I have zero wet condition race experience. If your car is set-up to your liking for dry pavement with dry tires, will it react the same if the track is wet on dedicated rain tires? Or does the wet magnify set-up problems that one either does not realize one has or has gotten used to? Or if racing wet you basically start all over with settings?

 

1st thing I do is disconnect my sway bars and put my Hoosier wets on. Other than that I have no adjustments possible to make except with my feet..

 

YES


Actually all of your presumptions are somewhat correct. Your car will most likely have the same balance in the wet as it did in the dry. And yes, it certainly will magnify problems that are being masked by grippy tires; i.e. minor understeer may become major, and some twitchiness may become very abrupt breakaway. And yes, if you can readjust settings, then you do want to.

The basic thing is that you have so much less cornering grip in the wet that your car feels like the springs are way too stiff, which they really are for the amount of cornering force that you can generate. So your car does not lean, and is therefore really hard to read in terms of tire breakaway. Anything that you can do to reduce the roll stiffness would help; disconnect sway bars, soften shocks etc.

 

Stay off the painted curbs and away from the apex, especially where the track slopes toward the apex. It not only tends to collect water, but all the oil, rolled up rubber and gunk that washes down there. Typically being off line gives you the most grip in the wet.

 

Everything changes in the wet. Much of what your car does, in the dry, is magnified. BUT there is less weight transfer so sometimes you get very different handling vs. dry.

In an ideal world here is what you should do for a wet race:
Soften spring rate.
Soften shocks.
Disconnect sway bars.
Shift brake bias to the rear. (Sounds backwards doesn't it. That is because there is less weight transfer.)
Raise ride height if the car is very low.

In the real world, do as many of these as you can. What you really want is a car this is predictable in changing conditions and that means substantial understeer. That setup lets you go into a corner, saw on the wheel a bit and feel how much grip there is, all the time. With oversteer, you are fighting the tail and never really learning how much grip there is until you exceed it and spin. Also with understeer, if you do overcook a corner, you have a chance to recover instead of spinning off track.

From a driving perspective, you always have to hunt for grip. Shiny parts of the track tend to have less grip - always look. Never assume the corner is the same as it was last lap. There are many times we find ourselves on a track that is wet on part on dry on part and it stays that way for many laps.

 

+1

this is for a bmw, so it may be worthless info here ....but i usually start with disconnecting the rear bar and pulling a good bit of rebound out of the shocks all around, then go from there....i try to setup the car so that it tends to understeer at corner entry transitioning to oversteer at corner exit (once you exceed the grip limits)...easier to control going in to a corner but won't plow off the track as you are trying to accelerate off the corner...square off the corners more and try to maximize exit speed (slow in, fast out)

 

Like Dave said...try to maximize your time spent pointed straight. That said, you may end up taking every corner differently. The "fast" line may not make ANY sense from the geometry perspective that you've been taught in DE's, etc. All the way around the outside may be the fastest line in the wet. Or all the way to the inside under braking and crossing over the track at apex to the outside for exit. Or, in some cases, the traditional line may just be the best way to get through a corner. Experiment every time you go around the track until you find what works best.

 

Very good advice here.
My .02 worth:
My car is set up well, rain vs. dry (I take no credit), so I don't change anything except tires.
I would go buy Hoosier rains, not change anything else, and go learn to drive in the rain. Rain separates the smooth drivers from the not so smooth. I wouldn't go changing things until I felt comfortable the car issues weren't driver issues. I don't think I'd go practice at a race, though, because you have the added disadvantage of other peoples skill or lack thereof. It's hard to "schedule" rain practice, I know. Just have rain tires and don't be afraid to get on the track. Rain takes lots of practice and slow, smooth technique with the steering wheel, gas, and brakes. I firmly believe that driving in the rain makes you a better driver in the dry.
Other than that, I can't add much more than these guys have. Just err on the slow, smooth side.

 

hi guys.

i am one of the guys who ALWAYS goes out during wet sessions; i am fairly well known at the DEs for being 'that rain nut!'. i've been out when it was only me and a few other cars, circulating around for 30 mins. then i came in, and no one else was going out for the next group (black or white) and i will turn around and go right back out!

i FIRMLY believe that learning to drive well in the wet will make you not only a good 'wet' driver, but also a great dry driver....

i agree with what has been said above, especially about driving different lines in the wet. i typically will 'recon' a wet track the first 3 laps or so, trying the surfaces all around; inside/outside lines, braking areas, etc. as said before, certain corners will hide grip in different spots, when wet. i try 'rim shotting' the turns, hugging the inside of the corner. i try braking in the traditional spots, and all the way on the inside, too. once i find where the grip is best, i make mental note of it and try to hit those spots, lap after lap.

as for technique, i very much subscribe to the 'gentler, softer' method of driving in the wet. BTW, i don't own a true set of 'wets'; my rain tires are full treaded Toyos (my drys are Hankook Z214s). i try not to shock any of the controls; i squeeze the brake softly, and then ease into it. same with the throttle, i ease into it and squeeze gently. i keep my hands very 'quiet', and minimize the amount of steering input. i shift gently, and typically 1000 rpm short of my dry shiftpoints. depending on traction, i may 'one gear higher' my way around the track, slightly lugging the slower corners in a higher gear.

when i am 'clicking' on a wet track, and really putting in some fast laps, there definitely is alot more slip angle happening than when i am running very fast dry laps. there is no flailing, or abrupt movements of the steering/brake pedal/throttle. there is just alot more slipping and sliding through the turn.

i find that many, many many (!) students are scared to death when driving in the wet (some can't even be cajoled into going out when it is raining). i try to talk them into going out and giving it a try, at a very reduced pace. let them get a bit more comfortable with the car, and its dynamics, at a very reduced speed. this really seems to help with car control, and also confidence, when we go out for the next dry session.

i typically am tracking FWD cars; but they are both set up to be as neutral as possible in the dry. take my honda for example: stiffer rear springs than front springs (about 50% stiffer). no front swaybar, and a large adjustable rear swaybar. adjustable shocks, set softer on front, and harder on rear. in the rain, i prefer to soften the rear shocks a few clicks, and also soften the rear bar. this is not a 'must do'; many times i have been out on track and run at racepace, with the complete dry setup on the car; it is just easier to run all-out laps with the rear softened up a bit.

i also typically run the cold tire pressures a bit higher for my rain setup; the tires don't heat up very much, and therefore don't 'grow' like they do when it is dry. my dry cold tire pressures are 28F/32R. for wet cold tire pressures, i usually run 34F/36R.

the only other insight i can give is that i have the most 'fun' driving a RWD car in the rain.... it is typically not any where near as fast laptime wise, but is FUN! (my 1996 Ford Mustang Cobra was a total hoot in the rain!). my FWD cars are really fast in the rain, when i ask them to be. but; huge but here -- nothing is as easy to drive fast in the rain as my Mitsu EVO. that car, basically totally stock suspension/tires/brakes was INCREDIBLE in the rain the two times i drove it in wet sessions. as i went around, it felt as if everyone else was on a cooldown lap, and i was on a flyer. it seriously felt like i was 'cheating' compared to all the other cars out there.... so easy to put the car whereever i wanted it, and so easy to apply power and correct the car's attitude.... it really is 'an unfair advantage'!!!!

todd

PS i typically pray for rain on raceday. it equalizes out my 'backyard mechanic built' equipment against some of the high dollar stuff that shows up in my class. everyone else out there is boohooing about the rainclouds, and i am floating about 1" above the paddock!

 

We don't get much rain here in Texas, relatively speaking, so we have fewer chances to practice rain driving. However, like many of you, I also try to take advantage of it when we do have those conditions. Unless there is mucho standing water, I run the same shaved RA1's that I run in the dry. I'll soften front sway & disconnect rear, and run all 4 dampers on full soft. I love how these conditions really help your mind focus on what the car is doing every single split second!

 

Like Todd, I too LOVE driving in the wet. SMOOTH is the name of the game. I would suggest not going crazy with adjusting your car, unless you have slicks, then I would change to treads since slicks would be dangerous.
A similar anology would be from going from slicks to street tires. The wet just limits your traction even more. The lines on a track can also change drastically. Mid-Ohio from 3 or 4 years ago before the repaving comes to mind. In the dry, the concrete was your friend with plenty of grip, but not in the wet.

The best advise is to go out there and work up your speed slowly...and HAVE FUN!!!

 

I change to street tires at fairly high pressures in the wet and spend the first couple of laps finding out what grips and what doesn't.

I find that, on tracks that have not been resurfaced lately, the rain line is pretty much whatever is not the dry line. The dry line gets slick as elephant snot from everybody turning there. At LRP, if you just stayed off the concrete at the apexes it worked fine.

Smooooooothhhhhhh is also greatly rewarded in the wet.

Many of my racing companeros won't drive in the wet.....more seat time and less traffic for me.

 

What do people think about wet tire pressures? I read above someone increases tire pressure. In SM, we drop them by a lot...on the order of 10lbs and this works for our light cars.

 

Depends on whether you are using a "real" rain tire or not IMO. A real rain tire is designed to make grip using it's soft compound, and thus you need to run whatever starting pressure gets them up to optimum pressure with some heat in them. Depending on the construction of the tire, their optimum pressure may be different from the harder compound slicks you normally run. It's best to talk to the tire manufacturer to find out their recs.

If you are running a R-comp of normal compound (like in SM), dropping the pressure lowers the spring rate just like removing the bars, etc. I could see some benefits to do that in order to make more grip and slow down transitions, as long as you don't drop the pressure to the point that the sidewalls roll too much and distort the tread. It also depends on tread depth...in heavy rain, you need a certain amount of air in the tire in order to allow the tread to best do its job of shedding water.

When you say that you drop pressures by 10 pounds, are you referring to starting pressures or hot pressures?

 

if you have brake proporting, I'd recommend turning down the rear brakes.

like others said, usually the wet line is anywhere but the dry line. typically the outside of the track.

Do Hoosiers last any better in the dry? (its been a long time since I bought rain tire..)

-I always ran full tread Toyo RA-1's at a rain tire, 'cause they could take a drying track... Hoosier were faster but would burn up after 2 dry laps...

in Fla, very typicall to have a heavy squall for 10 min, and 15 min just a few puddles.

-which hoosier is everyone running, and how long will they last on a dry/ing track?