uhear

Since my time on the track Ive noticed a new "bounce wobble shimmy or shake" when I get into 90's and definitely into the 100's. Much of it goes away above 110. I figure I flat spotted my tires in a couple places and with these wide beasts that is when I start to feel it.

Therefore let me suggest a second set of wheels and tires, regardless of the speed rating I think preserving your street tires is convenient to maintain daily ride smoothness.

LexVan

Most likely not flat spotted. Check your wheel weights. Maybe you threw one with all the heat generated. Or your tires have slightly walked on the rims and you're out of balance.

mtony

Sounds like you picked up some rubber off the track, especially if you went into the "marbles". Should get better with some more miles, but you really need to get some heat into the tire to clean them up.

chuck911

Until you get to the point where you're going through street tires so fast it pays to go to less expensive track tires, this makes no sense. If your goal is to help your street tires last longer that's a mistake because older tires just get harder and lose ride compliance and traction. Better to wear them out and have fresher rubber. If your goal is better track performance that misses because you're much better off learning on forgiving street tires. Of course lots of guys do it anyway. No law you have to do what makes sense.

Your much higher priority should be learning to drive the line without sawing the wheel and jabbing the gas forcing the car to work against itself more often than not. You'll go faster and your tires will last a lot longer without your having spent a dime.

uhear

Chuck911, I disagree.

I wish I would have "ragged" on a second set of wheels and tires instead of the ones I drive everyday. While learning and improving my track driving technique I have caused damage to my wheels or tires which will need to be corrected to eliminate a heavy vibration I have picked up at 90mph -115mph.

Sure wish I could slap my original set back on now while the others are being rebalanced etc...

chuck911

So your point is you need the track wheels because rather than learning the line you're going to keep beating them up on the rumble strip. Interesting argument.

uhear

Since you consider this an argument, NO my point is this, I AM LEARNING, which implies by itself that I will use-up my equipment differently than someone who is more experienced like yourself. Again, this was my first ever track day. The FACT that I have a developed a tire based vibration as a result of my aggressive track sessions is the action behind my statement. Stands to reason that had I used different set of wheels and tires, like so many others at the track, I could have preserved the set I use for everyday driving.

You perhaps assume all those drivers are changing to slicks, they are not. Even if my second set are GoodYear Supercar G2's, which is a street refined/track capable tire, the convenience of learning and beating on a 2nd set is appealing - looking back that is.

Like I said, I have developed a significant tire based vibration. Had I used a 2nd set I would simply place my originals back onto the car and poof everyday driving is smooth.

drcollie

uhear...

Its not normal to develop a vibration as the result of a track day, you may have thrown a weight, they are typically stick-ons and I always used to tape over mine with 'Gorilla Tape" for my track wheel set because I would lose weights left and right otherwise.

I don't currently run a second set of tires/wheels as I don't do that many events any more, even when I instruct i only do about 10 laps in my own car just to get a feel for track conditions or to take a student out to show them the line, so my streets are fine for my limited use. When I was really into track days in a big way, I ran a set of BBS wheels and BFG 1's as my track set as well as dedicated Hawk pads with their own rotors I would put on the night before an event (I got really fast at swapping out brakes and rotors!)

If you want to run a second set of wheels, get the smallest wheel diameter that will fit your car and clear the brake calipers, definitely a 19" set on a 991 - not sure 18" will clear the caliper but if they do then I'd run those. Smaller wheels weigh less, the tire rubber is less costly and you have more choices in brands, plus it reduces the ride height a little bit which keeps the car lower to the ground. Since the design trend for street wheels is to 20" and larger, there are always lots of 19" and 18" wheels for sale - grab a used, high-quality set. Forged wheels are lighter than cast, and you want that too in an ideal situation. Keep the offsets correct for you car you don't want the wheels hanging out the fenders as that's just more airflow drag.

As to the rubber, just burn off whatever is on the used wheel set first. Might take 5 to 9 track days to do that. Then you can decide if you are ready for R-Compounds when its time to re-tire them. Avoid slicks because you won't have a brake/suspension setup that can take advantage of their holding power anyways.

Hope that helps!

uhear

Great insight DRCOLLIE, valuable info to pass along too. At the advice of other great posts I do not see the need for slicks but might opt for a Max Performance Summer tire for the next go around. Thanks.

GrantG

Just thought I would mention that the Nitto NT01 is a full R rated tire (and a very good one).

paradocs98

Great info. Couple of questions, not to be argumentative in any way, but instead because I'm genuinely interested.

First, you made it to the instructor ranks very very quickly (after 25 trackdays). Do you think that was a function of you being a motorcycle racer and having some baseline knowledge of the track, or was it just particular to the organizers you were running with? In comparison, I've done 35 trackdays at this point over 3 years, and I don't think I would consider myself instructor material yet. I run advanced with SCDA, high intermediate with NASA, and white with Schattenbaum and Reisentoter PCA. I've been running solo for 2 years now. I could very well move up to advanced with NASA and black with PCA this season, but I'll want to make sure I'm comfortable with it first. I know I'm probably relatively conservative with my group placement, but I'd rather be the big/fast fish in the pond first, and then move up to the next group when I'm more than ready. So the point of all this is, do you think your experience or my experience is more typical--I really don't know, and I think it would be interesting to get your input.

Second, your experience with the intermediate student sounds pretty scary--glad you weren't hurt more seriously. What organization were you running with that allowed open passing in intermediate? You describe him trying to make an inside pass going into a corner, and without a point-by, two actions that would merit a black flag during most HPDE events. Did the red mist cause the student to attempt this foolish maneuver without a point-by, or did he receive a point-by and simply took the pass late into the corner instead of waving it off?

Sorry to go off-topic, OP, but these potential regional differences in HPDE experiences are interesting.

drcollie

I started instructing with NASA, and the east coast chapter in 1996 was very young and they had zero instructors - I was a better track day driver than the East Coast Chapter president, he needed instructors and being a motorcycle guy plus an autocross instructor already for BMWCCA I had pretty good car control. Also Summit Point Raceway had FATT's (Fridays At The Track) and they were desperate for volunteer instructors on a Friday so I was accepted there as well. Once I had those two credentials, I could instruct with most any club or group and did.

As for that incident in the crash, between T2 and T3 is a short straight and a passing zone at Summit Point. We got the point by, but my guy's car wasn't fast enough to make the pass since he was match-racing the same model car and the other guy wasn't going to back off the gas. While we initially came out of T2 at a higher exit speed, my student's car lacked the Wheaties to pull ahead so about halfway through that short passing zone I yelled out "YOU CAN"T MAKE CORNER - BACK OFF" and had he just got off the throttle then and tucked back in we'd have been fine. The other instructor in the car being passed SHOULD have said to his guy "Back off and let him go by" as he should have known we were all dirty for the corner, but that didn't happen either. My student pressed his luck and that as they say - was that. In retrospect, had I thought to do it - the E36 BMW has a hand brake in the center console and once we were off track I should have just reached over and yanked it to spin him out, but the thought to do that didn't occur to me until I went over everything post-accident to see what I could have done to prevent it.

I'm always spooked with the fast Intermediate guys who are trying to get to the Advanced groups. Its not my favorite segment to instruct because they are so quick around the course they can really wind a car up, but they get into dicey situations and freeze up or do the wrong thing and that results in some terrible problems. The Fast Intermediates always think they are racing for a trophy, too. Advanced guys not so much.

I like newbies the best! They listen, are somewhat apprehensive and I never really feel like we can have a serious event with the Beginner guys.

Oh, BTW, if you are still reading this UHEAR, I have your track wheels for you to get, pretty hard to find Porsche wheels cheaper than this...

http://www.6speedonline.com/forums/a...eels-sale.html

Duane

uhear

drcollie - I'm still here, will check them out. Thanks.