Low speed spinout on wet road - what happened?

[pablo]

I recently spun out under what I thought were low speed (but less than ideal) conditions and wanted the Forum's opinions on what happened:

o Standard freeway cloverleaf (280 South -> 85 North, for those in the bay area)
o Wet road (1/2 hour after rain)
o Stock 91 NSX, manual, 91 alignment specs
o Dunlop SP8050 front, SP8000 rear (couldn't find 8050s)
- 5k miles of wear (still plenty of good tread)
o TCS was ON

I was coming out of the cloverleaf around 30-35 mph, in 3rd gear. and had started accelerating to merge when the car spun. I'm pretty sure I eased off the throttle at this point, but after having spun at lease 90 degrees (only because it took me that long to react).

The one thing I did do (having recently read Bondurant's book) was to keep the steering wheel straight to keep the car in the lane. I feel very fortunate to not have hit anything, and that there was a gap in traffic right at that time. Nothing damaged but my confidence.

The last time I drove the NSX in rain was about a year ago, with the stock Yokos at 4k miles of wear. I'm pretty sure I took a cloverleaf at similar speed and had no problems. Since I didn't think I was driving at the limits, I wasn't paying extra attention, and may have missed a warning sign that the car was about to give.

Was this a case of driver error, bad tires (the SP8000s having less grip in the rear), TCS, or a combination? A low speed, bad weather version of the snap oversteer phenomenon? Was there some warning sign I should have noticed? If I had my wits about me, what should I have done?

I'm planning on going back to the Yokos after I wear out the Dunlops, but if the 8050/8000 mismatch is significantly increasing my chances of spinning, I may want to do it sooner.

Any advice appreciated.

 

[rcarlos]

The Yokohamas are great in the rain. One of the best days I had driving was during a heavy rain. I have the old alignment so the car may be less easy to spin.
Today I relocated some tires I have in storage. The two rear Yokos were much stickier to hand roll compared to the Michelin XGT Z I have on another set of rims.
The front XGT Z have little tread left and were really greasy. Not sure I will ever put them on the NSX.
I would blame the tires in your case.

 

[grippgoat]

What gear were you in? 30-35mph in second gear out of a clover leaf (I'm not clear, were you in the middle of the clover leaf, or were you accellerating as it straightened out?) doesn't seem like it should be anywhere near enough to allow a spin of any kind. About the only thing I could imagine would induce it would be slamming your foot to the floor in first gear, but the TCS should prevent that from doing much.

I'd honestly say it really sounds like there must have been something on the road that seriously compromised traction. I've been doing a lot of driving in the rain lately, and have autocrossed in the rain numerous times, and the car will still pull some pretty good G's on damp pavement. And my autocross experience has been that the car is easier to control with TCS on than off, but that my times are faster with it off.

Anyway, I know how scary it can be to have a spin like that. I had one in my integra once, and was lucky that I didn't hit anything, but I chalk that up to REALLY crappy tires, and pushing the car too much for a new suspension setup and not having it aligned yet. I also spun my NSX once at very low speed, when I was being careful not to use too much throttle out of a corner, but it still went around when I used the gas. I still to this day don't know what caused that. It was low speed like your situation, but the ground was also really weird (turning left from a down-hill road onto a level road).

The thing is, I guess, that in the NSX, depending on surface and tires, once it spins past a certain point, it can be impossible to catch. Maybe I've just gotten good enough at catching wiggles before they become a problem that I don't realize how hard it can be for other people to drive.

-Mike

 

[Vytas]

Maybe you drove over patch of oil or something slippery in that cloverleaf. I had a set of SP8000s on my NSX for about 12K miles with a few trips in the rain. The tires handled great, even on some curves. I now have Yokos since I upgraded to the seven spokers and have been using Yokos ever since.

Vytas

 

[hejo]

Answer: Wet road (1/2 hour after rain)

This is the slickest time on a road because all the oil on the road is bubbling to the surface. Here in Oregon the first rain after a dry spill is when accidents happen. Also being in a turn I'd suspect more oil to be on the surface from less maintained POC.

 

[DanO]

There’s lots of factors that could have led to this event. One could be that there was a somewhat dry patch of road somewhere in the turn so that when your front tires hit it, they gripped really well compared to the rear tires which sent the car spinning. In the wet, a driver needs to be aware of these dry spots and straighten the wheel slightly in these areas to avoid spinning the car. We had this condition this year at NSXPO turn 12 at RA Sunday morning. Turn 12 was wet except a little dry patch and if you were sliding a little bit in this area (odds were that you were ‘cause the track was slick) then when the front tires hit the dry patch near track out, if the driver didn’t quickly straighten the wheel, then the car would spin. There were several low-speed spins there that session (at least 3 that I saw).

The 8050/8000 tire mismatch could have led to the problem too as they are completely different tires, with the 8050 being much more sticky.

As always in spinout situations, the car was simply traveling too fast for the traction available to negotiate the turn, maybe an experienced driver could have saved the spin, or maybe not. A good rule of thumb for driving on the street is to always leave some traction in the bank in case a situation arises where you need to lift or go to the brakes. Only experience behind the wheel, preferably in a controlled environment like a race track, can one feel comfortable with where these limits are. Fortunately, nobody was hurt and I think it’s smart of you to try and figure out what happened so it doesn’t happen again.

Advice:
Have your alignment checked. A messed up alignment can cause the car to dart around unpredictably, especially in the wet.

When driving with mismatched tires or in any other situation that compromises traction (like in the wet), be extra vigilant and watch the speed in the corners. Remember, as traction is reduced, cornering speed is greatly compromised.

If you are interested in finding the cornering limits of your vehicle, then enroll in a few (it will take several to get the feeling) drivers education schools hosted at your local track. Gaining this experience is an incremental process and can take several years.

DanO

 

[pablo]

Wow. Thanks for all the great responses in such a short time!

Sounds like the consensus is that there was probably something unusual about the road, beyond just the rain. Very possible, as this was one of the first rains of the season.

As you can tell, I've always wondered how much the 8050/8000 mismatch has compromised the performance of the car. I've had them for 5k miles now and aside from this incident have not had any problems. Still, I plan on going back to the Yokohamas if only for peace of mind. I plan on attending driving school this summer and want to make sure I'm not taking any unneeded risks.

For now, I think I'll try to avoid driving in the rain, and keep practicing in Gran Turismo 3.

Thanks again.