First autocross this Sunday. Need tips please!

[N55_BBM]

My first ever autocross event is this sunday. I've tracked the car twice but never done autox. I wanted to know first of all if from a car-prepping perspective there's anything I need to do other than torque the lugs and check tire pressures... seems like autox is much less harsh on the vehicle but wanted to make sure.

Also, about the tire pressures, what's the recommended pressure for that? I usually do 40 front and 38 rear for the track...

Additionally, how's the whole tire-warming go with autocross where you're only doing a handful of <1 min runs? How do you guys warm the tires up, etc? I'm thinking I should calibrate them as soon as I get there from my 14 mile drive but then again not even sure...

Any tips are appreciated! thanks guys

[Focusedintntions]

It'd depend on the tires...but your tire pressures seem really high. Ideally you'd want to be 38 psi or less when hot.

[N55_BBM]

I have Michelin pilot super sports 225f 255r

[fboutlaw]

AutoX is pretty rough on your car. Lets get that straight.

I'd do the following:
Fronts: 42psi
Rears: 38psi

Bring a pressure gauge and check them after each run and bleed them back down to the starting pressures.

You need to run very high pressures at autox for the fear of rolling tires in very tight turns where the car is super compressed. The fronts should be higher than the rears as you can't get any negative camber on the stock suspension and therefore there's a higher chance to roll them.

Other maintenance:
- Check your brake pads
- Torque down your lug nuts
- Check all fluids
- Get under the car and check for anything loose
- Clear out everything that isn't bolted down inside the car

For your first autox, just have fun with it. Your times are going to suck, but don't let that discourage you. Just try to improve with each run. .5 to 1 second gains for each minute are reasonable goals when starting.

Non-pro tips
- Look ahead - past your current turn to set up for the next
- Smooth runs are faster than fast runs (will make sense afterwards)
- If you're not tripping ABS, brake Harder.
- Brake in a straight line... before turning. (use your traction for cornering instead of slowing)
- Grab a ride with other drivers if at all possible.
- Turn off your cellphone when driving.
- DSC off = Fun on!

[Lubo]

Originally Posted by fboutlaw

AutoX is pretty rough on your car. Lets get that straight.

I'd do the following:
Fronts: 42psi
Rears: 38psi

Bring a pressure gauge and check them after each run and bleed them back down to the starting pressures.

You need to run very high pressures at autox for the fear of rolling tires in very tight turns where the car is super compressed. The fronts should be higher than the rears as you can't get any negative camber on the stock suspension and therefore there's a higher chance to roll them.

Other maintenance:
- Check your brake pads
- Torque down your lug nuts
- Check all fluids
- Get under the car and check for anything loose
- Clear out everything that isn't bolted down inside the car

For your first autox, just have fun with it. Your times are going to suck, but don't let that discourage you. Just try to improve with each run. .5 to 1 second gains for each minute are reasonable goals when starting.

Non-pro tips
- Look ahead - past your current turn to set up for the next
- Smooth runs are faster than fast runs (will make sense afterwards)
- If you're not tripping ABS, brake Harder.
- Brake in a straight line... before turning. (use your traction for cornering instead of slowing)
- Grab a ride with other drivers if at all possible.
- Turn off your cellphone when driving.
- DSC off = Fun on!

All of you guys running over 40psi in tires must be riding on all season tires.

With 255/40 17 and -2.5* all around what seems to work the best at the auto-X is 32 cold or 34-35 hot for the front. Depending on the course and how you want the car to handle I run anywhere between 30-33 cold or 32-35 hot rear. It all depends whether I need more grip or more rotation.

With the Star Spec on OEM wheel in 225/40 18 F 255/35 18 R configuration and stock alignment, I was running anywhere from from 34-36 cold pressure front and it was enough not to roll over the tires. I ran higher rear as it helped a lot with rotation and evened out the grip between front and rear.

My recommendation would be start from factory specs and add or bleed from there

[Focusedintntions]

I run pilot super sports in the same sizes and on the track i run 35 up front and 37 in the rear when hot.

[N55_BBM]

hmm i'm kinda confused now.

shouldn't the front ones have higher pressure to tackle the understeer?

now I don't know what to set it at, lol...

[Lubo]

Originally Posted by N55_BBM

hmm i'm kinda confused now.

shouldn't the front ones have higher pressure to tackle the understeer?

now I don't know what to set it at, lol...

Higher pressure = less grip. you only need enough pressure to prevent roll over of the tire.

[N55_BBM]

but higher pressure on rears than on the fronts? thought it should be the other way around to compensate for understeer.. or is that just for the track?

[Lubo]

Originally Posted by N55_BBM

but higher pressure on rears than on the fronts? thought it should be the other way around to compensate for understeer.. or is that just for the track?

for most of the time I run same pressure front and rear. In Auto-X if it is a slow and tight course I will run about 2psi higher rear pressure as it helps with rotating the rear end.
Think about this way. Car is set up to understeer from factory.
Reduce the front pressure to the lowest point before you will start to see roll over.
Increasing pressure in the front higher than rear will mean that you are giving up traction which there isn't much to begin with.
By increasing rear pressure you will give up traction and therefore make the car a little bit more neutral.

I don't know how to explain it any better hopefully this article will provide some insight.
http://www.turnfast.com/tech_handling/handling_pressure

FYI at the track days I run 28psi cold front and 29psi rear.

[Focusedintntions]

What they said...increasing tire pressure reduces roll over and grip...you have to find a fine balance depending on how your car is set up.

[jvb6806]

i took my 128 out today for the 1st time on a set of RS3's and started at 35 cold on all 4 corners. once they heated up we set the rears to about 37degrees and stayed at around 130degrees across the tire (which was a perfect temperature).

the fronts we ended up bringing down a little bit to try and reduce some of the understeer and it seemed to be pretty good around 34 at temp.

it really all depends on the tire you have, and how hot it is outside. i would get a pyrometer and see what the readings say. i don't think you need to be anywhere near 40psi up front though. i personally didn't think the car pushed too terribly, compared to an S2k it understeers, compared to my old EVO is wasn't bad at all.

[DriveHard]

Originally Posted by jvb6806

i took my 128 out today for the 1st time on a set of RS3's and started at 35 cold on all 4 corners. once they heated up we set the rears to about 37degrees and stayed at around 130degrees across the tire (which was a perfect temperature).

the fronts we ended up bringing down a little bit to try and reduce some of the understeer and it seemed to be pretty good around 34 at temp.

it really all depends on the tire you have, and how hot it is outside. i would get a pyrometer and see what the readings say. i don't think you need to be anywhere near 40psi up front though. i personally didn't think the car pushed too terribly, compared to an S2k it understeers, compared to my old EVO is wasn't bad at all.

are you running camber plates / M3 arms etc etc or are you just stock. and what size Rs'3 are you running ??? I cant get the pressures that low in the fronts with out rolling them ..

Thanks

[N55_BBM]

had a great time out there yesterday, improved from 50.6s to 45.3s not bad .

I ended up with like 38 in the front and 36 in the rears. car was understeering quite a bit.. I guess I should've done 36 front and 38 rear instead?

I still don't understand why I run more pressure in the front tires for the track... makes sense the whole thing about how the car's designed to understeer so the rear needs more pressure. I'm just completely confused now, lol

[DriveHard]

Hey B.. Glad you had fun..

You have to be carful that when asking a question that the response is comparing apples to apples.. one guy may say that he had to do '" XYZ" to get his results, but like my question just above, It matters ALOT if he has camber plates and M3 arms etc etc etc..

In all the times Ive gone to the track, fronts were 2 psi higher then the rears every time... and you know how i mark my tires.. perfect roll right to the edge without going over the line. remember Im square set up on Rs3's with nothing but a anti-rollbar upgrade and alignment w/ pulled pins..

Our biggest problem is Front tire shoulde wear. You have to address that first with the correct tire pressure.. once you satisfy that, then you can play with the rear tire pressures depending on how loose you want to be. thats all the adjustment you have... other than your right foot LOL

Remember, you were on Brand new tires at your first auto x ( although you have tracked the car before)

lets see if anyone else chimes in with assistance.

P.s. after your first day, how did the shoulders look... and what was FTD for your class?? just so we have something to gauge by

regards,

Alex

[jvb6806]

everything on car is stock, brakes & suspension. i just picked it up from the dealer last week. the RS3's are 225/45/17.

shoulder wear wasn't bad at all. i can take a picture of them later if you want. it was REALLY hot! we only had maybe 2 mins between each run due to a very small run group and i had a codriver with me. the fronts tires were only good for the 2nd and maybe 3rd run of each session.

we were 2nd and 3rd in a 7 car class about .3 off of the class winning mini-S. i am ok with that considering the tire issues and it being the 1st time out with new car. it is a whole different world coming from the EVO to 128.

it looks like you also have the e93 FSB, that might be why your fronts take a bit more of a beating than mine. i am still up in the air on picking one of those up. i want to see what happens when i get the car out on v710's and hawk pads in two week. i should have something for the mini's then

i am glad to see quite a few people on here autoX. there were two 135's out there yesterday along with my 128.

[DriveHard]

Thanks for clarifying JVB !!!

Yes the mods you see in SIG are actual.. infact i need to add the Titanimum plates. I track more than I auto-x, I auto -x for the fun of it.. just chassing the clock for me.. it helps my fetish need for speed between track events.

The antiroll bar is GREAT on the street.. and seemes to be a definite plus on the track. at auto x, i have found that im breaking the rear free much easier than before and actually induced 2 pretty wild spins once. ( it was in the beginning of the season read cold BURRR the Rs3's need heat )

based upon what you say, i think i can go lower on my rears, gain some more heat hence more traction, and hook up better..

For my set up ( square 225/45/17 also BTW) at auto-x I set up the following

Fronts 36-37 cold ( paddock cold after casual drive to auto x for 5 miles)
Rears 34-35 cold

after first run i have +2lb front and just shy of +2 on the rear

@ 39 psi front 37 rear, I have no roll over on the fronts and i bleed down from there if i have to if the runs are close together and its hot out.

at the track 38 front cold 36 rear cold on the right hand tracks i go to i go 1psi higher on left front to help save the tire.. after a run they come back 40 /38 and they look ok.. outside shoulders are about 15 degrees hotter on left side of car.. left front is about 15 to 20 degrees hotter then inside shoulder .

[pixelblue]

I don't mean to add more confusion to this debate but more pressure (not over inflated) offers more grip than less pressure. I run slightly higher pressure in the back for more grip. Depending on ambient temps I start with 33 cold in front and 34 in back. Hot temps after a session is 39 and 40. last week at the track the air hose was not working halfway through the day and I had to run with slightly lower pressure and my times were slightly down. I don't know but that's what I have read and been told by people with more experience than me

read the section regarding tire pressure in the attached pdf

[jvb6806]

i think the sway bar and perhaps driving style are the biggest differences between our tire pressures. we had to be super smooth going into the corners because there was 0 grip up front after they overheated.

what temp range do you look for on the RS3's? some folks say them come into their own above 150 but i felt that is where they started falling off. i would think with 2deg of camber you could lower the fronts quite a bit from where you are at. my buddy that runs an STR s2k is somewhere in the 32 neighborhood with his, but he has a ton of front camber and a lighter car. he dropped the fronts down to 33psi for the last run in the AM which for the record is too low.

i am sure i will have some better data after the next event, unfortunately i won't be on street tires anymore so it probably won't help you too much. i was using a cheapo inferred pyro to check the tire temps but didn't really have time to record anything due to us hot lapping the car all afternoon.

i just ordered a brand new accutech pyro w/probe and a new longacer tire gauge so all my readings should be dead on from here on out. i know i should be writing all this down in a log book, but i am not sure i want to admit i am that nerdy yet.

[Amalfitano]

Originally Posted by jvb6806

shoulder wear wasn't bad at all. i can take a picture of them later if you want. it was REALLY hot! we only had maybe 2 mins between each run due to a very small run group and i had a codriver with me. the fronts tires were only good for the 2nd and maybe 3rd run of each session.

It's the perils of small club racing... the guys you ran with like the 6 heat day with two sets of run-work-rest, right?

This sunday's event with TSSCC is done in a four heat setup, where hopefully we have enough people where you will only work one heat, drive two, and rest in the other. We also run big enough it's not an issue to give co-drivers a full 5 mins between runs. In any case, I spray,spray,spray with Dunlops. You might not need to with the rs3's though.

Sadly I don't think my car will be ready for Sunday. My stop-gap H&R set rubs, and the ASTs won't be back by this weekend. I didn't think about the fact that Camber Plates alone knock down the ride height a fair amount. The other 1.2-1.5" from the sport springs simply slams it too much. It can't tuck under the fender lip like i get with the coilover setup...

[and 1]

Originally Posted by Lubo

All of you guys running over 40psi in tires must be riding on all season tires.

With 255/40 17 and -2.5* all around what seems to work the best at the auto-X is 32 cold or 34-35 hot for the front. Depending on the course and how you want the car to handle I run anywhere between 30-33 cold or 32-35 hot rear. It all depends whether I need more grip or more rotation.

With the Star Spec on OEM wheel in 225/40 18 F 255/35 18 R configuration and stock alignment, I was running anywhere from from 34-36 cold pressure front and it was enough not to roll over the tires. I ran higher rear as it helped a lot with rotation and evened out the grip between front and rear.

My recommendation would be start from factory specs and add or bleed from there

i have no idea how you can get away with 35psi (or less!) without bending the sidewalls over. either you don't drive very hard or you have some kind of ninja alignment. i wish i could drop 5psi...

last weekend during an autocross doubleheader, i didn't pump my tires back up after the first day, so second day i started with ~32 and figured i'd feel out the pressures as the tires heated up. i had scrub markings down to the lettering on the sidewalls. and this is with 3* of camber

i run 40/38 up front for both autocross and track. i used to run 42/40 for autocross before i did my camber plates.

[jvb6806]

Originally Posted by pixelblue

I don't mean to add more confusion to this debate but more pressure (not over inflated) offers more grip than less pressure. I run slightly higher pressure in the back for more grip. Depending on ambient temps I start with 33 cold in front and 34 in back. Hot temps after a session is 39 and 40. last week at the track the air hose was not working halfway through the day and I had to run with slightly lower pressure and my times were slightly down. I don't know but that's what I have read and been told by people with more experience than me

read the section regarding tire pressure in the attached pdf

there is no magic answer to tire pressures and grip. up or down for more or less grip. it all depends on the temperature of the tire and what the optimum temp range is for each tire and adapting your driving to that.

driving style plays a huge part it tire pressure and temp. if you are smooth you can run lower pressures while keeping the tires in the proper temp range, and not abuse the shoulder. the more aggressive you are the more pressure you will need, or you will have to run a super hard sidewall.

i understand what you are saying, but unless you are actually taking temperatures of the tires while they are being driven you can't really say for sure if the pressures need to go up or down to increase performance. or make alignment adjustments for that matter. of course there are rules of thumb for stuff like this, but individual car data is always best.

the hardest part of keeping front tire temps into range is not over driving the car and making the car understeer regardless of tire temp.

are you autoXing or roadracing? if you are on R1's hose will take longer to get heat into them than autoX R-comps or maybe even RS3's. what temperature were your tires when you pulled off at those pressures? were they fairly even across the tire?