4 wheel drive 4H, will not easily engage on the fly. Help

Good Evening,

I noticed while replacing the racks and pinion on my 2000 Toy Tacoma that the front hubs have been locked and I do not know how long they have been this way. I have always been able to shift on the fly under 45 miles an hour. After replacing the rack I noticed that when I am trying to shift on the fly it will not go into 4WH and the gears grind. I have to stop to engage the 4WH without grinding. Two other people drive this vehicle and praise God the truck doesn't get driven a lot but I was wondering what could the problem be. My wife seems to think the front hubs have to be locked for the shift on the fly to operate. I, not the other hand has been driving the vehicle for years and do not share the same sentiments. Can someone who knows more than he, help Please I would appreciate any help. Thank you in advance.

 

Your wife is correct. If you have manual hubs they must be in the locked position for shift on the fly 4wd.

basically when they are locked the front axles and driveshaft will be spinning as the vehicle moves in 2wd and will allow shift on the fly to engage since the front and rear driveshafts are spinning at the same speed.

when the hubs are unlocked the front axles and driveshaft will not be turning and shift on the fly will not engage.

 

NOOOOOOOOOOOOOOO!!!! My wife cannot be right..Just kidding. Thank you so much for your help.

So, does it hurt the truck if the hubs are always locked?

 

not really, no, as long as your truck is in good order. there will be a bit more wear and tear on your CV boots from constantly turning.

The most noticable difference is that it may affect your MPG from the added drag. I usually run with hubs locked during winter for easy 4wd shift on the fly, and unlocked during the summer

 

I wouldn’t leave them locked all the time, but fyi, 2nd and 3rd gen’s are permanently locked (as well as most 4x4 vehicles nowadays)

When I had locking hubs, I’d lock em before going offroad or when it was snowing out. Sometimes they’d be locked for days or weeks because I forgot but I’d try and unlock em

 

Thank you

 

Thank you

 

no problem, welcome to Tacoma World!