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From Chris @ Redshift Motorsports

"
Rear
Rear tire pressure is more complicated because it's a balance of ultimate grip, rotation, and how easy the car is to drive. I hear many people raising rear tire pressures to get the car to rotate better, and this is a very bad idea in my opinion. A tire with higher pressure will grip really well until it starts to slide, and then it's hard to control. I am a strong believer in running lower rear pressures. Why? Because it provides rotation without the tire sliding (which allows the car to rotate in a more controlled manner). You see, the lower the tire pressure, the more "slip angle" the tire will provide (because it's soft and flexes more). Slip angle is the angle defined by 1) the direction the tire is pointed and 2) the direction the tire is actually travelling. A good diagram is located here: Slip Angle Explained ...note the diagram is good, but I don't like the explanation they have much because a tire's slip angle isn't necessarily "sliding" as that page suggests... slip angle from a softer tire is simply the tire "working". Sliding is what happens when the contact patch cannot grip anymore, and slip angle actually decreases when the tire is sliding due to lack of grip (and this is where you spin or at least loose control).Stay with me on this.... so, with a softer tire, we get increased slip angle when the tire is working... and that increased slip angle is effectively "dynamic toe". Meaning, it's the equivalent of the rear tire toeing out a bit to let the car rotate better. Also, a softer tire is easier to control; so you get good rotation without risking a loss of control. I regularly run 24-27 psi in the rear tires on nationally prepped FWD cars and have run as low as 12 psi in back to see how a particular car would act (although I DO NOT recommend you try that). If I were to take a guess at what would be the fastest tire pressure setup on your 2006+ Civic, I would guess 35 psi front and 25 psi rear. Start at something more like 35 psi front and 32 psi rear, but then lower the rear pressure in steps and see how you go faster.ONE MORE POINT.... a softer tire provides additional slip angle well before the limit of the tire. This means that the rear tires are providing rotation for the car well before it's limit, and that makes it faster. For those who increase rear tire pressure to make the car rotate better, you are causing reduced slip angle in back and the car will feel "tight" and not want to rotate until the tire actually starts to slide, and that lack of rotation hurts your speed everywhere on course. Still, it is true that the fastest car will not have too low pressure in the rear tires because that will reduce rear grip; so some balance of tire pressure, spring rate, swaybar, shocks, toe, camber, and what you eat for breakfast is needed to win at Nationals. And if you've read this far, welcome to car development. ;)"
 

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Good question on the rear tire pressure. Go to Redshift Motorsports and read his thoughts on air pressure. In the past, I ran higher psi in the rear tires and had snap oversteer. With the lower psi, the oversteer is controllable.
Seems like Chris suggests lower rear pressures to avoid snap oversteer. My rear has 255s, so I'm guessing I have a lot of grip in the back, I have yet to experience oversteer that was too much, uncontrollable, or unpredictable with my setup. The rear comes around slowly on lift-off but not aggressively like other people have mentioned on here. I also have a 19mm rear bar (not the 24mm progress) and s-tech lowering springs which aren't the stiffest spring in the world. AND a ton of camber, like i measured the other day and its just a hair below -3.0, not -2.5 as I thought. That said I have wear on the tire all the way to the sidewall after an autox, and the whole tire gets warm so I think I agree with what chris said that rear camber is not a bad idea. Front is what I want next!
 

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Yeah I currently running stock suspension with the 24mm Progress bar set to medium. (Also have upper strut tower braces Front&rear. I don't think they do much :p) I'm learning how to pitch the car into corners and induce some oversteer. I also run some sticky tires.

So to your point. Yep I bet you've got a lot of grip in the rear, which would cause your understeer. I'm betting with a stiffer RSB that would help. Reading through Chris' article, I know a few stunt/ precision drivers do that exact same thing for certain maneuvers. Setting up the chassis to get as much mechanical grip down is ideal. When you up the rear tire psi your pulling grip out of the system and we want maximum grip.

I for one can't wait for my coils to get here. I'm so excited to my car better prepped for STX. I'm hoping I'll be pretty competitive. I'm not to far behind the leaders in the group.
 

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Yeah I currently running stock suspension with the 24mm Progress bar set to medium. (Also have upper strut tower braces Front&rear. I don't think they do much :p) I'm learning how to pitch the car into corners and induce some oversteer. I also run some sticky tires.

So to your point. Yep I bet you've got a lot of grip in the rear, which would cause your understeer. I'm betting with a stiffer RSB that would help. Reading through Chris' article, I know a few stunt/ precision drivers do that exact same thing for certain maneuvers. Setting up the chassis to get as much mechanical grip down is ideal. When you up the rear tire psi your pulling grip out of the system and we want maximum grip.

I for one can't wait for my coils to get here. I'm so excited to my car better prepped for STX. I'm hoping I'll be pretty competitive. I'm not to far behind the leaders in the group.
If you're not far behind the leaders you are cleary a much better driver than me! lol.

Class standings for STX [8 Cars] (01:58:39 PM)


T 1 37 James Tatad 2013 Subaru BRZ BFGoodrich*
65.265 64.352 65.005 123.723
60.666 59.371 59.494
T 2 48 Sam Tocci 2013 Scion* FRS Bridgestone
66.850(1) 64.798 64.735 124.148
60.406 61.449(1) 59.413 (0.425)
T 3 148 Alan Salnikov 2013 Scion* FR-S Bridgestone
67.512(1) 65.683 65.017 124.511
60.148 61.436(1) 59.494 (0.363)
4 107 Bob Day 2015 Subaru BRZ BFGoodrich*
68.775(1) 67.246 71.055(3) 129.550
62.304 65.697(2) 64.894(2) (5.039)
5 65 Serje Beaudry 2004 Mazda* Rx8 Bridgestone
68.827 68.531 67.831 130.660
63.401 62.829 64.548(1) (1.110)
6 7 Colin Kingsley 2015 Subaru BRZ BFGoodrich*
73.739(1) 68.742(1) 68.068(1) 131.557
64.958(1) 64.613(1) 63.489 (0.897)
7 86 Adam Wright 2014 Scion* Frs Bridgestone
70.875 69.112 69.673(1) 135.225
66.113(1) DNF 70.069(2) (3.668)
8 76 Adam Santella 2012 Honda* Civic Coupe Si Falken*
76.117 73.820 72.710 139.952
69.822 68.067 67.242 (4.727)
 

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Lol, maybe it's all a learning process.
My AutoX I was .5 seconds behind the STX Mini Cooper S that won. I saw that he's got Ohlins on that thing. Sweet!
I've also run on average about 2 seconds behind the STX prepped FRS/BRZ's on average. I feel like I'm getting faster everytime I'm out. So we'll see what happens once I get better prepped.
 

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Local autocross and National level events are night and day different. I can routinely win STX locally and some other events in California where the twins are everywhere in STX, but get destroyed at Crows Landing even for a local event. What it takes to be competitive Nationally is to drive your a** off because our Si's are at a disadvantage. It can definitely be done as STX Solo Nationals last year was won by a FWD Mini Cooper. Reason he wins Nationally is because he has built his car over many years and knows how to drive it. Do I think my Si can be competitive with my build? Yes, but not until I learn to autocross the car better. At the Crows Champ Tour, I gave up 3-4 seconds total by hitting cones on 5 of the 6 runs. At the Colorado Champ Tour I drove good but easily gave up .5 second on my quickest run on Sunday. Still finished 4th and in a trophy position but 3 seconds out of 1st. So, getting the car built is the 1st step, then learning how to drive it is the most important part of the whole process. I look forward to hearing how other STX Civic Si's are doing. Good luck.
 

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This was the Nationals, cars were from New York, Quebec, Midwest, lots of talented drivers, two of the guys were local (2nd & 3rd place). I'm doing the front camber next, hopefully I'll get a little more grip up front while cornering after that as I was understeering out of almost all the corners. I'd basically keep the car understeering just on the limit and left foot brake to trim the line as needed. On a plus note we had to go to 3rd for a big portion of this course, and the extra torque from the k24 compared to the k20 or the twins was definately a big help on that portion of the course. My fastest time I accidentally went from 3rd to 4th while aiming for 2nd... still improved over the prior time. If I'm looking for 2-2.75* front camber should I be thinking bolts or camber plates? Anyone have any suggestions?
 

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Good question on the rear tire pressure. Go to Redshift Motorsports and read his thoughts on air pressure. In the past, I ran higher psi in the rear tires and had snap oversteer. With the lower psi, the oversteer is controllable.
PSI is a great way to make small adjustments to oversteer/understeer, especially if you don't want to mess with dampening settings on your shock. I have front and rear adjustable sway bars and going from stiff to medium on the rear is a noticeable difference, and may not be subtle enough. Problem is, I am not usually in a position to make tire changes 1 psi at a time and to really lock the setup in.
 

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feredral rsr-r is a l.a. local favorites because it's cheap and sticky... falken rt615k & the new falken rt615k+ are pretty awesome too

this fg4 is using 235 nitto nt05, with full brace + buddy club racing spec coils, he can do a fwy interchange ramp from max 90~100mph (s2000) to a whopping 130mph without skipping a beat.

if your l.a. local, it's ramp from 605 north to 210 west towards pasadena. and federal are much stickier than the nt05


I haven't ran the RSR-Rs but I have probably had 20 sets of RT615ks lol. Good tire, I miss the old Azenis though.
 

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ad08r is on sale right now
Need to be careful when buying the ad08r, especially if the ones on sale are old stock with the 180 treadwear. Anything below 200 will bump you up out of street touring, not ideal. New ones are rated at 200 (same tire just updated rating) but what the actual tire says on the sidewall is what matters.
 

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"How are you left foot braking? I tried that the other day and the car cut my throttle. It was really jarring. I wouldn't want that in mid corner."

Been off the forums for a bit sorry for the delayed response, but I get the same thing about half of the time, half of the time it works (if it is just a quick touch), the other have of the time I hold it a bit longer to get a bit more rotation and then boom. throttle cuts and my whole corner is ruined. If there is a way around this other than just doing it quickly that would be super helpful to know!
 

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Again a late reply but I've left my konis alone for a long time. I have them where the rebound is just enough and "feels" even on all 4 corners from what limited experience I have. Every autox book I've read says the knobs basically just let you get them in sync left to right. I'm sure if you had them dyno'd you could be a bit more precise (got mine from procivic, didn't think of asking before ordering because I was inexperienced at the time) but from what I can tell, any fiddling with the knobs just throws off the car and makes it hard to adjust your driving accordingly. Not sure what the experts would say on that but that is just my experience. Higher psi out back and lower up front with the azenis tires seems to make them wear (and I don't have a pic but I wouldn't lie for no reason about this) exactly even front at no camber and back at -2.5. Every tire feels hot to the touch from the inside, to the middle, all the way to outer edge. The fronts certainly heat up faster, but it seems like a decent amount of rear camber might be the way to go. I'd love to get a thermal camera from work one day and sneak it out to an event and know for sure.
 

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"How are you left foot braking? I tried that the other day and the car cut my throttle. It was really jarring. I wouldn't want that in mid corner."

Been off the forums for a bit sorry for the delayed response, but I get the same thing about half of the time, half of the time it works (if it is just a quick touch), the other have of the time I hold it a bit longer to get a bit more rotation and then boom. throttle cuts and my whole corner is ruined. If there is a way around this other than just doing it quickly that would be super helpful to know!
Yeah I've tried this myself and the throttle cut is just to severe. Wish we could left foot brake. I find myself in the middle of an AutoX run thinking, "ooh I should tap the brakes right now".
 

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"How are you left foot braking? I tried that the other day and the car cut my throttle. It was really jarring. I wouldn't want that in mid corner."

Been off the forums for a bit sorry for the delayed response, but I get the same thing about half of the time, half of the time it works (if it is just a quick touch), the other have of the time I hold it a bit longer to get a bit more rotation and then boom. throttle cuts and my whole corner is ruined. If there is a way around this other than just doing it quickly that would be super helpful to know!
Also emailed Vit Viper about this and asked if there was a way to tune it out. He replied and said there wasn't one. Bummer. :(
 

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Here's an update of my setup and I would have to say its almost perfect for me. Attached some photo's I felt gave me some great tire perspectives.

Godspeed 2 way monomax coilovers - 12KG Front (full hard stiffness setting) 14KG Rear (5 from hardest stiffness)
Progress 24mm RSB - Hard Settings
Alignment set to -2 Front and -4 Rear for clearance, going to add camber to -3.
Running Konig Hypergram +25 17x9 with 255/40 Federal 595rs

My fastest lap at ButtonWillow 13CW was 2:10, easily could've squeezed out another 2-3 seconds.

BW__2118_Feb2418_CaliPhoto.jpg BW__3966_Feb2418_CaliPhoto.jpg BW__3054_Feb2418_CaliPhoto.jpg
 

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22 psi in the rear?? Curious why the low pressure? I ran 35 front 35 rear first day this weekend, understeered terribly. Next day I did 33 front 40 rear and the car was a million times better, far less shoveling understeer. Is there a method I am unaware of with low rear pressure? Experience tells me the opposite is what I should go for!
Since you have 255 rears, running low rear pressure creates a bigger contact patch on the rears and increase rear grip hence the understeer.

If I were to build an stx set up, I’d go with 245 rivals on 16x9 wheels, progress 24mm rear bar, os giken, chris’ bc racing with Bilstein inserts, factory crash bolts, poly bushings all around and whatever 100 cel cat and 3” headerback exhaust. That would be the easy button and close to the limit of the rules. Alignment wise, I’d max out the front camber with the bc camber plates, 1/8” toe out in front. 1/8” toe out in rear and probably 2.5 rear camber depending on surface. At Devens, I can probably get away with 1.5 to 2.5 to 3 and get enough rotation. If I ran Bridgestone, I’d run 1.5-2 in the back. As the rivals heat up, they will grip better especially with dual drivers. Single drivers, you want enough rear camber to warm up the rears so you don’t snap oversteer too much.

Within stx rules would be a tune to raise the rev limiter, maybe change out the driver seat to a kirkey, add harness.


Sent from my iPhone using Tapatalk
 

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I cant believe I am just finding this thread now...a month after my first track day.

I did HPDE1 at Carolina Motorsports Park back in May. My setup then was as follows

17x9 +40 Enkei TSV
255/40 Hankook Ventus V12 Evo2's
H&R springs on stock shocks
SPC front camber bolts maxed out at -1.75 degrees and the rear is natural camber at -2.5 degrees

I dont and didnt have any rubbing issues and my fenders arent rolled or pulled. I found that these car have a ton of body roll. I lowered my air pressure in the front to 28 psi and my rears to 30-32 psi. I just couldnt get enough heat in the Hankooks to stick the way I wanted them to which made the car push thru the corners with a lot of understeer. Also I knew I would need a lot more negative camber up front to help with my turn in response. I also realized that having a stiffer suspension is going to improve the car tenfold. My first session I was at a 2:32:88 and by my 5th session I was at 2:03:44.

Since that day and with my next track day not until November, I have some Yellow Speed Racing coilovers coming with stiffer springs (10k/12k). Adding these will drastically help the car by adding more front camber adjustment and stiffen the dampening. My issue with the springs would be the car hopping thru the corners after hitting a gator. Ive also ordered the Progress 24mm, and Im hoping to order a set of 255/40 200 tw tires and a spare set of wheels.
 
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