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FAQ Hubs

Frequently asked questions and DIY's for common mechanical & electrical problems and Isuzu maintenance, please check this section before posting new questions. If you have something to add here please contact a member of the FAQ Team.

FAQ Hubs

Postby pig75 » Tue Sep 08, 2009 7:43 pm

Auto Hubs:

To engage 4wd, stop the vehicle and shift into 4wd. This engages 4wd in the transfer case. Now the front driveshaft turns when the rear one does. This means that the front axle shafts and differential are also now turning. When an automatic hub receives power from the axle that is connected to, it engages. This is why the truck needs to be stopped when 4wd is engaged; when you start moving from a stop the hubs engage. Doing this at a slow speed ensures that they don't get a huge force from the drive axles, slamming them into engagement. Once the hubs are engaged the power that is sent to the front axle is now being transmitted to the wheels. 4wd is working.
To disengage 4wd, stop the vehicle, shift out of 4wd and then back up about 2 meters. This causes the front wheels to be pulled backwards away from the direction that the hubs were "pushing" them (for lack of a better term). This is where the hubs unlock. Then you can continue forward without the front axle causing un-necessary drag.
The big drawback to automatic hubs is that they have to un-lock and then re-lock when changing directions. So lets say that you are driving forward, in 4wd. The vehicle then gets stuck in some deep snow. You shift into reverse to back out. As soon as you start pressing on the gas to move backwards, the front axle shafts turn in reverse. This first unlocks and then relocks the hubs. In a properly cleaned and lubed hub, this only takes about 1/3 to 1/2 of a revolution of the wheel. When things get dirty or the hub gets stuck (most often due to dirt) this distance can be longer. It is also possible for the auto hub to not re-lock at all. Again, proper maintenance can prevent hub problems, but it is something else to pay attention to.
The other REALLY BAD clicking is caused by something else altogether: the axle shaft slipping inside of the hub. The axle shaft is splined, and the inside of the hub is also splined and fortunately for us those splines match. The axle shaft is held into the hub by a c-clip. This clip snaps into a groove in the end of the axle shaft, after the shaft has been slid through the workings of the hub. When the c-clip breaks or comes off, the axle shaft can then partially slid back out of the hub. When this happens there is only 1/3 to 1/2 of the splines making contact. When you apply power to the axle shaft, and there is this less contact area, the axle can actually slip inside of the hub, grinding the splines off of the axle shaft. This is the popping that can be heard when someone is off-roading with a broken c-clip.

Manual Hubs:

The real benefits to manual hubs are their simplicity. They are either unlocked or locked. You as the driver set them. Once a hub is locked, it won't just come unlocked.

Reassemble instructions for manual hubs:

Hub Flanges

Hub flanges are what you will find on all SOTF (Shift on the fly) and TOD (Torque on Demand) Isuzu trucks. They function exactly like a manual hub, except that you can't unlock them. They can be swapped for manual hubs, you will just have to remember to lock the hubs before you try to turn on TOD or shift into 4wd. They look like a 90mm round plate with 6 Allen-head bolts holding them onto the center of the front hubs.
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