My father and I have been wondering about something lately. On a 4wd truck, is the front driveshaft supposed to turn while the truck is in 2wd and does auto-locking hubs make a ddifference in this? On my '78 my front driveshaft turns regardless if it's in 2wd or 4wd. My father has a '94 F-150 and his front shaft doesn't turn. He said he can't turn it by hand either whereas I can turn mine by hand. Is one of our trucks screwed up or is it just the way they are now vs. back then??





1978 F-150 flareside. Primitive by todays standards but she was a jaw dropper back then. :-staun

 

Sounds like your hubs are locked in.....The driveshaft shouldn't turn when in 2wd.

 

I've checked the hubs. Mine are unlocked. That is.....unless there's something broke in both of them....


1978 F-150 flareside. Primitive by todays standards but she was a jaw dropper back then. :-staun

 

i cant say for the new truck but i have seen some trucks where the front drive shaft turns while they are in 2x, i havent really fiddled around with them to see but i think they may have had auto locking hubs, not sure though, sure the truck wasnt full time 4x originally? friend of mine had a blazer that was full time 4x and he put manual locking hubs on the front, driveshaft still spins and everything, but no power at the wheels.

 

I think it depends on what kind of transfer case you have full time/ part time. A friend of mine has a 77 high boy with a full time 4 wheel drive set up, so it's always in 4wd, it's kinda weird I know, I think it's a special edition. It just depends whether or not the hubs are locked in to engage 4wd in your case. I think the drive shaft spinning is natural.

 

I have the NP205 T-case and dad has the BW T-case. Both are part time cases. Only difference is I have manual hubs and he has autolocking hubs.

1978 F-150 flareside. Primitive by todays standards but she was a jaw dropper back then. :-staun

 

The autolocking hubs lock when you turn the driveshaft about 1/2 a turn.If you can't turn it at all then the hubs aren't unlocking.The part time setups will turn slowly when running down the road,the front axles also turn slowly while driving down the road.

Dennis
1979 F-250 4x4 460 4-speed 33"s
1977 Highboy 429 4-speed 35"s
1969 Ranger on a 1978 F-250 4x4
frame 466 560HP 4.10's 33"s

 

>The autolocking hubs lock when you turn the driveshaft about
>1/2 a turn.If you can't turn it at all then the hubs aren't
>unlocking.The part time setups will turn slowly when running
>down the road,the front axles also turn slowly while driving
>down the road.

Ok...dad told me he can't turn the front driveshaft at all when it's parked. I can turn mine w/o any problems. Now exactly how slow are you talking? I don't have any carpeting in my truck so I can see the front pumpkin and driveshaft through the hole in the floor for the clutch arm. I must say...that shaft turns mighty quick just like rear one does.


1978 F-150 flareside. Primitive by todays standards but she was a jaw dropper back then. :-staun

 

It may turn a little bit.. From the vibration of everything and wind and internal resistance and whatnot. If it turns the same speed as the rear, your hubs may be junk..

Can you turn the u-joints in the knuckles by hand easily? (the ones by the wheels) If not, your hubs (or possibly the u-joint) are broke. You need to have both sides free. Even if one side is locked you may have the driveshaft spin.

You should be able to spin the driveshaft with the hubs unlocked in both directions. I also had one once where the u-joint was siezed partially and it wedged itself inside the hub, (against the side of it) and that forced it to turn with the wheel.

On your dads newer truck with auto hubs (what year? I'm talking pre-97) the hubs lock when the axle shafts rotate a turn or two, some take longer than others. They unlock when you spin the axleshafts in the opposite direction of engagement (if they engaged while going forward, you need to back up to unlock them. if they're engaged from going backwards, you need to disengage them by driving forward)

You should be able to turn the driveshaft by hand and feel the hubs lock and unlock. I know I could on my 93 Ranger when it had factory crap auto-hubs.

 

Your 78 will turn slow, due to the oil in the transfer case being thick and casuing the front shaft to turn slowly. There are others things that help this, such as the fluid in the front diff. Your father's truck driveshaft should turn about a half a turn and the automatic hubs will engage. If the truck is on the ground, you will not be able to turn the frontshaft. If it's jacked up you should be able to turn it, but it will be harder to turn. If this doesnt work, put the tcase in neutral--it has to trun then or something in front end is locked up. If had a 95 with auto hubs, but changed them to maunual for around 50.00, since the Ford garage wanted 100.00 a piece for the auto's when one went bad

 

-Simple Check
Jack up the front end (with hubs locked out) and turn each wheel -it shouldn't turn your axleshafts -if it does, something's wrong with your hubs.

-Dan

 

Right Dan! Or you could also see what the shaft does while in reverse. Your linkage for the gear selector might be sloppy, and not fully engaging in 2wd.