Part Time 4wd w/Full Time 4wd option?

[snowcruiser]

To my knowledge every Part Time 4wd conversion for 80 series trucks remove the full time 4wd capability in exchange for manual locking hubs, and true 50/50 power distribution with the hubs locked and CDL engaged.

Here's my question. My sister's 2000 4runner LTD has a transfer case with the option for 2wd, full time 4wd, part time 4wd and low range 4wd. It would seem that full time 4wd is the same as the standard North American 80 series full time 4wd transfer case, part time on the 4runner would be equivalent to full-time 4wd on the 80 with the CDL locked and low is low. The 4runner however has the two wheel drive option without manual locking hubs and I am wondering if there is anyway to replicate this setup on the FZJ80 transfer case or if that is something inherent on the 4runner transfer case only?

Surely there is a reason this has not been done and I am merely trying to understand. thnx

 

[jynx]

2000 4runner, correct me if I am wrong, but I am pretty sure it does not have hubs up front, right? So that would seem to me that the "2wd" option would be the same as doing a part-time on an 80 by only swapping the hubs, my reverse logic would go something like this:

2wd - add hubs and run unlocked hit cdl

Part time - lock the hubs

4 hi - hit cdl

4 lo - go to low range

Not sure how the 4runner t-caseworks, but I am guessing it probably has something like the old ADD system that let's one wheel free spin for an apparent 2wd mode.

Most of the newer model vehicles actually do not have a true 2wd the front ends do not ever truly disengage, just the t-case stops sending power, but the front end isnt disengaged.

 

[86tuning]

4Runners, Tacoma and Tundra all have ADD (automatic disconnecting differential) which takes the place of manual hubs. The long axle shaft has a slider which disconnects that shaft from the diff. It effectively does the same job as manual hubs, but is selected by the ADD controller instead of walking outside and spinning the dials by hand.

When the ADD is disconnected the short-side shaft will spin up the diff side gear, which in turn will spin the spiders and spin the other diff side gear in the opposite direction. Because the other shaft is disconnected, the ring & pinion gears remain stationary. Less pumping loss from the ring gear slinging oil around, less overall wear and tear.

HTH.

 

[inkpot]

4Runners, Tacoma and Tundra all have ADD (automatic disconnecting differential) which takes the place of manual hubs. The long axle shaft has a slider which disconnects that shaft from the diff. It effectively does the same job as manual hubs, but is selected by the ADD controller instead of walking outside and spinning the dials by hand.

When the ADD is disconnected the short-side shaft will spin up the diff side gear, which in turn will spin the spiders and spin the other diff side gear in the opposite direction. Because the other shaft is disconnected, the ring & pinion gears remain stationary. Less pumping loss from the ring gear slinging oil around, less overall wear and tear.

HTH.

But doesn't that cause a lot more wear and tear on the pinions and side gears, as they usually move very, very slow. John

 

[jwbl1982]

2000 4runner, correct me if I am wrong, but I am pretty sure it does not have hubs up front, right? So that would seem to me that the "2wd" option would be the same as doing a part-time on an 80 by only swapping the hubs, my reverse logic would go something like this:

2wd - add hubs and run unlocked hit cdl

Part time - lock the hubs

4 hi - hit cdl

4 lo - go to low range

Not sure how the 4runner t-caseworks, but I am guessing it probably has something like the old ADD system that let's one wheel free spin for an apparent 2wd mode.

Most of the newer model vehicles actually do not have a true 2wd the front ends do not ever truly disengage, just the t-case stops sending power, but the front end isnt disengaged.

Why do you need CDL on in 2WD?

 

[jynx]

Why do you need CDL on in 2WD?

Depends on how the t-case actually works. If it is like an 80 then with the cdl off the case actually acts like a unlocked differential. Without the cdl on then the "diff" sends power to the "slipping" end. Without the cdl on, the open center diff would see the unlocked hubs on the front as a slipping wheel and would divert most of the power to the front resulting in no movement. Unlocked hubs, but locked cdl would split power but the hubs would not deliver any power to the front wheels.

That is only if the 4runner acts like an 80. If they are different, then all that goes out the window.

 

[TCH2FLY]

edit - never mind ancient thread