"Fixing" The Yanmar Tractor Steering Knuckle (Update)

 "Remember that all we have is 'on loan' from Fortune, which can reclaim it without our permission - indeed, without even advance notice.  Thus, we should love all our dear ones, but always with the thought that we have no promise that we may keep them forever - nay, no promise even that we may keep them for long." - Lucius Annaeus Seneca

 The tractor continues to provide nightmare fuel from a mechanical repair standpoint.  Ask me how I knew that taking the steering knuckle apart would turn into a sh*tshow, hahaha.

I took some pictures showing how much slop there was in the steering on this side.  The steering arm could move about 15 degrees before the shaft would begin to rotate.

Below:  Top-down view before beginning the "repair".  It took a pickle fork to remove the ball joint at the far end of the arm after removing the retaining nut.  These taper fit joints are incredibly tight.

Below:  Two photos showing the steering knuckle rotated all the way forward, then all the way back, without ever moving the steering wheel.  There was a lot of play in the joint, and it was between the arm and the shaft.  Compare photos at the joint between the upper and lower section.

 I removed the top nut, and found a shaft key that held the steering link arm to the shaft.  It was loose, because the shaft key had gotten beaten up over the years, and flattened slightly where the steering arm had smashed against it.  I removed it, and rotated it 90 degrees, and voila!  The slop between the steering arm link and the shaft was gone!

Below: A set of shaft keys, not mine.

Below:  Perfect repair!  Almost.  The steering arm is now snug on the shaft, with the key rotated.

However - there's always a "however" on this tractor...

When I removed the key from the shaft, the gear drive mechanism fell down a bit - it's a 4x4 tractor, so the front wheels are driven by the front axle.  The gears are no longer engaged, and now I can't get the gears to mesh again!

There's a small gap there that won't close up, and nothing I've done will get it to close up.  I've even tried rotating the hub while setting the weight of the tractor down on it, and it still won't fully engage the gears, allowing the hub to seat.  so annoying!  I'll keep trying, then see about finishing up the rest of the tractor.  I'd like to have it ready for spring.

I wish I'd known that there were oil seals involved in this repair, or I'd have bought some.  Hopefully they still hold after I get this thing together.

UPDATE 1:

I got off my lazy ass yesterday and finally removed the steering knuckle to see if I could figure out why it wouldn't go back together.  The answer was obvious once I had it out.

Below:  Take a look at the upper bearing.  It is no longer seated on the shoulder of the shaft.  When the steering knuckle fell down after I took the steering arm nut off, the bearing got popped upwards about 1/2 inch from where it belonged.  The steering knuckle is quite heavy.

Once the steering knuckle was reassembled, it was time to replace the steering arm on the shaft, and that's when I realized that no matter how I set the shaft key, there was still quite a bit of looseness in the steering arm.  Nothing that I did with the shaft key prevented the sloppiness.

Finally I cleaned up the key and took some measurements with a cheap-ass digital Harbor Freight caliper that I picked up using a coupon, for just such occasions.  On one side, it measured 9.6 mm, and on the other side, it measured 9.7 mm.

 Notice all the little dots on it?  They are on all four sides.

I'm not the sharpest tool in the shed, but this is a Japanese tractor, and so I'm pretty sure that this item should be 10mm x 10mm tool steel.  What I suspect happened is that this steering knuckle was taken apart at some point, and that the owner could not locate a metric shaft key.  Instead he used a piece of 3/8 inch (9.525 mm) square stock.  He made a key from the smaller size US measurement tool steel, then worked it over with a punch to widen it.  But it's not wide enough, and so there is slop between the shaft and the steering arm - which over time allowed the front wheel to crack due to side-loading as it flopped around.

I called all over the place, and could not locate any 10mm square tool steel, so I ordered 20cm stick off Amazon for ten bucks.   And this is why I'm almost certain that's what happened with this item.  It's not easy to locate 10mm x 10mm square stock out here in flyover country, and it's quite possible that Amazon wasn't around when this jury-rigged repair was made.   Another update will be forthcoming once the part arrives.

UPDATE 2:  I checked the other steering knuckle and it's even worse.  Check the match marks.  That's how much play it has.  So I guess this one is next, once the square stock arrives.

Update: Feb 8, 2022:

This arrived today.  It's not square stock, it's tool steel, but it should work just fine, once I round the edges slightly.  At least the dimensions are correct!