U/S skids vs O/S skids

[7db]

Was thinking about the difference between these this evening.

There's a lot you can do wrong which will encourage one to develop, but once smooth, does anyone else think of these as being (u/s) too fast and (o/s) off-balance?

[vonhosen]

Depends on where & when used.

I don't think of what I'd describe as an optimally controlled drift as off balance, I think of it as car attitude control.

[billgates e30]

i assume your on about oversteer/understeer

i don't think it has a lot to do with being off balance, but more to do with the drive of the car FWD/RWD

obvioulsy things such as bumps n the road etc can cause o/s in both cases (but this would fall under the off balance statement)

but in my limited experience, rwd cars can either push wide (i.e. understeer) when applying a little bit too much power, likewise it can also begin to o/s but alot of this can depend on the tightness of the bend, the speed involved, the gear that i was in, the weather conditions, and the setup of the car (tyre pressures etc)

for example, my car (RWD) prefers to understeer in general in the dry, but tends to oversteer on tighter bends and understeer on larger ones in the wet, changing the tyre pressures obviously make the car handle differently but it is unpractical to constantly change the pressures for wet dry driving as its an everyday car so i leave them at a compromise

i think it generally depends on the car, and the individual situation, but in most cases if your smooth then it shouldn't be a worry unless driving at the limit which in theory you shouldn't be doing on the road (although admitidly you must go near or beyond the limit in order to know where it is)

[Gareth]

once smooth, does anyone else think of these as being (u/s) too fast and (o/s) off-balance?

I used to encourage my car to u/s quite a lot without understanding it was something I was doing wrong. I just blamed the car. After getting some training, I rarely find this to be an issue unless I am playing[1], so for me, u/s is nearly always caused by being too quick into a corner.

[1] in which case I'm using the front tyres to scrub off speed.

[James]

Was thinking about the difference between these this evening.

There's a lot you can do wrong which will encourage one to develop, but once smooth, does anyone else think of these as being (u/s) too fast and (o/s) off-balance?

Not quite sure what you mean by this 7db, all be it I did think of you last night circling the A3 as I ate my Steak and Mash. Do you mean that generally if you US you will be going to fast? Probably yes. And as for OS being off balance, I have limited experience with RWD cars but think OS can be controlled and to one's advantage. I think it becomes off balance when the slide becomes to great or prolonged than intended.

[7db]

I'm talking about skids here rather than dynamic oversteer/understeer within the limits of tractions -- perhaps more clearly "terminal u/s" = "front wheel skid"

It's just that it strikes me that if you have an oversteer event, then there's enough grip there for you to get round, you just did it wrong at the wheel. Less steering would have got you round. You balanced the front and rear up incorrectly and mislaid the back.

If you're going too fast and simply cannot make it round the corner as there is insufficient grip and plough on, then if you get all the balance right and everything smooth, you're still going straight on.

That was my thinking. Obviously loss of traction owing to power oversteer/understeer is a different thing and is a good was t olose it on the exit. I'd argue that wasn't smooth, I think.

In StressedDave' example, it's a "loss of confidence" event which leads to loss of balance. There was enough grip to get round the corner, the driver just didn't balance it right between front and back.

Of course, if grip is not the issue, and actually what happens is running out of road (cos round the corner there's a dead sheep and the snake that killed it escaping on a skateboard), then dramatic fast unsmooth steering inputs would lead to Dave's terminal understeer example above, assuming these take over dynamics before the lift'off/braking brings the tail round.

[Porker]

I believe Dave's oversteering quiz question may be answered thus:

Coarse steering input = understeer = driver snaps throttle shut = weight transfer forward = oversteer.

Is that it?

( the "=" sign is there to indicate the next event rather than implying any kind of equivalence)

[7db]

I misread SD's post. O/S caused by quick steering means that the tyres don't have a chance to buld up the force, so the final steering angle settled upon is too big for the corner. Tyre forces build up, increasing turn in. Driver is off the throttle so increased steering angle helps the weight forward, together with increasing steering angle. As he feels it all going wrong, brakes may be applied to help unweight the rear....

It's the opposite effect to hinting.

[Porker]

Mmmm - that would appear to require a degree of clumsiness that I hadn't hitherto considered likely.

I imagine that many such incidents are immediately preceded by the words "She corners like she's on rails....."

[nuster100]

I imagine that many such incidents are immediately preceded by the words "She corners like she's on rails....."

Either that or "Hold my beer and watch this"

[899cc]

I generally look at it was being too fast, and too slow (with front wheel drive). If I take a corner too fast, and don't slow, it understeers. If I take a corner too fast, and slow too much, it oversteers.

[nuster100]

You could always try steering the wrong way then quickly the right way into a corner. (not on a publc road)

This would cause oversteer, even more so if you were to lift of as you steered the right way.

As I understand it, alot of it is caused by the way the weight of the car is distrubuted.

In my above example the quick steering of the car, throws the weight from one side to the other causing instability.

Imo understeer is caused by not grasping the situation infront of you and approaching at an innapropiate speed.

Jay

[jont]

You could always try steering the wrong way then quickly the right way into a corner. (not on a publc road)

You mean a scandinavian flick. There's an example of that here (Google video). Poor quality video, but you can clearly see the car go the wrong way before being flicked back in the right direction (with the consequent oversteer). This is also often used by people drifting to get the car to oversteer (intentionally)

Imo understeer is caused by not grasping the situation infront of you and approaching at an innapropiate speed.

Terminal understeer can also be caused in FWD by trying to accelerate while steering. It's not always caused under braking.

[7db]

Terminal understeer can also be caused in FWD by trying to accelerate while steering. It's not always caused under braking.

This can occur in a RWD as well - you don't need to break traction through torque applied at the driven wheels - a really good dollop of weight transfer will do this too.

[SammyTheSnake]

You mean a scandinavian flick. There's an example of that here (Google video). Poor quality video, but you can clearly see the car go the wrong way before being flicked back in the right direction (with the consequent oversteer). This is also often used by people drifting to get the car to oversteer (intentionally)

Here's another video of the same maneouvre. Not much better to see what's going on but it is a slightly clearer picture...

HTH
Cheers & God bless
Sam "SammyTheSnake" Penny