tcase falling into neutral?

[nightglide]

So something in my drive train is making a clunking/shuddering type noise/reaction. Almost only going uphill.....even a slight one....and worse when its cold.
I feel like the tcase is poping in to neutral for a brief second and then back into gear. Possible? One morning it even did it then started revving. I let off the gas instantly and then it was fine.
Could it be my tcase? Is lever adjustable?
I ordered twin sticks and was kind of waiting for them to dive into it but it seems like it might be getting worse and BJ's hasn't even processed my order let alone ship it yet
Any suggestions would be greatly appreciated.
77 j10 360/t18/Dana 20
Thanks guys

[Stuka]

Its a common issue for D20's that have a worn intermediate shaft to pop out of gear. But I have never heard of them popping back into gear.

For you it sounds more like your clutch is slipping. Does it do it in low range?

[rocklaurence]

Its a common issue for D20's that have a worn intermediate shaft to pop out of gear. But I have never heard of them popping back into gear.

For you it sounds more like your clutch is slipping. Does it do it in low range?

Yep-clutch is the only thing that will slip and then return. Maybe a sticking TO bearing?

[nightglide]

But its more of a quick clunk. And I can get on it hard and spin both new 35" tires on dry pavement no problem with no slipping or clunking???

[nightglide]

No slipping or revving of any kind. Just a quick clunk. And almost only going uphill...... Even slight ones. Was wondering if my tcase lever or linkage is somehow leaning back going uphill and falling into neutral???

[tgreese]

Interference with the body moving the shifter is common on CJs, but I don't know how often it happens in FSJs.

[Stuka]

Interference with the body moving the shifter is common on CJs, but I don't know how often it happens in FSJs.

If the FSJ has a body lift of any kind the D20 shifter will hit the body.

Even a badly worn detent ball wouldn't let the shift push it out of gear by going up a hill.
Does it do it continuously while climbing a hill?

[nightglide]

No body lift, stock shifters. Pretty much continuously uphill but no rhythm. If I leave it in 3rd and have motor working harder it does it less but more violently. If I have it in 4th and kinda lug it it does it more but less of a shuddered

[Stuka]

How easy is the shifter to move from 2wd high to 4wd high? Does it feel loose and sloppy? There is no way its actually hitting neutral as neutral is between 4wd hi and 4wd low. But maybe its moving enough to catch the front output now and then?

Always a possibility its in the trans or rear axle.

[nightglide]

Its kinda sloppy I feel.......first fsj I've ever had. Will the twin sticks help at all??

[Tatsadasayago]

I experienced a similar problem with a T-15/D20 combo in my 74 Cherokee. Turned out to be the shifter tubes were loose and would work their way in and out depending on the driving and throttle conditions.
You can diagnose this issue fairly easily by removing the floor cover, placing the transfer case in 2-Hi, disconnect the shift links and take a drive. If you feel this issue occur again you can quickly see if the linkage shafts (The two round shafts coming out of the TC) have moved. If my memory serves me correctly, in 2-Hi both shift shafts are to the rear of the transfer case.

[Stuka]

Its kinda sloppy I feel.......first fsj I've ever had. Will the twin sticks help at all??

Not if its caused by worn detend springs or worn intermediate shaft. With either it requires pulling the case apart.

[nightglide]

Good idea tatsasayago.I am pulling cover tomm and changing tranny fluid so I will disconnect linakage and see.
After driving it today.....I'm going to say it does feel like case is trying to engage front end while driving....

[rocklaurence]

Could it be binding and your perceiving it as slip. Maybe a piece of gear getting caught-in the Tcase or rear differential.

[nightglide]

It could be.....just the hill part has me confused......

[nightglide]

Drove it on the hi way tonight for the first time since buying it. 65-70 mph pretty much all downhill without much issue. Drove secondary roads home.....uphill.....50 or so.....did its clunking thing. Noticed when the lever is pressed all the way forward it can go to the right a little and a touch farther forward. When it clunks it not in that position anymore. When I got home I wired the lever all the way forward to the right. See how the ride to work is like in the am..........

[Tatsadasayago]

Your shifter should be forward and left in 2WD.
4WD High is straight back and to get to 4WD Low you have to move the lever back through neutral (centered) before going into 4WD Low which is forward and right.
The most common cause for the D20 walking out of gear in 2WD is worn or broken shift lever torsion spring.

From your description of the symptoms, the shift lever isn't moving when you experience this issue. When the TC walks out of gear in 2WD, the mainshaft slider gear disengages from the transmission output shaft gear and the TC is in neutral. This was a common problem with the D20 in the Cherokees and J-Trucks with the single lever.
If I am correct and your torsion spring is borked, the challenge will be to find a replacement...
Here's the exploded view of the shifter from the TSM:

Oh, and you might want to check to see if the shifter walks out of 4WD High or Low while you're at it. If it does, you're looking at opening up the TC to fix stuff. Not a difficult thing, but messy with the TC still in the truck.
If you need more help with this, be sure to shout out.

[nightglide]

Does the twin sticks kit get rid of all that?

[nightglide]

Would it be safe to drive it in 4hi with front hubs unlocked to see how it reacts? At what speed?
Might try that on my way home from work today. It's a 45mph road mostly uphill.........

[nightglide]

oh and my shifter lever is for sure not budging......I have it wired tight in 2wh..........