the day....but with the advancement in tires and specifically WIDER tires....they can pull far more....a skidpad is a mediocre test at best...since it is a fairly tight circle that you just drive around nonstop.....the G's any car could pull in a shorter turn is much higher.....for example Car and Driver tested a bunch of sports cars around Laguna Seca...the GT3 won with the best lap time...& I think its "transitional" G forces were about 1.69G.....I remember the Honda Civic Si was 1.55g.....

After riding in the Beast with the setup & tires you have.....I would guess you could pull around 1g on a skidpad & probably at least 1.5G peak in transition....

After the autocross on Sunday.....I was quite pleased with my 100% stock suspension S4 with just wider-grippier tires.....a great feel.....of course if I had your setup I could have shaved several seconds!!

Tahoe Shark

[QUOTE=IcemanG17]Tim

After riding in the Beast with the setup & tires you have.....I would guess you could pull around 1g on a skidpad & probably at least 1.5G peak in transition....

QUOTE]

The reason for the question is that "transition" is the point I want to stay away from. Far Far Away. The Pony Express has a fairly slow canyon to go through and I've only been able to run 130 - 135 average through it. Now in the 160 mph class I must step it up. A 160 average through the gap would just hit 1.15 G of lateral force in the tightest of turns. If I take the known G load of a stock S4 I know I will be safe. If I know what some of the track guys run I can better judge how fast to go in excess of the stock figure. I'm not excited about experimenting on race day. I hope this helps explain why I need the info to adjust my course notes.

Richard S

Tim, what's wrong with averaging 135mph through the canyon?....It just means you get to go faster on the rest of the course!!!!

Rich

Tahoe Shark

Not on the way back. Only 8 miles and that is not much time as you well know.

fabric

The skidpad test is mainly a measure of mechanical grip. If you have the aero equipment to produce any downforce, very little of it is measured in these tests, which are on a 300' diamater circle. If you can find the space to run larger circles and have something to measure, you may be able to get a better number.

Yeah, I know, that's really useful.

SwayBar

Here is my telemetry from Road America last July while doing a 2:37.187 lap; this is the third time I drove the car so I felt like a fish out of water.

http://www.roadamerica.com/images/maps/ra_map_2006.pdf

Turn 01: 1.52 G's @ 74 mph
Turn 03: 1.57 G's @ 60 mph
Turn 05: 1.26 G's @ 49 mph
Turn 06: 1.33 G's @ 52 mph
Turn 07: 1.29 G's @ 76 mph
Turn 08: 1.23 G's @ 53 mph
Carousel:1.44 G's @82 mph
Kink: 1.55 G's @ 101 mph
Canada: 1.55 G's @ 67 mph
Turn 13: 1.20 G's @ 82 mph
Turn 14: 1.56 G's @ 66 mph

The graph's x-axis represents 4 miles and is in feet, and the y-axis Lateral G's. Red is G's, and Green is MPH.

The car is an 89 GT with Bilsteins, 600 - 400 springs (..I think), Devek front sway bar, 11 x 18 Kinesis all around, 285 and 335 tires, and weighs in at 2900 lbs.

Hilton

Fascinating stuff.. the kink looks like a fun sweeping corner!

11" fronts as well? holy moly

cooleyjb

Swaybar somethings not right with your calibration in that unit. All of you left turns are considerably lower than the your right turns and baseline seems to be off a bit. Also the values you give look to be peak numbers which aren't as useful as sustained.

Also you need to be able to factor out the lean of the car and tilt of the corners to get true readings. For example the end of the carousel falls away and 13 is on camber for a good chunk of it. For every degree the car leans and track is from level it is a difference of .011 on the readout.

Very cool software and the interface is really nice though, great tool for comparing your car's laps.

IcemanG17

Tim
Do you have a G-tech......they can be found on ebay for around $300 or less....or even better a GPS datalogger like swaybar has......but the G-tech will work.....that way you could test on some corners at a track to see where your limits are....gives you an excuse to take the beast out for a DE while the G-tech records all the cornering forces..... 1.15g doesn't sound all that excessive to me for your setup....but the beast isn't super light either.... A quick jaunt out to Reno-Fernly should answer the question for ya! I'll hook up my cheapo G-tech the next time I'm at the track to see what it pulls....

SwayBar

I don't believe so since there is nothing to calibrate. Nothing more than proper orientation of the unit is necessary for the accelerometers. Here is the G2X's faq:

http://www.g2xpro.com/faq.htm

Perhaps that is because the left hand turns are much tighter thus slower (..5, 6, and 8), except for Turn 13?

Now that I've re-read this, I'm sure driver-error has something to do with it too!

Yes, those are peak numbers for a corner. As for sustained, that is why I provided the chart so one can have an idea of the resultant lateral acceleration curves. Unfortunately, the chart has it's limitations due to being a static image representing over 21,000+ feet, one complete lap, making for poor resolution as you noted.

The best portion for sustained on the posted chart would be foot-marker 12,500 to 15,000 which represents the Carousel, where the GT sustained between 1.20 and 1.44 G's through it. For comparison, my Z06 sustained slightly higher, and did a max of 1.51 G's; both at the apex which is approximately the middle of the rumble strip.

With the software, I can blow-up any portion of the track; so instead of looking at 21,000 feet of track in a chart with virtually zero resolution, I can look at 100 feet of track with lots of resolution and curve definition. Maybe I'll do that with the Carousel tonight and post the screenshots.

You may be correct, but from everything I've read, there is no need to factor anything for flat or banked curves due to the unit using the GPS in conjuction with the accelerometers.

No doubt; I'm very happy with it, and recommend it to anyone who's looking for a track data-logger.

Those were astute observations/comments; do you drive or hang-out at the track?

UKKid35

Should this be merged with the 2-6 failure thread?