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Understeer Recovery?

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Old 11-20-04, 11:06 PM
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videcormeum
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Default Understeer Recovery?

I attached a picture so you guys can better imagine this scenario.

So I was driving around my Nissan Sentra tonight just for the heck of it - and decided to go down to this low-traffic road with some twisties b/c there was some mist on the road.

Here's the specs on the Nissan Sentra SE for those that dont know:

Bone stock - 2.0 liter SR20 (145 hp, 136 torque) w/ auto tranny - FWD
16" alloys with Michelin 205/55/16 tires
Weight Distribution: 62/38 - front bias (That's right ... horrible)

I got to the road I was looking to drive and started my "run" I suppose you could say - I took "Turn 1" at about 35 mph and experienced minor understeer which I was able to control with a little throttle adjustment (gave it a little gas, straightened the wheel a tad, and then let off the gas) and it brought me around nicely.

So feeling pretty good about that I immediately approached "Turn 2" with a healthy dose of throttle and probably went into the turn (which has no real bank and veers slightly less sharply than the first curve) at about 45 mph .... this time, the understeer was horrendous. I was partially in the "new lane" and 2nd lane at the begining of the turn - I slid all the way into the third lane and was going about 35 mph by the end of the turn when I finally recovered.

SO - my question to you drivers out there - how does one recover from this sort of situation? Is there anything to do besides just hold on for the ride and not lock the brakes?

Specifically, how does one recover in a vehicle such as the one I'm driving? Or is there really not any great way to recover given the circumstances?

Thanks!

M.
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Old 11-20-04, 11:07 PM
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Here's the picture:
Attached Thumbnails Understeer Recovery?-untitled.jpg  
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Old 11-21-04, 12:23 AM
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drift it

(in your case with the ebrake)

Last edited by O. L. T.; 11-21-04 at 12:24 AM.
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Old 11-21-04, 12:23 AM
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FIrst off look where you want to go, not where your going. If you going into a corner too hot, make sure your out of the throttle. Then you want to lightly apply the brakes, this will help transfer the weight of the car onto the tread and unless your reallt flying this with the scrubing (loss) of speed you should regain control. .02
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Old 11-21-04, 10:43 AM
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ebrake is your friend =). i dunno, if u try to apply the brakes through a turn when ur coming in hot, ur liable to spin out..
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Old 11-21-04, 11:42 AM
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Its called trial-braking, its a racin technique. Unless your brake biasis is mainly at the rear, or the weight biasis is at the rear(rear/mid eingine) your not going to spin out.
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Old 11-21-04, 01:16 PM
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mmarshall
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The Sentra is not really designed for this kind of driving in the first place, With the possible exception of the Mini Cooper and Cooper S, You are almost always going to get sharp understeer in a front-drive econobox-based car, in the Sentra's case especially the non-SE-R and non-Spec V versions with the smaller tires and softer suspension.

Under the conditions you were in, I agree with O.L.T.'s comment about the rear E-brake. And, usually with a small front-driver......especially an undertired one.......cutting back sharply on the gas will take a lot of load off the front tires (which are doing double duty....driving AND steering) and give them a chance to dig in a little more without having the rear end snap out too quickly into drop-throttle oversteer and spin-outs.....which was classic on older rear-engine Porsches.
Generally you don't want to get on the brakes too hard because then you then place ANOTHER burden on the front tires, in addition to the other two....the car's forward weight transfer under braking will make the front tires steer, corner, AND brake....all three.....and that is just too much. Then you'll lose it for sure.

By the way, you were very fortunate, when you ended up in the third lane, that there was apparantly no oncoming traffic. And you, like many others, have just found out for yourself why, First, electronic vehicle-stability systems were developed, and, Second, why most enthusiast and racing cars are rear-drive.
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Old 11-21-04, 08:34 PM
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Originally posted by mmarshall
The Sentra is not really designed for this kind of driving in the first place, With the possible exception of the Mini Cooper and Cooper S, You are almost always going to get sharp understeer in a front-drive econobox-based car, in the Sentra's case especially the non-SE-R and non-Spec V versions with the smaller tires and softer suspension. *et al.*
First off - thanks for your reply. I generally concluded that FWD econo-cars aren't for tracking. But I still like to (try and) have fun driving.

Just so you know - that road I was on was one way only and was without any additional traffic - I take great pains to keep from ever putting anyone (outside of myself) in danger when I'm driving and I take passengers' and other motorists' safety VERY seriously.

Now - I just have to work on getting RWD ...

Thanks to all that replied.

M.

Last edited by whipimpin; 11-21-04 at 08:57 PM.
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Old 11-22-04, 09:55 PM
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careful with the ebrake. . . if the sentra is not lowered, you may just flip the car over. . .

Techniques can also very if you are entering or exiting the turn. You see, I just got a Scion xA and have been playing around with this stuff (it's my half priced Mini, with Toyota reliability which I plan on autox someday, $$mods are already goin in). If understeer occurs when entering the turn, I find that the best method is to take the load of the front tires and just try to cruise through the turn. Ebrake probably wouldn't help for this.

Exiting the turn? A tap from the ebrake may help you recover, but if I'm racing I go ***** out. If I were driving, I'd tap the ebrake and at the same time countersteer ever so slightly while powering out at full throttle (I got a small engine, but only 2300lbs).
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Old 11-23-04, 10:43 PM
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You guys DO NOT want to use the ebrake to help you if you are understeering into the corner. That will horibbly upset the balance of the car, it will not smothly rotate the car. Listen if you are constintly understeering into corners you are obviously carying too much speed, slow down, hit the apex and as you unwind the wheel gently apply the throttle untill the wheel is straight then its full speed ahead. Remeber "smooth is fast"
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