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MASTER THREAD: Comprehensive Road-Course Modification Guide — Optimizing the 3 for the track

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Was out at Gridlife Alpine Fest last weekend and took the win in Street Class. I got more aggressive with my alignment for this even and learned some things.

1. I don't like toe out in the rear. There are quite a few guides that say to give the car a bit of tow out in the rear and maybe with a rear wing that would work, but with no non factory aero it makes the car super unstable and turn in at speed. I dialed in a bit more positive toe this time than I had been and the car was great at speed. Not wild oversteer on entry.

2. I started to play around with a larger split in camber between the front and rear axles. I had my front camber up to 4.5 and my rear at 3. This felt really good although at low speed I could still use a bit more front grip. Tire temps were also in check for what I would expect. This is a bit of a strange track though in that it is a roval with lots of banking.

3. Playing around with the power split in track mode only consistently made me slower. 50/50 is best it seems at least based on how I drive.

Anyway here's the vid from the fastest lap. Set this on my second timed lap of the week and the second timed lap I have ever had on this track. Too much autoxer in me I guess.

 
Was out at Gridlife Alpine Fest last weekend and took the win in Street Class. I got more aggressive with my alignment for this even and learned some things.

1. I don't like toe out in the rear. There are quite a few guides that say to give the car a bit of tow out in the rear and maybe with a rear wing that would work, but with no non factory aero it makes the car super unstable and turn in at speed. I dialed in a bit more positive toe this time than I had been and the car was great at speed. Not wild oversteer on entry.

2. I started to play around with a larger split in camber between the front and rear axles. I had my front camber up to 4.5 and my rear at 3. This felt really good although at low speed I could still use a bit more front grip. Tire temps were also in check for what I would expect. This is a bit of a strange track though in that it is a roval with lots of banking.

3. Playing around with the power split in track mode only consistently made me slower. 50/50 is best it seems at least based on how I drive.

Anyway here's the vid from the fastest lap. Set this on my second timed lap of the week and the second timed lap I have ever had on this track. Too much autoxer in me I guess.

Congrats on kicking butt Tony! Hustling that car around as usual :cool:
 
Car looks great and this is great info. Where did you happen to find the OEM Performance rear sway bar rate?

When purchasing sway bars, I made a comparison chart of the aftermarket options. If the OEM P bar is about 103 lbs/in, this makes me realize the MPP rear bar is actually pretty similar to UPP. I'm sure they would tell us the actual spring rate because they're awesome.

Tube diameter (mm)Spring rate (lbs/in)Increase in stiffness from LR AWD non-P
OEM front296500
OEM rear16400
OEM P rear19.6103256%
So, I'm trying to assess how much of a rear sway bar I want, and the question I've ran into is if these OEM rates are remotely accurate.

So, assuming spring motion ratios I inferred from Redwood's Ohlins installation manual--at 38/50 = .76 up front and 32/50 = .64 in the rear--are close, I can calculate approximate wheel rates. The front swaybar attaches to the coilover, so I'm gonna assume that the front bar motion ratio is about the same as the spring one. For the rear, the bar attaches pretty close to the hub-to-lower-arm bolt, so I'm gonna assume the motion ratio is close to 1.

So, with 6/10k (allegedly) OEM springs and OEM sways I get these wheel rates
Front: (6*56+650)*(0.76)^2 = 570lbs/ in
Rear: (10*56)*(0.64)^2+103 = 332lbs/in
Seems kinda weird, for a ~50/50 weight distribution, which makes me think that OEM bars are hollow. Anybody has any idea if they are?
 
When I did a bunch of similar anti-sway bar calcs for my previous off-road vehicles (to justify keeping them removed for regular off-roading while quantifying the increased rollover risk), I saw something similar. Generally thinking, I have always understood higher overall per-corner spring rates on the front axle for three reasons:

1) Max deceleration is always higher than max acceleration, driving more front spring rate to mitigate brake dive.

2) Hard braking and hard cornering go hand in hand for a street car (I.e. for emergency avoidance), meaning the outer front corner needs to be able to handle a disproportionate force load during such events.

3) Manufacturers build in several understeer-enduring suspension traits because wrecks get dramatically more dangerous when vehicles get sideways. One such trait is a stiff front suspension and especially the anti-sway bar.
 
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Did a 2-Day Performance Driving School at Sandia Speedway in Albuquerque, NM! It is a relatively tight, 1.7-mile course with 14 turns. Top speeds were around 100-102mph on the front straight (~85-88mph in Chill Mode).

Initial Notes:
~1.5% per lap in Chill Mode
~4% per lap in Track Mode
~About 20% charge gained through the half-day plugging into a 14-50 outlet between sessions, even for 5 minutes at a time—worth it!

I initially started running in chill mode to conserve battery, but quickly realized how much the power was masking poor line management. Ultimately, my best time in Chill Mode was only 2 seconds slower than my best time in Track Mode. My instructors each did a few laps and described “Beast Mode” (anything outside of Chill Mode) as “chaotic.”
Car:
Tesla Model 3 Performance
April 2022 Build Date

MPP Front Upper Control Arms
MPP Rear Camber and Toe Arms
MPP Comfort Adjustable Coilovers (Full Stiff)
MPP Stainless Braided Brake Lines
MPP Master Cylinder Brace
MPP Compression Rod Bushing Inserts
UP Rear Anti-Sway Bar (set at full stiff)
Brembo 6-Piston Calipers
PowerStop Track Day Pads (F)
RacingBrake XT910 Pads (R)
Federal 595 RS-Pro Tires (275/35R19)

Camber: 3.2F, 2.5r
Toe: 1mm Toe in F, 1mm Toe Out R

Video:
-Short Timelapse
-Clip passing another student in a 370z
-Trying to keep up with one of the driving instructors in a Spec Miata while I was in Chill Mode (1:40.xx lap)
—-The instructor was letting me keep up. They normally run 1:36.xx as set up)
-Best solo run in Track Mode (1:38.xx lap, 50% battery)
-Goofing off on the skid pad
-A little whoopsie that happened early on the 2nd day from trying to be cute
Instructor comments after driving this car:
“[I did not want to like it this much…it doesn’t feel like a 4100lb vehicle…it is really set up well…one of the funnest cars I’ve driven on this track…]”

Note: I was surprised to only see a 2-sec difference between Chill Mode and Track Mode. The instructor put it best: “It is much more…chaotic…in ‘beast mode’ but not actually much faster on a tight track like this.”




I really want racing seats now. My arms are tired, but my left leg actually got the biggest workout trying to keep in stable!

[Media]

63D48ECF-FF71-4827-B2AA-09A10F738B7A.jpeg

44348B6A-8932-4DF4-9DDD-559861182769.jpeg
 
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I forgot to mention. I thought the autocross-focused toe-out and stiff rear anti-sway bar would cause issues, but it really never did. The car was very neutral to the point where one could could consistently use the throttle to change turn radius without messing with the steering wheel. My instructors (even in just a couple laps each driving my car) were much more competent at demonstrating it, but even I was able to do it pretty consistently by the end of the course.

Admittedly, speeds weren’t super high; I only hit 105 at the highest on the back straight with the right combination of a good corner exit, higher SOC, and later entry into Turn 1. More typical was the 100-ish seen in the video. There is definitely a noticeable transition exiting the oval portion of the back straight (at the end of the white wall), which is just before my braking zone. The only time the car felt unsettled on this track was braking hard after coming over that. I asked my instructor about my setup after they got to drive it, but they said that feeling was just me not letting the car settle enough before jamming on the brakes, and was NOT a setup issue! (Or at least, would not be worth losing what they felt was otherwise very effective around all 14 turns).

Also, thanks, @MountainPass.

Oh! The brake rotors definitely turned blue, but absolutely did not fade and the instructor immediately commented on the “great” pedal feel by turn ~6. @emotiveeng

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Racing Seats!

Okay, ever since I got my 200tw race tires, staying in the seat is honestly a chore. Literally the most sore part of my body was my left leg from either pushing against the door or jamming against the dead pedal. Riding passenger and leaning against the door at 1.2-1.3g feels like the door is going to pop open and I’m going to get dragged around by the seatbelt.

Anywho,

1) Can someone confirm Schroth SCH-16 for the E90 M3 Fits on both the passenger side and drivers side (assuming I get one of each)?

2) Can someone confirm, then, if the next best option is $4000 in Unplugged Performance seats + some 4-points?

A) Could I use the UP Seats with the Schroth quick fits? Or do I indeed need removable roll bar? I will do the bar if it makes for a better and or safer seatbelt mount, though I am really not worried about the roof collapsing in a rollover.

Thanks!

-Lindenwood

@Mash @MasterC17 et. al.
 
Racing Seats!

Okay, ever since I got my 200tw race tires, staying in the seat is honestly a chore. Literally the most sore part of my body was my left leg from either pushing against the door or jamming against the dead pedal. Riding passenger and leaning against the door at 1.2-1.3g feels like the door is going to pop open and I’m going to get dragged around by the seatbelt.

Anywho,

1) Can someone confirm Schroth SCH-16 for the E90 M3 Fits on both the passenger side and drivers side (assuming I get one of each)?

2) Can someone confirm, then, if the next best option is $4000 in Unplugged Performance seats + some 4-points?

A) Could I use the UP Seats with the Schroth quick fits? Or do I indeed need removable roll bar? I will do the bar if it makes for a better and or safer seatbelt mount, though I am really not worried about the roof collapsing in a rollover.

Thanks!

-Lindenwood

@Mash @MasterC17 et. al.
I can confirm that the quick fit will fit both sides. If you are going as far as buying a racing seat you might as well build a harness bar also and do a proper 6 point. There some universal harness bars out there that might fit, I am planning on building my own.
 
I can confirm that the quick fit will fit both sides. If you are going as far as buying a racing seat you might as well build a harness bar also and do a proper 6 point. There some universal harness bars out there that might fit, I am planning on building my own.
The two main desires driving racing seat consideration are 1) bolstering and 2) weight. Everything I have read suggests a 4-point will largely do the job of keeping me in the seat.

However, main concern with the Schroth belts in factory seats is that they rely heavily on the strength of the seat back to avoid spinal compression in a hard frontal collision.* That pushes me toward the Bar (and I agree it seems like a lot to spend $2500 on a UP bar just to mount seat belts), and then back to racing seats to at least offset the weight and for belt pass-throughs.

I do know they are DOT-approved and that the ASM makes them act somewhat like a 3-point during a frontal collision. But still, it is a concern…
 
I can confirm that the quick fit will fit both sides. If you are going as far as buying a racing seat you might as well build a harness bar also and do a proper 6 point. There some universal harness bars out there that might fit, I am planning on building my own.
I didn't buy passenger side, so not sure if it's the same SKU or different one.

UP kit for US and separate one for EU are still better option, but you lose motorized seat adjustments, lumbar support.

In EU version they use Sportsters and they have option for seat heating and airbag, but it doesn't work from the app.

The advantages of seat - still holds you better and they are much less bouncy seats, so you feel the car much better (including road harshness). With 4pt belt I don't have to hold my upper body by the steering wheel, but I still push left leg to the door a lot, that's true.
 
The two main desires driving racing seat consideration are 1) bolstering and 2) weight. Everything I have read suggests a 4-point will largely do the job of keeping me in the seat.

However, main concern with the Schroth belts in factory seats is that they rely heavily on the strength of the seat back to avoid spinal compression in a hard frontal collision.* That pushes me toward the Bar (and I agree it seems like a lot to spend $2500 on a UP bar just to mount seat belts), and then back to racing seats to at least offset the weight and for belt pass-throughs.

I do know they are DOT-approved and that the ASM makes them act somewhat like a 3-point during a frontal collision. But still, it is a concern…
I'm not very concerned about seat collapse. Doesn't look probable. Yes, it's somewhat steeper angle than recommended, but they certified those belts on very similar cars. Harness bar is very very heavy and very questionable in terms of added safety. And it's tons of prep work.
 
The two main desires driving racing seat consideration are 1) bolstering and 2) weight. Everything I have read suggests a 4-point will largely do the job of keeping me in the seat.

However, main concern with the Schroth belts in factory seats is that they rely heavily on the strength of the seat back to avoid spinal compression in a hard frontal collision.* That pushes me toward the Bar (and I agree it seems like a lot to spend $2500 on a UP bar just to mount seat belts), and then back to racing seats to at least offset the weight and for belt pass-throughs.

I do know they are DOT-approved and that the ASM makes them act somewhat like a 3-point during a frontal collision. But still, it is a concern…
Looking at the UP 4 point I wouldn't want to use it. The harness bar is in the wrong place and the angle of the rear tubes are too steep. I don't understand this design at all. It also appears to rely on the sheer strength of bolts for the lower b pillar point which is is no way legal for basically anything.
 
Looking at the UP 4 point I wouldn't want to use it. The harness bar is in the wrong place and the angle of the rear tubes are too steep. I don't understand this design at all. It also appears to rely on the sheer strength of bolts for the lower b pillar point which is is no way legal for basically anything.
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