Track = Gingerman
Elapsed Time = 1:39.776
Year / Model / Trim = 2017 SS 1LE
Date = 7/17/2021
Tires = Falken RT660 305/315
Mods = Ferodo DS1.11 pads, Ferodo Super Fluid, Hotchkis rear sway bar (softest setting)
*Start/Finish line was not being set early in the day. Further verification of time:
https://timetrials.scca.com/events/1...-1626527525-19
After trying out the Falken RT660 at the SCCA TT Nats, during one of the practice sessions, and really liking the way the tire acts on this car, I decided to grab a pair of 305/30R19's and 19x10.5 M716 wheels to compliment the rear 315/30R19's on 19x11 M716 wheels. I considered running the 275/30R19's I have, but after the one practice session I ran them, I see them wearing out really fast and being a lot more susceptible to over-heating. With 305's - larger heat sink. Plus I wanted to see what more grip up front would do.
I had tried this 305/315 setup in an autocross setting, nothing else different from the times I ran 275/315, and it's pretty notable how much more confident the front of the car becomes. In an autocross setting, the car seemed basically dead-neutral.
For the Gingerman TT, I also swapped over to the Hotchkis rear sway bar from the FE3 coupe bar I've been running. The reason I did this is because, at NCM, I noted a bit of understeer in the tight, technical sections of the track. It wasn't enough to kill lap times, but enough to force you to be a lot more careful about what you do with the car, how you setup corners. The Hotchkis rear bar, in the softest setting, provides a bar that has the same rate as the OEM FE4 bar, but allows for non-bonded bushing, freeing up the rear suspension movement. That is the reason why I decided to try the bar.
At the SCCA TT event, before I threw on the RT660's, I ran the OE SC3 setup. The reason being as I wanted to see how the car felt, what the car was doing, compared to how it acted prior, with the OE bars I've tried. If you page to the Group 1, Session 1 practice sheet, you'll see that my times aren't representative of "a fast lap" for the setup, comparing to my past times - my focus was to put down "a good time" and to note what the car was doing over trying for my fastest lap. In particular, the car would have some very mild push at corner exit of T11 of Gingerman. I also wanted to see how the car took T10b. From what I could tell, the Hotchkis bar, in the softest setting, seemed to keep the balance I remember from past events (including past Gingerman events); however, the rear of the car had a slightly different feel - it definitely felt a bit less "tangled". To be clear: the car was cornering just as it was with the OE FE4 bar, the roll stiffness balanced did not seem to have changed, but the rear of the car did seem to be able to move freer.
I am really eager to run at another tight, technical track to really see if the non-bonded bushings show a bit more.
On the 305/315 setup, as it moves closer to a square setup, I did notice the car become a bit more loose (balance more a bit more toward oversteer). I think there is a low-1:39 or high-1:38 there, from looking at my data. I wasn't able to improve my time during competition, as I kinda lost my head on my laps through the weekend, overly focusing on a few areas for improvements, and not minding other areas where I was a bit off. I was having issues with my PDR, at first, getting the Start/Finish line to set and then my laptop was all jacked up, so I couldn't analyze my data - once I got home and fixed my laptop, it was very evident I wasn't doing the T7-8-9 sequence right during competition, for some reason, and my line out of T2 evolved a bit too tight, which killed some speed out of T2.
If you guys haven't yet done the SCCA Time Trial events, I highly, highly recommend them!
On a scale of 1-10, with 5 being "neutral", 1 being "complete oversteer" and 10 being "complete understeer", I would rate:
-OE setup = 6
-FE3 rear bar = 6.5
-RT660 305/315 setup w/FE3 bar = 5
-RT660 305/315 w/Hotchkis bar = 4 or 4.5.
Update: I’m very confident that the Hotchkis rear bar is likely the ticket to curing my concern, as I’ve done some street driving on the shitty Metro-Detroit roads and the ride quality out of the rear of the car is noticeably better than before. A lot less shimmy from the rear over bumps. Much smoother.