For FR cars, wider front or rear track better?

[C32b]

There is no easy answer, ebcause the track itself is not the end of the story. The different width of front and rear tyre also play a part and not just the track.

Generally if the the same size of tyre used, definitely the front should have wider track in order for the car to be able to turn better

 

the 458 italia has a wider front track than rear track, 1672 vs 1606 mm but its front and rear tyres are 235 F and 295 R. The wider rear tyres seems to have a countering effect to the wider front track although we cannot tell which side this counter effect will end up biased to.

 

The 430 is also set up in this manner.

 

Yet, the Lotus Exige S has wider rear track and wider rear tyres, notwithstanding, we see constant praise for its excellent turning/cornering ability.

 

The JDM Honda Civic Type R has also received excellent reviews for its turning ability but actually has wider rear track than the front.

 

I believe that the relationship on front track vs rear track is not as direct as wider in front with same size tyres to increase turning ability but there are many other factors which when stacked together may outweigh the actual front rear track width differential/bias.

 

[Rb26dett]

the 458 italia has a wider front track than rear track, 1672 vs 1606 mm but its front and rear tyres are 235 F and 295 R. The wider rear tyres seems to have a countering effect to the wider front track although we cannot tell which side this counter effect will end up biased to.

 

The 430 is also set up in this manner.

 

Yet, the Lotus Exige S has wider rear track and wider rear tyres, notwithstanding, we see constant praise for its excellent turning/cornering ability.

 

The JDM Honda Civic Type R has also received excellent reviews for its turning ability but actually has wider rear track than the front.

 

I believe that the relationship on front track vs rear track is not as direct as wider in front with same size tyres to increase turning ability but there are many other factors which when stacked together may outweigh the actual front rear track width differential/bias.

 

the guru has spoken !

 

love the thread you started about brake ducts .

[Yc86]

If you do notice, many cars such as exige, ferrari, porsche & lamborghini have wider rear tyre & track. By your statement, these cars might be deemed poorly designed.

 

Do explain more on why such cars are setup this way if possible?

 

I think the choice of track width is a bit more complicated than what you just described.

 

lol.. was just a pun towards the Porsche, don't get me wrong.

 

A car that has wider tires doesn't mean it has a wider track, since track is the distance between the center of the tire on each side, unless the wheels are offset differently.

You've pulled some numbers, but I believe if you compare all racing orientated cars (FR or MR cars) including Formula 1, you will find a majority of them will have the front track wider than or equal to the rear. The reasons range from kinematics to rules and track layout. Autocross type circuits as seen in FSAE would see a wider front benefiting because the rear does not cut in that much (when the front clears the cone, the rear will clear it too).

 

Kinematically speaking, a wider front is more desirable because a wider track reduces weight transfer laterally, which due to tire load sensitivity, will see a reduced loss of (or improved) grip between the front wheels allowing the car to turn in better. The track of the vehicle also affects the antiroll moment and hence the roll stiffness distribution, but these can be compensated for by spring, damper and ARB choice.

 

Another reason why the rear would be narrower would probably be due to rules, where a limit is placed on the overall width of the car. (Weight transfer is the reason for trying to maximize track whenever possible). Narrower rear track allows them to run wider rear tires, which are beneficial in 'curing' the steady state oversteer tendency of rear weight biased cars.

 

Of course car design is not based on ideals but packaging, especially for road cars. On some cars, the asthetics or designer would insist on a wider rear track and bigger rear wheels because they look better and looks sell. It is then the engineer's job to work around that and improve things from another angle. Also, packaging of the rear especially for mid/rear engines with transaxle gearboxes and double wishbone setups might require a wider track to accommodate for misalignment with the driveshafts.

[Roto]

If you use a wide front, and obviously had the same tyres, the car move more with the nose...and the back is gona follow...but a important thing is the axle distance...this can of configuration I usually saw it in a small distance between axle like austin mini (1980's)...well all is geometry.. if you have a big FR i think is better work first in the rear axle, stiffed a little and some camber (0,8

[Badder]

it depends but generally

 

 

fwd tend to be more prone to understeer. modern fwds reduce the tendancy but still understeer is usually the limiting issue.

 

 

some things you can easily do to improve handling of fwd car (reduce understeer)-

 

- widder fronts

- more front camber

- soften the front (springs and anti roll)

- harden the back (springs and anti- roll)

 

 

with some all or a combo of the above you can improve the handling of most fwds significantly (but difficult to ever come close to rwd) and certainly improve front tyre life

 

 

big issue with fwd tyres is scrubbing. camber and widder will put more rubber on the road and hence increase grip reduce understeer and with more rubber you have better heat distribution/less scrubbing

Edited February 17, 2011 by Badder

[Caiecq]

How to use the ignition switch?

Most modern car ignition switch is a composite type, composed of a variety of functions. General ignition switch has 4 functions: First, lock the steering wheel; second turn off the ignition device; third start the engine; Fourth normal operation.

Car vehicle ignition key is allocated, and generally have two. And some car keys on the key number embedded pieces of metal, keys and vehicles in use before, should be removed with a number of the metal, and properly preserved. In accordance with the number of metal can be prepared to this car repair center to a new key (new key for the preparation, the service center will have a rigorous review procedure.)

When using the ignition key, the key should be plugged into the appropriate location as required, and then rotate to the four functions of a position in any location. Remove the key, you should first press and hold the key and release the switch lever, then rotate the ignition key to the (LOCK) locking position, you can remove the key.

General Automotive are the key reminder, if you leave the keys in the ignition switch, the driver opened the door, the alarm signal will flash or beep to alert the driver.

When using the ignition switch should note the following:

(1) the car is moving during the key or not unplug the ignition switch to lock the keys (LocK) position, as this would lock the steering wheel and lose steering control. Therefore, the driving need to disconnect the ignition, just turn the key off (OFF) location.

(2) The driver should take good care of the ignition key switch to prevent theft.

(3) Feng Zhou Fang stalled vehicles, should turn off the ignition key switch position to prevent the vehicle for a long time in a discharged state, causing accidents.

(4) the direction of using an ignition key switch has been locked, turn the steering wheel can not be forced to avoid the bad steering wheel and steering torque.

(5) Wo associated with the ignition switch lock device can not start the engine, so as to avoid the grass can not be transferred after the vehicle started moving downtown and gas; the second accident

(6) ~ α for the ancillary equipment stalls, the key to this position, the power supply board on a variety of ancillary equipment to be connected, such as electric horn power, the key to this position, to ring the bell.

(7) ON is connected to file, the key to the stalls, car power supply are all connected, all devices can be used, the engine power was turned on.

(8) When to start ART file, the key to this position, that is, open the starter switch, starter motor drive running start.

 

[Badder]

Wider rear reduces oversteer while wider front reduces understeer.

 

I think the answer depends on whether your car oversteers or understeers.

 

A FR car should be very well balanced in the first place. But they may be biased to either. So setting a wider track depends on which way the car is biased. Of course if the car is already perfectly balanced, then setting a wider track on only the front or the rear isn't a good idea.

 

correct