forman

Rebuilding a Jeep CJ-7 Dana 300 Transfer Case

32 posts in this topic

Hey I enjoyed the compressor story!
 
Today I was able to start disassembling the transfer case I followed your procedure and took some photos.
 
The impact driver worked great on the yoke nuts and to be honest most of what I disassembled today was very easily done. I have to admit once I learned the new to me transfer case nomenclature it went very well, I'm having fun.  

 

I noticed that the intermediate shaft had some wear, I could feel where the gears rode on the shaft. The gear teeth that I can see so far aren't showing any sign of wear I hope some of the photos will show.

 

In the first photo the bushing on the left looks rough on the outside.

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To assist with your rebuild and help other members at the forums identify and select genuine Jeep/Mopar parts by their original Mopar part numbers, I have compiled a parts PDF for the Dana 300 transfer case, 1981-86 Jeep applications.  Here is the PDF that you can view, zoom into for image clarity and order parts, using the factory part numbers:

 

Dana 300 Transfer Case Mopar Parts.pdf

 

I trust that this will be helpful when you describe various features and components, Forman.  Zooming into a PDF, you'll discover how clear, detailed and helpful these images can be!

 

Moses

 

 

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Moses those downloads are very important to me right now many thanks!

 

I worked on the transfer case during my lunch break today I utilized a tip from the author of Jeep CJ rebuilder's manual.  I used an air hammer with a blunt point to drive the rear output shaft through the rear output shaft front bearing.  It took longer to roll out the air hose and oil the air tool than it did to push that shaft through the bearing. A very smooth operation!

 

PHOTO 2 is of the rear section of the shaft after the rear bearing cap was removed.

 

 

 

 

 

 

 

 

 

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Just below the center of the photo are a pair of shift forks.  I was able to remove the set screw of the rear output shaft shift fork and remove the rear output shaft fork shift rod. Quite a tongue twister say that 3 times really fast ... almost as difficult as saying "I'm a sheet slitter I slit sheets" repeated several times. :D  However the other shift fork set screw does not want to be loosened with the tools I have.  I think I will try some heat applied with a heat gun tomorrow.  Then acquire a socket driven allen head if that doesn't work.  

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Thanks for the feedback on my Jeep CJ Rebuilder's Manual, Forman!  I've used this air impact "dancing shafts out of bearings" routine for years.  If you carefully control the blunt tip of the air tool and keep it in the pocket end of the shaft, the driving force is way less damaging than beating (factory likes to soft pedal this as "tapping") shafts out of the bearings. 

 

When a press is not practical, out comes my trusty air impact driver with a blunted chisel end! Always protect the shaft threads from impact tool damage, and begin with a light trigger pressure to make sure you have control. If the shaft pocket and blunt chisel are not a good fit, an old nut can be run onto the shaft, flush with the shaft end, to protect the threads from the driver tool.

 

Regarding the very tight set screw, I would use a hand impact driver to get the set screw loose.  You likely have one in your tool set for Japanese motorcycle case Phillips screws, and if not Harbor Freight would be pleased to provide.  Use an allen head socket and the impact driver to shock the set screw loose.  The combination of counterclockwise rotational force and inward pressure at the same time should work.  Don't pound on the driver too hard, shafts and cases can become damaged.  Sharp, solid blows to the impact driver head will suffice.  If you can support the shaft from the backside, that would reduce load on the shaft and prevent risk of bending the shaft at the set screw section.

 

To avoid ruining a lunch break, don't round off the hex in the set screw.  This is a very hard screw that would be extremely difficult to drill and "easy out".  You'd need to drill through to the taper point of the set screw, and realistically, even if you have ultra hard carbide drills, it could take from lunch to your punch-out time to remove that set screw!

 

Let us know how this set screw reacts.  The hand impact driver and an allen socket can help here.

 

Moses

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I know the one thing I did not want to do would be to round off the hex in the set screw.  I think I mentioned in an earlier post that I live in the middle of nowhere and purchasing parts takes a few days.  With an understanding that if I ruined the hex, then the removal of the shift arm and shift rod would be delayed probably until i cut the shift rod with a cutting torch.  I decided to give the removal of the set screw the old "college try".  I was limited by leverage so I made a simple tool and was certain that the alignment was straight.  I have to admit that I was thinking of giving up when the set screw "winked" and then gave up and let itself be loosed. I think I'll get those tools on order now.

 

The tool I made to help remove the set screw below

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Necessity is the mother of invention, Forman, you got a lot of leverage with that piece of strap!  Glad the set screw hex stayed intact.  Good job!

 

You're well on your way to a disassembled Dana 300...Do you have a glass bead blaster cabinet for cleaning up all the rust and scale?  I'd like to see the parts laid out in order, we can talk about the cause of the unit's whine and the lurch/surge noise. 

 

These are bulletproof transfer cases, and the helically cut gears make them quieter and closer in tolerance.  In "as new condition", a Dana 300 can handle 400 horsepower—and they have!

 

Moses

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I do not have nor do I have access to a bead blaster at least for the moment .  Do you have any other suggestions that might help me clean these parts?

 

I thought I would try to use the air hammer to push the shafts through their respective bearings... here is how I blocked up the case.

 

I shot video of the air hammer removal but unbeknownst to me my camera went to sleep due to a low charge and the video did not capture the shafts falling through the case.

 

Finally an empty case with input and output shafts. 

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What the heck here is the video.  I had to apply pneumatic force for an extended time on both shafts but the process worked very well.

 

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Yea, Forman!  Sharp and detailed photos and a video...You're on it, and this is very helpful to others...Thanks for being thorough and taking time to do this!  The Dana 300 project will be a big success story in the end.

 

I'm not in the habit of spending others' money needlessly; however, a glass bead blaster is a huge enhancement to your shop.  An affordable cabinet can be had new for around $400, a good used blaster might be had for a tenth of that price.  I've shared the TP Equipment unit that I currently use, it's ideal for transmissions, transfer cases, motorcycle engine rebuilding and such. 

 

When I was doing the book projects, I bought a rather large TP Equipment cabinet that enabled me to stick an entire Jeep axle housing into the cabinet.  (That unit went with our sale of the property.)  We made a conscious choice to downsize (recall the compressor story), and in the process, I bought my TP 360 unit, which is ideal for current projects.  Maybe a glass bead and soda "dual-purpose" machine would be an option.  I could convert this 360 unit if desired.  Instead, I'm using different glass abrasives and other select blast media for specific jobs.  We can talk about blaster cabinet choices at the tool forums...

 

The real issue with a blaster is air volume.  These machines are a black hole, as I shared in the compressor story.  22 CFM is a sensible target volume for the compressor, some get by with as little as 19 CFM.  Anything less will be daunting, and you also need a good size air storage tank for initial startup.  Size of the cabinet is immaterial, the air volume needed is determined by the blast gun. 

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Recent project with a TP Equipment 360 blasting cabinet and glass bead. Quick, thorough and optimal results, glass and soda blasting are the ticket! Make sure you have an adequate air source for bead blasting...

 

If your at-work shop has a large compressor that can keep up with a blaster, this might be worth pursuing for the shop.  Once you use a blaster effectively, you will never want to use a drill motor and wire brush again.  I'd like to see you pick up at least a used cabinet blaster if you have an adequate air supply. 

 

Otherwise, you'll be using a drill motor and wire brush to cut through the rust.  Some claim decent results with chemical rust removers.  Anyone want to comment here?

 

Moses

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I found a little time to clean some of the parts today.  I thought I would post some photos for reference and to ask for assistance in understanding the condition of certain worn areas.

 

The intermediate gear minus the needle bearings

 

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A close up of the shaft worn areapost-140-0-65870200-1392155954_thumb.jpg

 

the gear and interior close uppost-140-0-32945500-1392155971_thumb.jpgpost-140-0-49218500-1392155966_thumb.jpg

 

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Forman, how bad was the oil in this gearbox?  Did the unit starve for oil at some point?  Maybe from oil leakage?  The bearing spacer inside the intermediate gear was chafing against the gear, the shaft shows wear, and the gear teeth look like they were "spreading" away from the engaging gears—also, debris was running through the unit between the gear teeth.

 

Assemble this gear on the shaft with all parts in original positions: needle rollers, spacers and thrusts installed in order.  See if the gear is wobbling on the intermediate shaft or moving with a good deal of clearance between the gear, bearings, spacers and the shaft.  It looks like the intermediate gear was running "loose", and wear is evident. The end thrust plates are obviously worn.

 

Let me know what you find with this assembly.  This intermediate gear is abused and worn, and these are tough gears!  Here is the whine and lurch.  What do the engaging gear teeth and parts look like?

 

Moses

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The oil was thin smelly and leaking out.  I expected to find worn parts.  I found no gaskets while tearing down the transfer case, so I"m assuming it has been rebuilt before.  I apologize for taking so long and stretching this out but I am just busy putting out fires at work and home.  As for the other gears I have some questions that can be best answered by viewing photos so I'll get busy with that.

 

 

Thanks Moses I will assemble the gears and try to get a video of the clearances and play. 

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Clearances on this intermediate gear should help pinpoint the wear factor.  Your photos are always appreciated.  We're all busy, Forman, no pressure or timeline here.  This project will get done in due time...

 

RTV and anaerobic sealants were coming into play when the Dana 300 was built.  Gaskets are a non-issue, though seals and sealant can leak over time.  The earlier Spicer Model 18 and 20 units were notorious for leaking, they each used cut gaskets that suffered sorely from the twisting and stresses of four-wheeling and high torque.  The Dana 300 is prone to leakage at the bearing shim plates and lip seals.  The only gasket is at the inspection cover, which can leak but more often holds up okay, no twist or stress here. 

 

Family and work come first...You'll get to the Dana 300 when you can...

 

Moses

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I had the best intentions of getting a great video of a sloppy gear on its shaft.  What I got was just an ok video where the gear to shaft play is difficult to see.  I used grease to help the needle bearings and spacers stick together and make it easier to assemble.  It was cool today and the grease felt thick and sticky so I think the grease would make the tolerances seem tighter.  Here is the video and a couple of close ups of the intermediate large and small diameter gears.  I had .013" clearance between the gear and the case wall, The shaft is worn and the wear is easily felt while sliding a finger along the shaft.

 

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Great update, Forman...It's that "tends to wobble" that I was after.  The endplay is of course excessive, we knew that from seeing the wear at the end thrusts.  This intermediate gear/shaft looseness and wear were central to both the whine and lurching.

 

Typical of a tough Dana 300, the whole setup would have lasted a lot longer if the intermediate shaft, bearings and the gear itself had not become worn and loose.  This is not a "weakness" in the Dana 300, rather this unit took a beating over time, likely lacking oil when vitally needed.

 

Were it not for the pitting and scoring on the gear teeth, the upper photo shows a gear with normal tooth mesh.  The other gear is scored and pitted.  The abnormal tooth shape resulted from the loose and wobbly intermediate gear.  How do the mating gears look? 

 

Not sure what your budget might be or the end game for this Jeep CJ-7.  You've narrowed down the noise and backlash in this Dana 300.  If you have the time, lay out the other gears and parts, photograph or film them (whichever is easier), and I'd be glad to comment on what I see.

 

Based upon budget, we can talk about parts options for restoring this unit...

 

Moses

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I think I know the kind of photos I need to take for you to be able to see what kind of shape the gears are in.  Theses few are marginally good enough, I'll give it a little more effort and post some more later.

 

I am not sure the problems with my drive line are limited to the transfer case, I'm pretty sure the rear end has some issues also.  I don't wish to make troubleshooting more difficult.  I'm just stating the facts.  My budget for repairing the transfer case would be enough to restore with factory parts, if those are difficult to find or super expensive I might be able to buy aftermarket parts toward an upgraded condition.

 

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Forman, I need to share that these photos are professional grade.  Short of using benchtop studio lighting (which would be total overkill for our purposes!), these photos are certainly magazine level.

 

There are very clear indications of wear and fatigue, major concerns if we were talking about a day-in, day-out trail runner or installing a 5.7L GM V-8 in this chassis.  I like your hint about wear at other points on the vehicle.  There's no sense in doing a "blueprint" rebuild on this Dana 300 then have the Model 20 AMC rear axle, Dana 30 front axle and T176/177 transmission require major work—about the same time that the 4.2L six decides to give up!

 

Let's talk about reasonable restorative work here, aiming for transfer case survival to the point in time when the entire Jeep CJ has outstripped its duty cycle.  Or do you want the Dana 300 to be the first "as new" restoration piece with the whole Jeep intended for this level of work later?

 

Moses

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Thanks Moses here is a picture of what I usually take photos of.  post-140-0-60035700-1392339233_thumb.jpg

 

These photos are of gear teeth associated with the front output shpaft

 

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This photo is of the large gear of the transmission input assembly

 

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This Jeep will probably never see asphalt or highway speeds again, in fact that has been true for the past 15 years.  90% of the time it is in 2H, 4H when it is muddy (almost never) and 4L when climbing usually for about 3 minutes at a time.  Never over 30 mph. I love riding through the pasture with the top down and windshield lowered, it is quiet and comfortable... conversation with others is easy.  I have to say that the lurching is annoying, I'm ready for it to be gone.   The rear axle is probably next!

 

 

 

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I should answer your question about reasonable restoration.  Yes that is the right answer for this Jeep.  The engine was replaced about 4500 miles ago with a rebuilt 4.2 I6.  Soon we should talk about the under the hood problems and options.

 

Deep down inside I would love to rebuild and upgrade as much as I was capable of but that is just not an option with this Jeep, Perhaps when I retire I can buy it as surplus and go from there??

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First, the wildlife photography is terrific!  What camera and lens system are you using?  This is ultra sharp, very good depth of field control, too!

 

As for the Dana 300, the gear teeth patterns would be okay if hard metal had not circulated through this unit.  Note that the scraping evident at the teeth is uniform across the tooth faces, that's a good tooth contact pattern.  The concern is the depth of this damage.  These gears are typically 8620 or similar base metal with case hardening after machining.  The depth of case can average 0.035", sometimes more, seldom less. 

 

Given the case hardening, try to judge the depth of these striations from debris.  With the heavier gear lube used in a Dana 300, you can likely get by without replacing all of the gears.  We know that the intermediate gear is gone, especially if its inside wear at the needle rollers is contributing to the wobble and radial play.  Any gear(s) that you reuse must have normal contact patterns.

 

If you want to minimize cost here, you need gears with teeth that will mesh properly when using a new or "good used" intermediate gear.  If you seek out used gears, that's a gamble, because gears establish a wear pattern, and two used gears will increase the likelihood of tooth contact issues.  So, if affordable, a new intermediate gear would be advised.  You definitely need a new intermediate shaft, thrusts and the bearings.

 

Considering that this is a through-drive transfer case, in high range you simply need the input and output to lock up without play.  The bearings and support for shafts need to be on tolerance.  Make sure that parts will run in alignment.  Be certain that the 2WD to 4WD synchronizing mechanism will work properly and that the transfer case shift positions will not jump out of gear.  From photos, some of these parts look rough and worn.  Check shifter detent parts carefully, these are small parts that play an important role.

 

As for low range, if you can eliminate the backlash of the gears, caused mostly by a loose intermediate gear, replacing some of the other parts is elective.  You're not taking this Jeep over the Rubicon Trail with 35" tires and axle lockers.  You simply want the transfer case gears to mesh properly, shafts to stay aligned, and bearing end plays to be correct.

 

Note: These last points are covered in my Jeep CJ Rebuilder's Manual: 1972-86.  Proper end play shim adjustment at the bearing cap during final parts assembly is crucial.  Bearing play determines parts alignment and bearing life, keeping the shafts spinning true with the correct bearing preloads. 

 

Share what parts you think are reusable and how you're approaching the new parts needed...I'm here as a sounding board and extra set of eyes!

 

Moses

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I use a Canon 60 D camera and I believe that I was using a 55 - 135 EF-S kit lens.  I was also very close to the little buck fawn I was photographing.

 

I have discovered that the intermediate gear is no longer being produced so my options have been narrowed... I can replace all of my small parts with a Dana 300 master kit including intermediate shaft and hope for the best, or upgrade.  I really don't need an upgraded lomax type of transfer case but I was wondering if you knew of any other moderately priced kits?

 

To be honest the stock transfer case is all that I need for the type of 4 wheeling we do here on this ranch.

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I'd suggest finding a "good used" Dana 300 and taking the crapshoot approach that between two transfer cases, you'll have serviceable used gears and parts to work with...The gears in your unit have suffered sorely from metal and debris running through the teeth.

 

You're way up the learning curve now, Forman.  Try hunting for a used "core" transfer case that has the pan off and gears viewable.  Even on a budget, let's use a level headed approach and not put the current unit back together without resolving the initial problem.  I'm not pleased with the intermediate gear's reuse, and the other gears are not in the best of shape...

 

Moses

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I’m considering an upgrade kit rather than used parts.  Do you have one that you could recommend?  I looked at the Lomax gear from JB Conversions but was unsure if I needed to buy additional shafts along with the gears.  Confused about what to do here and don't want to make a costly mistake.

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First, you do need a quality rebuild kit that has all the wear parts and smaller items, too.  Advance Adapters has that handled with this "Kit".  You'll like the price and the thorough approach, now that you're familiar with the Dana 300's needs:

 

http://www.advanceadapters.com/products/400300r--dana-300-rebuild-kit/

 

This still does not include the gears or shafts, so that leaves those items.  Advance Adapters offers a 4:1 low range conversion, and I trust their gears, machining and hardening beyond any others I know.  This can be a spendy package but does provide all of the gears:

 

http://www.advanceadapters.com/products/430000--jeep-dana-300-401-low-range-gear-set/

 

As for the intermediate shaft and any other parts, try Jon Compton at Border Parts, Spring Valley, California.  Jon has maintained a line on the Dana 300 parts for decades and is reliable:  Phone (619) 461-0171.  If you do a "stock rebuild", he can likely help with the parts, too.  Please share my regards with Jon...

 

Moses

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