tjkj2002 wrote:
LEDfoot wrote:
I think you are confusing full-time 4WD and part-time 4WD.
Full-time 4WD means that you can drive it around full-time, whether you are on smooth sticky pavement or on dirt. In full-time 4WD the transfer case must include a differential so that the front and rear axles can turn at different speeds (while both still receiving power). This is exactly the same functionality as AWD except on AWD it is usually called center differential rather than transfer case.
Part-time 4WD you can only use part of the time because the front and rear axles are locked together and will bind when turning on try surfaces.
This is completely independent of the type of transmission used. If Jeep cannot make full-time 4WD work with a manual transmission there is a problem with the design in my opinion and rather than just deciding that they won't offer full-time 4WD with a manual transmission they should fix the issue.
I'm not confusing fulltime with part time 4wd.Sorry but you got it backwards,fulltime 4WD is not like AWD,fulltime 4WD you are driving(sending torque) to all 4 wheels(yes the the select trac has a center diff to allow for F/R axles turning at different speeds).AWD is not sending torque to all 4 wheels until wheel slipage is detected,AWD t-cases use a viscuase(spelling?) type center diff that when slippage occures then it locks to send power to the other axle,some now use a electronicly controlled center diff to do the same thing only faster.
Now on some fulltime available t-cases(like the Select Trac) also have part time 4wd,2wd,and 4-low,some fulltime cases like the ones used in the H1(NV218) only have 4hi(fulltime),4hi lock(locks the center diff,parttime 4WD),and 4-low---no matter what you do it's always driving all 4 wheels.In AWD vehicles(mostly cars and small SUV's) you rarely have any control over if it is 2wd or 4wd,it does it on it's own and it never drives all 4 wheels unless wheel slip is detected,and AWD t-cases are known to be weaker then full fledged t-cases.
I guess we're splitting hairs here but what you are saying is still not right. AWD and full-time 4WD is exactly the same thing. Now, there are many different flavors and configurations of AWD/full-time 4WD.
Taking your example of having one axle driving normally with the ability to send torque to the other axle when slippage is detected. This is how the Quadra-Drive on WJ Grand Cherokees work. (Is the Grand Cherokee AWD?) The older (ZJ) Grands had a semi viscous coupling with a default 50/50 split between front and rear.
Audi cars (arguably one of the pioneer of AWD cars) with the Torsen center diff has had a 50/50 front/rear torque split from the beginning (until just recently when they started changing it to ~40/60 to give a more RWD feel). Are Audis 4WD? Per your definition they would be.
There are actually very few AWD cars that are driven completely by one axle until power is needed at the other axle. Even the FWD setups with added AWD like the haldex setup used by volvo and the smaller Audi/VWs do by default send some torque to the rear (Volvo does 70/30 Audi/VW 50/50).
Either way, I maintain my point that if Jeep cannot get the selec-trac transfer case to work in full-time 4WD (or AWD if you will) with the manual transmission there is an issue with either one of those components or the design of the drive train itself.