Yeah defo sounds like something is off with the shifting mechanism internally.

You asked about common issues to watch out for, the only thing I can think of is the oil pump's arm. Basically it indexes into a slot between two ribs cast into the front case's half, but the contact surface is relatively small and sometimes the steel arm will rub thru the sift rib and allow the pump to rotate with the shaft causing a big mess inside. Some people drill and tap a hole thru the case half and use a steel bolt to keep the arm in place, I prefer to just weld a small plate that spreads the load across a much larger contact surface - either way gets the job done.

 

I'm glad you said this because I saw it years ago as a fix but then forgot completely about it. Great advice

 

Thanks! I did find some information about that so I'll definitely be doing that while I'm in there.

 

Took me long enough, huh?

So I found a pair of 1356s not far from me for cheap and picked those up. One manual shift, one auto shift. Against my better judgement I went ahead and threw the manual shift one in without really getting in to it. The 2/4 shift worked fine and the high/low shift worked fine, but when in either high gear it would make a strange ratcheting noise when coasting and it would sometimes act like it's in neutral when in reverse. Did some digging on that and found that it happens when the mode shift isn't engaging properly and it isn't completely shifting into high. So different case different problem.

I let things sit for a while as we went through a ridiculously hot few months with no breaks, but just this last week decided to crack open my original xfer case and see what the problem was with never coming out of 4.

No return spring! Completely missing. Not broken in the bottom or anything, it just isn't there. With the case sitting nose in the air so gravity would drop the fork back down it would go in and out of 2/4 no problem. Nothing grenaded inside, everything looked fine. Someone had just been in it before, and didn't put the spring back in.

Found some other stuff while in there. The pump arm had worn about halfway through the case. The chain was slack and had worn a good amount through the rod support for the electric shift - that by the way explains the almost crunchy sensation I could feel when rolling slowly.. it felt like the tires were compacting wet snow and definitely in the drivetrain but couldn't find it. I figured it must be in the xfer case and it was. The high/low fork in this one was also fairly worn on one of the bushings.

Cobra Transmission had a used spring for a couple bucks. I put in a new chain and a new high/low fork. I cut up a bolt and welded it to the pump arm then gave the insides a bit of a cleaning and back together it went. Not a complete rebuild, but I doubt I'll ever put as many as 20k miles on it for as long as I own it. Just a farm truck.

Went to do the swap and as I was draining the ratcheting xfer case that was installed, out came one of the high/low fork bushings with the fluid. Yup, that explains the shift to high not fully engaging.

Managed a brief test tonight and it seems to run great. No ratcheting noises, front driveshaft releases in 2high and in neutral. Goes in to low and then back in to high like it should. 4 high is a little hard to find I think but it was too dark for me to really test it.

Pump wear


Chain wear


Getting ready to stick them together


Stuck together!


Looks more crooked than it is, but the case does have a bit of a taper to it which I didn't account for. Did some grinding to get it close.


New chain, new (to me) return spring, and you can kind of make out the new fork at the bottom of the stack. Old fork in the back and you can kind of see how one of the insert bushings is blown out.

 

Well since ya’ll are cracking these things open, any chance you can give an itemized list of what you suggest replacing when I crack mine open? I’d just as soon order parts beforehand and replace all that I need to while I’m in there. Mines a manual shift on my 97 F-350. I can hear my chain for sure, and trucks got a third of a million miles on it.

 

They're dead simple.

Chain. <-- by far the most expensive at a whopping $130 lol
Forks
Bearings
Seals
Tailshaft bushing
Oil pump
Address the oil pump arm to case interface wearing problem.

You need snap ring pliers that don't suck, seriously. I have the parts store kind with replaceable scissor ends, won't work. I have the Craftsmen kind with replaceable tips, won't work. I got a set of dedicated solid pliers with inside/outside/straight/bent and they just barely worked.

From what I can tell the bearings and bushing are almost always perfectly fine and don't need to be replaced, but if you're in there you're in there, and they're cheap. One of them requires removing the planetary which has a snap ring that's notoriously difficult to get to.
I didn't do the bearings. I didn't even do the seals! 🫣. I'll take my lashings 🤷

 

Better late than never! Good info for me when I make the 4.9 a 4x4.

Wish I was in town, would have brought over my Cornwell snapring plier set for you to bum.

PS how are my old Alcoas treating you on the truck?

 

They're a lot nicer than the steelies I was going to run. Those things are damn heavy. The rest of the truck looks like if it was a horse I'd shoot it, but the wheels and tires are 👌