LOL, I didn't see anything in the manual about removing the base to get the steering shaft out but that's what you have to do. Once I removed the clip & shims from the shaft, I raised it high and then held it in place, out of the way with vise grips. Don't have anyone to assist me so I had to think overtime... I jacked the tractor up in front and that made removing all the parts much easier. I went to Sears and got some proper roll pin punches, the ones with a nipple on the end. Using that let me get the roll pin out. I used Kroil to break the rust.
It's been a long day. Took much of the day to switch steering from the ST120 to the ST110. I got it working beautifully and took the tractor around the house to be sure all was OK. Didn't tie down the battery, it was a short ride. Of course the battery slipped forward and the spinning fan cover ate into it like butter, spilling sulfuric acid onto & into the engine, ruining the battery. Trying to patch it with plastic epoxy & new sulfuric acid. Might work, if not, these batteries are $120 at Auto Zone....
Ran into the house & brought out two boxes of Baking soda, mixed it with some water and poured it on the engine. A lot of bubbling and a relocated battery later, the acid was neutralized. Of course now the tractor wouldn't start. Had to use a deep cycle battery to get it to start but eventually it did. Come to find out the spark plug wire leaks like crazy and even when dry, holding the cable & I get a shock. Spraying a basic solution with a mister all around the running engine and as soon as the plug wire gets wet, the engine stops.
I'm going to remove the upper fan shroud tomorrow and splice a better spark plug wire onto it & then cover the splice with a whole lot of teflon tape so it won't arc but then I'll have a good plug wire. Looking at the 12 HP B&S from the parts tractor, It looks like I can't just replace the wire like you can on a car, it's set well into the coil.
But I took some photos of what I found with the steering gear and sector gear. They are different and the one from the ST110 is smaller height & width wise and has tapers on the top & bottom. The one from the 120 has far more substance though the Sector gears are identical on both and both gears have the same number of teeth and apparently the same taper. Its easy to see why I needed to do this swap when you see them side by side. In the first sector gear photo you can see the wear on the teeth. In the second photo you see an intact gear. I'll post the dimensions of the different steering shafts/gears tomorrow for someone later on who might find it helpful.
The ST110 steering shaft is on the left.

There is wear on the sector gear which matches the wear on the ST110 steering gear on the left above.

This sector gear from the ST120 parts tractor is in great shape.

To make it easier, I transferred all the steering parts from the 120, Since the gear was larger, I figured the frame holding the sector gear and the steering rod might make a problem if I mixed them up. Perhaps all would fit but this way, all the parts bolted in just fine.
I'll post the measurements I took, later.
Gary
Edited by KA1J, October 14, 2016 - 07:03 AM.