confused about hubs

can't get my head around drive train, does the Jimny always have drive going to front wheels, vacuum switch just engages hubs and therefore drive to the front, if i fitted manual or fixed hubs how do i engage 4wd and low if i've disenged/blocked the vacuum system.
cheers Mike

First part of your question is yes so the second part of your question is if you fit manual ones it will be in 2wd or 4wd depending which of the settings you manually select on the hubs. If you fitted fixed hubs which are set to engage then you will have permanent 4wd.

Thanks mickt, what about engaging low?

In 2wd the transfer case only sends drive to the rear axle. The hubs disconnect so the front wheels aren't back-driving the front axle and propshaft.
When you engage 4wd a dog clutch in the transfer case engages, sending drive to the front axle. A switch is closed, signalling the vacuum system to lock the hubs so the front driveline is complete and all 4 wheels are driven.
Low range is simply a second set of gears in the transfer case, offering further reduction.
With manual hubs left in the locked position 2- and 4wd still operate as normal, but the front wheels are always back-driving the front axle, slightly decreasing fuel economy.

+1 on Busta's comments

Oops seems I did not know how also!! I do know though!

Thanks busta, but this is where i'm confused, if i have manual locking hubs, therfore doing away with the vacuum actuated stuff, locking the hubs on the wheels isn't anywhere near the transfer box so what sends a message to the transfer box to drive tthe front wheels, and is it a vacuum switch that sends a message to the transfer box to select low range, so i couldn't do that if iv'e disconnected the vaccums.

Selecting 4wd high ratio simply engages drive to the front axle via the prop shaft. In 2wd only the rear prop shaft is engaged. In 4wd both prop shafts spins.

macclad wrote: if i have manual locking hubs, therfore doing away with the vacuum actuated stuff, locking the hubs on the wheels isn't anywhere near the transfer box so what sends a message to the transfer box

Reading between the lines, I am assuming you have a push-button transfer. If that is the case, when the system "sees" a vacuum (whether you have vacuum operated hubs or not), a signal is sent to the 4WD controller allowing engagement of 4WD H when the button is pushed. It also allows progression to 4WD L. To operate the transfer case when you have manual hubs with a push-button transfer, you will need to either plug the vacuum lines (so that the system really does have vacuum) or short the vacuum switch (so that the system thinks it has vacuum).

White two wire plug that is below the battery attached to a small cylindrical reservoir with a mushroom like breather on the top, all the vacuum lines go into it. Unplug and bridge the wires on the plug, that gets the vacuum signal constant and gives the transfer box interlock signal.

Next is the vacuum line, blue one way valve from inlet manifold, again connected to the reservoir below the battery on the same side of the engine. Remove the hose from the top of the blue one way valve and block it on the manifold side. This is to stop any vacuum leak causing the engine to run poorly.

I recently fitted manual hubs and the above took five minutes. There is a pictorial guide in the wiki pages, sorry I don't know how to do a link......

sniper

Thanks sniper.

Macclad- to engage 4wd both the hubs must be locked/engaged and the transfer case needs to be put into 4wd. Some choose to leave the hubs in the locked position, in which case 2wd and 4wd are simply selected using the stick or buttons as normal.

By fitting manual hubs you have made all vacuum systems redundant.