4WD Trouble

[adamsanders]

I’ve been having to use my 4WD quite a bit lately and I’ve discovered an issue I’d like to get resolved. For some reason, my truck doesn’t seem to want to stay in 4WD. This only occurs in 4 Hi and the shifter goes in and out extremely smooth. Also, the shifter doesn’t actually pop out or move when this happens, I’ll just be moving along in 4 Hi and then come to a stop, and then when I try to pull out again the engine just revs and it’s as if my T-Case is in neutral. I can go back to 2WD, let out on the clutch a little, stop and it’ll go back to 4 Hi and work fine. Very rarely does it “pop out” while moving, it mainly just happens once I push in the clutch. I have a 1991 F-250 with a ZF5 transmission. Is there adjustment or something I can look at? Thanks

 

[79jasper]

Probably the shift fork pads. Pretty common for them to just fall off.
But.... you could possibly have the wrong linkage. There's a measurement, but I don't know what it is offhand.

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[DrCharles]

Could your shift lever have worked loose, or the plastic bushings gotten sloppy, so it's not moving the lever on the t-case fully to the correct position? 4H is next to neutral, after all... how does it behave in 4L?

I had a shift fork pad come out in the t-case fluid when I changed it after buying the truck. Still shifted OK but not that smoothly. It does shift better since I rebuilt the t-case and got a new shifter mechanism too

 

[adamsanders]

4-Lo works as it should. If my shift fork pad was bad would it eventually work like it does? It really just seems to happen when I’ve been moving and then push in the clutch. I haven’t had a chance to check the linkage on the T-Case. I doubt it’s the wrong linkage but I guess it could be severely wore. I assume the shift fork pads require a rebuild? I would also like to mention it seems to do it worse when it has a load behind it.

 

[79jasper]

The shift fork pads wont really require a rebuild. You can buy them separately.

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[adamsanders]

But you do have to drop the T-case and open it up right?

 

[79jasper]

Yes. Meant to say that.
And that might as well do the pump arm fix while you're in there.

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[adamsanders]

Is it worth it to fool with it? These seem like they’re a dime a dozen, probably could pick one up for $100.

 

[79jasper]

That's what I've done 3 times. Lol
You could buy one, rebuild it, then swap it.

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[adamsanders]

Ok that’s probably the route I’d take, if it is the shift fork pads will it ever get to where it won’t drive reliably in 2WD due to the pads?

 

[79jasper]

That's exactly how mine failed. Lost high range. Low worked.

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