COBB Tuning

Just an FYI guys- I'm at COTA today for the Edge Addicts event if anyone has any questions, wants some logs setup, etc. Just come find me between garage 24 and 25, white inTech 28' trailer and a yellow C5 Z06.

Thanks!

~Jared

Vintage72

If you are there tomorrow I will come by for a visit. Black GT4.

Houston GT3

A special thanks to Shake n Bake today for spending several hours with me at Chin at TWS. He established some nice reference laps for me (despite lots of traffic) & he helped me with my driving lines & breaking zones so much that I beat my best time by over two seconds & I'm now officially in the sub 2 minute club at TWS

ShakeNBake

Thanks for letting me get a bit of track time!
I think in 80F weather, you'll automatically get 2-3 more. It was ridiculously hot and muggy.

COBB Tuning

Only did Saturday for this event but feel free to swing by our Austin HQ for a visit whenever as well.

Thanks!

~Jared

Uncle Jed

Good times at COTA yesterday.

Vintage72

A BIG thank you to JPHUGHAN for being my brave instructor at COTA today. John/JP taught me an excellent line and he was a great instructor! I definitely made a little progress and I am not abusing the GT4 as badly. Thank you John.

jphughan

Thanks!! I really enjoyed working with you, and you improved a lot out there. Those light bulb moments are what I enjoy most about instructing, and you had a few in just one day. Also, thanks for the shift strategy that I stole from you for T10 and the carousel since I've still been experimenting with what gear is best at various points on track and found I liked your method there better than mine! The only thing I may still play with is shifting to 2nd when braking for T8 since this car does kind of bog through T9 in 3rd gear when taking the faster overall line (i.e. not going out wide for T8), but on the other hand it may not be worth it given that T8 is just maintenance throttle anyway and I'd be shifting back up to 3rd pretty quickly exiting T9, plus there's not a whole lot of power that can be put down through T9 anyway before you spin, as many cars that get greedy on the throttle have there. I'll have to wait until October to try it though. Don't stay away too long!

Vintage72

Good advice - I will start looking for my next event . . . . and as far as a shift strategy - just novice survival skills and blind luck

myBailey07

What is this secret, magical shift strategy being mentioned? 😳

Vintage72

1) John is just being nice and YOU are REALLY FAST - everytime I ride with you guys I realize how slow I am, and 2) Just my slow way of tracking the car - but on a good note I am now shifting into 4th between 2 and 3 after almost spinning and meeting the gravel trap at turn 3 with aggressive 3rd gear throttle input . . . I was really proud of my turn 2 exit which resulted in 3/4 red mist, near disaster

jphughan

Staying in 3rd through T10 (turns out full throttle isn't a problem at all because of where you are in the rev range coming out of T9) and also holding 3rd through the entire carousel. According to one of my passengers, I was doing 97 MPH at carousel track-out, and I didn't hit redline before I had to brake for T19. It was just about trusting that this car had enough rear grip to handle 3rd gear throttle heading down to the second apex. Maybe people running smaller diameter wheels and/or sticky tires might bump against redline due to the diameter and/or being able to carry more speed through the carousel and brake later? I doubt it though. Just be very careful with your throttle steer when you're way out wide halfway through the carousel.

myBailey07

It was awesome to see a bunch of folks this weekend at COTA again!

Good points. I like to learn from others that share!

But, shift strategy? Haha! The debate rages on at a level of driving way beyond our capability with no universal answer in sight and various strong opinions.

https://rennlist.com/forums/racing-a...-on-track.html

It is certainly personal preference based, and especially at a place like cota where the GT4 gearing is suboptimal for various sections, it is like a puzzle to solve depending on the weather, speeds, traffic, your own thoughts etc. It is part of the fun.

For me, my approach is as follows:

1. My car is not a race car and I’d like it to last as long as I can. Therefore, when there are two shift strategies (short shifting vs redlining) that gets me through a section and one is not clearly superior in terms of time, I will always select the short shifting one.
2. Short shifting often allows the car to be more stable through tricky corners and is often the safer option.
3. Redlining makes the throttle a lot more sensitive, often too much for my taste and I do not like it.
4. Short shifting on very hot days, something we see here in Texas often, is superior in terms of heat management, something I see as very important for a street car being tracked.

So, how do we apply that at COTA?

I was fortunate to work with a pro coach all day Saturday in order to help with, amongst other things, this and evaluate the impact of this on speed, time and car’s handling. Here are some examples.

T8: The car feels like it bogs down in 3rd. So, the question came up whether to go down to 2, or not? Rougness, negative camber and lack of run off space at T8 exit causes concern for losing traction in 2nd when car is more wound up. The problem wasn’t that I was in wrong gear for T8 in 3rd. There were two other problems holding me back from making 3rd the more optimal and safe gear. (1) I was too slow into T8 and (2) the inside rumble strip is too rough for the GT4’s suspension and slows the car down too much. So the answer lied in reducing braking for T7, carrying more speed into T8, braking less for T8, carrying more momentum, and just staying off the rumble strip. Once I did that, I ended up carrying more than enough momentum for 3rd to be the better and safer gear through there.

T10: My data showed that shortshifting to 4th through T10 is no slower than 3rd through T10. Shortshifting to 4th just before turn in also has the effect of giving the car a second to settle and stabilize just before you turn, which is good. T10 is off camber. Going through there flat in 3rd with the car highly wound works as LONG AS NOTHING GOES WRONG. Any moisture, too much rumble strip etc and you can lose traction as your suspension unloads or you slightly lift. You’d much rather be in 4th here if you lose traction. Ask me, I know ;-). I sometimes do it in 3rd if I come out of T9 too slow...

T13, T14, T15:

This section sucks in the GT4 gearing. In 3rd I felt like the car really bogs down in T13/T14 in 3rd, but in 2nd I run out of RPM just before T13 and into T15, so now I either have to shift a bunch in a short time, feather the rev limit, or go the short shift way and just stay in 3rd. 2nd felt faster though. What’s a guy to do?

My data shows consistently that it makes no material time difference which way I choose. So, instead, my coach worked with me keep the 3rd gear strategy here, and to simply brake less into T13 carrying more speed and another 300-500rpm through this corner which solved the “bogging down” feeling. So, that allows me to be in 3rd all the way from T13-T15. Next, I am going to work on picking up a few mph and rpm's through T12, which will allow me to be in 3rd all the way from T12-T15. Again, Not simply thinking about the gearing by itself, but the context of a larger speed/time/stability question the answer lied somewhere else.

Carousel:

This one for me is simple. I run out of revs in the carousel in 3rd. The coach also pointed to me that if I short shift into 4th at the right spot entering the carousel, that slight lift to do it, will help rotate the car towards the first apex I need to hit and help me carry more speed. My trackout speed here is over 105mph and I can go faster still, so 4th is a no brainer to me. (I am on stickier tires...)

For the same reason, the coach helped me to short shift into 4th going into T2 rather than coming out of T2 as, again, the slight lift to do it, helps rotate the car towards T2 apex and then allows me to get on the throttle 100% until I brake after T3 Apex. My speed under the bridge went up from around 100mph to 106mph and my T3 Apex speed went up from high 90’s to 102mph.

Lot’s of info. I guess my point being that I only use redlining when it is absolutely clear to me, proven by data, that it is the faster option, otherwise I save the car a bit and prefer the added stability and less throttle sensitivity that a lower rev range allows for.

Later dudes....

jphughan

^ Great write-up! Sounds like those stickier tires warrant some significant changes in strategy at least at CotA. For T8, I too stay off the rumble strips, but if memory serves, prior to turning into T10 I think I'm only in the mid-4000 RPM range in 3rd, so it's not very wound up there at all and a short shift to 4th at that point would be WAY short. I had been doing it out of force of habit from my M3, but the first time I held 3rd in the GT4, it felt absolutely manageable. In the wet I might well shift to 4th (or just use less throttle....), but honestly doing full throttle from T9 exit to T10 track-out doesn't even feel like very much acceleration, so I'm not too worried about control issues in proper conditions. I probably even have plenty of leeway to trail off the throttle mid-corner there if needed, but I haven't tried it. But on the other hand, I admit that as you say, 4th doesn't really feel any slower either, I guess because there's so little acceleration in the first place. Seems like six of one and a half-dozen of the other for me. But next time I'll still experiment with 2nd for T8 since I'm only on plebe Cup 2s. I have a feeling I'll decide against it though.

That's some serious exit speed on the carousel, wow! But when I was short shifting to 4th, I think my track-out speeds were always in the 80-88 MPH range, and that was after playing with both different lines and different shift points (before T16 turn-in, before T16 apex, and when way out wide before throttle steering in for T18), so 3rd is definitely working better for me at least with these tires. I tend to prefer short-shifting out of mechanical sympathy as well unless it's noticeably faster not to do that, but for me it seems to be.

T13-15 definitely isn't ideal for GT4 gearing. I take T12 in 2nd because 3rd is just miserable (especially if you're trying to take a pass after catching somebody under braking on the back straight), but trying to carry that gear all the way to T15 is impossible, and like you I don't want to shift up to 3rd for a couple of seconds just to drop right back down to 2nd, so I put up with 3rd from T13-15.

For T2, again I used to short shift to 4th out of force of habit with my M3, but I also went through T1 in 3rd in that car, and since I go through T1 in 2nd in the GT4, 4th for T2 would involve two upshifts on a fairly short downhill segment, and while I definitely modulate throttle to help with turn-in on T2, I don't think a gear change would improve things for me there, and I have plenty of rev range on exit to be fine until the braking zone between T3 and T4, although I do have to trail the throttle a little bit for T3 turn-in. No way could I do T3 turn-in flat out on Cup 2s. I seriously doubt the car would, but I know that I personally couldn't.

All that said, Mike Johnson is a pro driver who comes to a lot of Edge Addicts events as an instructor or private coach, and he's offered to drive my car around while I ride shotgun. I just couldn't make it work this weekend, but I'll be curious to see what he does -- and what sort of thoughts he has about understeer.

myBailey07

That's the nice thing about cota - a never-ending puzzle piece.

Yes, the stickier tires absolutely changed my gearing in some places, but affected brake zones even more. It is unreal how much braking power you gain.

The surprising thing to me was how much the heat affected the car and therefore the gearing. The power loss on the heat alone caused the need for down shifts in some areas.

As far as the pro riding your car, don't imagine for a second that they agree on shifting. They disagree as much as us DE hacks, but because they make their living out of it, they also tend to disagree much more passionately. Just check out the thread I linked in my original post.