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Post by dewittpayne on Jul 16, 2013 7:02:18 GMT -5
2011 Mustang GT, Koni yellow shocks, Stranoparts rear sway bar, front camber crash bolts to give -1.8 degrees negative camber, so pretty much fully prepped for FS except for tires. I'm currently using a set of 275/35/19 Dunlop Direzza II's. It looks like they need a lot of heat to work. Four runs at #7 wasn't enough even though I slid the tires a lot too much on my first two runs. I have tire blankets on order to see if that will help.
The car is a lot faster than I am, so I need all the help I can get. I'm currently registered in FS, but I can change that to tire class.
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Post by dewittpayne on Jul 20, 2013 13:26:22 GMT -5
I found a co-driver, Mitch Wagner, Heyward's brother.
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Post by cr89x on Jul 21, 2013 9:12:20 GMT -5
The ZI did not like being over heated. The ZII withstands more but they still do not like being overly hot, as with any street tire. Just monitor how much heat is being out in them. Tire pressures are key as well. On that big body you're looking mid 30s to 40. Seems like a decent setup you have going. When I was playing with s195 chassis, I found the front bar was best. I don't think I ever got around to removing the rear, but I know it would work very well. The 4.6 had a good amount of torque and the rear was hard to keep planted, granted that was on kuhmo ast and bfg g force. Just a few tips for you.
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Post by dewittpayne on Jul 21, 2013 20:54:33 GMT -5
Thanks for the advice.
I've been trying 36 psi, but I think that's too low. When I measured temperature across the tire with an IR thermometer after a run today, the center was cooler than the inside and the outside with the inside cooler than the outside. The car also pushes worse than it did when I had AD08's, although I'm not sure how much of that is bad technique on my part. That's one reason I was looking for a co-driver.
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Post by cr89x on Jul 22, 2013 15:28:52 GMT -5
More tire pressure will help for sure. Lack of camber for sure, but you can only do so much for that.
Unhooking the bar is simple to do also. Just be sure you have e tools handy to do it. You could easily run with it on, then unhook it one run and see how it feels. Most people will play with shocks and tire pressures at an event trying to feel a difference. If you're trying to figure out e setup, there are big changes that can easily be done. Just try stuff! That's what I've always done. Don't do small changes, do BIG changes so you can really feel a difference.
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Post by yellow CR on Jul 22, 2013 18:25:54 GMT -5
Z-II do not like to be very hot, they can get greasy when overheated.
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Post by srduck on Jul 22, 2013 18:54:15 GMT -5
It took 4 ~41s runs to get Licursi's Z2s up to temp at Triad a few weeks ago. After that it's just maintaining that temp. Spray after each run... spray extra if necessary. On my last run I could feel the rears getting slippery and giving up, so we sprayed the hell out of them with water after that run. Then he went out and beat me by half a second.
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Post by dewittpayne on Jul 22, 2013 19:24:27 GMT -5
But how hot is too hot? Has anybody made any measurements with either a probe tire pyrometer or an IR thermometer? I have both, but I usually don't have time between runs to do everything I need to do as it is.
I've been to two autocrosses so far on these tires and I haven't felt that they were greasy at all. Mostly it was terminal understeer, which is my fault for not driving within the car's limits. But I think those limits have come down from what they were with the narrower (245 vs 275 for the ZII's) AD08's I used to have. Well, the limits have come up on the rear tires. I'm getting more acceleration with less wheel spin off the line. And that may be part of the problem I was used to less traction on the rear so the car would rotate better and it was easier to induce power oversteer. Also, as I said, I need to run higher pressure in the front and I've gone one hole stiffer on the rear bar. That should work the rear tires a little harder and the front a little less. With a co-driver, I should be able to get more data too, if the weather cooperates. So far it's looking like only a 20% chance of rain at weather.com.
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Post by srduck on Jul 22, 2013 20:01:08 GMT -5
No idea on exact temps. We just tried to get them down to basically warm to the touch. Not uncomfortably warm... just cozy. If I had to wager a guess I'd say around 105-110 tops at the start of a run.
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Post by dewittpayne on Jul 22, 2013 20:13:51 GMT -5
No idea on exact temps. We just tried to get them down to basically warm to the touch. Not uncomfortably warm... just cozy. If I had to wager a guess I'd say around 105-110 tops at the start of a run. It's probably hotter than that. Rubber isn't a good conductor of heat so it will feel cooler than a metal object at the same temperature. I should measure somebody else's tires to get a control reading. I don't know why I didn't think of that before. The joys of getting older. |
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Post by yellow CR on Jul 23, 2013 18:25:56 GMT -5
I would guesstimate 140-150 degrees. If it is too hot for you to keep your hand on the tire it is overheated.
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Post by integra55 on Jul 23, 2013 18:45:28 GMT -5
with the pixie dust Toyo's ... I don't even feel the tire ... after the first run I start spraying them, and continue after each run
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Post by cr89x on Jul 23, 2013 22:49:31 GMT -5
There is a science to tire temps. It takes a lot to figure them out. Duckles guess isnt too far off really. Look at the bfg info provided on the tire rack website under technical documents. You will learn a lot on the temp aspect. Walter, I will teach you toyo tire temps  |
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Post by 1slowcrx on Jul 24, 2013 0:19:20 GMT -5
There is a science to tire temps. It takes a lot to figure them out. Duckles guess isnt too far off really. Look at the bfg info provided on the tire rack website under technical documents. You will learn a lot on the temp aspect. Walter, I will teach you toyo tire temps Walter's correct. Get ahead of them and stay ahead. Always spray the front's, almost never spray the rears. |
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Post by dewittpayne on Jul 25, 2013 14:39:49 GMT -5
I did a little testing on my local interstate cloverleaf interchange. Optimum hot pressure on the front looks to be 48 psi. At 50 psi, I'm seeing a little increase in the temperature in the center of the tread. My pyrometer isn't calibrated very well. At an air temperature of 74 F it reads 58 F. The tread temperature reading at 50 psi on the left front was 136 138 135 inside to outside. If the calibration is linear, that would be over 150 F. There was no sign of the tire giving up traction and my iPod accelerometer said I was getting over 1g lateral with no noise from the tires. It was getting sticky enough to pick up loose dirt at low speed. The wear barely reached the tip of the triangular markers on the sidewall using the white shoe polish method. I think I understand why I was having problems with understeer at 36 psi.
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Post by cr89x on Jul 26, 2013 15:41:24 GMT -5
Big car needs more pressure.
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Post by dewittpayne on Jul 29, 2013 9:13:04 GMT -5
I think higher pressure helped Saturday in the wet, thanks Dave O'Malley. Obviously it didn't give me any information on temperature. So I drove to a Southern West Virginia Region autocross near Charleston (another 200 mile trip). It was dry there all day and with a low entry, I was able to make a total of ten runs, four in the morning, four in the afternoon and two fun runs at the end of the day. 48psi front and 40 psi rear is now my hot pressure target. I sprayed the tires between runs in the morning and afternoon. It seemed to help, especially in the afternoon. However, I made the fun runs back to back with no spraying and the second run was a lot faster than the first and slightly faster than my best time. So the ZII's on my car do need some heat. How much is too much is yet to be determined.
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