Rain track setup

[Howard Jones]

OK my English brothers. Give me your knowledge on a rain setup for A GT40. Soft rebound on shocks? Min rate on Anti-roll bars. How about tire pressures?. Up from warm/dry day? Help!!

Other wet car related advice? I'm in California remember. We don't get wet here. Well... not much anyway.

Track day on Friday, gonna rain for sure. Track temp is gonna be in the low 50Fs.

[Russ Noble]

Howard,

More important than all that is wind the bias off the front brakes. If you don't know how much to go, it'll be trial and error till you get it right. For suspension setup, softer everywhere gives more feel but it's not going to make that much difference to times. Brakes is.

Good luck,

[Ron Earp]

Originally Posted by Russ Noble

For suspension setup, softer everywhere gives more feel but it's not going to make that much difference to times. Brakes is.
Good luck,

I don't know if I'd agree with that based on my (limited) rain experiences. Malcolm and I had his GT40 out at Donnington in the pouring rain for 4 hours. With his normal dry setup the car was just about undrivable in the rain - no bite and she wouldn't point. But, with the front roll bar disconnected and a soft setup it was quite drivable. No changes were made to the brakes at all and I felt the chassis setup was far more important.

The same is/was true of the Spec Miatas - we disconnected roll bars at Roebling and did just fine, no changes to the brakes were needed.

Ron

[Andy Besic]

I agree with Ron. Disconnect the sway bars. I love racing my Alfa in the rain...it's the only way we can beat the Lotus's and Porsche's. I found that using a gear higher everywhere can help with throttle control. Most important thing is Rainx and anti-fog on the windshields. I have seen more races lost in coupes due to no visibility than poor set-up.

Some tracks are different, but you will typically get better brake grip off the racing line. Every corner is different as well, but I have found there is usually alot of grip just wide of the racing line but not quite in the "marbles".
Racing in the rain is the best way to learn car control/balance.

[Ron Earp]

Originally Posted by b6gt40

control. Most important thing is Rainx and anti-fog on the windshields. I have seen more races lost in coupes due to no visibility than poor set-up.

That is about the most important thing, no joke.

Jeff and I stupidly sent a new driver out at an SCCA driver school in my Z, in the rain, and with no anti fog on the inside. While we got the chassis right, soft springs, bar off, the new racer to be couldn't see for squat and off the Z went into the wall. Not his fault, ours for not thinking all of that through and teaching him more about the wet driving and so on.

R

[Russ Noble]

Sorry guys,

If you find dry bias OK in the wet then you're braking much too early in the wet which will not help turnin either. Either that or you've got too much on the rears in the dry.

Once in the corner then it's just a balancing act of gentle weight transfer, which is made more progressive by softening the suspension, but it doesn't really gain anywhere near as much as correctly set up and used brakes will.

I agree with the anti fog.

Cheers

[Howard Jones]

Russ, The brakes on my car are the most developed, effective, and by far the biggest part of the performance of my car. I believe that I can only improve brake performance from here by running slicks. My fronts lock just at about 95% of the rears max grip. Feels perfect to me. So assuming my "dry" setup is optimal then are you saying I should reduce brake effort at the rear in relation to the front in the rain or should I bias it so the rears lock first? I'm not too sure about that. But if it works I'll give it a try.

I think that since I have never really pushed it in the wet I would like a understeering car rather that a oversteer condition.

Ron, Rain-X on the inside and outside of the windshield? How about the lexan? will it work on that?

I think we all agree on a soft setup on shocks and anti-rollbar. How about tire pressures? I would think that it will be nearly impossible to produce any real heat in the tires. So pressures should remain constant at the original pitout pressure. So should I run pressures at the (hot)target pressure ?

Aero aids at max downforce, correct?

[Russ Noble]

Howard,

No. In the wet you need more braking on the rear.

In the dry you can brake harder, because you have more grip and can get more weight transfer onto the front wheels, the harder you brake the more you can put on the front. I always set my cars up for maximum straight line braking with the fronts locking just before the rears. Anything else and it becomes too loose during turn in with the back wanting to step out. I think you've got your dry setup sussed.

In the wet you cannot get anywhere near as much weight transfer so relative to dry conditions the rears can be doing more and the fronts have to do less. In the wet with dry bias you will lock the fronts long before you approach the maximum retardation that is potentially available.

In the wet you want the same scenario as the dry with the fronts locking slightly before the rears. The difference to achieve that (every setup will be different) is likely to be a couple of turns of the balance bar to move the pivot point in the pedal sleeve closer to the rear master cylinder.

Hope that helps.

Cheers

[Dutton]

Howard,

Re chassis set-up, the guys have pointed you in the right direction.

When on track, suggest driving off-line at the VERY least in the turns. When driving on line, you'll usually find the surface to be a bit more polished; move even a foot off line and the track is far more likely to be a wee bit rougher, offering a fair bit more grip. Another throttle return spring wouldn't be a bad idea either.

Looking forward to reading about the adventure!

Best,

T.

[Ross Nicol]

Yes more brake bias to the rear in the wet. Reasons being less weight transfer from rear to front and lower speeds. I've had my best results in the wet up to this point but agree about the vision problem, very scary.

Ross

[Ron Earp]

Originally Posted by Russ Noble

Sorry guys,
If you find dry bias OK in the wet then you're braking much too early in the wet which will not help turn in either. Either that or you've got too much on the rears in the dry.

As with anything racing related, your mileage may vary.

In some the race cars I’ve had experience with there is no brake adjustment as they are spec cars and it is disallowed. One has to make do with what they have although the sway bars can be adjusted. On the little Miatas race kit sway bars have enough adjustment to make a difference in the wet weather handling characteristics.

Malcolm's GT40 did have bias adjustment but the braking had nothing to do with the on track handling that I described. The handling problems we experienced in the GT40 at Donnington in the rain were present in non-braking situations. The transformation of even simply disconnecting his front roll bar was absolutely amazing. The improvement was simply akin to night and day. I don’t doubt that some braking bias adjustment could have improved his car in the wet, but I’m pretty sure we got more “bang for the buck” on the adjustments we did. Might have been just his car setup from the get go.

The brake bias knob in my Z isn’t the only thing I reach for when the track gets wet. The first thing I do when the track gets wet is try to decide “do I really need to go out this session”. And, if the answer is yes, then put on the best “treaded” tires I have. Many racers INCREASE the tire pressure a bit over the dry temps to round the tire profile a slight bit and reduce hydroplaning (Hoosier recommends this for their DOT race tires I think, check their webpage). Bear in mind I’m generally in the boat of using non-rain race tires and I’m not sure the pressure increase would be all that important if you running a full-on rain tire. The DOT Hoosier R6s are really horrible in the rain, the DOT Toyo race tire is considerably better.

After some tire juggling and bar setting then you’ll need to make sure you can see. With respect to the anti-fog I have found through trial and error the regular Rain-X does not work on the inside. But Rain-X does have a inside fogging product that works like a champ. It is harder to find though since the days of non-AC defrosting cars are gone. We have a vendor at the track that carries it and I was able to buy it from him on a rainy test day at Roebling road. I don’t know if this stuff works on Lexan but it’ll work on your glass front windshield.

Let us know how you get on with your adjustments and be safe!

[Ross Nicol]

Yes good tires are critical for wet weather.I have the luxury of a blade adjustable front bar so I can go full soft very easily.Driving in a higher gear is good but I love testing the grip in 2nd gear out of a tight corner, however fast sweeping corners are scary too.Anyone care to say they feel 100 per cent confident in the wet? One thing though all drivers are in the same situation. Sounds like Malc must have his forty fairly stiff for the dry Ron or his wet tires are crap.

Ross

[Ron Earp]

Originally Posted by ross nicol

Anyone care to say they feel 100 per cent confident in the wet?

Ross

Hell no!

With my Z I've got 400/350 front and rear springs, a front bar with a lot of adjustment, and brake bias adjustment. The bias adjustment does a little, but the front bar adjustment does a lot. Might be the way the brakes are since they are drums in the rear with a proportioning valve, but it helps some. We can get the car to do okay in the wet but no matter what you'll need to watch that power application as you mention.

Out of all the things the biggest difference I've seen was between the Hoosier R6s and the Toyo RA1 - you'll be convinced the Hoosiers will lead to death and destruction in the full wet while the Toyo's are drivable and give some confidence. I'd like some full on rain race tires but it doesn't seem to be wet on race weekends a whole lot here and the rain still bothers me a bit. I don't have enough wheels either. I've got ten wheels, eight shod with Hoosiers, two with Toyos (not on purpose), and I need to get two more wheels to make a full set for some rains. We've had a drought here in the Southeast for most of 2007, now watch 2008 be the wettest year on record since we've been discussing wet weather driving!

R

[Malcolm]

When Ron drove my car it was seriously wet, the wettist I have ever taken the car out in. Plus at Donnington the airport/planes nearby drop an awful lot of Avgas on the track to make it more interesting. Wheelspin in any gear followed by aquaplaning to your hearts content. Great fun!

Back then my car was overly stiff in set up, mainly for track use so not good on the road. Also running rubbish in the wet Dunlop Post Historic tyres and fixed rate sway bars and no brake bias adjust. Now running rising rate springs, dual rate dampers, fully adjustable sway bars and Avon radial rubber. However brakes still not adjustable although the parts for that are on the shelf.

Agree with all the comments above but for me, I won't put in adjustable brake bias until I have a guage for checking the settings against. My kids love getting in the cars and fiddling.....

[Ron Earp]

Originally Posted by Malcolm

Agree with all the comments above but for me, I won't put in adjustable brake bias until I have a guage for checking the settings against. My kids love getting in the cars and fiddling.....

I thought you had some brake bias in there, my bad. Good thing we didn't try to adjust it huh?

Line pressure gauges can be useful. Jeff and I used one to figure out a front brake problem on his TR8 that was due to a slightly collapsed brake flare. Hard to find without the gauge.

Ron

[Howard Jones]

Great.

1. full soft on front sway-bar or disconnect all together.
2. full soft on rear bar or disconnect.
3. Much softer on shocks
4. Rain-X outside front windshield.
5. Find inside Rain-X stuff
6. I will use new street all weather tires. Z rated Sumotomos
7. I have a bias valve in rear brakes so I will turn up rears to get a rear bias.
8. I will run my normal tire pressures 27F 28R and see how it goes, don't expect much from tire pressures.
9. TAKE IT EASY

I will have a on board video cam, we'll see how it looks and if I can, I'll post it. I have never done a video posting before so we will see.


Thanks everyone

[Ron Earp]

What'ca gonna do now if it doesn't rain?

[Andy Besic]

Howard,

I generally agree with your list, however, this is a fantastic opportunity to learn about set-up AND driver input. The nut behind the wheel is usually what could benefit from the most adjusting. If you have the track time I would start with your current dry settings and make one change at a time. You will learn more about your car, how to set it up, and how to drive it in different conditions. The best drivers can still win races in poorly set up cars, because they know how to adapt to changing conditions.

Think slow and have a blast!