D20 in Full Size Jeep

I know this is not a CJ question I thought I would ask the forum for their input. My son and I restored a 69 Gladiator pickup. It has been on the road for a few months. Since the beginning the T-case(D20 mated to a T-14) never seemed to be positively engaged. Now when we put the case into 2h, it clunks. However when we put the case into 4h or 4l, there is no noise. We removed the shifter case and without having the benefit of looking I can not tell if anything is amiss. We also pulled off the gear box cover and it looks like the clusters are not fulling engaging . There does not appear to be any chipped or broken teeth. Someone on the FSJ forum felt there may be possibly a bent fork. Its hard to see if the forks are bent or otherwise damaged.

 

Can you clarify what you mean by clusters? The 20 uses sliding gears to engage the various ranges. In 2 wd only the sliding gear should be moved forward to engage the tranfer case input gear. Nothing else should be moving. It's common for the engagement teeth to get worn and sloppy. I would seriously look at the shifter further. It's very common for these to get worn and hard to find one that is not due to them getting full of water and not being kept lubricated. Many even had a zerk fitting on the housing but still didn't get lubed regularly. I'm guessing you have the "U" shifter that has a "U" shaped shift pattern?

 

If it's the original shifter, it's the U-shifter. I would take the shifter completely apart and wash everything clean in mineral spirits, then if there are no broken parts, put it back together lubed well with some light-weight grease. Look here http://oljeep.com/gw/74_tsm/8-TransferCase.pdf at figures 8-4, 8-5 and 8-15. There is a nice description of how the shifter works next to 8-4.

Repeating what Nick wrote, the pawl and end of the shift lever wear out on these shifters, and if they are badly worn there's not much you can do to repair them other than disassemble, clean and lube. But just being gunked up with old grease and dirt is also common... and they aren't the smoothest operating lever to begin with.

 

I do have a U pattern shifter. I am going pull out the shifter case. and clean up the pawl. The spring looks down right corroded. Can I have a bent fork or cloud it be that the roll pin in the fork egged out the hole in the fork?

 

Seldom do the fork hole get egg shaped. Rarely do the forks get loose, and the fork is held to the shaft by a set screw, not a roll pin. It is possible the set screw has come loose but that should be readily apparent if the shaft moves and the fork doesn't. I would have someone move the shifter and check and see if that movement is being transferred to the shift rails on the outside of the transfer case. If not, the shifter is an issue that needs resolved first before digging deeper into the transfer case.

 

I was going to post some worse case scenario shifter pictures but apparently I threw out all those shifters. Two things that wear the most is the bottom of the shifter and the pin on the side of the shifter. I've taken a few apart that had worn slots in the shift rails but that was usually due to absolutely no lubrication left in the housing. On very rare occasions the tube that goes between the shifter to the front of the TC have come loose. It's not that common but something else to check.

 

Had my son move the shifter thru the gears. Initially nothing would move. I noticed that there seemed to be a lot of slop in the shifter case.Then for some unknown reason, he was able to move through the gears. Herm the OD Guy has a good used shifter case and its been ordered. I cant see anything wrong in the gear box. My buddy is going to look this am. Maybe he will see something that I am not seeing.

 

Still waiting on Herms "good" box. My buddy and I looked at it again. We both agreed that the problem lies in the shifter box. (never bet the house on old jeep diagnoses)The t-case itself looks good also. I took the old one out and soaked it. Seems to work better going to wait on the new one. Hopefully, the problem will be solved.

 

Our CJ has a J box shifter. I guess someone needed a transfer case for it at some point and found one from a full size. I had trouble with it when My wife brought the Jeep home and as I recall there were some loose set screws inside were allowing the guts in the box to just slide along the rails without shifting the transfer case. Once everything was cleaned and tightened up it shifts fine. Although it still feels crappy.
There's a twin stick kit out there on the market if you're interested in one of those.

 

still awaiting the delivery from Herm. I soaked the old shifter case in parts wash. There is absolutely no resistance in the case. If I turn the case on end, the shifter rods slide right through to the other side of the case. I believe there should be some sort of detent at each shift position.

 

Yes there should be. The detent springs are most likely broken (common) or the poppet balls are gummed up/corroded in place. Jeep in their infinite wisdom used plastic plugs for the detent bores and common for water to get in there causing all kinds of problems. IH used metal threaded plugs, much better. Stupid thing is most Jeep front housings are tapped for the threaded plugs.

 

Inside the shifter itself has no balls, detent or otherwise.

 

Just for clarification, I was talking about the shift rails going into the transfer case itself. If you were talking about the rails into the shifter unit then, as PackRat indicated, no detents there.

 

Replaced the shifter case and the problem still exists. Still clunking going into second in 2H. No noise in either 4H or 4L. I will check the u-joints. Can it be the rear axle? My thoery is when the T-case in engaged, less force is exerted on the rear axle. Guess I cant rule out the the transmission.

 

Replaced the shifter case and the problem still exists. Still clunking going into second in 2H. No noise in either 4H or 4L. I will check the u-joints. Can it be the rear axle? My theory is when the T-case in engaged, less force is exerted on the rear axle. Guess I cant rule out the the transmission.

Forgot to include this fact: I did find what was left of a large cotter pin in the t-case pan. Looked through the TSM and cant find where a cotter would go on D20

 

Re: D20 in Full Size Jeep

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Some transmission output shafs use a cotter pin and castellated nut to retain the transfer case input gear. If the cotter pin came out it!'a very possible that nut is loose and allowing the input gear to move around. That could certainly cause the symptoms you describe.

 

Have d18 in my 57 cj, that has a output shaft nut and cotter pin. The d20 does not have the cover on the rear of the t case. I was also told to pull the rear axle cover and check out the ring gear,etc.

 

That doesn't fix the problem of where the cotter pin came from. That should be a clue of something going wrong.

 

Discovered another possible cause of the problem. My son put the truck on jack stands to check the u joints. I noticed that when I spun the the front drivers wheel the passenger spun. The lock o matics were on free. The drivers side hub is making a noise. My theory is if the one wheel is spining the axle and then tcase, the bang could be originating there. By the way, the u joints looked good. Any merit to this idea? Heading out to the garage shortly to take the lockomatic apart.