Tuesday, January 28, 2014

Maintenance: Jinma 254 tractor front axle repair


I know popping tie rod ends loose, dropping front drive hubs and replacing bad oil seals is not a big deal to many, but I’m slightly mechanically challenged.

OK, OK, I can hear my race car building, suspension geometry designing, engine modifying, championship winning brother laughing from 1300 miles away; so I guess maybe I should admit that I’m a little more than slightly mechanically challenged.

What got me into this mess was the hydraulic steering ram boot on the tractor getting shredded by our moderately rugged property. That poor boot rides right down there in the weeds, cactus and brush, and by the time I finally broke down and replaced it the thing was in a half dozen pieces. On top of that the oil seals in the vertical shaft of the left front hub had gone bad to the point where I had to add gear-oil to the front axle just about every time I got the tractor out because what I put in last time was now laying in the pan I tucked under the hub when I parked the tractor down in its barn.

Knowing it was necessary but still not happy about it, I got the parts manual out then went web surfing. I found a few brief mentions of this particular repair but it seemed like there wasn’t a whole lot of detail there, at least not that I could find during my minutes and minutes of research. I took that as a sign that it should be a no brainer, I mean it must be so basic that other people just don’t see the need to write a tutorial on it, right?

Well apparently I missed that basic class because as things went on it became obvious that I hadn’t a clue.

With great trepidation I made my way over to Affordable Tractor and bought the parts I knew I needed plus some parts I didn’t know I needed. Fortunately Affordable Tractor has a very customer friendly approach and the mechanic over there gently corrected my undereducated list, or maybe it was just my obvious lack of knowledge making him feel sorry for me, at any rate not only did I walk away with all the right parts but I also got some hints and tips to go along with my booty. By the time I left with my $58 worth of parts in hand the whole job seemed pretty straightforward.

Unfortunately I seemed to have lost that straightforward part somewhere between the parts supplier and home.

It took me over a month and three separate tries before I even got past the first step!!

All I had to do was pop the tie rod end, hanging out there on the end of the steering ram, loose from the hub, unscrew it, slide the new boot on the ram and reverse the procedure. Only problem was I couldn’t get the dang thing loose!

I removed the castle nut on the end of the tie rod shaft, turned it over and screwed it back on partway to protect the threads then whacked the end of it somewhat timidly with a dead-blow hammer. Nothing. Whacked it harder – same result. Again, even harder this time. Still nothing. About this time I decided I had whacked that little nut as hard as I dared; so I put everything back where it belonged, including all the bits from the bottom end which I had removed out of ignorance of what the heck I was doing, pumped it full of the grease I had removed trying to figure the thing out, and vowed to do some additional research.

I suppose I then tried to just forget the whole thing; hoping for that out of sight out of mind solution; but it kept nagging at me so I finally broke down and contacted someone who I figured would know, my brother. He said the trick was to back the castle nut off then whack the side of the eye the tie rod shaft was going through with a hammer, a big hammer, and really whack it using a two-handed, round-house swing. According to him this would deform the eye just enough to release the tapered shaft. Now that made sense, and I trust my brother on things like this, he’s been doing this kind of work since Junior High, but when the metal of the eye started to deform under my repeated and violent attention while the shaft stayed just as stuck as ever, I got scared. Once again I put things back where they belonged, parked the tractor down in its barn, put the pan under the hub and made a note to buy more gear-oil. Stick with what works; right?

At some point in the week or two following my second unsuccessful imitation of a mechanic I remembered coming across a brief note about using a tie rod end puller from Harbor Freight. Of course I couldn’t find this write-up again (Got to start bookmarking these things rather than relying on a memory that apparently can’t be relied on.) but one day, for reasons that had nothing to do with my aspirations of becoming a mechanic, we made a 90 mile run to a town that just happened to have a Harbor Freight, so I stopped in and sure enough, I found the puller!

Of course I was still just as gun-shy about the whole maintenance thingy and it took a few weeks of that puller sitting there on my workbench before I bit the bullet and got the tractor out of the barn again.

Well I’ll be damned but it worked!

I put the puller in place against the turned over castle nut, tightened up the bolt and waited a minute, tightened it up some more and waited again. About the 4th time BANG, and the tie rod end dropped loose!

This was one of those good news, bad news situations though. I could now replace the ram boot but since I had the tie rod loose it only made sense to continue on and get those leaking seals replaced, them being the same hub and all. Oh damn!

I drained as much oil from the tiny little drain plug in the middle of the front axle as I could then dropped the bottom plate on the left hub to drain the considerable amount of oil hiding down there as well. I have to do it this way because the little 7mm plugs with the tiny square ends that you are supposed to use for draining the hubs have been stuck since the day I bought the tractor. Not only are they stuck but the little square ends are hopelessly far from square anymore since I have vigorously attempted to get them loose through a variety of means several times.

Just like the guy at Affordable Tractor told me to do, I then unbolted the knuckle arm which gave me access to the 17mm bolt in the top of the vertical shaft. Since that shaft has to spin to do its job, trying to back the bolt out of it with a wrench just – well – spun everything. I tried holding the hub still with my other hand but was way too weak for that to work, so then I tried clamping locking pliers on the hub for a better grip, but still couldn’t hold the dang thing still. With a flash of inspiration I hunted around until I found a steel bar I could jam between a couple of the studs and brace against the ground,  but quickly realized all that was going to do, assuming I could grow the third arm I needed to hold everything in place, was tear up the threads on some studs.  (Yeah, I know put the nuts back on the studs first. I didn't think of that at the time.) Finally I had one of those DUH moments (As Click and Clack the Tappet brothers say, I need a dope-slap.) and successfully used the shock and awe method of taking my 30 year old yet almost new out of the box impact wrench to it. Worked like I knew what I was doing!!

Fortunately I had been warned that once that bolt was removed the hub would drop out of the housing pretty easy so I had a floor jack under the assembly and the whole thing lowered right out as advertised. Now to the bench!

I have a seal puller, don’t know why but I have one, but it’s one of those hook and lever types and I bent the crap out of one of the hooks trying to pry the first of the two seals out of the housing. I suspect what I really needed for this job is one of those hook and hammer type of pullers, but of course I don’t have one of those!

It took a while, a lot of that while spent repeating things I already tried before (And with every failed attempt Einstein’s definition of insanity; ‘Doing the same thing over and over again but expecting different results.’; went through my mind, mocking my efforts; ) but I finally got frustrated enough to set caution aside and managed to deform the first seal enough with a viciously wielded screwdriver to get it out. Now I was feeling my oats so I used an old Chinese chisel I don’t mind messing up (Kind of appropriate don’t you think? Using a Chinese chisel to attack a Chinese tractor?) to cut through the second seal and get it free, being careful to cut only seal on not gouge the crap out of the housing!

As I was doing this I was also carefully making a diagram of exactly how the seals were placed and which way they faced. That might be second nature to some, but not to me and after all this struggling I didn’t want to do something ridiculously stupid (Hey, it’s happened before – with disturbing frequency I might add. . .) and wreck the whole project.

After carefully cleaning all the surfaces, I tried getting the new seals seated in the housing by lubing them and the housing with a touch of grease and tapping around the edges with a short piece of hardwood I had laying around, but every time I hit one side the other would just pop up and the whole thing turned into a Chinese fire drill! (Get it! Chine – oh never mind.) So I went hunting around the shop for something I might have more success with. I got lucky and had a 2” PVC coupler in my plumbing bin that was just the right diameter. I also had a scrap of 2” PVC pipe in the same bin. I shoved that into one end of the coupler and lowered my new tool over the shaft and against the carefully positioned seal. Being too lazy to bother cutting my scrap of pipe, I then went hunting for a step-stool I could stand on to get high enough to tap the end of the pipe with a hammer. A few gentle blows and some checking with the calipers to make sure I had it in far enough to clear the second seal, and the first was in place and ready to go. The second seal went right in on top of that just as easily. Talk about luck!

Now it was just a matter of reversing the whole process and putting the tractor back together again without having any leftover parts. With the benefit of some spectacular failures in the past, I’ve learned to take lots of photos as I go as well as to lay out every bolt and part in order on a length of butcher paper, no matter how easy and simple the job seems. When it’s time to put things back together again I just start with the last parts I laid out and work my way back to the first. If I pick up a part or bolt or screw and can’t remember where it went I go back through my photos and reboot my memory.

I had been warned not to turn over the edge of the seal when working it back onto the shaft which would let that teeny tiny little spring in there get away so I was a bit nervous about that as I cleaned everything well and got ready to impersonate a competent mechanic. With a little grease coating the appropriate surfaces and one hand stabilizing the hub while the other worked the jack, I carefully slipped the seal onto the shaft, took a moment to recovered from the shock of my success, then worked the splines into place as I seated the hub back up where it belonged. Now it was just a matter of putting the new boot on the steering ram, bolting parts back on where they came off of, refilling the axle with gear oil then taking a test drive.

Admittedly I only drove the tractor far enough to get it back down to its barn, about 200 yards worth, but did take some unnecessary turns along the way and it seemed to be fine up to that point. Besides, it had been a long and stressful process and I didn’t want to push my luck and discover I did it wrong; a variation of that out of sight out of mind thing.

I read where one guy did this job in under an hour. Well it took me more like 4, but I got it done and now I think it’s time to kick back with a book and take it easy the rest of the afternoon.


  1. I have the same issue. Went to replace the steering boot and found the left front hub seals were leaking badly. I plan on using your adventure description when I set to replace them. Thanks for the advice and pictures.

    1. Wow! I haven't looked back at this entry in a long time and didn't realize how many hits it had. I thought my Showering While Camping entry over in my other blog was the hit winner but this entry almost triples that one.

      Good luck with the repair, but if mechanically inept me can handle it I suspect you will do just fine.

  2. This is almost exactly what I am going to do this weekend! Except just the felt washer type seal and the rubber boot needs replaced... I hope! I really appreciate the explanation and pictures! You also speak my language. I am assuming that I don't "have" to replace the other seals if it is just the felt washer seal that is leaking.. We will see!

    1. I'm the forgotten backwater of bloggers. If I get a couple dozen hits on an entry I'm doing pretty dang good! (Most the entries in this blog have hit-counts in the single digits and there are two with hit counts of zero!) But this tractor repair entry, my 4th ever blog entry by the way, has around 350 now hits which makes it second only to an entry on converting a cargo trailer to a travel trailer in my other blog


      Unfortunately I'm not sure you will be able to get away with just changing out the felt washer. You see it really isn't a seal but more of a collector of seepage from the real seals. (As well as keeping some of the grit and grime of the real world out of the innards of the hub.) If the felt is black and squishy with oil it's because the real seals aren't sealing well anymore. Best case scenario you have a bit of grit trapped between the rubber lip of the seal(s) and the shaft and it can be cleaned out when you drop the hub, but don't be too disappointed if you end up needing new seals to stop the carnage - I mean leakage. Good news is that if that's the case and your new felt washer gets gunked up before you get new seals installed, you can clean it up in a little solvent and reuse it.

      Cheer up, it's been nearly two years since I replaced those seals and the edge of the felt washer is still dry and white - well, white-ish anyway. I figure if I can manage that repair then pretty much anyone can.

  3. Haha... well it's amazing on how little information there is about these darn tractors! I did change out the felt washer only, BUT per your above post, the current felt washer was soaked and pretty much disintegrated within the shaft. There was also TONS of this oily mud goo on top of the seal. I was able to clean all that stuff out and used about 2 cans of brake cleaner making it look like new. Hasn't started leaking yet! :-)

    1. Cool! I once parked my tractor in a couple feet of oozing mud that came suspiciously close to reaching all the way up to the air vents in the front axle. (Though calling it 'parked' might be misleading since there was nothing voluntary about it and it had everything to do with stupidity. . .) I was able to get the tractor back out by setting the bucket on some timbers and lifting then repeatedly curling and resetting the bucket to help claw my way out. (To this day I pretend that part of the property doesn't actually exist and stay away from it!)

      I immediately drained and replaced all the oil in the front axle, afraid I might have contaminated it, but the later failure of the seals in the left hub might still have been the result of that ill-advised wallow.

  4. Oh man.. I did the same thing!!! Except I decided to get more traction by loading up my front loader and turn my wheels... needless to say, I bent the heck out of my steering rod! I finally took your approach that you mentioned above, and then couldn't figure out why my front tires were facing different directions! Bought a new rod "drag link" is what the official name is for 30 bucks and now am as good as new!

  5. Thank you!
    I greatly appreciate your resource. I am hopeful to replace my seals as well.