[Autocross] Points Event #8 with TSCC: November 2023
Last Autocross of the year!
But First - What about Points Event #7?
Last month I co-drove a friend (Danny)’s Toyota MR-Spyder which he had just gotten new wheels/tires for to fully prep for ES class. I did not really get any great video, and grid was moving so fast that it was low on the list of priorities.
It was pretty fun car but had some wild shaking under hard braking, accel, and while turning. There was nothing “loose” at all but it felt very strange. We DID find that shaking the RF wheel HARD while sitting on the ground could produce a VERY faint “ting ting” type noise. We thought it might have been a wheel bearing or something. All the wheels seemed tight, etc. I recommended he look over the suspension and everything VERY carefully.
I followed up with Danny at Event #8 - he let me know that it turned out he was running OEM lug nuts (Toyota uses a mag seat style) on the new wheels which were a 60 deg conical seal. As a result the lug nuts were bottoming out on the rotor/hub just SLIGHTLY before actually holding torque on the wheel. This could have been VERY bad, especially considering he drove it about an hour each way to get to the event. This was discovered when he found marks of the lug nuts sliding against the wheel face:
So moral of the story: Make sure you have the correct lug nuts (or lug bolts in VW case if not converted) for whatever wheels you are running! OEM takes an R13 radius seat, as do the Apex wheels designed for VW/Audi applications. If you go for Konig wheels, you need to get 60 degree seat lug nuts (or bolts). Always verify with the wheel manufacturer!
Side note: Danny beat me by about 0.3 sec in his car at Points Event #7. Driving a mid engine car is very strange, and it had been about 5 years since I’d driven one on an autocross course. It requires a very steady trail braking to turn, otherwise it pushes like crazy on corner entry, and any amount of throttle makes it also push like crazy. It’s not terribly different than a FWD car, but the car doesn’t rotate on it’s nose, it rotates right where the driver is. Rather than inducing slip angle on the rear tires primarily (FWD), you must induce it on all 4 at once. Very fun to drive, wish I’d had a few more runs to feel it out more (and without the violent shaking of wheels being loose. : )
Thanks for coming to my Ted Talk, now onto Points Event #8:
For Points Event #8, I had a good friend of mine, Greg come down from Maryland to codrive. This was his first time running a DSG equipped car and seemed to like it.
Tire grip still seemed way down up front, so I think the Kumhos while still having pretty decent tread left, are at the end of their useful “fast”(ish) life. I’ll be looking forward to trying something better next year. Looking heavily at the Nankang CR-S v2 since they like heat, and the front tires overheating seems to be the biggest problem with this front heavy strut FWD car.
I’m also testing a modified MK8 PCV valve to send to one of those who have done the (basic) retrofit, but still had some issues when autocrossing:
More will be explained in the coming article/video (along with results of 18 others who’ve done the retrofit), but in a nut shell this did not produce any ill effects on my car, so will be getting tested once more at VIR for one day, then swapped out and sent to a friend in Florida who did the MK8 (basic) retrofit and still was able to have some smoking problems when driven 10/10ths autocrossing.
Basically I confirmed that it’s not sucking oil up through the holes at any kind of noticeable rate (it has also been on my car for about 3000mi now), and not getting any kind of cornering related knock retard. I had a single blip on one cyl to -4.5 deg, and a short period of -2.250 avg KR towards the end. Not the 10.00deg + of KR that is typical of ingesting oil via the PCV.
Points Event #8 Results:
I managed to finish 2nd in XA (behind an LFX swapped RX8 by 0.017), 5th in the TSCC Provisional Classes PAX grouping, 19th in PAX overall (of 104), and 13th in Raw time overall (of 104). Note: RTE is just a Raw Time/Exhibition class for people that don’t care about classing with a PAX of 1.00.
Greg finished 4th in XA, 7th in the PC PAX class, 30th in PAX (of 104), and 20th in Raw (of 104).
The video at the top came from my phone, but a buddy of mine, Alex happened to catch what I believe is the same run in HD slow motion. This is super useful to see what exactly is happening to the car on course:
So what can be seen from the video above?
The body motion is smooth and controlled.
There’s no bouncing of the chassis over surface bumps or cracks (not obvious in the video, but it is a very rough lot). You can see the inside rear wheel leaving the ground and coming back a few times due to driver input, but the body itself is not bouncing. The one exception is due to the understeer at 1:10-1:15, followed by abrupt lift of the throttle with the wheels turned. This is more obvious if you watch in HD at 0.25x playback on YouTube.
On corner exit at the VERY end, the car is starting to unweight the inside front tire quite a bit.
The car needs more front camber.
It IS true that if you are lifting an inside rear tire, that the rear end of the car has no more roll stiffness to offer and it will only hike the inside rear tire up further if more spring or sway bar is added.
The caveat is that it could be lifting the inside rear on corner entry (pretty common), constant speed steady state cornering (also common), and/or on corner exit. Corner exit is where you’re trying to put power down, and is perhaps where the most time to be gained is when setting up a FWD car.
Lifting inside front tire on corner exit only = Needs more rear spring rate.
Part of me wants to make the car better, but at the same time I know there is more time to find in my own driving than there is at throwing any parts at the car with the following exceptions:
More camber. Not sure how yet, but it needs it to minimize outside edge wear.
New tires. Because I’m sick of the V730s and I typically put a new set on every season anyway.
As it is now: the car doesn’t ride like ass, and it is still pretty damn good overall handling-wise. Modifying to the point of ruining the car for daily use is exactly what I do NOT want to do. With that said, I still have a pair of 7in long 450lb Eibach springs from my Mazda2 that I just never sold. I may try to see about fitting them with absolute minimal effort to assess over the winter just for the heck of it.
If a spring rate change works out, then going stiffer on the front sway bar (H&R 28mm, vs the existing 26mm) might be warranted to further improve the body roll situation. I’ve considered lowering the car slightly, but I’m not terribly worried about it.
What about the Data?
I have Simos Tools logs of all of our runs, but honestly I was just kind of having fun at this event more than anything. Greg has the in-car videos which I’m currently waiting on. The only videos I have are from the hood pointed at the driver which are pretty cool, and may upload later as picture in picture with Greg’s footage.
I may eventually upload our best couple runs and try to put the data over them, but otherwise seeing what was going on with the suspension in slo-mo was a huge win for the weekend.
Overall results for the year:
Out of 40 drivers who qualified for season PAX championship points, I ended up #8 overall which I’m pretty happy with considering I screwed myself out of the easier STH PAX partway through the year, and did a few codrives in other vehicles.
Next up: VIR December 9-10 to close out the track season as well!
