Ratio of wheelbase to track width.

[cranknpiston]

How to decide the ratio of wheelbase to track wWidth?
Like what should be the track width for a particular wheelbase (say 54" wheelbase), or what should be the wheelbase for a particular track width? Considering the fact that the vehicle is a Baja ATV (max. allowed wheelbase: 108", max. allowed track width: 64".)

 

[Tmoose]

If cornering is involved, generally the wider the track the better, especially on pavement.
Unless CG is at ground level, in which case it doesn't matter, or the vehicle must pass between trees or rocks of a known minimum spacing.

The great Jim Hall biased the radical but kind of goofy 2H toward narrowness , perhaps for better aerodynamics, and John Surtees' debut was not able (or perhaps willing?) to lap as quickly as Hall had in the 2G or ever get closer than 4 seconds or so to the pole position in any race.

 

[BrianPetersen]

As always, "it depends".

Wider track width is better for maximizing cornering G-force without rolling over. Narrow track width is better for fitting between obstacles. If the criterion involves negotiating a slalom, the increased cornering G's allowed by a wide track width may be negated by the vehicle having to go much further side to side in order to negotiate the slalom.

Long wheelbase is better for ride quality and stability in general, worse for tight-parking-lot maneuvering, worse for the above-mentioned slalom course. If the overall length of the vehicle is defined, it's usually not wrong to make the wheelbase as long as you can within reason, because weight hanging out beyond the axles is generally bad. But urban transit buses have relatively short wheelbases and long overhangs (with the engine usually hanging out way beyond the rear axle!), because maneuverability in tight quarters takes priority over how quickly the bus can negotiate an autocross course.

I'm not aware of any "ratio" that is "optimum" between the track width and the wheelbase. Production vehicles cover a pretty wide range.

 

[JackAction]

For a Baja ATV, I would consider the smallest track and wheelbase possible considering:

[ul]
[li]There is no overhang (i.e. the wheels are truly at the four corners) such that the tires can manage dips without having the edges of the body touching the ground;[/li]
[li]The track is wide enough such that it cannot rollover. Don't forget to consider having the car on an inclined track;[/li]
[li]The wheelbase is long enough such that the weight transfer under hill climbing AND possible acceleration will not flip the vehicle.[/li]
[/ul]

Having the smallest track possible will help in maneuvering side-to-side and having the shortest wheelbase will help going over the top of hills (if the axles are close together, the car has less chance of having the center portion of the frame touching the ground).