hello i have a 78 ford 3/4 ton 4x4 and when i put it in 4x4 and drive through the snow or on solid ground it will go for a while then it will jump out of 4x4. in 4 hi and 4 low. then some times it will jump then stay in 4x4. anyone had this happen, or know what the problem is?

 

any one know what to do? i need my 4x4.

 

Just grabbing at straws here, but I had a 77 F150 some years ago. It would jump out of 4 high. I got to looking at what was going on and found that a PO had apparently cut the hole wrong for the transfer case shifter. It was about 1/2" too far forward. When you pulled it into 4 high it would pinch the boot and then when you threw the torque at it, it would pop out of gear. You couldnt hear the lever hitting or vibrating against the floor board because it was insulated by the boot it had pinched. I enlarged the hole a bit and moved the boot back a bit and solved the problem. The truck had been a repaired roll over before I bought it so who knows how the hole ended up wrong..............But if yours is jumping out of 4 high and 4 low that may not be your problem but worth a look. Id also look at your linkage and see if it looks worn. It could also be the detent ball on the shift fork rail is worn or has a broken or collapsed spring.

 

My guess was going to be improper engagement as well, but from a bad shifter bushing. Under the cab, there's a bolt that the shifter sits on, and it has a plastic bushing. When they go bad, then there's slop in the shifter, and this could lead to improper throw length, causing it to not fully engage.

The reason I think this is because both high and low 4wd are at the extreme ends of the shift pattern.

 

Does anyone know where I can get a replacement plactic busing for the
tranfer case shifter?

Thanks,

 

Not sure where to get the bushing, but while you have the shifter out to replace the bushing, do yourself a favor and drill and tap the sleeve that holds the bushing for a grease zerk. Youll also have to drill the bushing to allow grease to get to the shaft. Then just give it a pump of grease every time you service your truck. It makes for silky smooth transfer case operation and will save a bunch of wear on your new bushing. They get full of mud and grit which can make them so you cant even shift it. That's how I came across this little fix. I had a 77 that you couldnt move the shifter after a while. But then again that truck lived in the mud.......LOL I've done this to every dent Ive owned since..........Works great!!!!!!

 

You might try NAPA. They seem to actually carry stuff like that. Sorry I can't be more help.

 

what size thread is a grease fitting? are they pipe?

 

They make several sizes of grease fittings, 1/4 x 28 and 1/8" pipe thread are most common. There are also several metric sizes. I usually use the 1/4 x 28 for this mod.

 

Thanks, I'll give them a try. I'm replacing my NP203 with a NP205 and during the replacement process I noticed a lot of slop in the shifter... What would be cool is if I can
find a brass bushing instead of the plastic one.

 

Are you sure it isn't one of the hubs lockins doing this ?

 

the shifter has slop in it but when i put it in 4 hi you can wobble the shifter around and it still stays in 4 hi i went for a drive and it makes a loud "clunk" but it did not kick out of 4x4 this time. on my left hub the arrow dont line up with the "free" and "lock", but if i crawl under my truck and try to turn the shaft it wont turn. the t case is in 2wd when i try to spin it so i think that means the hubs are working? i am lost on this one i cant figure it out.

 

You may have wear in the linkage at the transfer case itself or a pin has come out. Or possibly a broken shift rail. I'd look ALL the linkage over good.