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Understeer


TAFKARM

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I'm comfortable handling oversteer.

I killed my first car with terminal understeer and to be honest, I've never really got a handle on how to handle it except cross my fingers, close my eyes, pucker up and hope for the best. Appreciate its best to avoid understeer in the first place (slower entry, transfer the weight onto the front etc) but once you're in an understeering slide, whats the best way out of it. (I mean, as opposed to straight on into lamppost / marshalls post* delete as applicable).

 

@AdamR ?

 

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Ease off the power and wind off the steering lock, was what i was taught, many moons ago. Mind you, understeering towards a wall it can be tricky to force yourself to turn the wheels towards the wall! The natural reaction is to add more steering, which just makes things worse. Soon as grip comes back, start steering again, but being careful not to overdo it. Gentle inputs.

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Lift off to restore grip or reduce the steering request slightly. Best to practise on a quiet roundabout in 3rd and gently increase the speed until it starts to loose grip( don't use the same one as UPS Van Drivers)

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And for discussion!

I've never tried it, nor done any courses where it was taught, but I have heard of it being taught!

On a modern car with full traction control and anti skid/vehicle dynamics control. there is a school of teaching that essentially says, if you're out of control and heading towards an accident, brake as hard as you possibly can and steer around the thing you were about to hit. That way all possible electronic aids are fully engaged to "emergency" level, and the car's active safety systems will do everything possible to try and get the car to follow the path you're steering. I think the theory is that even if not totally successful, it will still do a better job than an unassisted driver.

Note though, this may only be something taught with high performance machines.

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If you're near Rockingham or Silverstone, I can really recommend attending Carkraft.  I've done it a few times now and the skidpan session you really do learn how to react to each situation. Of course, only practise will make perfect (and most importantly, an instinct!).

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Yeah, I did the skid pan training years ago at Three Sisters - back in the days when they had the specially adapted car there, with the hydraulic rig. (Enabled the instructor to cause the car to enter any type of skid he wanted, pretty much on demand, as long as you were moving).

The training makes a huge difference.

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Depends what caused the understeer mate, and which the driven wheels are. In a Westy, assuming you ignored all your own advice in your opening post, usual cure is to ease off the throttle. One thing Adam taught me was that sometimes you can put too much steering lock on and you can almost correct understeer by coming back off the steering lock a bit too, which I must admit is a huge amount of fun in the Mazda!

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1 hour ago, RussH said:

I'm comfortable handling oversteer.

I killed my first car with terminal understeer and to be honest, I've never really got a handle on how to handle it except cross my fingers, close my eyes, pucker up and hope for the best. Appreciate its best to avoid understeer in the first place (slower entry, transfer the weight onto the front etc) but once you're in an understeering slide, whats the best way out of it. (I mean, as opposed to straight on into lamppost / marshalls post* delete as applicable).

 

@AdamR ?

 

Handbrake :d

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If you've got a stiff lsd, then a boot full of throttle may make matters worse.

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3 hours ago, Dave Eastwood (Gadgetman) - Club Secretary said:

And for discussion!

I've never tried it, nor done any courses where it was taught, but I have heard of it being taught!

On a modern car with full traction control and anti skid/vehicle dynamics control. there is a school of teaching that essentially says, if you're out of control and heading towards an accident, brake as hard as you possibly can and steer around the thing you were about to hit. That way all possible electronic aids are fully engaged to "emergency" level, and the car's active safety systems will do everything possible to try and get the car to follow the path you're steering. I think the theory is that even if not totally successful, it will still do a better job than an unassisted driver.

Note though, this may only be something taught with high performance machines.

Yes, before I retired I was a traffic officer and we were indeed taught the capabilities of a car on a skid pan with abs, traction and stability control. The students drove towards a chicane of cones at speed and let the car do its thing under heavy braking and then did it again with everything turned off which proved to all of us that the car was much more competent than we were. Absolutely amazing what all the toys could make the car do!

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Go full lock and you'll spin on the spot.  Better than hitting a wall in my opinion.

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5 minutes ago, SootySport said:

Go full lock and you'll spin on the spot.  Better than hitting a wall in my opinion.

in an understeer situation, going full lock will result in, er, more understeer...!

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29 minutes ago, CraigHew said:

in an understeer situation, going full lock will result in, er, more understeer...!

Correct. You're front end is sliding, adding more lock just delays getting grip.

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Yep, as has been said, a gentle, progressive lift off the power will encourage some weight transfer gradually to the front (a sharp lift will cause it to 'dig in' and you may end up with lift off oversteer - which is fun but maybe not what you need in panic mode), and reducing lock will usually allow the front tyres to recover.

This may be tricky to explain in text, but basically... Slip angle is the difference in angle between the direction the car is travelling and the front wheels are pointing. When you are in an understeer condition, the front tyres are in the 'Exceeding the limit' part of the following graph:

td_grip_graph.jpg

Therefore, by reducing the amount of lock - and thus slip angle - you can get them back into the green range. We're taking in the order of 2-3 degrees of front wheel angle here though, so it's a fine line and takes a while to learn how to 'feel' what the tyres are doing through the steering wheel. You can also listen to them though, as tyres will have a chirp in the green position of the graph and a distinct squeal once you start to push them into the red bit.

As a related aside, this is why road tyres are more fun / easier to learn to drive (properly!) on than sticky ones. They have a wider working window for slip angle, so you have more of a 'back of a spoon' than a 'knife edge' to play around with:

Post1.1Figure5.jpg

 

As you said though Russ, a big part of driving quickly is in keeping the car out of wild understeer - usually by using the brakes and throttle to steer the car instead of the steering wheel.

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