Perfect Handeling *

Franza1

Supermoderator & Area Reps Manager
In my Never ending quest to have the best handling starlet possible i have compiled and absorbed alot of information and i thought it was about time i shared it with you lot. I am going to keep some of the specifics regarding some of the handling bits and pieces i have done to my car until it is all finished and properly setup. here is some useful information for you all to mull over in the mean time.


NOTE: It is important to develop the car around your own driving style and characteristics. Do not just bolt on what everyone else bolts on. Use your own wits and experience in deciding what works and what doesn't.

This will offer more results, rewards and spare cash in the pocket.

Factors that affect a car's handling

Driver & Familiarity with the Car
Handling is a property of the car, but different characteristics will work well with different drivers. A tool is only good if you know how to use it. No 1 recommendation is getting to know your car and how it reacts in different circumstances and conditions. it's not a nice feeling if your expecting an understeer and get a massive overstear and end up facing the wrong way perched on a ditch. you needs to take extra care for the first few months after buying a car, Other things that a driver must adjust to include changes in tires, tire pressures and load. Remember handling is not just good or bad, it is also the same or different.

Center of gravity height

Height of the center of gravity relative to the wheelbase determines weight transfer between front and rear. The car's momentum entering the corner acts on its center of gravity to tilt the car forward or backward during braking and acceleration. Since it is only the weight on each wheel that changes and not the location of the center of gravity the effect on over/under steer is opposite to that of an actual change in the center of gravity in other words when a car is braking the weight on the front tires increases and on the rear decreases, with that change in their ability to take sideways load, causing oversteer.

Body lean can also be controlled by the springs, anti-roll bars or the roll center heights.

Center of gravity forward or back

In cornering because of the center of gravity front-heavy cars tend to understeer and rear-heavy cars to oversteer.

When all four wheels and tires are of equal size a weight distribution close to "50/50" produces the better handling compromise. Although A car with "50/50" weight distribution will understeer on initial corner entry. To avoid this problem, sports and racing cars often have a more rearward weight distribution. In the case of pure racing cars, this is typically between "40/60" and "35/65." This gives the front tires an advantage in overcoming the car's initial weight transfer thus reducing corner-entry understeer. your personal setup is best done by trial and error to try and find what best suites your driving style.

Yaw and pitch ( Body Roll )

The Yaw ( Sidewards Sliding, Drift ) of the car tends to keep the direction the car is pointing changing at a constant rate. This makes it slower to swerve or go into a tight curve, and it also makes it slower to turn straight again. The pitch ( Forward and Back Rolling ) of the car takes from the ability of the suspension to keep front and back tire loadings constant on uneven surfaces and therefore contributes to bump steer ( front or rear of the car skipping across the road ).

Tires, wheels and Unsprung weight

For more details on this have a look at the other two articles i wrote links are below

Wheels and unsprung weight > http://www.toyotagtturbo.com/forums/showthread.php?t=64

Tyres > http://www.toyotagtturbo.com/forums/showthread.php?t=65

Breaking

This is another big subject and I'm still not fully read up on it so I'll get back to this later.

Aerodynamics

I never seen the total relevance in this for a road car like a starlet as there is not much that you can do without effecting the cars usability.

Rigidity of the frame

The frame will flex with load, especially twisting on bumps. Rigidity is considered to help handling. At least it simplifies the amount of factors you have to take into consideration when setting up a car. usually people think the stiffer the frame of the car the better the handling but this is not necessarily true as you can have the frame too stiff again this is all down to the set-up you prefer or feel comfortable with.

Common handling problems

When any wheel leaves contact with the road there is a change in handling, so the suspension should keep all four wheels on the road in spite of hard cornering, swerving and bumps in the road. It is very important for handling, as well as other reasons, not to run out of suspension travel and "bottom" or "top" out.

It is usually most desirable to have the car adjusted for a small amount of understeer, so that it responds predictably to a turn of the steering wheel and the rear wheels have a smaller slip angle than the front wheels camber angle and roll stiffness in front and back to minimise the variation in handling characteristics. A driver can learn to deal with excessive oversteer or understeer, but not if it varies greatly in a short period of time.

The most important common handling problems are.

Understeer - the front wheels tend to crawl slightly or even slip and drift towards the outside of the turn.

Oversteer - the rear wheels tend to crawl or slip towards the outside of the turn more than the front.

Bump steer – Basically the front or the rear of the car skipping across the road like a stone across the top of water

Body roll - the car leans towards the outside of the curve.

Weight transfer - the wheels on the outside of a curve are more heavily loaded than those on the inside.

Slow response - sideways acceleration does not start immediately when the steering is turned and may not stop immediately when it is returned to center.

Ride quality - you'll have to make a decision early on which is more important to you

Ok Here is a Rule of thumb guide for correcting any issues you may have with handling

Table.jpg


References

Wikipedia and numerous other sites on the net as well as some practical experience and questioning people i know.

I'll leave this open for any comments or Corrections anyone may have.
 

Jay

Admin
Excellent article Frankie. :)

The only thing I would add to that :

It is important to develop the car around your own driving style and characteristics. Do not just bolt on what everyone else bolts on. Use your own wits and experience in deciding what works and what doesn't.

This will offer more results, rewards and spare cash in the pocket.
 

Franza1

Supermoderator & Area Reps Manager
Excellent article Frankie. :)

The only thing I would add to that :

It is important to develop the car around your own driving style and characteristics. Do not just bolt on what everyone else bolts on. Use your own wits and experience in deciding what works and what doesn't.

This will offer more results, rewards and spare cash in the pocket.

Very true Jay Added at the top of the article. Chears
 

cameroon95

Member +
I think i may be experiancing "bump steer":rolleyes:

My car can seem to pull to a direction when I go over certain parts in a road, most noticeably centres of roads or different surfaces.

Is this the case?
 

Franza1

Supermoderator & Area Reps Manager
I think i may be experiancing "bump steer":rolleyes:

My car can seem to pull to a direction when I go over certain parts in a road, most noticeably centres of roads or different surfaces.

Is this the case?

That Could Very well bit it or tram lining. Does it happen mid bend or on the straight?

Tram lining is when the car follows the camber of the road or undulations in the road
 

monka

Member +
nice,

although have to disagree with one bit on that chart, the tyre pressures

you say to reduce understeer, increase front tyre pressures, and reduce rears?

to reduce under steer you want more grip at the front, like when on the drag strip, and less grip at the rear.

you have slightly more grip on tyres when the tyre is lower in pressure, as it has a graeter contact patch,
 

gv1.3

Admin
excellent info Frankie.
I was gonna add rep but you already got called Dylan so you've had enough good feedback for today :)
 

Franza1

Supermoderator & Area Reps Manager
nice,

although have to disagree with one bit on that chart, the tyre pressures

you say to reduce understeer, increase front tyre pressures, and reduce rears?

to reduce under steer you want more grip at the front, like when on the drag strip, and less grip at the rear.

you have slightly more grip on tyres when the tyre is lower in pressure, as it has a graeter contact patch,

Not necessarily. it increases the tendency for the tires to flex and the sidewall to come into contact with the road loosing grip. it also has a pendulum action letting the car sway from side to side on the tyres. Reducing tyre pressure is good for straight forward grip but not for side to side lateral motion. Think of it like having worn bushings. More pressure means a stiffer side wall where as lower pressure means having a Softer sidewall.
 

Nwimie

Member +
nice info :] usefull thread. gotta say my glanza is the best handling car ive owned love how it drives.
 

paylos

Fresh Recruit
hello...
have any one from this forum change the rear camber? i have a ep82 starlet and i want to tell me how a can do it... thanks
sorry for my bad english...
paul
 
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