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  1. #1
    Super Member 3RRL's Avatar
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    Oct 2005
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    6,818
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    Foothills of the Giant Sequoia's, California
    Tractor
    55HP 4WD KAMA 554 and 4 x 4 Jinma 284

    Default 4WD Repair Jinma 284

    To make a long story short, I busted the 4wd on Loretta's 284.
    Ever since reading about how careful to be ... not using 4wd when using the loader for example, we have been using it sparingly and only when needed. Well, when I was using her 284 to rip trenches for the sprinkler systems, I needed to use 4wd to pull through the hard Earth. I heard (and felt) that the 4wd was no longer working properly.

    But it was strange ...
    It felt like it wanted to spin the fronts and did at times, but then it would slip making a "click click click" noise. It seemed like the 4wd was still working except under heavy load. That's when it would "click" over and the fronts would not spin (no 4wd) at that time.

    Anyway, there have been several threads about 4wd not working so I read up on them and the other links.
    It seemed that many of them had to do with the 6 steel balls at each end of the front drive shaft perhaps coming out of there position. But there were also some where the front axle broke. So the first thing I did was jack up the tractor (all 4 wheels off the ground). Then I started turning the front tires. The front drives seemed to be OK and so did the front differential. There was no grinding noise whatsoever and when I turned one front, the other tire turned in the opposite direction. I jerked them back and forth quickly to see if anything sounded broke in there, but it all seemed good.

    I removed the cover to the transfer case and physically checked to see it the gears were good.
    I also checked to see if the lever was moving the engaging gear from 2wd to 4wd and that was OK too. Then I started to remove the front drive shaft. After removing the cross brace on the bottom that covers up part of the drive shaft, I removed the hose clamps and slid the cover back to expose the front engagement. I removed the snap ring (which was good) and saw that the 6 steel balls were all in there behind the star shaped washer. I did the same to the rear engagement and looked at it too and it seemed just fine.

    I decided to lower the fronts only and leave the rears jacked up but on a rolling floor jack.
    I carefully started the tractor, put it reverse and gently let the clutch out. Well, the tractor moved ... the fronts were engaging alright!! I did it in forward and same thing. So the 4wd did work under light load but slipped under heavy load. At that point I was pretty perplexed and decided to call Tommy at Affordable Tractor for his advice. He explained several possibilities and told me I should have completely removed the front drive shaft. Dang, I knew I should have done that and not just "eyeballed" the joints.

    After explaining to him what the tractor was doing, I asked if it was possible for the balls to wear a groove in the splines so they had to "jump over" the splines? Because (to me) that is what it seemed like it was doing ... that thought was going through my mind when the tractor was acting like I described. He said it was possible. In any case, he said he had all the parts I would need no matter what.

    So I jacked the tractor back up and removed the front drive shaft.
    First photo shows the front engagement which I left on the tractor because it was so clean and perfect. Second photo shows the front part of the drive shaft with the grooves for the balls. The snap ring and star washer (ball keeper) were in great shape too. Oh, and my chickens were keeping company while working...
    Rob-

    Rob-
    ...The Older I get...the Better I Used to be...
    Member of the Month

  2. #2
    Super Star Member EddieWalker's Avatar
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    May 2003
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    16,185
    Location
    Tyler, Texas
    Tractor
    Several, all used and abused.

    Default Re: 4WD Repair Jinma 284

    I just love the chicken pictures!!! That's too funny that they follow you around and just sort of hang out on the tools. I hope they don't make a mess. I bet your buddies at the country club wouldn't believe it!!! LOL

    Good luck on the repairs.

    Eddie

  3. #3
    Super Member 3RRL's Avatar
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    Foothills of the Giant Sequoia's, California
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    55HP 4WD KAMA 554 and 4 x 4 Jinma 284

    Default Re: 4WD Repair Jinma 284

    Then I removed the rear drive shaft engagement housing right at the transfer case.
    Once I removed the drive shaft and coupling, the transfer case shaft was exposed. And indeed, the 6 balls had worn a groove into the shaft. It was exactly like I had pictured in my mind. The balls were turning the front drive shaft under light load, but under heavy load they would "jump over" the splines...no 4wd at that point.

    There was a broken snap ring but no snap ring groove on the shaft.
    In the close up of the "coupler" which is the part that houses the balls, you can see that the front of it is bell mouthed and worn. I mic'ed the balls and they were still round (sort of) ... 8mm or around .3149". The tubular dowel behind the spring was OK too.



    Next was to remove the shaft from the transfer case so I could fix it.
    Tommy told me to tap it forward and it should come out ... which it did. These photos below are of the parts diagram in the manual and the actual "gear and shaft" inside that little transfer case (parts #19 and #24). The manual calls that housing which projects down the "transfer case". Last photos shows the good spline on the front coupling and the ruined spline from the transfer case.
    Rob-

    Rob-
    ...The Older I get...the Better I Used to be...
    Member of the Month

  4. #4
    Super Member 3RRL's Avatar
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    Foothills of the Giant Sequoia's, California
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    55HP 4WD KAMA 554 and 4 x 4 Jinma 284

    Default Re: 4WD Repair Jinma 284

    Thanks Eddie,
    Yeah, don't tell anybody but I love those chickens.

    Anyway, I checked the shaft for hardness and a file skipped across it, so it was plenty hard.
    My plan was to weld up the grooves and also the sides of the shaft. I would do the same to the housing part. Then I would re-cut the grooves on the shaft and inside the housing. After doing some math, I came upon what clearances they (the Chinese) had in there. It was like .040" per side and I thought that was too much. Also, there was more engagement from the balls to the housing than to the shaft, so I decided to make it about equal in each part. I had to put my Miller 330 APB TIG elder together to do this welding. You can see it between the surface grinder and one of my milling machines. Once I got it set up, I welded both the outer housing and the shaft up. I used H-13 tool steel rod so it would be plenty strong and hard.



    When I finished welding the parts, I turned them on my lathe.
    On the shaft, I had to use the same diameter as it was because there is a bearing which slips over that end. I was going to make it larger to lessen the clearance between the two, but duh...
    On the housing, I welded enough to make only .020" per side clearance from shaft to housing. This cut the original clearance in half.
    Rob-

    Rob-
    ...The Older I get...the Better I Used to be...
    Member of the Month

  5. #5
    Super Member 3RRL's Avatar
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    Foothills of the Giant Sequoia's, California
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    55HP 4WD KAMA 554 and 4 x 4 Jinma 284

    Default Re: 4WD Repair Jinma 284

    After turning the parts, I set the milling machine up.
    I used a Harrig #1 Grind-All up and indicated the shaft in (first pic below). That way I could turn it in 60 degree increments. I also depth gaged the existing spline grooves to be sure my math was correct (2nd and 3rd pics). They were .141" deep just as I had measured from mic readings. I used a milling vise to clamp the shaft while set up in the Harrig. I used a 5/16" (.3125" dia) carbide end mill to recut the splines and stepped it over .010" to each side for a little clearance. Not all the weld cleaned up but it will be better than factory now with the correct groove depth and less clearance.



    Once I finished machining all 6 splines, I moved over to the surface grinder.
    The shaft was still in the Haring. I measured where the other snap ring was on the front of the shaft an ground a snap ring groove in the same place on this rear shaft (1st and 2nd pics below). I had a set of snap rings and used one that fit the shaft. The groove came out dead nuts. After that I surface ground the front of the coupler leaving a witness of the original machine marks. Then I set it up in the mill and bored out the grooves in it (3rd and 4th pics). Again, I stepped over .010" per side for some clearance. Also, in figuring the clearance between the parts and balls, I wanted less than factory so I made an adjustment to get that cleared by .010".
    Rob-

    Rob-
    ...The Older I get...the Better I Used to be...
    Member of the Month

  6. #6
    Super Member 3RRL's Avatar
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    Foothills of the Giant Sequoia's, California
    Tractor
    55HP 4WD KAMA 554 and 4 x 4 Jinma 284

    Default Re: 4WD Repair Jinma 284

    Getting to the end of the repair now ...
    I realize that CV joints use ball bearings and most of that is because the joint not only has to mate to transfer power, but it also has to swivel. In this case, once the joint has been made via the balls, there really is no swiveling. With that in mind, I decided to use 5/16" hardened dowel pins (.313 dia) and cut them about .400" long. What does that do? Well, instead of having one contact point around the equator of the ball, I now have a cylinder making contact up and down the entire groove. So I cut off some dowel pins I had and fit them into the grooves between the shaft and housing. They fit perfectly with very little clearance...at least a lot less than what was stock. And there should be no "jumping" over the splines anymore.



    I knew re-assembly would be harder than with the balls, but once I got everything lined up like on the bench, the whole shebang went together and fit like a glove. After filling the trans fluid back up, I immediately tried it out. Man, the 4wd was smooth as can be with no clicking or anything. There is still enough clearance for everything to be assembled and work correctly. But I feel it's an improvement over the stock set up. I say this because on my Kama, the front drive shaft has a multi-splined coupler that slides (fits perfectly) from one spline on one shaft to the other. So I feel making the Jinma connection closer to that of the Kama (by using dowel pins instead of the balls) will be an improvement.
    Rob-

    Rob-
    ...The Older I get...the Better I Used to be...
    Member of the Month

  7. #7
    Gold Member
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    Jun 2007
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    280
    Location
    Southern NY

    Default Re: 4WD Repair Jinma 284

    Rob my goddaughter is down in Texas working for NASA Do you want me to see if there's any openings? Just amazing the fixes you design and implement. . . more on the level of Rocket science. Thanks -Ed
    2007 Jinma 284, LZ-20FEL, LG-6BH, 5'BB

  8. #8
    Super Star Member Diamondpilot's Avatar
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    Jan 2007
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    15,305
    Location
    Daleville, IN
    Tractor
    Jinma 254/284 Ford 861 Powermaster at work

    Default Re: 4WD Repair Jinma 284

    Great job Rob. You are now out of the dog house since you fixed her tractor. I can see her in the second to the last picture sitting over there in a chain making sure you did things right!!!

    Chris

  9. #9
    Gold Member TTTTTT's Avatar
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    Mar 2008
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    Location
    Bowmanville, Ontario
    Tractor
    Dong Feng 354 (Oct 2008)

    Default Re: 4WD Repair Jinma 284

    Rob,

    Absolutely amazing. Of course with your skills and innovation not surprised at all. One problem is you are going to put our valued parts suppliers and resources out of business! But then again i guess yo can make custom parts for all the rest of us if that happens

    Great documentation as well

    Dave
    DF-354 (Oct.2008), Town Sunny 404 Loader,
    Town Sunny 3pt BH -6',
    3pt Log Splitter - 26",
    3pt 12" PHD
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    Hydraulic Toplink.
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  10. #10
    Elite Member
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    limerick pa lycoming county pa
    Tractor
    kubota bx23

    Default Re: 4WD Repair Jinma 284

    Rob
    How dose the joint keep lube in there?

    tom
    If it ain't broke we will help you brake it
    If it is broke we will help you get it fixed!


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