718 Cayman GTS Autocross Super Street Build
05-18-2021, 10:23 AM
#91
Racer
I regularly used launch control when I autox'd my '19 GTS last year and had one event where the LC behaved the way @Greg_STL described: fine on some starts and bogging down on others. I never did figure out what was going on—and I've since moved-on to a GT4—so I'm not much help in trouble-shooing, but Greg's not imagining the behavior.
05-18-2021, 10:26 AM
#92
Burning Brakes
I definitely believe it, just never experienced it other than I had it cut out before I went where it hit a limiter then died off right away before I let off the brake so I caught it and restarted the procedure. I never had it bog though but those could have been.
05-18-2021, 11:42 AM
#93
Rennlist Member
If you are not a left foot braker, activating LC which requires you to hold the brake with the left foot while WOT on the throttle with the right. The car can be in Sport, Sport + or Individual mode. The first few launches, I had mixed results but since have consistently launched but repeated launches will eat your tires and likely premature wear to your pdk. I think the tendency is as the car screams up to 5k to prematurely lift the left foot which weirds out the computer a bit. For non-90 degree turn starts though, it is a riot. As for TC, I press and hold. I've tried multiple alignments since buying. For the record, the prior owners alignment sucked. I've tried more and less rear toe in and am not using an adjustable bar to balance grip.
05-19-2021, 08:12 PM
#94
I had my track inspection today for a June DE event and took the opportunity to have my alignment adjusted. I did not get a before reading because the tech loosened the top strut nut and pulled it to get max camber before putting it on the rack. I have a before reading but it was post strut adjustment so is not really worth posting. The camber results were -1.38 degrees front and -2.07 degrees rear (after converting the minutes to decimal degrees). I think that is close to what is expected for a stock suspension. I'm not sure how to convert the minutes of toe into inches but the screen shots of the results are below....
PS: No faults recorded against the PDK but they did update the software that all the 4.0 liter PDKs are getting. They did a couple launches post software update with no issues. I'm not sure that proves anything one way or the other because a PSM or traction control event during a run could have caused the issue and just doing a couple straight line launches in a row isn't quite the same thing. Still, I'm going to optimistically hope that all is good there.....
PS: No faults recorded against the PDK but they did update the software that all the 4.0 liter PDKs are getting. They did a couple launches post software update with no issues. I'm not sure that proves anything one way or the other because a PSM or traction control event during a run could have caused the issue and just doing a couple straight line launches in a row isn't quite the same thing. Still, I'm going to optimistically hope that all is good there.....
Last edited by Greg_STL; 05-19-2021 at 08:15 PM.
05-20-2021, 12:30 PM
#95
Burning Brakes
This is the best one I know of. Its from SmartStrings so if you ever need it again, you can always get it from their online manual for the string system.
Your alignment to me looks fine. Good baseline that should be safe and you can go from there.
Last edited by abqautoxer; 05-20-2021 at 12:33 PM.
05-20-2021, 07:40 PM
#96
I didn't realize the toe was measured at the rim but that makes sense as it is a more consistent item on the car where the tires change in size with pressure and wear and roll off on the shoulder making it hard to determine where point to measure would be.
So the formula would be SIN (toe angle) = (toe in inches) / (diameter of wheel inches). Or solving for toe would be toe in inches = (diameter of wheel in inches) * SIN (toe angle).
24 minutes = 0.4 degrees so toe = 20"xSIN(0.4) = 0.140" which to the nearest 1/16" of an inch is 1/8". Surprisingly enough, that is what was requested. Learned something - thanks.
So the formula would be SIN (toe angle) = (toe in inches) / (diameter of wheel inches). Or solving for toe would be toe in inches = (diameter of wheel in inches) * SIN (toe angle).
24 minutes = 0.4 degrees so toe = 20"xSIN(0.4) = 0.140" which to the nearest 1/16" of an inch is 1/8". Surprisingly enough, that is what was requested. Learned something - thanks.
05-20-2021, 07:49 PM
#97
Burning Brakes
Except when you use toe plates. Thats one thing to consider if you ever check toe with them is that the number will be higher on those since most are well over 20" apart on the slots. So some conversion to be done and I never had the formula until now, thanks.
05-21-2021, 01:51 AM
#98
Rennlist Member
I have a new PDK GTS 4.0 that I have taken to two AutoX events. I usually run just a couple events a year and am coming out of an Audi TTS. I'm not super competitive but I enjoy the events. I ran the first event with the stock everything, factory alignment, sport plus, and with a long press on the PSM to disable all of the nannies. Our usual lot has lots of sand/gravel in spots and traction can be an issue. We actually use a broom and blower on the walk thru to try to tame it some. I placed 24th of 57 by PAX and was not really happy with the car with all the nannies off. I talked with a 987 Cayman driver that came in 10th and he said he runs with PSM on. I realized with all the nannies off that I probably turned off torque vectoring as well.
So, event two, I ran with everything the same but PSM on. I felt that the car did rotate in the slaloms much better but I felt I was fighting the PDK at times. I actually saw it jump up to 4th gear coming out of a tight 180 corner. I was also having issues getting launch control to actually launch. It would hold the RPM before launch but then it would bog down and slowly accelerate in higher gears out of the starting box. WTF. I didn't try to launch on the first run, good launch on run 2, bad on run 3, bad on run 4. I tend to let my car idle between runs but I actually shut it down between run 4 and 5 and got a good launch again on run 5 but it again failed to launch on run 6. Weird. I've launched my TTS for years and my wife's 997 without ever having issues and I bogged down the Cayman 3 times out of 5 tries. I know there is a PDK update that is getting applied to GTS 4.0s as they go in for service - mine has not been in yet - so maybe some first year glitch? I did place 15th of 56 so I did improve but I left not very satisfied since the PDK was annoying me. I didn't have any issues with the launch control when I ran in the first event when I had the long press PSM off.
Questions:
1. When you say you run with PSM off do you mean the single press that gives the sport PSM settings plus traction control or do you mean the long press that turns off all PSM and turns off traction control?
2. My understanding is that break torque vectoring is on with PSM on, and PSM short press off, but off with PSM long press off? Can anyone confirm?
3. I'm going into the dealership on Wednesday to get a track inspection for a June DE and an alignment. (I'll ask to get the PDK software updated). I'll try to get what additional camber I can get but I'm less sure of what toe settings to ask for. Any suggestions for a dual use (Autox, Track) toe settings? So many of the other threads talk about putting in offset toe links in the rear which I can't do if I want to stay in SS.
4. I didn't have any issues with the launch control when I ran in the first event when I had the long press PSM off. Is there a chance that the PSM was causing the PDK to shift to higher gears as part of its stability programing?
My plan is to go for the single press PSM at the next AutoX event. I'll see if that middle ground helps. I will probably wind up going to manual shifting eventually but I want to try to figure out the PSM settings with as few other adjustments first. I was lucky enough to get at set of 255/285 RE-71s before they went out of stock and bought a set of BC Forged 19x8.5ET50 / 19x10.5ET40 wheels that keep me in SS. I'm trying to wear out the Michelin PS4S that are on my OEM wheels so I can put an all season on for the winter. I'm going to try at least one more autox and one DE event before I swap over the tires/wheels.
So, event two, I ran with everything the same but PSM on. I felt that the car did rotate in the slaloms much better but I felt I was fighting the PDK at times. I actually saw it jump up to 4th gear coming out of a tight 180 corner. I was also having issues getting launch control to actually launch. It would hold the RPM before launch but then it would bog down and slowly accelerate in higher gears out of the starting box. WTF. I didn't try to launch on the first run, good launch on run 2, bad on run 3, bad on run 4. I tend to let my car idle between runs but I actually shut it down between run 4 and 5 and got a good launch again on run 5 but it again failed to launch on run 6. Weird. I've launched my TTS for years and my wife's 997 without ever having issues and I bogged down the Cayman 3 times out of 5 tries. I know there is a PDK update that is getting applied to GTS 4.0s as they go in for service - mine has not been in yet - so maybe some first year glitch? I did place 15th of 56 so I did improve but I left not very satisfied since the PDK was annoying me. I didn't have any issues with the launch control when I ran in the first event when I had the long press PSM off.
Questions:
1. When you say you run with PSM off do you mean the single press that gives the sport PSM settings plus traction control or do you mean the long press that turns off all PSM and turns off traction control?
2. My understanding is that break torque vectoring is on with PSM on, and PSM short press off, but off with PSM long press off? Can anyone confirm?
3. I'm going into the dealership on Wednesday to get a track inspection for a June DE and an alignment. (I'll ask to get the PDK software updated). I'll try to get what additional camber I can get but I'm less sure of what toe settings to ask for. Any suggestions for a dual use (Autox, Track) toe settings? So many of the other threads talk about putting in offset toe links in the rear which I can't do if I want to stay in SS.
4. I didn't have any issues with the launch control when I ran in the first event when I had the long press PSM off. Is there a chance that the PSM was causing the PDK to shift to higher gears as part of its stability programing?
My plan is to go for the single press PSM at the next AutoX event. I'll see if that middle ground helps. I will probably wind up going to manual shifting eventually but I want to try to figure out the PSM settings with as few other adjustments first. I was lucky enough to get at set of 255/285 RE-71s before they went out of stock and bought a set of BC Forged 19x8.5ET50 / 19x10.5ET40 wheels that keep me in SS. I'm trying to wear out the Michelin PS4S that are on my OEM wheels so I can put an all season on for the winter. I'm going to try at least one more autox and one DE event before I swap over the tires/wheels.
I see no benefit to running with the nannies on, they'll just slow you down. I ran Sunday with all of mine off and we got rain... I also see no benefit to using LC at these events on that surface. I was just flooring it and off I went. According to data, I was losing very little to the Tesla off the start to the first element and he's got a butt load of TQ and grip with AWD. If you lift even in the slightest way the car will cancel the LC and bog as you described. You have to make sure you keep that foot all the way down. I'd also run the car in manual so you don't have to worry about it shifting all over the place.
Last edited by sgreer78; 05-21-2021 at 12:51 PM.
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WillyDaP (06-22-2023)
05-21-2021, 10:19 AM
#99
Rennlist Member
Hey Greg-
I see no benefit to running with the nannies off, they'll just slow you down. I ran Sunday with all of mine off and we got rain... I also see no benefit to using LC at these events on that surface. I was just flooring it and off I went. According to data, I was losing very little to the Tesla off the start to the first element and he's got a butt load of TQ and grip with AWD. If you lift even in the slightest way the car will cancel the LC and bog as you described. You have to make sure you keep that foot all the way down. I'd also run the car in manual so you don't have to worry about it shifting all over the place.
I see no benefit to running with the nannies off, they'll just slow you down. I ran Sunday with all of mine off and we got rain... I also see no benefit to using LC at these events on that surface. I was just flooring it and off I went. According to data, I was losing very little to the Tesla off the start to the first element and he's got a butt load of TQ and grip with AWD. If you lift even in the slightest way the car will cancel the LC and bog as you described. You have to make sure you keep that foot all the way down. I'd also run the car in manual so you don't have to worry about it shifting all over the place.
05-21-2021, 12:52 PM
#100
Rennlist Member
05-21-2021, 08:19 PM
#101
@sgreer78 - Yeah... you and I are not on the same level of skill. I hit 10th in one of our events once in 3-4 years (running 2-3 times a year). I think you had 6-7 first place finishes last year alone.... But thanks, I do appreciate the advice. I think going to manual will be the way to go as well. I was trying to ease my way into learning a new car. I used to run my TTS in manual but it would shift 1-2 in manual but never another gear up or down. That was a crutch in the software to keep from over speeding in first gear. I didn't want to miss a 1-2 shift in my new car. But, I've got two events in now so the third event I'll try to run manual and that should help on the starts (no LC) and with the one crazy up shift and bog I got on that tight hairpin. I'm still learning.
05-21-2021, 11:44 PM
#102
Rennlist Member
@sgreer78 - Yeah... you and I are not on the same level of skill. I hit 10th in one of our events once in 3-4 years (running 2-3 times a year). I think you had 6-7 first place finishes last year alone.... But thanks, I do appreciate the advice. I think going to manual will be the way to go as well. I was trying to ease my way into learning a new car. I used to run my TTS in manual but it would shift 1-2 in manual but never another gear up or down. That was a crutch in the software to keep from over speeding in first gear. I didn't want to miss a 1-2 shift in my new car. But, I've got two events in now so the third event I'll try to run manual and that should help on the starts (no LC) and with the one crazy up shift and bog I got on that tight hairpin. I'm still learning.
05-24-2021, 01:19 PM
#103
Rennlist Member
I just ran the Chicago Nat's Tour which had 10 SS drivers which included Yom driving a borrowed GT3 on older BFG's, 4 C8 drivers (Clark and Pendergast), another GT3 (Miles and Shea), and a GT4 (Kirchner). It was my first event on Yoks in the car which has a DSC Sport controller with PASM and a CMS front sway bar. I did 4 runs on the TNT and car felt a little pushy but on pace. On Saturday, car had a noticeable understeer which increased within (ie. worse during runs) and through all runs to the point I was having to manage terminal understeer. Courses, aside from horrid start segments, were fairly technical day 1 and more point and shoot day 2. After day 1, I coned my first run and while I picked up time and sat 6th, two spots out of trophy, .3 out of trophies, the car was miserable to drive. I opted to soften the FSB to the 2nd softest hole setting for day 2 but hate making big changes mid event with the uncertainty as to whether it will really unsettle the car. Day 2, I came out determined to pick up time and spots. Right away, I felt the car was much less pushy but coned away my first (fastest run) of 3. Despite pretty assertive spraying, it just seemed like the Yoks were strong run 1 and hard to extract more pace on runs 2 and 3. Finished 5th, 1.1 out of trophies day two. My sense is the GTS is at best a AS car in an ever deep water SS field as it needs MOAR camber but I still love the car. So there's that.
05-24-2021, 03:53 PM
#104
Rennlist Member
Not really the same thing other than being mid engine, but I could never get the GT4 to drive how I wanted it to with the front bar stiff, and I was able to stiffen the rear as well. Always ran rear on full stiff, front on soft with re71, med with BFG's. Sounds to me you were just overdriving the front of the car. But that's me sitting at home wishing I made it up there to run with you guys...
05-24-2021, 08:37 PM
#105
Rennlist Member
Not really the same thing other than being mid engine, but I could never get the GT4 to drive how I wanted it to with the front bar stiff, and I was able to stiffen the rear as well. Always ran rear on full stiff, front on soft with re71, med with BFG's. Sounds to me you were just overdriving the front of the car. But that's me sitting at home wishing I made it up there to run with you guys...