lift off oversteer

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tiptopd
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lift off oversteer

Post by tiptopd »

I just learned about lift off oversteer. Caused by the weight being transferred to the front. Now does that only happen when you lift off during turning or can it also occur when you let go the throttle in the straight line and then just steer (while coasting in gear).
This got me thinking because this is how i steer around corners. I brake on the straight line (regulate speed) and than just coast in gear around the turn. Doing that, the car is naturally being engine braked so i think the weight is actually shifted on the front wheels. Do i risk oversteer doing this ?
Just to be clear what i am asking:
When you let go the throttle, is the weight shifted forward the whole time the car is being engine braked or is it shifted forward just that moment when you let go the throttle (you get a small jerk) and after that it balances out ?

Sorry if i am not clear, just having trouble explaining
IMBoring25
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Re: lift off oversteer

Post by IMBoring25 »

Last things first...Jerk is most of what you feel due to human physiology, but changes from the static weight distribution will continue to exist as long as you continue accelerating or braking or cornering (or driving on a slope, for that matter). In the special case of lift-throttle oversteer, the beneficial changes from static weight distribution will cease to exist when the acceleration does.

Weight distribution factors should not be an issue on public roads. If they are, you are driving too hard and putting everyone around you at risk. You should be aware of the possibility of oversteer (even with FWD vehicles), but the only time there should be any chance of seeing it on public roads is in extremely low-traction situations, and there are other phenomena at work in those cases.

For any drivetrain, watch for areas where surface condition may be variable. Most vehicles are statically front-heavy (especially FWD ones). Cornering across a slick patch or bump, weight distribution or the slightly different paths the front and rear tires take may cause the rear axle to break loose when the front didn't. Inappropriate use of throttle or brakes (or in extremely low-traction situations, the clutch or even shifter) can also cause it, but usually by directly applying enough force to break tires loose, not by making enough difference in weight distribution to cause it.
Rope-Pusher
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Re: lift off oversteer

Post by Rope-Pusher »

I was going to say that to experience lift off oversteer, one, or two, would prolly half tubey travelling at high engine rpm in one of the lower gear ranges before they lifted their foot off the throttle - there wouldn't be much deceleration to force the weight transfer if you were driving 45 mph in 5th gear and pulled your foot off the accelerator pedal....but then I decided not to say that, so I posted it instead.
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theholycow
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Re: lift off oversteer

Post by theholycow »

As stated above, if this becomes an issue on the road then you were driving too fast/hard to begin with. On public roads you're expected to leave plenty of margin for error.

That said...yes, it can happen going straight but it will take a lot more severe weight shift. I had it happen once when I hit a heavy, slushy windrow (the line of snow that gets pushed off of the side of a plow). I wasn't looking far enough ahead and I was going too fast, and I jumped off the throttle just as I hit. My front tires got mired in it, exacerbating lift-off, and one was in it worst than the other, imparting a twisting force on the car and I spun out. I was young and inexperienced...now I'm old, grizzled, and overconfident. :lol:
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