For FR cars, wider front or rear track better?

[Viceroymenthol]

as above

 

for handling, straight line as well as in corners

[Lethalstrike]

as above

 

for handling, straight line as well as in corners

 

Wider rear track should theoretically be better for FR cars, since it reduces roll and enhances grip for the rear driving wheels.

 

If wider front track was used for FR cars, perhaps it may help to dial out some over-steering characteristics which may already be inherent in the chassis.

 

This is based on some of my basic understanding only, may not always apply in real life since they are many factors to consider also. (tires, suspension settings etc)

[Viceroymenthol]

Wider rear track should theoretically be better for FR cars, since it reduces roll and enhances grip for the rear driving wheels.

 

If wider front track was used for FR cars, perhaps it may help to dial out some over-steering characteristics which may already be inherent in the chassis.

 

This is based on some of my basic understanding only, may not always apply in real life since they are many factors to consider also. (tires, suspension settings etc)

 

thanks.

 

on a sidenote, i have seen some people say that during karting, wider front track width are used, as it helps the vehicle rotate when cornering. this may have to do with inherent front-rear weight distribution of the vehicle as well.

 

theoretically speaking the end with the wider track width will grip better, so is it safe to say that in a threshold cornering situation for FR cars, the front steered wheels will continue to maintain direction/traction and the rear powered wheels will slide?

[Viceroymenthol]

i found this when googling:

 

http://www.eng-tips.com/viewthread.cfm?qid=165852&page=1

 

it is a lot of physics, and i think there is a simulation program available that lets you figure out the variables

 

interestingly, these are the cars with wider front track

 

Noble m15 89mm wider at front

Ferrari F430 53mm wider at the front

Lamb Gallardo 30mm wider at the front

 

except

 

Porsche Cayman 42mm wider at the rear

 

i think it has a lot to do with the position of the engine which affects the weight distribution

 

so if cayman and 911 which are mid (cayman engine is afore of the rear axle) and rear engined (911 engine sits slightly behind the rear axle) and the weight is all in the rear half AND they have wider rear track to maintain stability (wider track, less weight transfer when cornering), shouldn't a front engined rear drive car be wider in front to have less weight roll in the front?

 

in F1 cars, the fuel cell position is important as well but that's getting too detailed and finely tuned for road cars

Edited May 4, 2010 by Viceroymenthol

[Lethalstrike]

i found this when googling:

 

http://www.eng-tips.com/viewthread.cfm?qid=165852&page=1

 

it is a lot of physics, and i think there is a simulation program available that lets you figure out the variables

 

interestingly, these are the cars with wider front track

 

Noble m15 89mm wider at front

Ferrari F430 53mm wider at the front

Lamb Gallardo 30mm wider at the front

 

except

 

Porsche Cayman 42mm wider at the rear

 

i think it has a lot to do with the position of the engine which affects the weight distribution

 

so if cayman and 911 which are mid (cayman engine is afore of the rear axle) and rear engined (911 engine sits slightly behind the rear axle) and the weight is all in the rear half AND they have wider rear track to maintain stability (wider track, less weight transfer when cornering), shouldn't a front engined rear drive car be wider in front to have less weight roll in the front?

 

in F1 cars, the fuel cell position is important as well but that's getting too detailed and finely tuned for road cars

 

Gallardo, F430 and M15 are all mid-engined. If what you said is true, then logically all of them should be wider at the rear instead.

 

I think its much more than just weight distribution (ie position of the engine)...

 

[Viceroymenthol]

Gallardo, F430 and M15 are all mid-engined. If what you said is true, then logically all of them should be wider at the rear instead.

 

I think its much more than just weight distribution (ie position of the engine)...

 

exactly.. it is interesting to note that mid engined porsches having wider rear but the mid-engined noble, ferrari and lambo have wider front tracks..

 

then again we are assuming that the engine is the heaviest factor in weight distribution...

 

how much of a factor in handling does front camber and toe have, coupled with the wider front track?

[Lethalstrike]

exactly.. it is interesting to note that mid engined porsches having wider rear but the mid-engined noble, ferrari and lambo have wider front tracks..

 

then again we are assuming that the engine is the heaviest factor in weight distribution...

 

how much of a factor in handling does front camber and toe have, coupled with the wider front track?

 

Hell lots of difference it makes if appropriate settings are made in conjunction with a wider front track.

 

Its about optimizing the front tires' contact patch with the road, taking into account the graduations and changes of the road in which the front suspension will be subjected to. Probably accurate corner weighting is needed to make a judgement on the best settings to use...

 

Its the combination of all these parameters that really makes the difference in handling. (camber, toe, ride height, etc).

 

They used to say FF cars will almost always under-steer and exhibit torque steer characteristics, but just look at the FD2R Civic (front double-wishbone) and the latest Ford Focus RS (with Revo-Knuckle front suspension).

 

Both handles damn well without the feel of being pulled through corners when driving them. And both front tires have to handle high loads of both driving and steering the vehicle, with 220 and 300 bhp respectively.

 

 

 

 

[Sky61]

for me,my rational would be rear tyres would be wider to utilise the grip(hence traction) on a FR car as the rear wheels are being powered by the driveshafts. for the front, its just the steering rack that controls the steer angle,hence a narrower frnt profile tyre would be easiler to maneuver, aiding handling... Of course a fine balance must be made between handling and traction or u'll be getting the understeer or oversteer characteristics of the car in question...

[C32b]

as above

 

for handling, straight line as well as in corners

 

I would say you need to customize it on the car you are talking about. The FR car in question can be affected by the overhang, weight distribution, aero balance, alignment, the specific needs of the track and the list goes on.

 

I am no suspension guru but I do appreciate that settings of such things should be taken with an open mind and considering fully as many variables as possible.

[Caltis]

Hell lots of difference it makes if appropriate settings are made in conjunction with a wider front track.

 

Its about optimizing the front tires' contact patch with the road, taking into account the graduations and changes of the road in which the front suspension will be subjected to. Probably accurate corner weighting is needed to make a judgement on the best settings to use...

 

Its the combination of all these parameters that really makes the difference in handling. (camber, toe, ride height, etc).

 

They used to say FF cars will almost always under-steer and exhibit torque steer characteristics, but just look at the FD2R Civic (front double-wishbone) and the latest Ford Focus RS (with Revo-Knuckle front suspension).

 

Both handles damn well without the feel of being pulled through corners when driving them. And both front tires have to handle high loads of both driving and steering the vehicle, with 220 and 300 bhp respectively.

 

Both grip and handle well in corners because of the LSD. Take the LSD out and it will be a different car...Focus still will have the torque steer because of the tranverse engine mounting, only longitudinal engine will have lesser torque steer effect (main difference is due to the gearbox location and difference in axle length)

[Thedream]

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.

[Vhtfhwlego]

Actually, wider camper in front solve the problems already.

Set up 2

[Thedream]

Actually, wider camper in front solve the problems already.

Set up 2

[Sinifm]

Same theory as F1 car.

[Yc86]

The ideal track depends on the weight distribution and purpose of the car. For straight line performance, track doesn't matter and it is the wheelbase that's more important.

 

An equal or wider front track is generally the way to go because of the way weight shifts diagonally when the car is decelerating and turning at the same time. The severity depends on the CG height and wheelbase of the car also.

 

Only poorly designed cars which placed form over function in their design need to have wider rear tires and hence wider rear track than the front to compensate.

 

When you change the wheel offset, you are changing more than just the track. You're changing the scrub hence steering feel which gives more feedback and might make you think the car is cornering harder. You're also changing the tire's self aligning torque which affects the way the tire is deformed and producing grip.

 

There is no rule to camber increasing or decreasing oversteer, and often the amount of camber used is more than what is required as radial road tires are much stiffer compared to competition slicks. Also static camber is far from the actual camber the car sees as the suspension geometry changes while the car is moving. The gains you get from toe changes will be more pronounced than camber change.

[XALmoN]

think about it this way..

 

your front wheels lose grip, you understeer, your rear wheels lose grip, you oversteer.

[C32b]

The ideal track depends on the weight distribution and purpose of the car. For straight line performance, track doesn't matter and it is the wheelbase that's more important.

 

An equal or wider front track is generally the way to go because of the way weight shifts diagonally when the car is decelerating and turning at the same time. The severity depends on the CG height and wheelbase of the car also.

 

Only poorly designed cars which placed form over function in their design need to have wider rear tires and hence wider rear track than the front to compensate.

 

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.

[Kr_toy]

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