Reviving a G1900

Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
I am not familiar with the 2160. Does it also have the pivot in the middle and this U-shaped frame part over it (see picture)?

The Delrin blocks would work very well then, even if there is a bit of play in the pivot. Mine is practically play free now. But now the steering box is the main factor, was not visible before with the wobbly axle, and now this is bugging me.

The manual states 50mm play at the steering wheel ex factory (5mm minimum). I think it can be made better, I want a precise steering, you never know, maybe I have to follow Alvin Straights example at some stage. :giggle:
 

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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Glow plugs

The engine had white smoke after starting for a few seconds. It starts fine though and does not use any oil. So I suspected the glow plugs.

Checking them is easy, take the three nuts off that connect the power rail and take the power rail off. Take an ampmeter with about 15A range (or more) and connect one wire to the battery plus and hold the other side to each glow plug top. There should be a current of 10ish to 12ish amps flowing. If not, the glow plug is faulty.

IMG_20250402_132127.jpg

I found a faulty one, took it out and put an aftermarket glow plug in. Attached the power rail and the wire. Engine starts fine now without smoke.
 
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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Brake switch repair

My brake switch was faulty and I had it bridged with a wire. I had bought switches but it turns out they are the wrong ones, the brake switch is normally closed and opens when pushed in.

It is always worth trying to repair things, you have nothing to loose and can't make it worse but you have the chance of fixing things.

I took the switch out, pulled the rubber gaiter from the back, removed the silicone potting compound and desoldered the wires. Then I removed the pressed in aluminium from the back on the lathe until the black lid popped out.

IMG_20250403_160126.jpg IMG_20250403_161315.jpg

You can also use a small grinder or similar. After taking the top rubber off and removing the clip ring everything comes apart.

IMG_20250403_192504.jpg

The plunger has an isolated part in the back with a copper ring. This ring is the contact together with the two contact springs. The spring in the middle is there to push the plunger back.

IMG_20250403_161351.jpg

I polished the copper ring and the two contacts and cleaned up everything else.

IMG_20250403_161748.jpg

Before pressing in the lid hold everything together and test the switch. It has to be closed when the plunger is out and it has to open when plunger is pushed in. Mine had contact now but due to the wear on the two contacts it hardly opened, so I inserted two small plastic washers between the metal and the plastic plunger. That worked perfectly now.


I made a little tool for pressing the housing together again, one with a conical shape (20 degree angle) and a cylindrical one as a slieve over the threaded part. The small spring is for holding the black plastic lid in place when pressing everything together.

IMG_20250403_170853.jpg

I applied some lithium grease compatible with electric contacts on everything and put all parts back together. The press tool over it, into the vice, a bit of a squeeze and we have a nice pressed end again.

IMG_20250403_172407.jpg

Now the cables soldered back on and acid free electronics silicone applied to the back.

IMG_20250403_174028.jpg IMG_20250403_174116.jpg

Push the rubber cap on and wipe off excess silicone squeezed out. I also added two washers because I did not like the thin nuts directly on the slotted sheet metal. Repaired and fully functional switch ready to go into the tractor.

IMG_20250403_174502.jpg
 
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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Speed and brake pedal

The speed pedal was all wobbly, the usual, lack of grease, hence rust and worn out. And the brake pedal had been crudely cut off, welded and bent to make it fit into a cabin at some stage.

I removed everything and machined down the speed pedal shaft inside the bearing part to 15mm. The outside for the arm I left at 16mm, otherwise I would have to modify the arm too.

IMG_20250403_141511.jpg

I drilled the pipe to 17mm diameter and added a grease nipple that Kubota had forgotten in their design.

IMG_20250403_145947.jpg

Now I made a slieve of 1mm brass sheet metal and pushed it over the diameter reduced part of the shaft.

IMG_20250403_153628.jpg

Everything pushed in, pedal and arm attached again, a squeeze out of the grease gun and a bit of grease applied to all the linkages and springs and I have a nice play free speed pedal again.




Repairing the old brake pedal was too much effort so I had bought a cheap second hand one, removed the rust and spray painted it. A new brake pedal rubber from Kubota and a new grease nipple and it is ready to go into the tractor.

IMG_20250403_175306.jpg

Fitted the refurbished switch, adjusted it, greased everything including all linkages and I have a fine fully working brake pedal again.

IMG_20250403_182143.jpg
 
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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Fuel lines

When I first looked at the tractor I had noticed that the fuel pipes were kinked, squeezed, to about half the cross section. I wanted to replace those. And while I am at it I may as well replace all the fuel hoses too.

First I drained the tank and then took the seat and fender off. Dirt collected over 30 years greeted me. Yikes !

IMG_20250404_105741.jpg IMG_20250404_111028.jpg IMG_20250404_111034.jpg

Cleaned that up a bit.

IMG_20250404_130638.jpg IMG_20250404_113338.jpg

Then I took the fuel pipes and hoses out. Here you can see the kink. Don't know how anybody managed to do that, they are well protected by the frame.

IMG_20250404_133508.jpg

I made new pipes from Cunifer with the holders made of brass soldered on.

IMG_20250404_185720.jpg

Everything back in.

IMG_20250404_210353.jpg IMG_20250404_210410.jpg

The minus contact of the battery cable wasn't very healthy, it could not be tightened any more, so I made a new one.

IMG_20250404_230114.jpg

Took much longer than I would have thought but nevertheless a successful day :)
 
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Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
5,858
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Austin, Texas
Seems a bit cleaner now!
 
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lugbolt

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ZG127S-54
Oct 15, 2015
5,398
2,083
113
Mid, South, USA
the kinked return pipe is normal, a lot of them had it. I think it was probably manufacturing "defect" which didn't cause any problems, other than our OCD hating it.

the front axle pivot is an interesting design, and it is often neglected, as two of mine were. One of them I had to physically disassemble the bearings and mower drive, remove all of that from the tractor and then spread the frame mounts enough to CUT the axle pivot completely off, as it was stuck like chuck. Once the axle was out of the chassis I was able to press (50 ton press....and it buried the gauge needle!) the remainder out of the axle, then had to go in and weld up the worn areas in the axle itself, remachine (mill) and FINALLY got to reassemble it all. The axle needs to be about .005 larger than the pivot tube, because if you try .000, it will seize pretty quickly and there's no place for grease to pass around the tube once you grease it-and it's wise to grease it OFTEN. Getting that part out was a test of my patience, believe me! My mom's got that mower now an it's been mostly fine other than a few years ago dad couldn't get it to start (didn't know how to bleed the system after running outta fuel), he hit it with the starting fluid and broke the ring lands out of the pistons. I rebuilt it last winter and mom's been using it since. It desperately needs power steering, and I have an EPS assembly from some old 4 wheeler but the problem is the lack of space to get the EPS to fit, ain't a lot of room under the dash. The G2160 is a little bigger in that area, for that reason (EPS fits).

On steering play most of the play I've seen is inside the steering gear assembly. You can pull it all apart and rebuild it, but I'm not sure how one can tighten up the slack in the splined shaft to sector gear slop. I tried to weld it (TIG) but the sector gear is made of something I'm not familiar with and I couldnt' get it to hold. I mean, it lasted a little while but finally broke loose while I was mowing, no big deal it just developed the "normal" slack in the steering again. Once you get it apart you'll see what I am talking about. I thought about maybe heating the sector up and letting it cool (shrinks it slightly) but because I was not familiar with the material, I didn't want to do that. I want to say it's powdered metal but I am not 100% positive. Have a look for yourself and keep us updated.

THe steering post has a rubber bushing at the top, which is supposed to reduce vibration from the 3 cylinder engine (all 3 cyl have a rocking couple that can sometimes be felt), and that rubber needs lube once in a while or the steering gets kinda odd feeling. Mom's was just worn out so I made some new UHMW bushings for it and put a grease fitting under the dash to get a little bit of lube in there once a year. One pump is all it needs, doesn't need to be sloppy just enough to put some lube in there--and keeping in mind, because of the radiant heat of the radiator, sometimes that grease (depending on the grease and the climate) will just fall out anyway. I did put a groove in the upper bushing that holds an o-ring but it won't completely solve it. Just something I do once a year, and she doesn't use the mower all that much anyway-about 35 hours a season, give or take. Small yard, under 1/2 acre total. She uses her Polaris for everything else as far as yard work. That little thing was a GREAT investment for her (well I actually bought it for her, but you get the idea). Couldn't pass it up for the money.
 
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NCL4701

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L4701, T2290, WC68, grapple, BB1572, Farmi W50R, Howes 500, 16kW IMD gen, WG24
Apr 27, 2020
2,915
4,539
113
Central Piedmont, NC
I somehow missed most of this thread. Just now read it. The quality of your work and breadth of ability displayed is very impressive. Thanks for documenting your G’s restoration journey.
 
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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
the kinked return pipe is normal, a lot of them had it. I think it was probably manufacturing "defect" which didn't cause any problems, other than our OCD hating it.
Interesting that you saw more of those kinks.

I have seen reductions or wider parts as a damping mechanism in Diesel fuel lines but I do not think that this is intentional. It looks to me as if something hit the pipes and pushed them onto the frame, the forward pipe has another kink on the outside too, see pictures. I could not see anything that could have caused that, but the cutting deck is off. Kubota offered a "Mower swing stopper" option, maybe that has to do with the fuel lines being hit by the deck.

... Once the axle was out of the chassis I was able to press (50 ton press....and it buried the gauge needle!) the remainder out of the axle, then had to go in and weld up the worn areas in the axle itself, remachine (mill) and FINALLY got to reassemble it all. ...
Looks like you had some fun with that front axle :oops:.
And I thought mine is bad...

On steering play most of the play I've seen is inside the steering gear assembly. You can pull it all apart and rebuild it, but I'm not sure how one can tighten up the slack in the splined shaft to sector gear slop.
So far my steering play was 360 degrees (!) when I got the G1900. Strange though that the previous owner was using it this way and that it did not dawn to him something may be wrong :). Adressing one of the ball joints reduced the play to 90 degrees and repairing the front axle reduced that to about 40mm (1 1/2") at the steering wheel. So far the steering gear play wasn't even noticable, but yes, you are right, now it is the major contributing factor.

Have to take it apart and see if it can be improved. There is a cheap G1900 (without engine) for sale in the UK that I would like to get for spares. That way I could repair parts, like the steering gear, while still using my mower and then swap them out. But transport is too expensive, was thinking already collecting it myself, taking some parts off it should fit in my car. But there is still the ferry expense...

Your steering wheel bushes modifications are noted, thank you again for the hint, will do something there too.
 

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lugbolt

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ZG127S-54
Oct 15, 2015
5,398
2,083
113
Mid, South, USA
those are the exact kinks I saw on a lot of them. Pretty sure they did it at the factory, maybe while installing the engine to the frame. dunno, but it was quite common to see those. I don't remember taking a new one apart enough to note it, but some of them back in the 1990's had under 100 hours and I did indeed notice it on those as well, going off of memory.

I thought about making all new steel fuel lines on my old one but decided it was getting too close to mowing season and (2) it didn't hurt anything. So I reassembled the mower after winter service and sent it back to dad. Winter service, I pull the fenders off for cleaning and inspection every year. Good thing to do. This past winter I found a couple fuel leaks and an oil leak on mom's current 1800; she didn't know about them apparently but I went ahead and fixed them. Easy enough to do, before it swarms in the middle of mowing season when I get real busy at the shop. She's already had to mow her yard 3 times, and from mid may through late july, it'll be twiced a week. Oddly, though, those old mowers don't use much fuel, so she can run ALL season on a tank of fuel. That's the ONE thing I miss about my g1900. The ZG127 cuts better and a little faster, but in comparison it DRINKS fuel. 4-5 tanks a season usually.
 
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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Rear wheel steering linkage ball joints (rod ties)

I have the rear axle steering apart because I had to do something about the appearance of the rims (spreading muck on the freshly painted front wheels as somebody suggested here was not really an option :giggle:) and the excessive play and possibly increasing damage was a concern. So all the linkages are out.

The steering linkage ball joints were fairly good but not tight any more and one had a bit of play, about 1/10mm (0.004"). The parts seem not available any more and one is welded into the tracking bar, so potentially expensive. The threads are M16x1.5 on the bar side and M12x1.25 on the ball side.

I always wondered how those ball joints are being manufactured but could not find anything. Millions of the same videos explaining how to change a ball joint cluttering up the search results. Any hints in that direction would be appreciated.

So I thought squeezing the whole thing a bit may be suitable to reduce the play or make it tighter. So I made two little tools, one slieve for the top and one sitting inside the recessed part at the bottom.

Into the press and slowly increasing the pressure I got a really nice tight and play free fit again. It took only from 2 to 2.5 tons of pressure.

Selecting two suitable nuts from a socket set and a vice should produce the same result I believe.

Another small step towards a precise steering.
 

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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Rear wheels

After doing the front wheels, the rear wheels looked really shabby and were very rusty.

IMG_20250405_092618.jpg IMG_20250405_092640.jpg

Taking the tyres off both had tubes in them, as expected. Straightening the dented edges first. Then the usual corrosion treatment with CSD disk, sandblasting, phosphoric acid.

IMG_20250405_175850.jpg IMG_20250406_133920.jpg IMG_20250406_155407.jpg

Then two thin coats of epoxy primer for 60-80um total thickness. This time with different colouring in it. For the front wheels the dealer had omitted to add the colour pigments, so I was basically spraying clearcoat which was, well, challenging :) I had to use a bit of filler for the pitted inside of the rims. Not visible from the outside but I do not want to see an uneven surface when lying under the tractor. :)

IMG_20250406_202620.jpg IMG_20250407_190122.jpg

And then the top coat.

IMG_20250408_105101.jpg

I have some runners, not really visible but may take them off at some stage. A good excuse to buy one of those nifty blades to remove them. What did a friend on mine say: "Professional spray painters also get runners. The difference to the amateur is that they know how to remove them." :ROFLMAO:

One tyre was cracked already but the other was fine, so I had ordered only one replacement. Taking the tyres off on the tyre mounting machine I damaged one of the tyres and of course, applying Murphys law, it was the good tyre. So had to order another one and paid shipping cost again. So I paid shipping cost twice, normally when you order two tyres shipping is free... At least I have two new tyres now.

New valves, fitting the tyres was a doodle (you learn from mistakes) and I have nice new rear wheels.

IMG_20250414_165523.jpg IMG_20250414_165944.jpg
 
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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
A lot of it is from working on old cars. But very much applicable to old Kubota tractors too :giggle:

And I had bought 5kg of nuts and bolts from a G1900 dismantler in the US and got them electroplated, so I can put everything back together quckly without having to wait. Have to cut the grass too.

I have shelves full of nuts and bolts but of course Kubota is using an unusual M10 fine thread and their head size is smaller than the DIN standard at the time and has that recess. I wanted to keep everything original. Well, kindof, I make some small modifications too :)

So we can formulate a law here: if you have n types of bolts you will need type n+1. This applies to infinitely large n. :)
 

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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Rear wheel steering (disassembly)

First we have to drain the HST fluid. You realise that latest when you pull the king pin support off. Don't ask...

Then we loosen the wheel nuts, jack up the rear of the tractor, support the frame or the axle arms, remove the wheel nuts and take the wheels off.

IMG_20250419_072342.jpg

We see the steering parts now:

orange - wheel hub
yellow - axle support
green - knuckle arm
blue - king pin
red - king pin support
purple - drive u-joint

Take out the split pins on the crown nuts of the steering bar and the tracking bar and remove the nuts. Remove the bolt at the front of the steering bar and remove it.

IMG_20250407_143540.jpg

Remove two bolts and nut holding the bottom knuckle arm and take it off. Take off the three bolts at the top and take off the king pin. Now slide off the axle support together with the wheel hub and the drive u-joint. When doing that mind the o-rings at the top bottom.and the thrust bearing at the bottom may fall out too.

IMG_20250407_150600.jpg

Clean meticulously where the king pin support meets the rear axle, take out the four bolts holding the king pin support and pull it off.

IMG_20250407_152601.jpg

The drive shaft is sticking out now.

IMG_20250407_152913.jpg

Keep everything meticulously clean around this area because it is directly in contact with the HST hydraulic fluid. Keep everything protected from dust and dirt while you are working on the parts.

IMG_20250407_154656.jpg

We can take the parts to the work shop now for further disassembly.
 
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Hugo Habicht

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Equipment
G1900
Jun 24, 2024
321
462
63
Ireland
Rear wheel steering disassembly (continued)

If we dig away about half an inch of grease and dirt outside the wheel hub we will find a small clip ring holding the u-joint. Remove that clip ring (goggles!) and pull out the u-joint.

IMG_20250409_102354.jpg

Remove the clip ring on the inside holding the wheel hub and pull put same. Clean away the grease and dirt of the past 200 years.

IMG_20250409_103954.jpg

Remove the large clip rings in the axle support (goggles !!!) and take out the wheel bearings.

On the king pin support remove the thrust bearing at the bottom (if still in there), remove the plastic bushings top and bottom and the two o-rings top and bottom and the o-ring to the rear axle.

To remove the rear drive shaft bearing the seal ring has to be removed. I used a puller tool for that but it may be possible to use hooks or screw drivers, the seal ring typically is destroyed taking it out anyway.

IMG_20250408_154424.jpg

Now we can remove the clip ring and pull put the bearing.

IMG_20250408_154647.jpg

Now we clean all parts and have them lying in front of us.

IMG_20250419_093226.jpg

From left to right:
- drive u-joint
- clip ring wheel bearing
- wheel bearings
- axle support
- king pin (above)
- knuckle arm (below)
- clip ring wheel bearing
- clip ring wheel hub
- wheel hub
- clip ring u-joint

And the king pin support.

IMG_20250419_093248.jpg

From left to right:
- seal o-ring axle
- king pin support
- king pin bushing (above)
- seal o-ring (above)
- knuckle arm bushing (below)
- thrust bearing (below, not shown)
- seal o-ring (below)
- rear drive shaft bearing
- clip ring bearing
- drive shaft seal ring
 
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lmichael

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Equipment
Kubota G2160
Apr 23, 2021
676
314
63
Rockford IL area
Wow, that looks like an incredible amount of work. I'm simply kind of dreading yanking my mower deck out LOL. I think that deck weighs nearly as much as the entire Honda 4514 tractor my G2160 replaced LOL. It's the only way I can get my grease gun fitting on the zerk for the mower drive shaft lubed. Otherwise I can't flex it far enough to get the grease gun on the nipple. Dumb design really.