Experienced AutoXers w/ Hoosier S04s HELP
10-03-2004, 10:30 PM
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Experienced AutoXers w/ Hoosier S04s HELP
Hello Everyone!
I know this is a hot topic on here but I depserately need your help with my new tires. Here's the deal......I am a VERY experienced autocrosser running a 99 996 with PSS9s, Fikse Wheels and an aggressive alighnment setup. I have been running on Hoosier S03s for 4 years now and have ALWAYS LOVED them. I run 18" wheels with 245/35-18 in front and 285/30-18 in the rear.
Just this past week, I bought a set of S04s and this past weekend (10/2-3) went to a 2-day event in south Florida to practice for a very exciting and EXTREMELY fast (3 mi long and over 110 mph in 3 places) autocross in Key West next weekend.
Unfortunately, I did not have a very good experience with my new S04s this weekend and that is why I need your help. Just to let you know what transpired, I began the weekend running at temps that are a few lbs higher than what I ran with my S03s. I started running 33 front and 36 rear on my first run and I found alot of sliding. Second run I dropped them to my S03 temps (31 Front / 34 Rear) and this was much better, although still a little sliding. I found the fronts to be sticking fine but the rears were still shaky. Third run I decided to go higher in the rear up to 38 lbs and this was an absolute nightmare. Not only did I find the car could not hold a line due to the rear but for the first time in 6 years, I spun!
I have heard claims that I need to be up in the high 30s in the front and 40s in the rear but that sounds completely ludicrous to me!! Especially since I spent the entire 2nd day autocrossing at my normal S03 temps and did not have a problem except for being slower that I would have liked! I found the tires did not want to go much faster and when I did push them I found there was very little to no warning at the limit. Furthermore, I need to find a comfortable and fast setup before this weekend. This is where all of you experienced autocrossers (who preferrably drive cars similar to mine) can help me.......
What tire pressures would you suggest I run on my S04s in my 996?? This autocross I am going to is very fast, very dangerous (a lake on one side and the ocean on the other) and not for the faint of heart! I have been competing in this event for 12 years now and I have yet to lose my class. This year, I will be on these new tires (which I am not fond of) and I seriously need your help ASAP with TIRE PRESSURES!! PLEASE ADVISE!!! Thanks so much!
I know this is a hot topic on here but I depserately need your help with my new tires. Here's the deal......I am a VERY experienced autocrosser running a 99 996 with PSS9s, Fikse Wheels and an aggressive alighnment setup. I have been running on Hoosier S03s for 4 years now and have ALWAYS LOVED them. I run 18" wheels with 245/35-18 in front and 285/30-18 in the rear.
Just this past week, I bought a set of S04s and this past weekend (10/2-3) went to a 2-day event in south Florida to practice for a very exciting and EXTREMELY fast (3 mi long and over 110 mph in 3 places) autocross in Key West next weekend.
Unfortunately, I did not have a very good experience with my new S04s this weekend and that is why I need your help. Just to let you know what transpired, I began the weekend running at temps that are a few lbs higher than what I ran with my S03s. I started running 33 front and 36 rear on my first run and I found alot of sliding. Second run I dropped them to my S03 temps (31 Front / 34 Rear) and this was much better, although still a little sliding. I found the fronts to be sticking fine but the rears were still shaky. Third run I decided to go higher in the rear up to 38 lbs and this was an absolute nightmare. Not only did I find the car could not hold a line due to the rear but for the first time in 6 years, I spun!
I have heard claims that I need to be up in the high 30s in the front and 40s in the rear but that sounds completely ludicrous to me!! Especially since I spent the entire 2nd day autocrossing at my normal S03 temps and did not have a problem except for being slower that I would have liked! I found the tires did not want to go much faster and when I did push them I found there was very little to no warning at the limit. Furthermore, I need to find a comfortable and fast setup before this weekend. This is where all of you experienced autocrossers (who preferrably drive cars similar to mine) can help me.......
What tire pressures would you suggest I run on my S04s in my 996?? This autocross I am going to is very fast, very dangerous (a lake on one side and the ocean on the other) and not for the faint of heart! I have been competing in this event for 12 years now and I have yet to lose my class. This year, I will be on these new tires (which I am not fond of) and I seriously need your help ASAP with TIRE PRESSURES!! PLEASE ADVISE!!! Thanks so much!
10-04-2004, 12:41 AM
#2
Two rules of thumb:
A3S04s need a good, hard heat cycle or two before they come in. Not a drive-on-the-freeway or Tire Rack-style heat cycle -- an actual lapping session or full day of autocrossing. If this was the first time you'd ever driven on that set of A3S04s, that may be why you were sliding a lot.
Also, A3S04s need higher pressures than A3S04s. 5 psi is a minimum -- I know of a notable BMW guy who's run successfully at the national level with 15 psi more in his A3S04s than he used to use in his A3S03s .
Steve
A3S04s need a good, hard heat cycle or two before they come in. Not a drive-on-the-freeway or Tire Rack-style heat cycle -- an actual lapping session or full day of autocrossing. If this was the first time you'd ever driven on that set of A3S04s, that may be why you were sliding a lot.
Also, A3S04s need higher pressures than A3S04s. 5 psi is a minimum -- I know of a notable BMW guy who's run successfully at the national level with 15 psi more in his A3S04s than he used to use in his A3S03s .
Steve
10-04-2004, 04:23 AM
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The GT3 that finished 3rd and 7th in ASP at SCCA Solo II Nationals in Topeka was on A3S04s (245/35-18 and 305/30-18 on stock width wheels) with 36 psi front and 38 psi rear. These are nearly the same pressures I ran with A3S03s in the 996 I used to own. I ran them three runs on the warmup course two days before Nationals competition to scrub them in. The surface is old concrete.
Leeds
Leeds
10-04-2004, 01:03 PM
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Thanks Guys for the tips!
Hey Leeds, great job at the Nationals. We were all watching you and Greg in the GT3. Just out of curiousity, is that your new toy? Also, what did you have done to it? Lastly, was that guy in the 99 996 who finished behind you driving your old car? Just curious. Again Leeds, thanks for the tire pressures and if you have any suggestions on anything else, let me know. Much appreciated!
Hey Leeds, great job at the Nationals. We were all watching you and Greg in the GT3. Just out of curiousity, is that your new toy? Also, what did you have done to it? Lastly, was that guy in the 99 996 who finished behind you driving your old car? Just curious. Again Leeds, thanks for the tire pressures and if you have any suggestions on anything else, let me know. Much appreciated!
10-04-2004, 04:25 PM
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The GT3 belongs to Val Korry who generously let us borrow it. Val was unable to make it this year do to injuries sustained in a crash during a race at Pacific Raceway at the end of August. He's doing well.
The car had headers and Sachs shocks from a cup car, 600 and 800 lb H&R springs, OMP seats that were showroom samples from the shop, exhaust fabricated at the shop and stock size Fikse wheels (Val wants to run in SS next year). We got the car Thursday before Labor Day weekend and three of us put 58 runs on it over three days (Porsche Club, SCCA, Bremerton Sports Car Club) on HR3S04s as we had no A3S04SA until we took delivery of them in Topeka.
The car was a real handful at first but was working pretty well by Monday. We adjusted shock, sway bar and tire pressure settings and thought we might have to change rear camber. We realized that the sway bars in a GT3 are smaller than the GT3R bars most people add to 996 and the front of Boxsters and ended up running stiff sway bar settings and not adjusting camber. In a case like this, tires are set for maximum grip and not used to balance the car since that can be done using the shocks and sway bars.
Wednesday I headed off to Nationals 1900 miles away. A transfer pump in my Suburban's fuel tank failed and only about 3/4 of the tank was available at 7 mpg.
On Saturday of the Nationals Warmup I ran three runs, adjusting the front high and low-speed shock compression because of the grippy concrete surface. The next day I took three more runs on newly mounted A3S04s and then ran Nationals on Tuesday and Wednesday.
I was expecting to be behind the Lotus Elans but drove well on Tuesday to be in the last trophy position. On Wednesday it rained hard early and my first run was in the partial wet as I run early in the group as I am the tire warmer. I spun exiting a turn accelerating for the finish in a low area that was still quite wet. My third run was the only completely dry run and I just didn't push hard enough, dropping just behind the Lotus Elans, one place out of the trophies.
The major problem with the car was the Sachs shocks. Many people commented how bouncy the car looked even though the balance was fine. It explains why Greg always swaps out the factory shocks for something like Motons or JRZs in his customer cars and the Alex Job Racing GT3RSR for which he is the chassis engineer.
Yes, the 1999 996 driven belonging to Jeff Barstow is my old car, and it and Rob Boynton's GT3 were also set up by Greg. When I had it I ran -1.9 degrees camber front and rear and didn't have the sway bars set very hard. I had single adjustable JRZs, but Jeff now has 3-way adjustable Motons I think.
As for tire pressures, we run lower thank many people including Hoosier recommend. Over the years I've consistently heard higher pressures from manufacturers but ended up lower. On my stock class 2003 Boxster S with GT3R front bar and 245/35-18 A3S03s I run 36 psi front and 36 to 38 psi rear. A Boxster in my area that ran at Nationals started in the low 40s on his A3S04s has since lowered to the same range I'm running on the older models. Neither of us think the new tires feel much different from the older ones except that they may take a little more time to come in. I've seen a couple drivers upset with the A3S04s last spring and then end up happy after a couple more runs. I've also heard that the A3S04s may have more of a problem with overheating.
Leeds
The car had headers and Sachs shocks from a cup car, 600 and 800 lb H&R springs, OMP seats that were showroom samples from the shop, exhaust fabricated at the shop and stock size Fikse wheels (Val wants to run in SS next year). We got the car Thursday before Labor Day weekend and three of us put 58 runs on it over three days (Porsche Club, SCCA, Bremerton Sports Car Club) on HR3S04s as we had no A3S04SA until we took delivery of them in Topeka.
The car was a real handful at first but was working pretty well by Monday. We adjusted shock, sway bar and tire pressure settings and thought we might have to change rear camber. We realized that the sway bars in a GT3 are smaller than the GT3R bars most people add to 996 and the front of Boxsters and ended up running stiff sway bar settings and not adjusting camber. In a case like this, tires are set for maximum grip and not used to balance the car since that can be done using the shocks and sway bars.
Wednesday I headed off to Nationals 1900 miles away. A transfer pump in my Suburban's fuel tank failed and only about 3/4 of the tank was available at 7 mpg.
On Saturday of the Nationals Warmup I ran three runs, adjusting the front high and low-speed shock compression because of the grippy concrete surface. The next day I took three more runs on newly mounted A3S04s and then ran Nationals on Tuesday and Wednesday.
I was expecting to be behind the Lotus Elans but drove well on Tuesday to be in the last trophy position. On Wednesday it rained hard early and my first run was in the partial wet as I run early in the group as I am the tire warmer. I spun exiting a turn accelerating for the finish in a low area that was still quite wet. My third run was the only completely dry run and I just didn't push hard enough, dropping just behind the Lotus Elans, one place out of the trophies.
The major problem with the car was the Sachs shocks. Many people commented how bouncy the car looked even though the balance was fine. It explains why Greg always swaps out the factory shocks for something like Motons or JRZs in his customer cars and the Alex Job Racing GT3RSR for which he is the chassis engineer.
Yes, the 1999 996 driven belonging to Jeff Barstow is my old car, and it and Rob Boynton's GT3 were also set up by Greg. When I had it I ran -1.9 degrees camber front and rear and didn't have the sway bars set very hard. I had single adjustable JRZs, but Jeff now has 3-way adjustable Motons I think.
As for tire pressures, we run lower thank many people including Hoosier recommend. Over the years I've consistently heard higher pressures from manufacturers but ended up lower. On my stock class 2003 Boxster S with GT3R front bar and 245/35-18 A3S03s I run 36 psi front and 36 to 38 psi rear. A Boxster in my area that ran at Nationals started in the low 40s on his A3S04s has since lowered to the same range I'm running on the older models. Neither of us think the new tires feel much different from the older ones except that they may take a little more time to come in. I've seen a couple drivers upset with the A3S04s last spring and then end up happy after a couple more runs. I've also heard that the A3S04s may have more of a problem with overheating.
Leeds
