: So the V can pull .9 g stock huh?



Mowgli
02-13-05, 02:56 PM
How about .93, in your 2nd week of ownership? :sneaky: Note the number on the left. Thats on the stock craptastic F1 runflats too.

http://img.villagephotos.com/p/2005-2/944597/Geewhiz-S.JPG

I do have a question, anyone know how this accelerometer is built? Is it an analog or digital device? Weight+potentiometer? Micromechanical device (silica substrate)? And why only 1 D.O.F.? Why not a 2nd DOF in fore/aft as well?

Just curious, if anyone's got the information.

Devil_concours
02-13-05, 02:57 PM
.9g is a skid figure and few owners have already hit over 1.1g

DgtalPimp
02-13-05, 03:08 PM
Just to make sure you don't think those are real "G" numbers. the meter is gets it input from the yaw sensor in the V and is a "driver G" number. I also like to see how high I can make the G reading go. If you hold the button down (left most button on the steering wheel) you can reset the G reading to zero.

Mowgli
02-13-05, 03:14 PM
1.1 huh? Well, like I said its only my second week, gimme time. :coolgleam

Does it "spill" over 1g? Or does the readout show 1.10?

I'm betting its a micromechanical device - that makes sense to me: the silica substrate stuff was just taking off around 95, and the auto industry was very intersted in the research (Texas Instruments' R&D). Ten years from then to now seems about right from research to product. They're really cheap, the downside is they're inaccurate - I mean they're good enough for g readings like this but you couldn't integrate them over time to get velocity or integrate again and get distance without taking the error up a couple orders of magnitude with you, right?

Anyhow, it is fun. Great car.

DgtalPimp
02-13-05, 03:21 PM
Here is the post for some images of G reading above 1.0 (http://www.cadillacforums.com/forums/showthread.php?t=14976&highlight=yaw)

Mowgli
02-13-05, 03:51 PM
*balloon, burst* Can I win a prize for the highest under 1,000 miles? lol

Soooo, is there any truth to the rumors about OnStar being able to read the g meter and calling owners whilst in mid-autocross thinking they had an accident?

(Or to void a warranty?)

thebigjimsho
02-13-05, 06:24 PM
How about .93, in your 2nd week of ownership? :sneaky: Note the number on the left. Thats on the stock craptastic F1 runflats too.
For as bad as the F1s wear, I wouldn't classify them as craptastic. For dry grip, there is maybe the Michelin Pilot Sport 2 or BF Goodrich g-force T/A KD that can outperform it and that's it. I'm the type that will drive his car home from an autocross on his competition tires just for the joy of grip. I really wish these things lasted longer. I will not compromise.

ctsvett
02-13-05, 06:32 PM
1.27 is the highest I have seen: Proof here-->

http://www.cadillacfaq.com/faq/imglib/misc.html

Oh and it is not 100 percent accurate. If you are going up or down in elevation, it will read higher. So, in all fairness, its only accurate on a level ground.

Reed
http://www.cadillacfaq.com

benjet
02-13-05, 10:24 PM
*balloon, burst* Can I win a prize for the highest under 1,000 miles? lol


uh unfortunately no, :sneaky: :-p

@ mile 600 I was (the very first CTS-V to be) doing laps at Infeneon Raceway (aka Sears Point) I think I was @ 1.17 or so, not to mention the hard eights we were doing with the evo 8 guys (= ride alongs) in the empty (flat) parking lot/paddock.

Mowgli
02-14-05, 10:16 AM
Does anybody have solid info on how this thing is implemented? All I've found via searches is guesses.

To me, as an engineer, it using the yaw sensor as input seems to be a convoluted, expensive, and backwards way to gather g data. A true yaw sensor would be a gyroscope and intrinsically more expensive than a micromechanical accelerometer. If the "yaw sensor" is really just an algorithm getting its input by reading shock/suspension displacement and calculating yaw angle then thats even more unreliable since acceleration/deceleration forces would distend that data even further. Not to mention now you're talking 2 degrees of extrapolating the data to arrive at lateral g, and if thats the case, well I'm just going to turn this screen off as its basically worthless.

Curious as to exactly how this is implemented so I can make a decision on how much of a "toy" I should regard it. Any GM engineers here able to shed some light? DgtalPimp, do you have anyone you can get the full scoop from?

Innocent Bystander
02-15-05, 12:00 PM
The input from the lat accel gage comes from a "combo sensor" that reads yaw rate and lateral acceleration. AFAIK, the sensor is on a chip so I guess that classifies as a micromachined device?

As far as the accuracy, I've heard that the numbers are pretty close to actual, independent skidpad numbers. Once you get into inclines and banks, the numbers don't compensate for that so you reach above 1.00 pretty easily.

Mowgli
02-15-05, 04:30 PM
For as bad as the F1s wear, I wouldn't classify them as craptastic. For dry grip, there is maybe the Michelin Pilot Sport 2 or BF Goodrich g-force T/A KD that can outperform it and that's it. I'm the type that will drive his car home from an autocross on his competition tires just for the joy of grip. I really wish these things lasted longer. I will not compromise.

I'm going to have to disagree due to personal experience with them. My 03 Cobra (419hp stock) came with F1s stock also, the non-runflat version in a bigger footprint (275s on 9.5" rims are stock), and I generated better numbers both in launches and around Nelson Ledges with both a set of Khumos (of all things) and, later on, Nittos. Both I'm sure you'd agree being low-end tires. Then I mounted a set G3s and they were comparable. So from my experience there's quite a selection of tires that, depending on what you want to do, outperform these. After two very different vehicles, I've come away not a fan of the F1s. But you know what they say about opinions....

The two tires you mention are also very nice tires, I'm probably going to be mounting Pilots once I burn these tards off.

SBONES
02-15-05, 04:48 PM
i pulled .89 one way, and .91 the other. The turn was banked

urbanski
02-15-05, 05:05 PM
The two tires you mention are also very nice tires, I'm probably going to be mounting Pilots once I burn these tards off.
which is why i almost intentionally burn out as often as i can....out with the bad as they say!! :D :devil:

lawfive
02-15-05, 06:59 PM
To me, as an engineer, it using the yaw sensor as input seems to be a convoluted, expensive, and backwards way to gather g data. A true yaw sensor would be a gyroscope and intrinsically more expensive than a micromechanical accelerometer. If the "yaw sensor" is really just an algorithm getting its input by reading shock/suspension displacement and calculating yaw angle then thats even more unreliable since acceleration/deceleration forces would distend that data even further. Not to mention now you're talking 2 degrees of extrapolating the data to arrive at lateral g, and if thats the case, well I'm just going to turn this screen off as its basically worthless.

Engineering, shmengineering. If the numbers are meaningless, I still want to post the biggest meaningless numbers I can!

-- Jerry

PS: Keeping the gauge on g's also keeps you from being bothered by noticing things such as the TPS never hitting 34.

PPS: Maybe they should rename the gauge from "g's" to "m's".

PPPS: I suppose a good on-board inertial navigation system [gyro+accelerometers] would be useful when I lose the GPS satellites in a parking garage, or in downtown Manhattan. So, if you had the gyro ANYWAY...

Koooop
02-16-05, 12:20 AM
"Engineering, shmengineering. If the numbers are meaningless, I still want to post the biggest meaningless numbers I can!"

That's hilarious! I'm right there with you!:banana:


1.07 - .98 in the first couple of weeks! The 1.07 came on the street in a very flat, unbanked corner at very highspeed and very sideways! This thing is 3,800 lbs of GO KART!

Yeehaw!