R-Comp Tire “fade” during a race?
08-08-2011, 10:07 AM
#16
Race Director
..Maybe dropping off as much as 3 seconds between early fast laps and late in the race (3 mile lap, 1:50-1:55 range, around 95mph avg spd). If I dont get a clean run on the first or second lap of a qual session or race, forget it. Tires are already starting to drop off as early as lap 3 or 4. Feel greasy, start to squeal on turn-in and have to wait to get on the power to keep the back end in line.
Tire pressure and temp have to tell the story. You may need to run your 2 laps the come into the pits and check tire temps and pressures. Then go out and run 10-12 laps and check tire temps/pressures. My guess is that tire temps will be much hotter and so will pressures. From there you may need to increase or reduce camber and change cold tire pressure. I don't run R6's so I don't know optimum temp and pressures, but remember with pressures if you start too low it can increase alot during a run. Has to do with the tire moving around generating heat. My guess however is taking data will tell you where the issues.
When I ran R888's I could see from tire temps that I needed less camber as I was overheating the inside shoulder of the tire more that outside edge. When I reduced camber I got to a more uniform temp spread. When ran with more camber the inside would heat up and cause sliding around. Of course if the outside is getting too hot you need more camber. This why you need tire temps. It seems like what every you do to the car it is best at 2-3 laps in. So that is what you want to shoot for after 10-15 laps. Seems like you get to optimum tire pressure and temps then shoot right past it.
I can see a drop off of few tenths from your first 2-3 laps, but anything over 1 second is too much. Sounds like you are overworking the tires. Could be driving style or a set-up that is putting too much heat in the tires too fast. Tire temp and pressures are the only way to find out.
08-08-2011, 04:49 PM
#20
Rennlist Member
3 seconds a lap is SERIOUS problems. if its all tires, then it has to be alignment. I cant imagine any tire costing that much time, unless I was going from a slick to a toyo RA1. could also be you are cooking the tires. might not be enough tire for the weight and power of the car. if you are a spec class, then you are stuck, if not, maybe its a sign that you need more tire or need to go on a diet. 
I started this post because I have been struggling with fading/slowing lap times since using R6’s, past 5-6 years. Maybe dropping off as much as 3 seconds between early fast laps and late in the race (3 mile lap, 1:50-1:55 range, around 95mph avg spd). If I dont get a clean run on the first or second lap of a qual session or race, forget it. Tires are already starting to drop off as early as lap 3 or 4. Feel greasy, start to squeal on turn-in and have to wait to get on the power to keep the back end in line. Have used both 245/16s and 245/285/18s, similar results. These are new tires for the race events, so stickers for the qual run, maybe a warmup. So 1 to 2 heat cycles going into the sprint race.
I dug up old lap times from club races going back to ‘99 to confirm what I remember - prior to R6s I used to have relatively consistent lap times start to finish using various tires: from SO3s & SO4s and BFG R1s, to burning up old Toyos and Yokos during Enduros.
Not sure what the issue is.
Tried a range of tire pressure w/ the R6s over the past few years, but still have not found the sweet spot. Typically run around 27-28 cold, 33-35 hot pressures. Have tried lower and higher which both seem worse.
What are you guys using/seeing for optimum temps at the end of a long session or race?
Other than tire temp/pressure - what kind of car setup parameters would you look at? Alignment specs and spring/damper balance, not much else (?).
I dug up old lap times from club races going back to ‘99 to confirm what I remember - prior to R6s I used to have relatively consistent lap times start to finish using various tires: from SO3s & SO4s and BFG R1s, to burning up old Toyos and Yokos during Enduros.
Not sure what the issue is.
Tried a range of tire pressure w/ the R6s over the past few years, but still have not found the sweet spot. Typically run around 27-28 cold, 33-35 hot pressures. Have tried lower and higher which both seem worse.
What are you guys using/seeing for optimum temps at the end of a long session or race?
Other than tire temp/pressure - what kind of car setup parameters would you look at? Alignment specs and spring/damper balance, not much else (?).
