Peak lateral G's....

Chiketkd · #1 07-02-2005, 11:33 AM

I lent my G-Tech to AmazonParrot for a few weeks, and decided to get it back this morning to do a little testing with my current suspension set-up:

1) stock springs and struts
2) polyurethane bushings f&r
3) 16x8" RX-7 wheels shod with sticky summer-only 225/50 Dunlop SP Sport 8000 tires (200 treadwear)
4) -0.5 camber front, -0.2 camber rear

Followed the directions in the g-tech booklet, and turned it perfectly sideways across my dashboard and levelled it out to 0.00 g's. I selected the mode for the g-tech to measure peak lateral g's...

For the course, I took my car down a tight twisty road (Afton Mtn Road) with a 40mph speed limit and several caution signs advising driver's to navigate turns at 5-20mph...

Afton Mountain Rd:
http://maps.yahoo.com/maps_result?cs...s&BFKey=&mag=2

I decided to go down Afton Mtn rd twice, the first time keeping the car under control, w/o breaking the tires loose (came close a few times). At the end of the first run, the g-tech had recorded a peak lateral g reading of 0.89.

I then repeated the course a second time with the goal of breaking my tires loose. I suceeded three times. Afton Mtn rd is truly an amazing road to drive, and has a good mix of tight off-camber turns as well as a few banked on-camber turns - the peak lateral g-force my g-tech recorded this time around (probably the time I broke all four loose on a banked turn) was 1.01.

-Chike

P.S. The error reading on my g-tech pro when recording g forces is + or - 0.1g's. However, I've been able to test its accuracy in measuring acceleration at the dragstrip. On a run where I recorded a 15.21 @ 89.5mph, my g-tech recorded 15.20 @ 91mph. Also, from reading several articles in Road & Track and MotorTrend when they measured instantaneous peak g's when driving along a road course or track, it is very possible for a car (e.g. Honda S2000) to record a peak lateral g reading of 1.0 (or higher) especially if there are a few on-camber banked turns along the course (when the car would record .90g in steady state lateral cornering).

ensteele · #2 07-02-2005, 11:43 AM

Wow, the information is interesting, but I would have liked to be there and watch you drive that stretch of raod!

SVXRide · #3 07-02-2005, 01:13 PM

Chike,
For the readings to be 100% accurate you have to stay on level ground (due to the use of accelerometers to make the measurements). I'm guessing you had some "vector addition" going on unless the road had no incline/decline at all.
-Bill
p.s. now, find yourself a big flat parking lot that you can turn into your own personal skid pad....now we're talking!!

Chiketkd · #4 07-02-2005, 04:42 PM

I decided to use my wife's '02 Lancer ES as the 'control' in my little experiment. It still has the factory Dunlop SP 20 FE M+S tires (treadwear 320) in the 185/65/14 size, comes with only a front sway bar, and is a cute little grocery getter!

A few magazines (Car & Driver, MotorTrend) have tested her car over the years and recorded lateral g readings of around 0.75-0.78.

I went back to the same Afton Mtn Rd to see what readings I would get...

I was able to break her car loose very easily in the turns, and noticed very heavy understeer at the limit. All in all, this car doesn't like to be hustled down a mtn road!

The peak lateral g's my g-tech pro recorded with her car (with the front tires understeering heavily at the limit) was 0.72.

-Chike

P.S. Bill, it would be nice to find a level parking lot but there aren't too many around here. I'll try to scout a place out and report back!

P.P.S. Btw, the highest lateral g's a magazine recorded for an SVX in skidpad testing, was by Motortrend who got 0.92g's in their 9/91 test of a '92 LS-L.

Amazonparrot · #5 07-02-2005, 05:00 PM

Chike, use the lot up at piedmont college or over at Sams club, both are fairly massive.

-Andrew

Chiketkd · #6 07-02-2005, 07:20 PM

Quote:

Originally Posted by Amazonparrot

Chike, use the lot up at piedmont college or over at Sams club, both are fairly massive.

-Andrew

Piedmont's lot was the one I was thinking of going to - however, I know it's a popular police hang-out. I wouldn't want to attract too much attention!

-Chike

SVXRide · #7 07-02-2005, 08:39 PM

Quote:

Originally Posted by Chiketkd

Piedmont's lot was the one I was thinking of going to - however, I know it's a popular police hang-out. I wouldn't want to attract too much attention!

-Chike

Just tell them you're from Subaru and you're doing R&D on a 2007 model

-Bill

Chiketkd · #8 07-03-2005, 07:54 PM

I took SVXRide's advice and went to a level parking lot at Piedmont VA Community College (recommended to me by AmazonParrot).

As it was the 4th of July weekend there was no one around, including the police, and I was able to utilize an entire level section of parking lot...

I levelled out my g-tech to 0.00g and put it in the mode to measure continuous lateral g's - where you have have to maintain the lateral g reading for a minimum of 3 seconds.

I started out in a clockwise direction (driver's weight on the outside - 170lbs) around the middle of the parking lot and navigated a path to give me a skipad diameter of ~200ft. As I approached the limit of adhesion, I noticed a slight benign understeer, which was easily to modulate. The result - 0.93g's. I then repeated the exercise and got the same result.

I then took my car around the skidpad in an anti-clockwise direction (driver's weight on the inside). Once again, I found my SVX very easy to modulate at the limit...and on my back-up run, was able to duplicate the result of 0.97g's.

(camera was at a weird angle when I took this pic)

This car is definitely a great handler and corners better than anything I've ever driven to date ('90 300zx TT included)!

-Chike

SVXRide · #9 07-03-2005, 08:20 PM

Quote:

Originally Posted by Chiketkd

I took SVXRide's advice and went to a level parking lot at Piedmont VA Community College (recommended to me by AmazonParrot).

As it was the 4th of July weekend there was no one around, including the police, and I was able to utilize an entire level section of parking lot...

I levelled out my g-tech to 0.00g and put it in the mode to measure continuous lateral g's - where you have have to maintain the lateral g reading for a minimum of 3 seconds.

I started out in a clockwise direction (driver's weight on the outside - 170lbs) around the middle of the parking lot and navigated a path to give me a skipad diameter of ~200ft. As I approached the limit of adhesion, I noticed a slight benign understeer, which was easily to modulate. The result - 0.93g's. I then repeated the exercise and got the same result.

I then took my car around the skidpad in an anti-clockwise direction (driver's weight on the inside). Once again, I found my SVX very easy to modulate at the limit...and on my back-up run, was able to duplicate the result of 0.97g's.

(camera was at a weird angle when I took this pic)

This car is definitely a great handler and corners better than anything I've ever driven to date ('90 300zx TT included)!

-Chike

Chike,
Nice! I may have to take a drive out there to check out what my car will pull with the Hoosiers

-Bill (could 1.0Gs be in the offering?)

Chiketkd · #10 07-03-2005, 08:26 PM

Quote:

Originally Posted by SVXRide

Chike,
Nice! I may have to take a drive out there to check out what my car will pull with the Hoosiers

-Bill (could 1.0Gs be in the offering?)

Bill,

I'll bring my g-tech to the Subaru Challenge meet in September. I'm sure the parking lot area will be large enough for us to do a little testing on the side!

Btw, I'm sure 1.0g is not out of the question for the mods you have done with your car!

-Chike

P.S. I must say, after all this spirited driving over the last two days, I have a serious pain in my neck that won't go away. Ouch!

Chiketkd · #11 07-03-2005, 09:29 PM

Quote:

Originally Posted by Chiketkd

Bill,

You might be able to see in this pic that the center caps from my RX-7 wheels are missing (similar to what you did). I finally got tired of people asking me if my car was some kinda weird Mazda and popped them out this weekend (as I had some free time on my hands). However, I painted the inner axle caps a nice silver color to make the absence of the caps less noticeable...

-Chike

Matthewmongan · #12 07-03-2005, 09:41 PM

i feel you on that. every other week since the meet i have had to drive a 96? olds 88. that car is so soft the first week i had the suspension checked out. i've goten used to the balls deep stiffness of the svx over the past few years that normal cars i drive feel impotent. i transed a ferrari 355 for an import dealor in baltimore county that was comparible in firmness to the svx, most of the high ends i got to drive were eather too hard or too soft.

Chiketkd · #13 07-04-2005, 02:55 PM

Quote:

Originally Posted by Matthewmongan

i feel you on that. every other week since the meet i have had to drive a 96? olds 88. that car is so soft the first week i had the suspension checked out. i've goten used to the balls deep stiffness of the svx over the past few years that normal cars i drive feel impotent. i transed a ferrari 355 for an import dealor in baltimore county that was comparible in firmness to the svx, most of the high ends i got to drive were eather too hard or too soft.

Matt,

I can't say I've ever had the opportunity to drive a Ferrari 355 before - but it's pretty cool to hear that the ride quality is similar to an SVX. I'm pretty happy with the way my car is currently set-up in the handling department, but I would definitely like to add some custom springs from Mychailothat'll keep the stock ride height, but stiffen the ride some more. This'll help dial-out some slight body-roll I've noticed...and hopefully push my car closer to the 1.0g mark!

I must say, the sticky rubber and adjustment to camber have probably had the biggest effect in improving cornering. Popular tires like Pirelli P Zero Nero M+S are great all-season rubber, but with a tread wear of 400, wouldn't be the stickiest in the turns...

-Chike

Matthewmongan · #14 07-04-2005, 04:08 PM

whats a good wet dry tire. in salisbury i have no need for all season as it doesnt snow.

Matthewmongan · #15 07-04-2005, 04:18 PM

Quote:

Originally Posted by Chiketkd

Matt,

I can't say I've ever had the opportunity to drive a Ferrari 355 before - but it's pretty cool to hear that the ride quality is similar to an SVX. I'm pretty happy with the way my car is currently set-up in the handling department, but I would definitely like to add some custom springs from Mychailothat'll keep the stock ride height, but stiffen the ride some more. This'll help dial-out some slight body-roll I've noticed...and hopefully push my car closer to the 1.0g mark!

-Chike

the bigest diference between the f355 and the svx was body roll. you can really feel that the svx wants to andle better but when the 3500lbs body starts to lean the tires follow suite. i think harder springs and some nice "low pro" tires with thick side walls will help out. personaly i wouldnt lower the car because it will f up the geometry of the suspension.