Stock Toyota Locking Front Differential Actuator Control Question

[Spiritus]

The vehicle is a 1995 LN108 Hilux 4 door Japanese domestic market pick up truck with a 2.4 Diesel Turbo AT.

Bought an english manual diesel Hilux/4Runner manual, and the front diff actuator on my truck is simply not anywhere in it, I am told that it is stock by some Japanese friends. Talked to some Aussies, and none of their Hilux's had factory locking front diffs they say.

The diff is definitely locked at least at the low speeds I am willing to try with the tires chirping like that, but I cannot find a switch for it. Do any USDM models have this type of set up. Does anyone know how it is typically controlled?

 

[KidVermicious]

If the 1995 Hilux you bought is anything like the '95 4Runner sold here in the states, then what you have is what's called an Auto Disconnect Differential, which uses vacuum to engage an actuator on the drivers side CV shaft when you select 4WD. It has the same effect as unlocking the manual hubs on earlier trucks, it minimizes wear and strain on the 4WD components. But it's not a "locker" in the technical sense of the word, and that's probably what's throwing the guys you're talking to in Australia - a locking differential is a whole different bucket of fish.

 

[Spiritus]

If the 1995 Hilux you bought is anything like the '95 4Runner sold here in the states, then what you have is what's called an Auto Disconnect Differential, which uses vacuum to engage an actuator on the drivers side CV shaft when you select 4WD. It has the same effect as unlocking the manual hubs on earlier trucks, it minimizes wear and strain on the 4WD components. But it's not a "locker" in the technical sense of the word, and that's probably what's throwing the guys you're talking to in Australia - a locking differential is a whole different bucket of fish.

Thank you for that. After looking up ADD, determined that my front diff is modified to be locked (Not sure if welded, or Detroit style), and this is causing the front right wheel to always be engaged. My fuel economy is not terrible but it was not what I expected, on the flip side though this truck was handling OUTSTANDING in the rain. Now I know why.

Planning to install a manual hub on the right side to disengage it when it is not raining for fuel economy.

 

[KidVermicious]

If you're going to do a manual hub swap, do both sides and take the ADD out.

Here's how you know for sure if your front is locked: first, jack up the passenger front. Now start the truck (make damned sure you're in Park or neutral and have the ebrake engaged and wheels chocked please) and put it in 4wd. Try to spin the passenger front tire - if you can spin it forward, you're not locked. If you can spin it backward but not forward, you've got an automatic locker. If you can't spin it either direction, you've got a spool or somebody welded the diff.

FWIW, automatics and spools are horrible on slick stuff. If your truck ever sees snowy roads that you'll want four wheel drive on, consider finding somebody with a stock diff to trade with.