Is my 4wd synchronized with my transmission?

[1978 Homebuilt Fords]

So yesterday I took my 78 f150 for a test drive after getting a few bugs fixed, and when I came around a corner, I hit a big area of ice, and went slipping and sliding sideways up the road. It crossed my mind to put in 4wd while I was sliding, but I didn't want to because I was always told that the truck had to be stopped and in neutral. Is that truth or myth?

 

[Slug]

Assuming you have to manually floor-shift the transfer case into 4WD, and that you have manually-locking hubs, it may not even engage in 4HI unless you are at slow speed and in neutral with the hubs already turned to the LOCK position. I don't believe it will engage 4LO unless you are at a standstill. Shift on-the-fly is, I think, a later option (?)

 

[pjtoledo]

used to have a '77 F150 with the manual transfer case and lockout hubs.
both axles must be at the same speed, that means not while spinning or turning or braking.
when moving I would reduce throttle enough to take stress off the drive train then engage 4WD HI.
I won't admit to what speeds I actually shifted into & out of 4WD, but it was way above what the owners manual recommended.

4 lo does need a complete stop, or at least good ear protection and a supply of replacement parts.

 

[pjtoledo]

Assuming you have to manually floor-shift the transfer case into 4WD, and that you have manually-locking hubs, it may not even engage in 4HI unless you are at slow speed and in neutral with the hubs already turned to the LOCK position. I don't believe it will engage 4LO unless you are at a standstill. Shift on-the-fly is, I think, a later option (?)

the np205 will shift into whatever mode the shift lever tells it to do. if those hubs aren't locked it's gonna be crunch time.

 

[bobbywalter]

As last long as the hubs are locked and your not spinning the hell out of the tires going in and out of 4 high is not an issue.

 

[1978 Homebuilt Fords]

So yeah I do have manual floor shift 4wd with locking hubs, and a np 205, and I'm assuming from what pjtoledo said, that it might not be the best idea to be cruising with traffic and just shift right into 4hi

 

[1978 Homebuilt Fords]

Also, what is the purpose of the transfer case having a neutral? If I shift my transfer case into neutral, and then shift my transmission into gear, it does nothing. I'm wondering if there's a specific purpose for that?

 

[Slug]

Thanks for the clarification!

 

[85_Ranger4x4]

Also, what is the purpose of the transfer case having a neutral? If I shift my transfer case into neutral, and then shift my transmission into gear, it does nothing. I'm wondering if there's a specific purpose for that?

Flat towing.

Or in the case of a NP205 you can modify the shift rails and control each axle independently and put one end in neutral for various maneuvers off road.

 

[lil_Blue_Ford]

Dunno much about the older stuff but it sounds like it’s pretty well covered. All of mine have shift on the fly. Unless I’m gonna be running on the highway, I’ll usually lock in the front hubs and run it in 2wd all winter. Hit a slick spot or the roads get bad, back off the throttle a bit and into 4hi and go. 4lo requires being stopped, it doesn’t like it any other way. Interesting side bar though, I worked maintenance for a company awhile back and the two company trucks were 2008-2015 Chevys. I had to run salt up to the other building and going up a hill I lost traction. Reached down to put it in 4x4 and nada. Lever would not move. Tried to stop and figure it out but that only put me sliding back down the hill and drifting sideways. Had to shove the brake pedal to the floor and lock up all 4 tires before it would let me shift. Scary. And on a newer truck. Found both were like that, no shift on the fly with Chevy trucks. Ehh, I’ll stick to my Fords, lol

 

[1978 Homebuilt Fords]

Dunno much about the older stuff but it sounds like it’s pretty well covered. All of mine have shift on the fly. Unless I’m gonna be running on the highway, I’ll usually lock in the front hubs and run it in 2wd all winter. Hit a slick spot or the roads get bad, back off the throttle a bit and into 4hi and go. 4lo requires being stopped, it doesn’t like it any other way. Interesting side bar though, I worked maintenance for a company awhile back and the two company trucks were 2008-2015 Chevys. I had to run salt up to the other building and going up a hill I lost traction. Reached down to put it in 4x4 and nada. Lever would not move. Tried to stop and figure it out but that only put me sliding back down the hill and drifting sideways. Had to shove the brake pedal to the floor and lock up all 4 tires before it would let me shift. Scary. And on a newer truck. Found both were like that, no shift on the fly with Chevy trucks. Ehh, I’ll stick to my Fords, lol

That sounds like it would be pretty sketchy! Ive never owned a Chevy but it would be just like them to make 4wd complicated

 

[RonD]

You can shift any transfer case from 2WD to 4high and back again as long as the front hubs are locked, won't hurt a thing
If front hubs are unlocked then do not shift transfer case until they are locked, and not much point in shifting transfer case to 4WD in any case, lol

If you have Auto Hubs and an Electric shift then you can also shift back and forth for 2WD or 4high, it has an electric clutch in the transfer case
Never seen Auto hubs with manual transfer case, but if you had that you would have to stop before shifting transfer case


When front hubs are locked, and assuming same size tires, then both driveshafts are spinning at the same speed so no grinding as gears mesh
If you were sliding or wheels had lost traction there might a little grinding but wouldn't be much, and probably wouldn't be a good idea to shift into 4WD at that time in any case, it would add a new wrinkle in your current control situation, could be better or could be worse off

2WD or 4WD on ice doesn't matter, 60 ton tanks slide on ice, ice is the great equalizer, 0 traction with what ever you are driving, lol

 

[85_Ranger4x4]

That sounds like it would be pretty sketchy! Ive never owned a Chevy but it would be just like them to make 4wd complicated

GM (and Dodge) used the same t-case your truck has in the same time frame.

Dodge used them into the 90's in Cummins trucks.

 

[wildbill23c]

So yeah I do have manual floor shift 4wd with locking hubs, and a np 205, and I'm assuming from what pjtoledo said, that it might not be the best idea to be cruising with traffic and just shift right into 4hi

Manual shift transfer case can be shifted into 4hi at any speed if your hubs are locked in, if not DON'T, you'll cause a lot of front end drive train clashing and possibly break stuff that's sitting at rest. With a manual shift transfer case and manual locking hubs your whole front drive train from the drive shaft, to the wheel hubs is in free mode, just sitting there not moving so shifting to 4WD while moving is gonna cause a lot of unorganized chaos.

I lock the hubs in on my Bronco 2 and just leave them through the winter, that way I can shift into 4WD if needed and not have to get out and lock in the hubs in deep snow. Once the hubs are locked in, your front and rear axles are going to be at the same speed if you are just driving along, but a sudden loss of traction causing wheel spin on the rear axle and you engage the 4WD you'll get a lot of clashing and grinding as the front and rear wheels are spinning at different speeds at that point.

To shift into 4WD in a situation like above, let off the accelerator so the wheel spin stops, you'll still be sliding, but you can then engage the 4WD and all will be fine, except for the sliding, you'll still do that LOL.

A shift to low range requires a full stop and shift to neutral or disengage the clutch and shift to low range, then release the clutch or shift back to drive. You still need to have the hubs locked in of course for the 4WD to work, that is unless you just want the low range for such things as moving a trailer around your property or something like that which leaving the hubs disengaged and just shifting to low range will give you 2WD low range...doesn't cause any harm.