considering manual hubs

[DmaxMaverick]

This is not uncommon with helical gears (diff and TC), and the reason for backing up. Unlocking the hubs relieves the load from the drivetrain, allowing the gears to disengage. You can do this by unlocking only one hub, or backing up, or driving a distance with some on/off loading. Moving the TC shifter is passive, meaning it only "suggests" the desired gear range (2H/4H). The compulsory "back up" is specifically related to the auto hubs, which are also loaded helical gears.

[flomulgator]

So basically I was still stuck in 4hi then?

It seems then that I could leave the hubs lock but reverse it like when I had the autos and it would unlock the system? How do I do effectively do the "on/off loading" instead?

Also, the vibe at speed is worse than when I had autos and would take it from 4hi to 2hi on the freeway and sped up.

[DmaxMaverick]

The TC should disengage (on the fly) over a short driving distance (mile or so/less), regardless. If it isn't, then something else is wrong. The load/unload is nothing more than acceleration, then deceleration. A couple series of this should unlock it. You may also consider measuring your tire diameters (roll out). If they are off significantly, it can cause a continuous condition of drivetrain loading, which can prevent unlocking. Using synthetic lube in the TC also helps.

[flomulgator]

Okay it sounds like I'm stuck in 4hi then.
Definitely did the load/unload thing (highway version)
All 4 tires are pretty new, purchased together
Full synth all around
TC case may be low though as rear driveshaft seal leaks. Could this be the issue?

[DmaxMaverick]

Okay it sounds like I'm stuck in 4hi then.
Definitely did the load/unload thing (highway version)
All 4 tires are pretty new, purchased together
Full synth all around
TC case may be low though as rear driveshaft seal leaks. Could this be the issue?

Ding..ding..ding.... You betcha!

If it was low enough, for long enough, it may have burned off the shifter fork bushings, which exaggerates the sloppy shift characteristic. Which transfer case (round tag on the rear case half), and what fluid?

[flomulgator]

Ah thanks for the resolution Dmax. I knew I should have topped that off before a trip in which 4wd was going to be seen, but I ran out of time, motivation, and supplies the night before I left. I have no idea what my shifter case is but I'll check next chance (not before I drive home though) based on your description.

Will also need to check on the fluid but Redline 90w-140 would be a good guess.

When I drive through the passes tomorrow I'll really try to give the shifter hell

[DmaxMaverick]

The TC should be serviced with ATF, in almost every case (the reason I ask for the TC model). Using heavy diff/lube oil will cause shifting issues (and premature failure), when ATF is called for. Redline ATF is good stuff, if that's what you have.

[flomulgator]

I was just guessing as I don't have my records here in vacationland, I almost certainly used ATF if thats what it called for; I take my lube seriously. The Redline part is probably true though.

I think the underside is stained red too so that would make sense. Stupid rear seal. Stupid old truck. If it weren't for the help of you and other people on this site I'd have given up on the beast years ago!

I like to think that if it I'm not fixing something then I'm not learning anything. At least that's how I stay positive.

[DmaxMaverick]

......I like to think that if it I'm not fixing something then I'm not learning anything. At least that's how I stay positive.

No doubt! Unfortunately, it seems I've "learned" a lot more than my fair share....

[a5150nut]

No doubt! Unfortunately, it seems I've "learned" a lot more than my fair share....

These old trucks also give a good lesson in patients and understanding.