Oversteer or Rotation?

strengthrehab

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Exactly what I'm using. Stiff rear springs (1300 lb/in) and stock GTPP rear bar

As Brian knows.
 

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Healthy slip angle or sliding, the difference isn’t easy to discern or diagnose over the internet w/o video.

Unless the car is (de)tuned to have significant understeer at the limit, chances are you’re going to have to respect the fun pedal on the exit of slow corners where the available torque in a low gear can easily exceed the grip available after you subtract the grip needed to hold your line.

anytime you add gas, you’d better be unwinding the steering wheel at the same time, and lets hope you aren’t using a twitchy “track mode” throttle mapping or ecu tuning whichcan make it very challenging to roll on the throttle smoothly.

if the car wants to spin on corner entry with no throttle applied, it could be a driver technique issue with brake release or possibly related to a setup issue with swaybars, or rear tires are shot, or a rear alignment issue, or ... you get the idea. Generally tho with a high hp car set up to handle neutrally, you can’t just go full throttle right at the apex of a tight corner (some throttle yes, but not full send), you have to unwind the wheel and straighten the line a bit.
 

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You'll feel when you have good slip angle. In FWD cars, that technique along with trail braking makes you a lot faster. With RWD, it helps you put the power back on a little quicker. But an actual slide will slow you down, even if you correct for it. It all just comes down to experience and feeling what the car is doing. Smooth flow comes from smooth inputs. The #1 mistake of novice drivers is deathgripping and sawing the wheel. #2 is not looking far enough ahead of you current position to set yourself up appropriately for the next corner.
 
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Yes, that's too much unless you have substantial front spring rate. Obviously that's not the only part of the setup that matters for this, but it definitely contributes significantly.

Stock GT PP/EB PP bars are a good spot to be in.
A bug rear sway bar causes instability at low speeds?
 

NightmareMoon

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A bug rear sway bar causes instability at low speeds?
A stiffer rear swaybar will generally reduce the grip on that end of the car, yes.

You use stiffer swaybars to keep overall body roll in check, or to make a car transition from side to side faster than the springs alone will allow, or to fine tune oversteer/understeer balance, but the general rule of thumb is that making a swaybar stiffer reduces grip on that end of the car. Bigger isn't always better. You want as much as you need and not more.

If you're used to racecars looking like they have no body roll, its because those cars also have aero and may need to keep the front low and close to the ground for aero purposes, not because a flat car develops more grip, because aero aside, they don't.
 

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but the general rule of thumb is that making a swaybar stiffer reduces grip on that end of the car. Bigger isn't always better. You want as much as you need and not more.
Yup! They're a fine tuning device.

It's often you see SCCA street class/stock class cars using swaybars as a little bit of a crutch to get some roll stiffness on cars with very soft springs. In those cases, it's often that the improvement to dynamic geometry and responsiveness outweighs the theoretical grip reduction from lateral load transfer.
 

Plimmer

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Had a technical question. Some tight hair pins I clip I noticed that the back becomes a little loose (is this what "lively" means?) Which I don't really mind as much because I am still on the correct racing line. However, I was told from someone with way more experience than I that sliding is not fast. So if my rear becomes a little loose then that is an indication of entering the corner too fast?

Is what I am experiencing called oversteer where more speed equals a power slide or is this what Randy Pobst calls rotation?
Easy way to decide if this is helping or hurting is whether you are waiting for the car to settle before getting on the gas or are you able to gas out as planned.

Fastest lap times come from being on the gas as much as possible. As soon as you unsettle the car with a slide that causes you to wait then you’re loosing time. If your slide sets you up to get on the gas earlier or harder, then you might be going faster.
 

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A stiffer rear swaybar will generally reduce the grip on that end of the car, yes.

You use stiffer swaybars to keep overall body roll in check, or to make a car transition from side to side faster than the springs alone will allow, or to fine tune oversteer/understeer balance, but the general rule of thumb is that making a swaybar stiffer reduces grip on that end of the car. Bigger isn't always better. You want as much as you need and not more.

If you're used to racecars looking like they have no body roll, its because those cars also have aero and may need to keep the front low and close to the ground for aero purposes, not because a flat car develops more grip, because aero aside, they don't.
Good post.

Race cars also tend to have very stiff suspension. Stiff suspension will reduce body roll. There is one thing (in addition to aero) that rolling is bad for and that's suspension geometry. Whenever the suspension moves and especially when the car's body rolls, the suspension geometry tends to suffer at least some amount. A race car can be set up so the suspension doesn't move very much, which keeps the suspension geometry closer to ideal.
 

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I wrote a big schpeel, but nixed it. As long as it's not so much rotation that you have to countersteer, it's beneficial. Once you have to start correcting, it's an issue. If you go past neutral on the steering, then it's definitely slowing you down.
 

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Yup! They're a fine tuning device.

It's often you see SCCA street class/stock class cars using swaybars as a little bit of a crutch to get some roll stiffness on cars with very soft springs. In those cases, it's often that the improvement to dynamic geometry and responsiveness outweighs the theoretical grip reduction from lateral load transfer.

Brian,

What charactoristic of a suspension in the midcorner through corner exit that causes the car to feel like the slip angle is good but the chassis skips over the tarmac like a rock skipping on the surface of a lake? Is this too much spring not enough bar? Can shock settings be helpful?
 

ice445

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Brian,

What charactoristic of a suspension in the midcorner through corner exit that causes the car to feel like the slip angle is good but the chassis skips over the tarmac like a rock skipping on the surface of a lake? Is this too much spring not enough bar? Can shock settings be helpful?
I'd say that's an issue with the dampers being too stiff or having the rebound set incorrectly. But I'm not an expert like some others in here.
 

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Brian,

What charactoristic of a suspension in the midcorner through corner exit that causes the car to feel like the slip angle is good but the chassis skips over the tarmac like a rock skipping on the surface of a lake? Is this too much spring not enough bar? Can shock settings be helpful?
In my experience that behavior is actually too much bar as a portion of the roll stiffness and/or bad damper match. Too much compression and rebound damping, possibly.
 

fatbillybob

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Thanks,...I'l try messing with shocks. I'm on vorschlags pretty big rates I think 600F/800R iirc but stock PP1bars but front bar deboned and free to rotate so less rate there like stock front bar. When at 8-9/10ths my car cuts like a knife. When I lean on the car the best I can describe is the skipping rock on water and that is really costing me laptime.
 

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