Wet setup
 

This weekend coming is my first time in the car on a wet race weekend. Been my luck over the last 3 years that all days have been dry. I would love some tips what I can do to set the car up better for the weekend.

In terms of adjustment, I've got front / rear swaybars and damping on my suspension, and of-course tire pressures.

Any feedback appreciated.

In the midwest, the common SM setup was to disconnect an endlink from each swaybar and add a couple psi to each tire. Then, lick the stamp.

Depends how motivated you are... Add a few psi and book it if you want to keep it simple. If you're motivated you can soften the sways and shocks. Personally I wouldn't disconnect the former tho, makes it too unpredictable when the car slides (unlike on snow).

Driving-wise, start slow and get a feel for the grip... Grip level can vary A LOT from track to track when wet, some are borderline undriveable. Try to drive off the racing line where you can get away with it, experiment.

A good dry setup is a good wet setup. This is all extremely dependent on what tires you will be running, how wet the track is, and how good you are at driving in the wet.

You usually never have enough time to actually dial in a wet setup due to the track NEVER being the same. You always hope for a track to dry out, hence leaving a dryish setup on the car...

A very good tip for driving in the rain is that you can easily do about 70% of what you could do in the dry in a straight line. So braking and acceleration should be very similar to the dry. Its when you start mixing braking and turning or accel and turning is where you have to have to be the master. Always do the full session in the rain.

I hope all my competitors take this approach.
There is most certainly a different optimal setup in dry vs wet. Ideally you would literally change everything to adjust for the lower grip level. I would recommend reading "The Art of Racing in the Rain" or anything from Ross Bentley.

In order of simplest to most complex to adjust:

1. Increase air pressure - Tires will not heat up in the rain, so pressure increase will be much lower.
2. Reduce sway bar rate - Less weight transfer due to less lateral grip. This is also super easy. The SM guys start with disconnecting the rear sway bar first.
3. Reduce spring rates & damping - Less lateral grip means you can setup the suspension for more mechanical grip, rather than a compromise designed to keep the suspension off the bumpstops.
4. Decrease Camber - Less tire roll / wheel deflection due to lower lateral loading, so less camber is required to maintain the contact patch. Also helps hydroplaning resistance.

Thats a great list.

For someone who has never raced their car in the quote "3 years" they have had it in a wet session, I would still do the baseline dry setup. Drive the entire session, take video, look over data, take notes, and adjust accordingly.

Reason you cannot say exactly what to do is, you don't know how much water, how the track surface is, how the drainage is, how fast the car is, what tires, driver skill, etc.

Until you know what the above equates to the handling of the car, run it in the state you know. :2cents:

...did you just tell a professional motorsport mechanic and driver to read a Ross Bentley book?

:party:

Not sure what good making myself ugly cry is gonna do about developing a good wet setup, but ok...

For the OP who is looking for tips on racing in the rain, I would say those are decent options to get his feet wet.
I worked with Ross Bentley less than a month ago, so yes, I would recommend the OP read Ross Bentley.

Despite usually qualifying well in the wet I find our car to be way too stiff for proper wet weather handling. When it is this stiff the catch from letting go is VERY sudden.



So can you expand on your philosphy here?

I stand to be corrected by experience/knowledge but for the record, I would prefer to run a softer damper, spring rate and bars. Being a 1-2 man team (inc driver) and not pro with a budget AND very short times between races, We make do with wet weather tyres around 28 psi cold and soften the suspension approx 1/2 to full.

If we have time we will also raise the ride height in the (naieve?) attempt to reduce the camber and improve feel and the grip / no grip transition..... YMMV.

But in the end it is the driver, being confident, smooth and precise.

Barend, I will be there Sunday racing in Improved Production if I can be of any help.


edit: Totally agree with the following, great advice.

A very good tip for driving in the rain is that you can easily do about 70% of what you could do in the dry in a straight line. So braking and acceleration should be very similar to the dry. Its when you start mixing braking and turning or accel and turning is where you have to have to be the master. Always do the full session in the rain.

When I say a good dry setup will be a good wet setup, I am inNO way saying that it will be optimized and or perfect in the wet. Hence why I said good. :)

There are a lot of tire manufactures that make rain tires with softer side wall construction, super soft compound, etc. So for this reason I say try the dry setup first. You could be easily surprised that the car is decent AS IS. When you get a better idea on what path to take, you make an educated change to your best knowledge on chassis setup. Everyone is acting like overall balance is going to stay the same with making changes to soften the entire chassis, not always the case...

An example I have had both in cars and out of the car, where you/driver have the rear axle over powering the front with grip. This is not a favorable chassis balance to run in the rain. No turn in, mid to exit snap over steer when back to throttle (to much steering input), but decent in high speed. So ways you can fix it is softening the front axle in some fashion to gain grip. If we softened the whole car then the problem would still be here. Just an example and not always the case. I am trying to get the point across of understanding what is wrong, rather than just making a change because you have the capability and the ground is wet. Not every situation is text book.

My first wet session would be:
-current dry setup for that track
-24-28 PSI all around for tires
-tape on the grill for water temp

Mid session/second session:
-Tire Pressures as needed
-Damper (canister pressure and or clickers) as needed
-ARB's as needed
-Aero for mid-high speed stability and since drag is most likely not an issue
-Its not wrong to think about changing springs and or camber, but damn do you have to be FAR off to get to that point.
-Hopefully the rain went away and now your back to your dry setup hauling the mail with just wheel change. https://www.miataturbo.net/images/icons/icon6.gif

Back to the driving, because I think there is more to it...

In the wet everything likes to get asked what to do. So you ask the brakes, hey can I stop this car? yea sure! then you get into it hard. Same thing with steering, hey can I turn now? Ok lets go!, but what about the throttle?....to soon and you get the quick wiggles. This is where your skills are honed and or honored on how well you can balance your maximum traction and transitions of loads. Smooth is key with your feet and hands.

When the time calls I always like to square things off or do a" diamond". This allows for later braking, sometimes past the normal dry apex. Then a tighter, more aggressive turn in. The goal here is to actually get the turning done quicker and more aggressively, so the car ends up "straight" quicker. We can then get back to the power sooner and drag race off to the next corner.

Driving the whole session to find the grip. Try the dry line, try a car width off line, try the middle of the track, try the outside. You would be surprised on what works sometimes it only takes a little bit to make up a bunch of time in the wet...

Make sure to take notes, get in car video showing the steering wheel, and have data. You want all this to be able to generate a setup quicker (if needed).

Excellent break down thank you!

your thoughts on raising ride height for weight transfer etc....?

I prefer to keep the car at its optimum ride height. Not saying I wouldn't change ride height on a particular axle to get the balance correct.

Thats the cool thing about racing and cars, there is more than one way to get it done.

Try it and back to back it, if its faster then don't tell anyone. :)

My Cliffs notes response:

Much higher base pressures than dry set up.

More rear brake bias

Race set up should be very free, like qual set up.
- An understeering car in the wet is miserable and dangerous. A car that is neutral to slightly free can be positioned with the pedals and driven quickly.

Experiment with all areas of the track surface during practice. Spend some time after those practice sessions thinking about the various surfaces and how they reacted to standing water, wet and dry.

If you decide on a wet specific tire and the race develops a dry line, remember that you might have to deliberately drive in the wet in some areas to keep the rubber from overheating.

Lick the stamp

Thanks everyone for your feedback and suggestions.

Here's what I did.
- Ran brand new NT01's, Thanks for the suggestion Mark
- Softened up the car as much as I could, swaybar and dampers
- Set tire pressures to 28psi up a few psi from where I normally start out.
- Adjusted driving style

How did it go?
- Session 1, was really wet, puddles and little rivers on track, Session 2, there was a dry line forming but track was still cold
- Tires never got up to temp in first session, we only had 4/5 laps (it's a TimeAttack event), just about reached 30psi. Drying session I let out a 1.5psi, but I should have dropped maybe 2.5-3psi as the tires ended up a bit hot at 34psi
- I ran way too much camber ~4degrees, pyro also reflected this when the track started drying towards end of the day
- Time was competitive but not outstanding
- Learned heaps