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Discussion Starter · #1 ·
Inspired by Steevo's original 1886 mechanical restoration and Kohler OHV V-Twin swap and his more recent HT20 restoration, I have decided now is the time to swap the original Kohler K532 engine for a more modern Kohler CH25s OHV V-Twin engine.. The original Kohler runs good but burns quite a bit of oil thus the reason for the swap. I purchased the new Kohler this past winter locally and it has been sitting in my bench since that time.

I started the removal process this evening around 5:00 PM and has it out on the garage floor by 6:30 PM. Everything went fairly smooth and the drive shaft came off the hydro unit very easily with a squirt or 2 of PB Blaster. Same goes for the drive shaft to engine crank shaft. The engine is up for sale complete from air filter to oil pan along with the entire harness, gauges, warning lights, and voltage regulator.

A cool start video of the original Kohler from this evening was taken prior to the swap beginning:















 

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Subscribed! Looks like a good project!
 

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Save that firewall from the old K-motor, you'll want it for your new v-twin. It will bolt right on.
 

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Discussion Starter · #6 ·
Will do! Coming off tomorrow.
 

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Discussion Starter · #7 ·
I didn't do too much more this weekend on the swap but did find some obsticals that will now need to be overcome::fing20:

1. I failed to realize the original Kohler K532 had a 1-1/8" crankshaft whereas the new Kohler has a 1-7/16" diameter shaft. I now will have to figure out a driveshaft to go from the engine to hydrostat. From what I have researched so far the only yokes that are made with this diameter and key way are Series 14 but they are physically much larger.

2. The orbital valve I purchased a while back came from a John Deere 425 originally and they did not use fittings to connect the hoses/lines but rather a a push fit oring setup known as "Plug-O". I have yet to find any hydraulic fitting manufacturer who makes these in order to adapt to standard JIC or NPT fittings. Now I either have to sell the unit and purchase a different one or do what Steevo did with his and purchase John Deere tubing and cut the ends off and adapt to standard threads using compression fittings.

On a bright note I did draw up an adapter to machine to be able to use the original stub shaft so will not have to purchase a Kohler one. Lastly, I also took measurements to make an adapter plate for the engine since the original engine crankshaft centerline height is 1-3/8" higher that the new motor.
 

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Cakes,

On the drive shaft, you could have a drive shaft shop change the front yoke on your shaft to a Spicer 1000 series u-joint size, then get a crankshaft yoke to match that.

I use these guys for all of my drive line parts:
Northern Drivetrain, LLC: Spicer 10-4-383

As for the engine riser/adapter, I made mine 1" high, which lowers the engine a little, lessening the drive shaft angle a little..
The only things that change with engine height are the drive shaft clearance over the hydro pedal control cross-shaft, and the belt length. If you are buying new belts anyway, there is no real advantage to setting the crankshaft exactly the same height as the K-engine had it, other than not having to slice off a little from the bottom of the firewall plate, which I did have to do with my 1" height.

Every fraction of an inch in additional space you can make for the steering valve and hoses above that drive shaft is a bonus.

By the way, where do you plan to mount your steering valve? If you add a plate in the column area like JustinR did, you will really want the other model of orbital valve with the threaded side ports, so you can use elbows directly on it for hose clearances, and that extra 3/8" lower drive shaft will help.
 

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Discussion Starter · #9 ·
Steevo...I think I can take care of my driveshaft concern using Series 14 U-joints on the engine side and Series 6 on the hydrostat side. This will be with a rectangle shaft.

As far as the engine height goes, I think I am going to get it as close to original height as possible for a few reasons. First is the Series 14 yokes are bigger than the original Series 6 and my belts are brand new.

Lastly, the orbital valve will be installed similar to your latest conversion of your HT20 and yes threaded swivels will be needed. I anticipate hooking up the hoses before installing the valve.
 

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Cakes,
I have a 1455 that had an engine swap before I got it. It used the original one piece drive shaft and kept breaking u-joint bearings. I had a 2 piece drive shaft made that stopped that problem. The breakage was caused by the engine moving on the rubber mounts.
I am not sure if your HT20 has a one piece drive shaft or a 2 piece one. If it is a 2piece one, it should be fairly easy to match the engine PTO shaft.
Dave
 

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Discussion Starter · #11 · (Edited)
I made some major gains today.

I took my stub shaft adapter design and machined it according to the drawing and the results are exactly what I was looking to accomplish. I now can use the original stub shaft with the modern engine. The only modification to the original stub shaft was some clearance on the ring on the back side for the socket head cap screws that are countersunk in the adapter to mount it to the engine. This minor modification will not affect the purpose of the ring which in my opinion not takes all the load when the PTO is engaged.

Next I received the bushings and bearings from McMaster today to rebuild the front axle. All went very smoothly with only the axle pivot bushings giving me any sort of trouble. I simple split them with a screwdriver and they came out. All the old grease and debris was removed and the new bushings and bearings installed. I also removed, cleaned and checked for function the original zerk (grease) fittings and loaded the front axle spindles, pivot and PTO bearings with grease so we should be good for some time to come. Again, no cosmetic restoration was done save for the removal of years of old grease, crud and dirt.

Lastly, I also finished machining my solution to the crankshaft height difference (1-3/8") between the (2) engine. I had a large piece of 3/8" thick plate steel so I cut it down to size and am using the original Kohler K532 mounting bolt pattern on the original plate. I then "borrowed" a piece of 1" thick plate steel from work and made an adapter plate to mount to the bottom of the newer Kohler V-twin. My plan is once I get the location of the engine/stub shaft realitive to the front PTO pulley, I will transfer the mounting holes from the 1" thick plate to the 3/8" thick plate and secure them through all (3) plated using 3/8" bolts.









 

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Looks great!
 

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Discussion Starter · #14 ·
Saturday Update!!

First thing I did was purchase a different orbital valve on eBay that popes up this morning. It comes with a steering column as well. Only major difference is the lack of a power beyond port but it is essentially the same as the unit I used on my 1225. I will plumb the valve directly from the hydrostat and then to the lift valve.

The first part of the hand work today involved removing the large steering gear in preparation for the power steering upgrade.

Next was the first installation of the engine onto the (2) adapted plates. Once I lined up the stub shaft to the PTO pulley I worked on centering the engine left to right while keeping a close eye on the hydrostat input shaft.

My gut tells me I may need to cut some length off the output shaft of the engine to get the desired driveshaft angle. Also I may need to modify the hydrostat foot pedal rod to make some clearance due to the larger 14 Series yoke I am going to require.

All in all a good day!

Lastly, I am 9th inking about rebuilding the rear end while the driveshaft is out. Does anyone know is a kit is available or the McMaster P/Ns that I would need?







 

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Discussion Starter · #16 ·
It's been a while since an update. As stated in my previous post I received the new orbital valve and the rebuild kit will be here on Monday. In preparation for that I wanted to make room in the original dash board to be able to get it high enough so it is out of the way of the driveshaft.

What I did was separate the steering column portion on the dashboard from the other (2) pieces. I then slit the front face about half way down from the top horizontally. I made slices vertically from the top where the original steering wheel went though to the horizontal slice. The steering column at the hop was removed. The sides were bent out so the widest have is now approximately 3.5" or so. I mounted the (2) sides to the tractor, traced the modified column area and removed the interference. Now the valve will fit up nice and tight so there will be plenty of room for all the hydraulics.

Lastly, I have decided to use a modified Weasler 6 Series yoke with a 1-7/16" shaft coupling to join the new motor to the original driveshaft. Update will be this week.







 

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I'm not sure I followed what the mod was to the steering shaft area on the tower.... is it now wider at the bottom or the top or deeper in all respects from the tower itself?
 

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Discussion Starter · #19 ·
The reason for modifying the tower is to be able to place the orbital steering valve (for hydraulic power steering) up and out of the way of the driveshaft and to allow for more room for the additional hydraulic hoses. The column is only wider than original but no deeper. The steering wheel should be fairly close to the original location as well.
 
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