Offroad-Express

Can anyone tell me why a part time 4wd vehicle gets drivetrain wind-up on tarseal and a fulltime 4wd vehicle does not?

thanks

Most full time 4WD's have either a centre diff(part of the transfercase) or run a viscous coupling. That is why full time 4WD's with centre diffs have a centre difflock so this can be locked to achieve true 4WD, and then you need locked front and back diffs to get ALL FOUR DRIVING .
With part time 4WD and no slip or differential action you get:::

DOG KNOTTED,

FITZY.

gomulletgo wrote:Can anyone tell me why a part time 4wd vehicle gets drivetrain wind-up on tarseal and a fulltime 4wd vehicle does not?

thanks

Because part time is supposed to be used "part of the time - when you are actually offroad", full time is really for your normal driving. Some makes also call them all wheel drive or Quattro (remeber Audit Quattro TT).

Basically, as Smokey said, part time transfer case locks the front and rear solid so there is no give between the front and rear (i.e. no differential action).

Typically, if you have open front and rear diffs, with part time system you are running a true two driving wheel system and with a full time system you are running a true one driving wheel system (unless it can also be locked, then you also have two driving wheels) ....

Without the give front and back, something has to give or the binding will break something (usually the most expensive and weakest link in the drivetrain).

And the reason for the center diff, the front wheels turn a bigger radius than the rear wheels, just like an outside wheel turns a bigger radius than an inside wheel hence why some form of slip is needed in the center otherwise windup happens which is remedied by either disconnect or diff or other means.

Mike