Daytona In December
06-20-2012, 11:25 AM
#31
Rennlist Member
I'm mixed on HOD, I heard they got better but then I got this video 2 weeks ago, I can't imagine beeing on track with these people.
Watch till the end, it ends just like you think it will.
http://www.youtube.com/watch?v=Lv-_p...ature=youtu.be
Looks like super solo, but even more aggressive. Bit much for a DE.
I Hope the Audi club is in control!
Watch till the end, it ends just like you think it will.
http://www.youtube.com/watch?v=Lv-_p...ature=youtu.be
Looks like super solo, but even more aggressive. Bit much for a DE.
I Hope the Audi club is in control!
Yikes...listen to his instructor at the end.:eek
http://www.youtube.com/watch?v=XrRpd...9&feature=plcp
http://www.youtube.com/watch?v=XrRpd...9&feature=plcp
So both these cars ate it in the same spot. I've only run Homestead once, but what happened there?
What did they do wrong? And why did the car come back to the inside like that, in both cases. The second guy obviously got super lucky, but why would the car just slide to the outside if you went into a spin there.
I was behind a car yesterday at Laguna and was riding his butt a bit waiting for a clean spot to pass. I saw him watching me in the mirrors pretty heavily and his lines started getting sloppy. He ran wide in T4 and went 2 off. Then 4 wheels off. He then jerked it back on the track at speed. He got traction as soon as he hit pavement, but was pointed at the wall. Which is where he ended up. That was pretty obvious. These incidents at Homestead don't seem as obvious.
06-20-2012, 11:29 AM
#32
Rennlist Member
This is the main reason I ran Daytona (first time ever there) with specific tires for the event at a cost of near $2500 once shipped and installed.
I had some data from the Traqmate site, so I could run some estimates.
1.- Playing on the safe side, I took the high lateral g-forces detected by Traqmate at the banking and used the lower averages, they are around 1.0g. Traqmate doesn't detect downforce, so it cannot determine how much grip the angle of the banking is generating. For this missing measurement, I used the infield turns and the bus stop that are on flat surface, with peak g-forces on the 1.4g-1.6g on DOT-R R6.
2.- Using the high average g on the flat turns, and low average g on the banking, there is a 0.6g difference.
3.- For my car (09 Fiat), I used the maximum static weight, that is full tank of fuel, a passenger, total of 3,600 lbs, with a 45/55 weight distribution. This gives close to 2,000 lbs on static weight to the rear axle and 1,600 lbs to the front axle. Using the (overrated on the safe side) 0.6g added on downforce (or extra weight) by the banking, this adds 1,200 lbs to the rear axle, for a total of 3,200 lbs. The front gets to 2,600 lbs.
4.- My Fiat has lift at 125mph on the rear axle, and 0 lift in the front, so at Daytona speeds is producing lift front and rear, but I use 0 lift for these estimates. Cars with wings need to calculate the extra downforce caused by wings.
5.- At the Banking the car is under low forward acceleration, so I move front weight to the back by 10% to simulate this load. Front axle now at 2,350 lbs and rear axle at 3,450 lbs.
6.- The car is tuning slightly at the banking (based on slight steering wheel angle) so the right side is loaded, I used a 60% right load and 40% left load to estimate these values. New weights:
LF: 940 lbs
RF: 1410 lbs
LR: 1380 lbs
RR: 2070 lbs
Now, the diligence was to find a tire that could tolerate a 1410 lbs static load for the front and 2070 lbs for the rear. I found the 265/30R19 and 345/30R19 MPSC to be close to these values. The specific 345/30R19 is the tire used by the Viper ACR, a car that generates 1000 lbs of downforce at 150mph, and weighs almost 4,000 lbs with a full tank of fuel and a passenger.
Most of the blowouts at Daytona happen after NASCAR T4 when most cars develop the highest lateral load combined with the highest speed. By the start/finish line the speeds are higher, but lateral load have been reduced drastically.
The correct procedure (rather than using estimates), is to apply zip tie to the shock rods at each corner on static weight with a full tank of fuel, driver and passenger. Drive the track, and measure how much the zip ties have moved from static. Knowing your corner weights, and your spring rates, you will be able to determine how much extra weight the track added to each corner. For example, let's say Trakcar's 3.8RS has a Right Rear corner weight of 1,100 lbs, and he runs 600# springs, the zip ties moved 40mm after a Daytona track session, so the track applied 950 lbs to that corner and the tire took a load of 2,050 lbs (1100 lbs static and 950 dynamic). In this case, the rear tires should be able to handle a 2,050 lbs load.
The typical Hoosier sizes used by the GT3 have loads in the range of 1400 lbs, and surely such loads are exceeded at Daytona, so despite of Hoosiers tolerance above the maximum load they assign to their tires, exceeding the load substantially will cause a tire failure. When I hear people saying: "I ran XX tire at Daytona and the car was fine", I just think how lucky they are.
Cording tires is the less of the worries. Daytona requires less camber, -1.5 degrees at most, with -1.0 ideal on the rear axle. The major problem is overloading the sidewalls and causing a total tire failure.
Choose your tires wisely, and you'll be safer.
I had some data from the Traqmate site, so I could run some estimates.
1.- Playing on the safe side, I took the high lateral g-forces detected by Traqmate at the banking and used the lower averages, they are around 1.0g. Traqmate doesn't detect downforce, so it cannot determine how much grip the angle of the banking is generating. For this missing measurement, I used the infield turns and the bus stop that are on flat surface, with peak g-forces on the 1.4g-1.6g on DOT-R R6.
2.- Using the high average g on the flat turns, and low average g on the banking, there is a 0.6g difference.
3.- For my car (09 Fiat), I used the maximum static weight, that is full tank of fuel, a passenger, total of 3,600 lbs, with a 45/55 weight distribution. This gives close to 2,000 lbs on static weight to the rear axle and 1,600 lbs to the front axle. Using the (overrated on the safe side) 0.6g added on downforce (or extra weight) by the banking, this adds 1,200 lbs to the rear axle, for a total of 3,200 lbs. The front gets to 2,600 lbs.
4.- My Fiat has lift at 125mph on the rear axle, and 0 lift in the front, so at Daytona speeds is producing lift front and rear, but I use 0 lift for these estimates. Cars with wings need to calculate the extra downforce caused by wings.
5.- At the Banking the car is under low forward acceleration, so I move front weight to the back by 10% to simulate this load. Front axle now at 2,350 lbs and rear axle at 3,450 lbs.
6.- The car is tuning slightly at the banking (based on slight steering wheel angle) so the right side is loaded, I used a 60% right load and 40% left load to estimate these values. New weights:
LF: 940 lbs
RF: 1410 lbs
LR: 1380 lbs
RR: 2070 lbs
Now, the diligence was to find a tire that could tolerate a 1410 lbs static load for the front and 2070 lbs for the rear. I found the 265/30R19 and 345/30R19 MPSC to be close to these values. The specific 345/30R19 is the tire used by the Viper ACR, a car that generates 1000 lbs of downforce at 150mph, and weighs almost 4,000 lbs with a full tank of fuel and a passenger.
Most of the blowouts at Daytona happen after NASCAR T4 when most cars develop the highest lateral load combined with the highest speed. By the start/finish line the speeds are higher, but lateral load have been reduced drastically.
The correct procedure (rather than using estimates), is to apply zip tie to the shock rods at each corner on static weight with a full tank of fuel, driver and passenger. Drive the track, and measure how much the zip ties have moved from static. Knowing your corner weights, and your spring rates, you will be able to determine how much extra weight the track added to each corner. For example, let's say Trakcar's 3.8RS has a Right Rear corner weight of 1,100 lbs, and he runs 600# springs, the zip ties moved 40mm after a Daytona track session, so the track applied 950 lbs to that corner and the tire took a load of 2,050 lbs (1100 lbs static and 950 dynamic). In this case, the rear tires should be able to handle a 2,050 lbs load.
The typical Hoosier sizes used by the GT3 have loads in the range of 1400 lbs, and surely such loads are exceeded at Daytona, so despite of Hoosiers tolerance above the maximum load they assign to their tires, exceeding the load substantially will cause a tire failure. When I hear people saying: "I ran XX tire at Daytona and the car was fine", I just think how lucky they are.
Cording tires is the less of the worries. Daytona requires less camber, -1.5 degrees at most, with -1.0 ideal on the rear axle. The major problem is overloading the sidewalls and causing a total tire failure.
Choose your tires wisely, and you'll be safer.
06-20-2012, 01:34 PM
#35
Race Director
! video he lost it in T1 off the front straight as they were running the banking that day....other video he lost it going into T10 which is the turn off the back straight if you are not running nascar 3/4 banking.
06-24-2012, 09:41 PM
#38
Rennlist Member
As I said earlier in this thread, they used way too much curb, which significantly upset their cars, and held steering input way too long. Both those curbs are best avoided...
06-24-2012, 10:42 PM
#39
Race Director
In 2nd video...his instructor...Davidi Tuety who's a respected instructor from what I've heard....said he did nothing wrong.
06-25-2012, 12:25 AM
#41
Race Director
06-26-2012, 02:05 PM
#45
Drifting
Holy crap, I just watched it! Same problem--too much curb, big bumps, failure to unload steering, ran out of talent. Saw it coming 2 laps earlier.
If I coach you and you hit the wall for any reason other thhan tire failure, I will punch you in the helmet and yell DUMBASS. That's what I would have done in the first video...
If I coach you and you hit the wall for any reason other thhan tire failure, I will punch you in the helmet and yell DUMBASS. That's what I would have done in the first video...
