2wd vs 4wd option mod diy

[mrhonnesty99]

Just wondering I noticed some Toyota cars have the option of 2wd or 4wd like rav4 and tundra, has any one done such mods to make it possible to drive in 2wd instead of 4 at will with the help of a toggle switch or push ?

[katekebo]

It would be a MAJOR mechanical modification.

The reason that some 4WD drive cars can be driven in 2WD is because they have one of these:
- a transfer case, or
- a central differential / clutch, or
- a front differential, or
- front wheel hubs
that can engage/disengage the power to the front wheel.

In case of the Highlander, the central and front differentials are part of the transaxle and there is no space to modify / replace them with another differential that would allow on-demand 4WD. In theory, such differential could be built, but as far as I know nobody is making one - and designing and building one would be a major engineering project.

Probably the easiest way to disconnect traction to the rear wheels would be to modify / replace the rear differential or install a clutch on the driveshaft. Still, this would not be an easy task because there isn't much space for the additional components (actuator, etc.).

With the type of 4WD that the Highlander has there really is no need to have a 2WD option. The cars that have an on-demand 4WD system are typically design for off-road use, and their drivetrains are much more substantial / stronger than the "crossover" type of drivetrain that the HL has. The HL 4WD system was intended to provide better traction / control on snow and ice, but is NOT intended for serious off-road use.

You can learn more about different types of 4WD under these links.
http://www.rubicon-trail.com/4WD101/...e_4WD_awd.html
http://en.wikipedia.org/wiki/Four-wheel_drive

[mrhonnesty99]

Originally Posted by katekebo

It would be a MAJOR mechanical modification.

The reason that some 4WD drive cars can be driven in 2WD is because they have one of these:
- a transfer case, or
- a central differential / clutch, or
- a front differential, or
- front wheel hubs
that can engage/disengage the power to the front wheel.

In case of the Highlander, the central and front differentials are part of the transaxle and there is no space to modify / replace them with another differential that would allow on-demand 4WD. In theory, such differential could be built, but as far as I know nobody is making one - and designing and building one would be a major engineering project.

Probably the easiest way to disconnect traction to the rear wheels would be to modify / replace the rear differential or install a clutch on the driveshaft. Still, this would not be an easy task because there isn't much space for the additional components (actuator, etc.).

With the type of 4WD that the Highlander has there really is no need to have a 2WD option. The cars that have an on-demand 4WD system are typically design for off-road use, and their drivetrains are much more substantial / stronger than the "crossover" type of drivetrain that the HL has. The HL 4WD system was intended to provide better traction / control on snow and ice, but is NOT intended for serious off-road use.

You can learn more about different types of 4WD under these links.
http://www.rubicon-trail.com/4WD101/...e_4WD_awd.html
http://en.wikipedia.org/wiki/Four-wheel_drive

i noticed that its not a real 4x4 like my jeep cherokee had, the jeep would spin all 4 at the same time and had a type of slip diff, while the highlander has 4wd only for traction, i got stuck in the snow with low profile tires and it would spin at will either front or back and rarely all 4 at times, so yes you are correct its not a full real 4x4. guess am going to have to live with it.

[nov0798]

Turn off the traction control, and it will spin all 4 of em!