Diagnosing Bad Transfer Case

[wbdodgeiv]

My new-to-me '67 35a2 has a transfer case will not stay in high.

I think it may have started when I attempted to back up my driveway in high and it popped out of gear right before I jammed the clutch down to keep the engine from stalling. I backed up in low just fine.

Fast forward a couple weeks of not being able to drive due to a lack of title, I drive down the drive way in low, shift to high and it wont stay in gear, promptly popping out of gear.

I pulled tunnel cover from the cab and removed the top cover from the xfer case, it appears that the fork is making a full throw. If I slide the shifter up into high, reach down and grasp the jack shaft and give it a turn it will easily pop if out of gear.

Is there any way to other way to determine that it is shot before I break down and pull it to put a new one in?

 

[Billy Bobbed]

You removed the trans cover.

 

[armytruck63]

Hey wbdodgeiv, welcome to the site. I agree that you probably removed the transmission cover. The transfer case is behind the transmission and is canted way over to one side. You will might be able to remove more of the cab floor to get to it, but most likely you will have to lower it down and out from under the truck to work on it. Not really hard, but the transfer case is considerably larger than the transmission and HEAVY.

There are some VA members on the site that might be able to help or at least watch you work.

 

[glcaines]

The transfer case popping out of high range is not that uncommon. I've seen at least two deuces with the lever tied in high range with a piece of rope. I've also seen some previous posts describing what causes the X-case to jump out of gear. I think you'll find some help if you perform some searches.

Oh, and welcome to SS.

 

[wbdodgeiv]

I removed the small cover (~4"x4") with the vent from the top of the xfer case and can see the shaft and fork move when the transfer case lever is moved - it bottoms out on each side of the opening I was hoping to avoid having to drop the xfer case as it looks like a pita.

I will have to read up on how to remove more of the floor, the rear tunnel cover was easy to remove but doesn't seem to offer up much real estate for slinging the case to drop it down (dont have a transmission jack and the bottom isnt flat anyway.) I am thinking about making a temp top cover with a lifting eye...

 

[wbdodgeiv]

The transfer case popping out of high range is not that uncommon. I've seen at least two deuces with the lever tied in high range with a piece of rope. I've also seen some previous posts describing what causes the X-case to jump out of gear. I think you'll find some help if you perform some searches.

Oh, and welcome to SS.

I physically cannot hold up and keep it in gear. Had thought about blocking the fork over into high for the time being but I cant get up the driveway in high... If a lock were viable I could make a new cover that was taller and held the block, but this just seems like a good way to get stranded away from home with a long way to drive at 30mph.

 

[1crook]

Hey wbdodgeiv, welcome to the site.

Take a look at these threads, they discuss transfer case diagnosis and repair (if possible-see the one about gear wear).

http://www.steelsoldiers.com/deuce/14890-slipping-out-high.html#post146294

http://www.steelsoldiers.com/213760-post1.html
http://www.steelsoldiers.com/deuce/20809-transfer-case-jumping-out.html


If you find that yours is no good, I do have some nifty freshly rebuilt units:

Govt. rebuilt Deuce air shift transfer case - Steel Soldiers::Military Vehicles Supersite

Come to the SS GA Rally and I'll cut you a deal

 

[wreckerman893]

Could be a linkage adjustment out of whack.

I have a deuce that won't go into low range.

Did everything I could but it looks like a transplant is in order.

 

[gimpyrobb]

Check to make sure the linkage is adjusted so the detent catches while in the upper position.

Dang it, Richard beat me to it.

 

[wbdodgeiv]

I will verify the linkage catches on the detent ball, if feels like it does. I will also inspect the innards with a mirror to check for chipped teeth.

I will preface this with "I've never seen the inside of it", but if the teeth edges are messed up and causing it to pop out, would it be possible to increase the throw on the shift fork so there is more tooth engagement?

Modifying the thing isn't the problem, getting it out and apart seems like a huge pain. Why they didn't put a lifting eye on the CG...

 

[clinto]

if the teeth edges are messed up and causing it to pop out, would it be possible to increase the throw on the shift fork so there is more tooth engagement?

Modifying the thing isn't the problem, getting it out and apart seems like a huge pain. Why they didn't put a lifting eye on the CG...

I don't think the linkage is the only thing that controls the depth of gear mesh, so once the gear is worn, that's that.

Swapping them isn't difficult-do a search for transfer swap by author "FMJ"-he has some good pictures of removing and installing them with a tranny jack.

 

[Floridianson]

If at all possable go over head with chain hoist.

 

[wbdodgeiv]

I got all the drive shafts loose before I ran out of light. Tomorrow I will unhook everything else and I plan to use a chain fall with a 4x4 from the bed to the windshield to drop it out the bottom.

I am thinking at this point the best price I have seen would either get me a rebuilt for $700 or a used in the $300 range. $300 is better but free is best so I am considering building up the teeth and re machining.

 

[Billy Bobbed]

ok uh ya

 

[wbdodgeiv]

I got the thing out and broken down today. Dropped it down with a chain hoist. Went pretty easy except for all the anit-vibration mounts were shot. I am also going to replace all the hardware I removed with new.

On the inside it looks just like the pictures in a thread that was linked to earlier. The teeth were worn to a pointed on both the high and low side, I don't know how low range even worked.

I've decided to replace the input shaft assembly with one from a sprag case that is semi local then put it all back together. I am just worried that the replacement case is about to go as well.

Real lousy design IMHO, all these huge gears and the input shaft just barely engages the splines. I don't think it is worth pressing the input shaft assy apart to fix it. I do wonder if the synchros were removed and the housing modified to accept a longer throw that would fix the mesh problem.

The shaft seals seem like they are in fine condition, but all of the gaskets are gone now. Is the gasket kit required or can I use liquid gasket mat'l? The date on the top of the case was 12-19-05.

 

[gringeltaube]

..............................................
Real lousy design IMHO, all these huge gears and the input shaft just barely engages the splines.....

.... apparently you are the first one to confirm it after I reported about this 3 years ago...!

I do wonder if the synchros were removed and the housing modified to accept a longer throw that would fix the mesh problem........

No, I don't think you had to mod. the housing for that! Better consider removing some material from the gear's and clutch collar's faces, to allow for more travel/engagement. Possibly the shift shaft also needing some attention...
Not sure, I've yet to try to accomplish such a poor-man's TC re-engineering process....

Is the gasket kit required or can I use liquid gasket mat'l?

Instead of a gasket I've used loctite 518 to seal both case halves, with good results.
Re-shimming all 4 bearing retainers for correct bearing preload (for intermediate and output shaft bearings) is a must anyways, so final thickness of the gasket or no gasket at all, doesn't matter.

G.

 

[wbdodgeiv]

I got the replacement sprag case from Jim Henry's Trucks & Equipment (www.henrystrucks.com/) for $300 less parking brake assy. He also had air shift cases for $500 less parking brake assy.

I removed the upper in put shaft assy and it honestly didnt look any different to me than the one I removed from my xfer case. I decided that since I had help to get the thing back in on Saturday I should put it back together anyway.

I used some NAPA high temp, oil resistant RTV to seal the case back up. We will see if it holds or not. I ended up not reshimming the retainers. I think they were way too loose before. I had zero endplay when reassembled but the drag when spinning the shaft was not excessive.

Long story short it works. The syncro's are working in the case now, the lever is quite stiff to operate but I think that once it gets some oil slung onto it it will be OK.

Now I just have to fix the frozen PTO and the everything on the truck should be in working order...

 

[wbdodgeiv]

I forgot to add that I did press the old input shaft assy apart. The teeth on the gears appear to be gashed quite a bit so that they will engage with the set of teeth when syncro's stop the relative movement between all of the parts. As surface that the synrco's engage is tapered as they wear they will engage further.

I think the root cause of the failure mode is that the teeth do not engage much when new, this leads to grinding. In order for the mesh to remain constant the syncro's need to wear at the same rate as the teeth.

I wonder if never shifting on the move increases the wear on the drive teeth as the syncro's never wear? I will have to post some pictures but the teeth on the original case look better than the ones in the replacement. The gashing that was done is a larger surface than the wear lands! I am thinking the the engagement of the dogs was the differentiating feature between the cases due to syncro wear.

As I have the extra input shaft, and I fully expect to replace the xfer case again, I plan to figure out how to get this thing reworked. I am thinking that a modification to the syncro would allow full throw. I rarely split shift the truck, I would trade the syncro for a case that will not leave me stranded having to return in low gear any day of the week.

 

[gringeltaube]

OK, good job! Keep us posted with details and pics of what all can/must be done to make them live longer....

G.