(This is my experience. Follow your manual for proper repairs. Use these instructions at your own risk.)
[FOLLOW UP NOTES: In the text below, I made a couple of observations after I reinstalled the steering box. These point out where I would probably do things a little differently.]
A. TOOLS / PARTS:
1. Tools
1/2" ratchet and extension
3/8" ratchet and extension
metric sockets (10mm, 12mm, 14mm, 17mm and 19mm)
breaker bar
stout flat head screwdriver
philips head screwdriver
PB Blaster
rubber gloves
steel punch
2. Parts
How do I know which parts to buy? I re-use what's serviceable, and replace what's bad. It will be pretty obvious. Here's what I ordered from Hoye Tractor:
(2) SB-262 STEERING COLUMN BEARING $15.79. (Each part includes 1 bearing and 1 race. You will need 2 (upper and lower). Makes little sense to go this far and not replace the bearings.)
(1) SW-440 STEERING WHEEL (COARSE SPLINE) $73.97
(1) YANMAROM Yanmar Operation Manual $34.99 ** (If you order the YM1301D ops manual, you will get the YM1401D manual instead. There is no English language YM1301D operations manual.)
(1) YANMARPM YANMAR PARTS MANUAL $39.99 *** (Japanese language, copy of original, but the part numbers and exploded diagrams are instructive.)
(1) 22x35x8TC SEAL _ $2.88. (This is the sector shaft seal.)
(1) 194262-15330 SECTOR SHAFT GASKET $5.84. (Yours will tear, so anticipate this.)
(3) SCS-3 STEERING SHIM (appx .2mm) $1.17. (Located between steering box and shaft tube. I bought 3, in case I needed to adjust for steering bearing tolerances (see below)).
After inspection you may need additional parts. They are expensive. I reused my old sector shaft and lower steering shaft, saving well over $200. Time will tell if that was a good idea.
B. STEERING BOX REMOVAL:
1. Remove steering wheel cap and steering nut (19mm nut and washer):
Cap pops off, doesn't unscrew. After removing the steering nut, I used PB Blaster and a couple firm taps with a rubber mallet and small block of wood to coax the steering wheel off the spindle. You might want to use a puller if you plan to reuse your steering wheel. 17 splines on steering wheel.
2. Remove pitman arm:
a. First, remove the 22mm nut at the end of the sector shaft, left side of tractor, near footwell.
b. Install pitman arm puller (Napa $14) as shown. DON'T USE A PICKLEFORK as you will damage the ears on the sector shaft. However, persuasion is required, so as I applied tension to the puller, I used PB Blaster on both sides and let it sit for a few minutes. Every few minutes I tightened the ratchet until I felt it reached the limits of the puller, and tapped all around it with a hammer, mostly from behind. It finally gave way.
3. Remove the 5 phillips head metal screws from the dash cover plate, and set the cover plate aside. It gives better access to the steering shaft from behind and below.
4. Remove steering shaft grommet. Easiest for me was to push up from under the dash.
5. Remove the steering box from transmission housing:
a. First, remove the four sets of 17mm bolts and lock washers that attach the steering box to the transmission housing.
b. Next, remove the two 10mm bolts and lock washers attaching steering tube under the dash housing. One bolt is located on either side of the steering tube flange, shown next to the socket in the photo below. They screw out / in from below the dash flange. I didn't need to disconnect any electrical. NOTE HOWEVER -- that the steering tube doubles as a primary support element for the entire dashboard.
c. Cut the wire tie located on the steering tube. Remember to replace later. Actually this would be a good time to start your parts list, when it comes time for reinstallation.
d. Then, while SUPPORTING THE DASH, remove the steering box. Gently pull the entire assembly to the right and down, pull the top of the steering shaft spindle down through the hole in the dash, and remove.
B. DISASSEMBLE, CLEAN AND INSPECT
a. First noted was the curious little plug on the back side of the steering shaft. See discussion below.
b. Next I found a hex head plug. Remove using allen wrench #6. This plug serves as both gear oil filler hole and overflow.
c. Remove four 12mm bolts and washers holding the steering shaft housing to the steering box. This will expose one or more metal .22mm shims - two, in my case. Shims are factory installed to take up any free play between the steering bearings and races. Note there are shims. but no gaskets.
d. Remove the sector shaft: First, remove the three 12mm sector shaft cover bolts and lock washers. The fourth (center) 12mm nut is the jam nut for your adjustment screw. Leave that in place for now. Rotate and pull the sector shaft cover and sector shaft until the entire assembly is free of the gearbox. In my case, a little persuasion was required to pull the sector shaft splines through the seal on the opposite side of the cover, due to rust. Use a light touch; these parts are very expensive. My sector shaft was covered in grease, and in perfectly serviceable condition, so I will reuse it. Sector shaft shown in photo below.
e. Remove lower bearings. My lower bearings / race were ok, but pitted. Water and rust accumulated at the bottom of the housing, owing to leaks originating at the top of the steering column. There is no bottom drain.
f. Clean everything thoroughly. Inside the steering box, I used gasoline and an old toothbrush. Whatever grit is left in the assembly will grind away at your new parts.
g. Remove the steering shaft from the tube. I used a small piece of wood to tap the steering wheel splines down through the steering tube upper bushing (this is where water leaks occur), and pulled the entire 2-piece steering shaft down and through the tube. From right to left, this photo shows a) the lower most portion of the steering tube containing the upper steering bearing race, b) the junction between the upper and lower steering shaft; c) the culprit - rusted out upper steering bearing; d) the worm gear; and e) the recirculating ball mechanism that turns the sector shaft.
h. Remove and replace bearing races (upper and lower).
After cleaning, I observed that my lower race looked pretty clean. I already bought the new parts, so I tried carefully prying it out with a flat head screwdriver.
This was an impossible task; I gave up after about an hour. It wouldn't budge using a screwdriver, heat and PB Blaster, and I didn't want to damage the race since it was pretty clear I was going to reuse it. (If you're determined to get yours out, I considered one method described online using a small arc welder. Or take the gearbox and new parts to your machine shop.) My lower race was good enough to save.
My upper race, however, was badly pitted. It had to be replaced. I put the entire steering tube in my vice, upside down, applied PB Blaster and heat, and started hammering away. Alternate heat to the lower tube, ice to the race, apply more PB Blaster, and repeat over and over. After destroying one screwdriver, mine finally broke free. I scarred up the lower tube body pretty badly, but I got the burrs out with a dremel stone. This is the steering tube in my vice, after I removed the upper race.
Then I hammered in the the new race, using a large socket. Its important to remove the burrs, so the race can seat properly.
New upper race fitted into the steering tube:
Side view.
[FOLLOW UP NOTE: Here's where I would stop and replace the sector shaft seal before going any further. Unfortunately I didn't think about this until I had already replaced the steering shaft. That was a mistake. After prying out my seal, I noticed I had to remove more rust. By waiting to replace the seal, I had to be extra careful not to introduce rust and steel wool particles on my newly assembled and greased steering shaft. You should replace your sector shaft seal, and do it before reinstalling the steering shaft into the gearbox.]
C. RE-INSTALLATION
a. Bearings
The YM1301 series used a 2 part steering shaft. The shaft must be disassembled to install the new upper bearing and race.
The lower bearing fits into the lower seat (the one I didn't replace!).
First, remove the cotter pin:
Then tap out the roll pin with a steel punch - I only took mine out as far as necessary to separate the two halves of the steering shaft.
Here's the disassembled unit showing the lower shaft, cotter pin, and the roll pin still attached to its hole in the upper shaft:
Don't lose the spring inside the upper shaft!!
After removing the old broken bearing, I used a wire brush to clean the old rust and grime in the bottom of the gearbox (clean off all old rust):
New bearing installed with widest side DOWN. I greased everything.
Here's the reassembled shaft with new upper bearing installed:
Install lower bearing, wide side UP, into the lower race. Then reinstall the steering shaft into the steering box, with the teeth of the recirculating ball mechanism facing rearward. This will allow the sector shaft gears to mesh smoothly with those of the steering shaft.
Side view. Notice the orientation of the recirculating ball mechanism on the lower shaft - its teeth are facing the sector shaft hole:
Now it's time to install the shaft tube back onto gearbox. Shims (shown) are required for proper preloading of the bearings. I'm no expert this, but my goal was to tighten the 4 12mm bolts and still rotate the steering shaft by hand. This took a couple tries. Assemble, check tightness, add / remove shims, reassemble, etc. I think I added too many shims, so check your manual for preload instructions:
[FOLLOW UP NOTE: 2nd mistake - I used too many shims, so unfortunately I'll be re-doing some of this. Lesson is to check and recheck your preload before reassembly and reinstallation.]
Steering tube reassembled, with new bearings. No gasket, and no gasket cement needed. Hoye says these .2mm shims create a leak proof seal. [FOLLOW UP NOTE: no leaks].
b. Re-install the sector shaft.
I re-used my old one. First, center the recirculating ball mechanism on the steering shaft's worm gear, inside the gearbox. To do this, I temporarily placed the steering wheel on the upper splines, rotated full left, counted the turns to full right (4.25), and then turned back left 2 1/8 turns. This centers the gear, ready to accept the sector shaft.
Clean all gasket mating surfaces and apply gasket cement to the gearbox and sector shaft cover. Place gasket on gearbox; the cement will hold it temporarily, until you insert the sector shaft and mate the two gasket surfaces:
On mine, I never did remove the sector shaft cover from the sector shaft. It simply pivots on the adjustment screw. We'll see if this was a good idea or not. Apply gasket cement to the sector shaft cover; align and insert the greased sector shaft into the opening, and tighten the three bolts. This kinda tricky, aligning the sector shaft while keeping grease from contaminating the gasket:
c. Sector shaft and seal.
This is where I noticed I should have already installed my new sector shaft seal. My old one didn't leak, but I thought it best to use a new seal at this point:
Pry out the old seal and inspect the seat. Mine was a little rusty, so it was time for more steel wool and a little scraping with a knife. Had I done this earlier, I wouldn't have to worry about getting rust and steel wool fibers in my new bearings. Note the rust:
Pretty well cleaned up; ready to install new seal:
New seal installed. It just presses in by hand. Or you can seat it with a light tap from a block of wood.
Re-assembled gearbox, steering shaft / tube, and sector shaft:
d. Lubrication (90 weight gear oil).
This was a mystery to me at first. I figured the upper hole on the steering shaft was the fill hole, and the #6 allen head plug is the overflow. However I've been told that the upper hole is for something else - maybe a steering wheel horn wire or something. Also, I found no info on capacities. So, I guess the port at the allen head plug serves as both overflow and filler hole. It sits at approximately the same height as the upper steering bearings, which MUST be lubricated. So the oil must be at that level, or above. I used a CLEAN dish soap bottle to apply new gear oil into the small opening. This also gave me the means to measure the amount of oil being used.
Note the top of the steering box is slightly elevated to prevent oil from running out the top:
I was surprised that I reached the top level with just a little over a cup of gear oil...
So I installed the allen head plug (a little teflon tape never hurts), and I added another cup of gear oil into the upper hole, until it just about overflowed. I figured what the heck, couldn't hurt, and I want those upper bearings to be lubricated.
e. Install steering box back into tractor.
Reinstallation is the reverse of removal. Nothing complicated here. First I cleaned and greased everything up:
The new steering wheel was a gift to myself for saving a bunch of money on the DIY repair.
And that's it. I may need to pull the whole thing out again, to check the preload on my steering bearings. I think I used too many shims. But it works well. Adjusted tire pressure, and adjusted my front alignment to reduce the overall load on the steering gear.
I read that it is very important to adjust / readjust the steering stops on the tractor's front axle at this point. Check Hoye website for instructions to adjust steering stops. I followed some directions I found online, and finished up.
[FOLLOW UP NOTE: After final assembly I still had too much steering play, so I'll need to pull the box and remove some shims. Otherwise -- a significant improvement.]
Enjoy!