Snap oversteer

crzyone · Post by **crzyone** » Tue Jan 09, 2007 3:58 pm

Found this vid on youtube, good example of snap oversteer. Looks almost impossible to recover from at these speeds.

http://www.youtube.com/watch?v=FEkihkT1B3Y

Series8217 · Post by **Series8217** » Tue Jan 09, 2007 5:10 pm

repost

crzyone · Post by **crzyone** » Tue Jan 09, 2007 5:13 pm

:doh:

Post by **eHoward** » Tue Jan 09, 2007 9:42 pm

perfect. I was looking for a good video to prove that Fieros own Zs in the twisties

TrotFox · Post by **TrotFox** » Wed Jan 10, 2007 1:22 am

I had something similar happen to me on the freeway. Guy in the middle lane decided to take a right hand exit as I was aproaching on the right. He was doing ~70... I was around 90 and inexperienced with the ways of high speed handling! I tried to make the exit but under heavy braking you can guess what happened.

The good news is that I managed to reverse the spin and head away from the gaurdrail. I estimate I was down to 70 when I went sideways off-roading in the exit's median. Broke the right-rear bead loose, threw the Camber full negative (top of tire out,) and packed the wheel half full of mud. Scraped the front wheel lip but good and wedged grass into the bead but didn't break it. The car made a full 270 before coming to a stop in the grass. : ] Had to replace that RR knuckle as it got bent...

Red 5spd Formula
Trot, the lucky, fox...

p8ntman442 · Post by **p8ntman442** » Wed Jan 10, 2007 11:46 am

Huh, and I thought locking all 4 tires when entering the spin would have stopped it.......

Pyrthian · Post by **Pyrthian** » Wed Jan 10, 2007 11:58 am

that was just plain old oversteer
snap oversteer is when you actually temporarly recover, and it snaps around the other way.

The Dark Side of Will · Thu Jan 11, 2007 9:45 am

Correct. That's plain old overesteer caused by equal tire lift-throttle reaction. He came in too hot, backed off and the car came around. That's what you get when your back tires aren't wide enough.

Snap oversteer is something different and has more to do with mistuned dampers.

The Dark Side of Will · Thu Jan 11, 2007 9:47 am

p8ntman442 wrote:Huh, and I thought locking all 4 tires when entering the spin would have stopped it.......

That just makes the car continue to spin in a straight line rather than randomly veering across the track as tires gain traction unpredictably.

Pyrthian · Post by **Pyrthian** » Thu Jan 11, 2007 10:34 am

The Dark Side of Will wrote:
p8ntman442 wrote:Huh, and I thought locking all 4 tires when entering the spin would have stopped it.......
That just makes the car continue to spin in a straight line rather than randomly veering across the track as tires gain traction unpredictably.

right. if he was by himself, yes, gassing it and trying to recover may have worked, but, being in traffic - he did the right thing by getting the vehicle still as quickly as possible.

crzyone · Post by **crzyone** » Thu Jan 11, 2007 7:27 pm

Maybe I should have titled this "Oh Snap, Oversteer!"

The Dark Side of Will · Thu Jan 11, 2007 9:18 pm

Pyrthian wrote:
The Dark Side of Will wrote:
p8ntman442 wrote:Huh, and I thought locking all 4 tires when entering the spin would have stopped it.......
That just makes the car continue to spin in a straight line rather than randomly veering across the track as tires gain traction unpredictably.
right. if he was by himself, yes, gassing it and trying to recover may have worked, but, being in traffic - he did the right thing by getting the vehicle still as quickly as possible.

The Fiero doesn't have the horsepower to recover from that via drift.

stimpy · Post by **stimpy** » Fri Jan 12, 2007 12:22 pm

So would my experience dodging the van that stopped dead in front of me while I was going 55 ish: I hit the braks and fishtailed to the right, wound up going into the next lane, then fishailed left to go straight at 70 ish; was that snap oversteer?

Damn near fudged my shorts, I'll tell you what.

The Dark Side of Will · Fri Jan 12, 2007 12:51 pm

That sounds like snap oversteer.

Weponhead · Post by **Weponhead** » Sat Jan 13, 2007 12:23 pm

fiero = MAD CRAZY snap oversteer.

TrotFox · Post by **TrotFox** » Sun Jan 14, 2007 9:09 pm

So when I popped off/on the brakes to reverse the spin after the guy jumped over was snap oversteer following normal oversteer?

Learn something new everyday.

Red 5spd Formula
Trot, the gray, fox...

The Dark Side of Will · Sun Jan 14, 2007 9:25 pm

Was that you in the vid?

TrotFox · Post by **TrotFox** » Mon Jan 15, 2007 2:54 am

The Dark Side of Will wrote:Was that you in the vid?

No, I was asking in reference to my story up above. First skid with brakes on started to send me into the guardrail so I let off the brakes and the car immediately reversed it's spin but thankfully put my in the median instead. Probably saved the car...

Trot, the gray, fox...

The Dark Side of Will · Mon Jan 15, 2007 10:07 am

By being on the brakes you unload the rear contact patches and reduce rear cornering grip. The back end starts to come around and develops a very large slip angle. When you let off the brakes, the weight transfers back onto the rear tires, they bite and the large slip angle sends the tires back the way they came. However, because the car was so far sideways and the rear tires were too narrow, it develops enough momentum to swing through and oversteer the other way like a pendulum. Wider rear tires putting the traction center at or behind the CG would reduce this effect dramatically. This is also the rear why a trailer with insufficient tongue weight sways back and forth.