Lateral G question

what's the highest lateral G anyone has seen from a reputable source on a car with NO aero effects? No wings or undertrays allowed.

Sustained or instantaneous?

petegossett wrote: Sustained or instantaneous?

I see what you did there. I'm guessing he is talking skidpad numbers, not crashes.

I thought that meant sustained vs. peak Gs...I know it's possible to go over 1 without downforce but I don't know by how much. Average production cars with good suspension and tires can reach 1.0-1.1 sustained.

stroker wrote: what's the highest lateral G anyone has seen from a reputable source on a car with NO aero effects? No wings or undertrays allowed.

10Gs (limited by the range of the accelerometers).

It hit a tirewall head-on.

Giant Purple Snorklewacker wrote:

stroker wrote: what's the highest lateral G anyone has seen from a reputable source on a car with NO aero effects? No wings or undertrays allowed.

10Gs (limited by the range of the accelerometers). It hit a tirewall head-on.

Winner winner chicken dinner.

I've seen 1.6-1.7 in a kart. No aero though.

Giant Purple Snorklewacker wrote:

stroker wrote: what's the highest lateral G anyone has seen from a reputable source on a car with NO aero effects? No wings or undertrays allowed.

10Gs (limited by the range of the accelerometers). It hit a tirewall head-on.

That would be longtitudinal not lateral

It's been a long time, so I'm probably wrong, but IIRC reading about something like 1.3g's instantaneous on DOT Hoosiers in autocross.

Zeitgeist wrote:

Giant Purple Snorklewacker wrote:

stroker wrote: what's the highest lateral G anyone has seen from a reputable source on a car with NO aero effects? No wings or undertrays allowed.

10Gs (limited by the range of the accelerometers). It hit a tirewall head-on.

That would be longtitudinal not lateral

No... it would be both. It spun, flew up in the air, rolled, and came to rest back on it's wheels. It maxed out all three axis.

petegossett wrote: It's been a long time, so I'm probably wrong, but IIRC reading about something like 1.3g's instantaneous on DOT Hoosiers in autocross.

Sustained that would be impressive...for instantaneous Gs you should be seeing over 2G even on street tires.

I've been in FSAE cars without aero pulling 1.4-1.5 steady state. That is the maximum for me.

I've heard of sustained 2+g at autocross and 1.7-1.8g at road course, in non-aero cars on race rubber.

I've also heard of sustained .8g on gravel

Lateral grip is 90% tires, the suspension just has to be tuned to work with that amount of grip.

Anyone know if there's commonly available information on how much tire wear is impacted by sustained high lateral G? For example, does tire wear increase on a linear, geometric level the closer you get to the limit of grip?

I would think tire wear has more to do with steering input and slip angle than actual "grip"

Rob R.

The Cobalt SS has a meter in that pod above the dash. It stores the highest peak readings until you cut the ignition. I see 1.20 frequently on a warm day at Hallett on Direzza II's. Can't vouch for accuracy. Hallett has some bumpy corners which probably drives the peak up a bit. Just FWIW.

My Radical pulls 2 Gs in turn 5 at Summit Point - the slowest corner. The car has a wing, but it's not particularly effective in T5. Hoosier 35A compound bias ply slicks, 7" F, 9" R.

At Charlotte NASCAR T3 I saw 2.2 Gs @ 140 mph, lap after lap.

Our GRM Challenge miata from $2010 (1st place finish that year) would pull 1.4 G's in skidpad testing on an asphalt lot with used race rubber. No aero at the time. There was definitely more to be had from that setup too. I would guess with brand-spankin' new Hoosiers and ~3 degrees of camber (we only had 1.5-2 degrees at the time) you could pull 1.5+ G steady-state with no aero.

For another point of reference, the girlfriend's C-Stock RX-8 (that's OEM springs/ride height, and OEM suspension other than shocks) would pull 1.1-1.2 G or so (steady) on worn Hoosier A6's and a good alignment.

Peak lateral force doesn't mean much IMO. You can get spikes when tossing a car into a corner right before you loose traction that will go appreciably higher than you can achieve in steady cornering.

stroker wrote: Anyone know if there's commonly available information on how much tire wear is impacted by sustained high lateral G? For example, does tire wear increase on a linear, geometric level the closer you get to the limit of grip?

I bet tire wear increases exponentially with lateral grip, then spikes even higher as soon as you break the tire loose (pass peak grip).

As an example, lets say you were to puttering around a skidpad at 0.7 G and you observe X tire wear rate. I'd bet if you go flying around at 1.4 G you would see more than 2X tire wear rate. If you break the tires loose, and start skidding/drifting around, your tire wear rate is going to go much higher (say, 10X)