Manual / 4WD shifter

[BP1971]

New 1971 Bronco owner. 3 speed manual. Always in 2H. I am not the most technical guy, learning as I go.

Driving down the road, twice in the past week, while in 3rd gear engine revs when gas pressed. Not in gear even though in gear. Pull over, shift into 4H, then back to 2H, manual then reengage and I can drive.

Is this a linkage problem, transfer case, etc? It's almost like the Bronco shifts into neutral on it's own and I have no gears. I am not touching / accidentally hitting the 4W drive shifter.

Thanks.

 

[nickgp]

Sounds like the shift rails in the transfer case are worn. The rails have a detent(depression) machines into them. A ball bearing rides in the depression under spring tension. This keeps the transfer case in the desired position. Once it’s too sloppy, it pops out of gear like your describing. Recently had this issue and had to remachine the rails.

 

[.94 OR]

I am wondering if the main bearings in your 3-speed are well worn too. My 3-speed used to pop out of 3rd gear when coasting over the top of hill transitioning from power to coast to decelerate. I talked to a transmission guy and he said with the bearings being worn it allowed the internals to float and actually let the small gears disengage. If there is that much movement in the output shaft I would wonder if that movement is transferred to the transfer case and causing the input gears to move and possibly help "pull" it out of gear. The detent springs in the T-case could be sacked out and the shift rails could indeed need trued up.

 

[DirtDonk]

Usually with the 3spd transmissions, if it's kicking out of gear on the transition between cruise/accelerate and decelerate, it's in the transmission. Again "usually" if it kicks out of gear under power, it's a t-case issue.
Of course, you can tell that right away by needing to shift the trans to get it back in gear, or shift the transfer case to get it in gear.
Just saying it's consistent with the t-case popping out in this case.

Has happened to quite a few people in recent years unfortunately BP. Not all are the same thing either. Sometimes it's a worn or loose output shaft, sometimes other things.
You may just have to start digging into it, but some others here can tell you where to start first with that. Maybe checking play in the output, maybe checking the detent balls and rails.
But it sounds like it's shifting in and out pretty easily by your description of putting it in and out to get going again.

What about pushing it into 4-low the next time? Since it's in the opposite direction on the shifter, this may change the dynamic somehow and lead you to some other clues.

Good luck. And welcome to classicbroncos too! Hope you get it sorted easily. Congrats on the new-to-you '71 too!

Paul

 

[SHX669]

What they ^ said .
I assume you have a T - Shift transfer case . I would start with the easiest thing first -
Check to see of you're actually going all the way into gear . If you still have the gear indicator that says 2hi - 4hi - 4 lo etc don't go by that . The indicator is adjustable and can slide forward and backward somewhat . Loosen the housing , pull the shift lever until you're certain you're in gear then tighten the housing. Another culprit can be the shift linkage out of adjustment - bent - or worn . The shift lever will move but the linkage won't push/pull the shift rails far enough to fully engage the gears .

 

[BP1971]

Thank you all for the info, extremely helpful.

 

[Rustytruck]

Put the truck up on jackstands. Leave the truck in neutral and parking brake off. Grab the drive shaft near the back of the transfer case and try to wiggle the driveshaft around. If it wiggles about it needs to be fixed. WHAT EVER YOU DO DONT PUT A BUNGEE ON THE TRANSFER CASE SHIFT LEVER.

 

[Pa PITT]

RUSTY WHY ON THE BUNGEE.
.. Now I'm asking because I've thought of doing just that for mine .... '''BUT'''...
Mine jumps out of 4x4 low range but I'm only driving 5 mph in my pasture..
I think mine is adjustment on the linkage.
... but just wondering why on the bungee.

 

[Rustytruck]

Putting a bungee on the shift lever pushes the shift fork in the transfer case to one side and wears out the side if the shift fork and the side of the groove it rides in. As far as i know there is no new source of these these parts and you need to chop up another old transfer case for replacement parts.

 

[Pa PITT]

... Holy SMOKE I guess I'm glad I have a spare T/C setting .
My T/C JUMPS OUT OF GEAR IN ABOUT 3 minutes of drive time . Not normally a big deal unless it's very wet &I'm not watching .
Or when I'm pulling a plow or a planter in sand . When it jumps out in sand under a pull It doesn't sound to good.

 

[SteveL]

Is the 3spd a floor shift? If its slipping out of 3rd and not the t-case you might be able to adjust the rods between the tranny and the shifter to go a little deeper in 3rd. This is on a floor shifter.

 

[JB Fab]

RUSTY WHY ON THE BUNGEE.
.. Now I'm asking because I've thought of doing just that for mine .... '''BUT'''...
Mine jumps out of 4x4 low range but I'm only driving 5 mph in my pasture..
I think mine is adjustment on the linkage.
... but just wondering why on the bungee.

What Rusty said!

If it pops out of rear low into neutral it is most likely the input shaft has a bit of endplay (usually the bearing in the adapter), causes the input gear to rotate in an elliptical motion (VERY VERY slight), causes the sliding gear to walk off the end of the shaft into the neutral position. If it is a "T" type case it can be made worse by the ramped profile of the shift-rails.