Driving in the rain

[Bash]

Ladies & Gents,
know I know that some of us "baby" their cars so much that they don't take them out if its overcast...not me man, I have it to drive it!
Planning on taking a drive to Augusta GA today & showers expected. My 86 gets a little tail happy as well as misses due to water thrown up on the dizzy.
Any advice apart from the obvious, slow down & carry WD40?
Bash

[GH85Carrera]

If it there is water on the road and it might even possibly be 1/16 inch of rain, slow down to 55 MPH max. Tires will hydroplane at the square root of the tire pressure x 10.

Easy example: 36 PSI tire, has a square root of 6 and then x10 =60. At 60 you will hydroplane. One reason the big trucks can go faster is they run 90 PSI or more. With a 90 PSI tire the square root is 9.48 x 10 = 94 MPH. Hopefully none of them are going 90 in the rain. They may not hydroplane but the traction on the road is lowered for everyone.

[Bash]

Ah, math.
Never a strong suit. Any "dry" tips for the engine?

[GH85Carrera]

I have an 85 Carrera. I have driven it for many long hours in rain on road trips. It seems to rain on me every year on my road trips. I drove clear across Tennessee (east to west) in a solid rain once. No issues at all.

I have OEM plug wires and and distributor cap. I dose the inside of the cap with a light coat WD-40 before I button it up. I have never had even the slightest problem with rain causing a problem.

I did have a weird misfire after washing the car once. It was not the ignition system, it was one of the injectors. I replaced it and that cured the issue.

[Dantilla]

Here in the Seattle area, if you won't drive in the rain, the car becomes no more than garage clutter.
The factory tested the car while being soaked. It rains in Germany, after all......

The hydroplane thing is true- I have an early Miata that usually has 26-28 psi, but there is a dramatic improvement when wet when the pressure is increased to 35 psi.

[sand_man]

My 993 is a daily driver. Sees plenty of rain. I am fortunate in that I am able to work from home when we get snow/ice here. These cars don't melt. I am a conservative/defensive driver and much more cautious in the rain. I worry about the idiots around me. Never ceases to amaze me at the reckless abandon people seem to drive with, in crappy conditions. Just slow down a little...SHEEEESH!

[ckelly78z]

I just yesterday had to drive my 04 GT mustang in a driving rain 60 miles. Make sure to turn the corner before accelerating (got sideways a couple times) and just don't really push it, brake early, and stay away from other cars.

[onewhippedpuppy]

When I had my 1970 911T it was my daily driver. Rain, snow, storms, everything. Toss some good tires on and away we go! The 911 is an immensely capable car in bad weather, the rear weight bias gives you excellent traction even on slippery roads. Assuming of course that you don't drive like a moron, in which case the rear is even happier to pass the nose.

[Chocaholic]

I'm no help. My 911 hasn't seen a drop of rain in years.

[sand_man]

Even my 930 with mods, was excellent in the wet. Very solid! Of course, one of those mods eliminated the light switch "widow maker" 3LDZ turbo in favor of a better performing K27-7200HFS turbo, which spooled much more predictably.

[masraum]

I used to have an 88 targa and drove it daily train or shine. I also never had any problems due to rain, and I've driven through torrential downpours and even had water come up the hood between the headlights. My new boxster is also a daily driver.

[ckelly78z]

In all fairness, a good set of tires makes ALL the difference in wet conditions. My Mustang mentioned earlier has about 1/3 tread of new tires, therefore a handful in the wet.

[pavulon]

and get a diesel!

[Rinty]

Originally Posted by sand_man

My 993 is a daily driver. Sees plenty of rain.

I had a 993 for a number of years, and drove it in heavy rain on a couple of trips with no issues, whatsoever. You could lean on it pretty good in the corners, and there was no slippage. It would hydroplane a bit in standing water, but was easy to control. The tires were Sumitomo III's.

After having heard many stories about driving 911s in the rain, I was pleasantly surprised.

Perhaps the trailing arm cars are harder to control, but I don't know.

[masraum]

Originally Posted by ckelly78z

In all fairness, a good set of tires makes ALL the difference in wet conditions. My Mustang mentioned earlier has about 1/3 tread of new tires, therefore a handful in the wet.

Absolutely, high performance, summer tires grip better in dry and wet weather than other tires. The only thing you MIGHT have to worry about with max performance summer tires is increased propensity to hydro-plane, but that'll vary quite a bit by tire model.

[Amail]

Originally Posted by GH85Carrera

If it there is water on the road and it might even possibly be 1/16 inch of rain, slow down to 55 MPH max. Tires will hydroplane at the square root of the tire pressure x 10.

Easy example: 36 PSI tire, has a square root of 6 and then x10 =60. At 60 you will hydroplane. One reason the big trucks can go faster is they run 90 PSI or more. With a 90 PSI tire the square root is 9.48 x 10 = 94 MPH. Hopefully none of them are going 90 in the rain. They may not hydroplane but the traction on the road is lowered for everyone.

This must be an oversimplification, no? Wouldn't a bald tire at 60 psi hydroplane before a treaded tire at 36 psi?

[Bash]

Well we made it
Do the words"cats & dogs" mean anything to you?
The trip took an extra hour & a half. Some motorists were pulling over for a spell
A few things learnt
1. If you drive to the conditions, theses cars are great
2. You need to take a rag, ventilation sucks
3. SUVs are false security
4. WD40 rocks
5. There is nothing like a 5 year old a sleep in a car seat in the driving rain to help you understand that arriving on a set schedule is over rated

B

[masraum]

Originally Posted by Bash

2. You need to take a rag, ventilation sucks

I never had a problem with mine, you've just got to understand how it works. Sometimes, it's even optimal to have both the heat and AC on.

[Bill Douglas]

When I was young and silly I was cruising along at about 160kmh - that's about 100mph, and I saw a sign that said "warning surface flooding". I looked around and could see big puddles on the side of the road, but the road was dry, so I carried on as I was.

Whooo, I came over a slight ridge and there was a pool of water for about 120 or 150 meters. Luckily I had the sense not to brake and just kept going. Physics as they are kept the car going straight ahead and it sailed (pun intended) over the top fine. It did a bit of a correction when it hit dry road at the other side, but not enough to throw the car around.

Umm, not the sort of thing I would want to try again.

[onewhippedpuppy]

Originally Posted by Amail

This must be an oversimplification, no? Wouldn't a bald tire at 60 psi hydroplane before a treaded tire at 36 psi?

Yes, because tire design also plays a huge part in your ability to handle wet roads. All other things being equal I think Glen's comment is correct, because higher tire pressure reduces the surface area and also the tendency to "float" over wet surfaces.