Harry's GPS Suite Forum

Hello, I am curious if there is a max G force the iphone can calculate? Does it stop at 1 on the app?

Thank you

Not sure this is still true for the latest generation, but it seems the sensor delivers a range of +-2.3G in 3 directions with a resolution of 0.018G.

Harry

Ok thank you. I guess it was just me. At the track a few weeks ago it would go to 1 but never past. Wasn't sure if it was the iPhone 6 plus or it was the actual g forces. I just thought it was odd that it would hit 1 quite a bit but never over.

Thanks

Street legal sports cars are typically somewhere between 1.2 and 1.4 G max. There are exceptions, but they are rare.

- Harry

Harry wrote:Street legal sports cars are typically somewhere between 1.2 and 1.4 G max. There are exceptions, but they are rare.

- Harry

You need pretty good tires and suspension to get that high. The OEM tires and springs on most cars won't do that. You should be able to move the iPhone with your hand and get higher than 1g readings.

I'm running ohlins coilovers , Yokohama ad08r's, Aeromotion wing, homemade front splitter. Have about 30 grand in mods on the car.

AD08R's probably aren't the best tires out there anymore. Bridgestone RE-71R's are probably better. But with the aero you have on the car, you should be getting much more than 1g even with those tires. Are you sure your front tires aren't rolling over due to low pressure and insufficient negative camber? Are they old enough to have heat cycled out? Too much rebound on the front shocks will cause corner entry understeer too. Have you tried both portrait and landscape orientation for the iPhone?

gplracerx wrote:AD08R's probably aren't the best tires out there anymore. Bridgestone RE-71R's are probably better. But with the aero you have on the car, you should be getting much more than 1g even with those tires. Are you sure your front tires aren't rolling over due to low pressure and insufficient negative camber? Are they old enough to have heat cycled out? Too much rebound on the front shocks will cause corner entry understeer too. Have you tried both portrait and landscape orientation for the iPhone?

It's more likely my driving. It was my first time at the track. I never really pushed it enough to lose much traction except to get a little oversteer at times. The tires had more grip than I was using. A better test is when i go to Big Willow which I have done many times prior to all the upgrades.

I love the ADO8's though. I have ran with w/ a Boss 302 on Toyo 888's with my tires showing metal. This is my 4th set. But I think I am going to try the hankook Ventus R-S3 (Version 2) because I want to go 285. I am running 265 now. I may try a R compound next year once I get a little more skill.

As far as camber I am running about -2.5 up front and 40psi hot in the tires. They have pretty stiff sidewalls. Got a flat once and didn't even know it. I smelled burning rubber so I pulled over and that's when I could see it.

I think my setup with a pro driver could easily hit 1.2g. I haven't taken much time to adjust the coils. I am running 10k springs on front and 12k on the rear. I have the rear dampening set stiffer than the front. I also have aftermarket sway bars on front and rear as well as stiffer bushings. I may play around with dampening next time and lower the car a little more to get the splitter closer to the ground.

Thanks for all the info

The same thing applies to rear shock damping too. Too much rebound on the rear will cause corner entry oversteer. Have you done any formal suspension analysis, like a weight transfer worksheet, to see if your ride height, spring and anti-roll bar rates are in the right range?

No the car out handles my ability. I'm working on getting my lines down perfect every lap then I'll play around with the suspension. The person that installed it did set it up but I'll fine tune it when I get my laptimes consistent. I have only done 4 track days and have dropped my time by about 30 seconds from the first one. Actually dropped 15 sec my first day and the rest over the other 4. That was before I upgraded suspension, brakes and aero. Once I get back to that track I'll see what I can do time was and once I reach the time I can't beat I'll start adjusting things. Watching video from my fastest lap there are still places I can improve in my lines. Plus the last corner before the straight is a tricky one. It always temps me to turn in to soon then I have to go back wide and turn in again getting that turn down will help a lot since it's before the longest straight on the track.

I didn't have a lap timer either so it was difficult to tell which corners I'm improving on and which ones I'm going backwards on. Hopefull next month we hit that same track. We do have a track day at the end of the month but it's another track I have never tried. So I just watch videos on it to get an idea.

Thanks for the advice.