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This is the story of converting my Allis-Chalmers B-210 variable speed transmission to a Sundstrand hydrostatic transmission from an Allis-Chalmers 7016H.  It is NOT a step by step description, since I went around in circles a time or two and got sidetracked several times.  I certainly didn't do anything step by step...      ;<)       Kent

Click for a closer view

I chose to replace the whole rear end of the tractor by swapping the needed parts off a "parts tractor," including the bevel gear box (BGB), cone clutch PTO, and Sundstrand hydrostatic transmission.  My B-210's bevel gear box needed replacement or major rebuild ("slop" in the gears plus a wallowed out keyway for the front variable speed pulley), and my center PTO setup was also very worn.  I chose to use a Sundstrand hydrostat since parts are no longer available for the Vickers hydrostat that originally came in the B-series.  I found it cheaper to buy a complete 7016H parts tractor with a good transmission, BGB and PTO assembly than it was to rebuild the BGB on my B-210. 

Once I got the parts tractor home and degreased the rear end, I disconnected the driveshaft and linkages, and took the whole rear off the tractor by unbolting the four bolts that hold the BGB to the frame.  I did the same thing to the B-210, while supporting the tractor frame on jackstands, then rolled the hydro over and bolted it right in -- the same four bolts hold it to the rear of the frame, just like the variable speed.  The easiest part was over... now I had to modify the controls and linkages of the B-210 to control the Sundstrand.  The pictures and description below try to describe that in enough detail so that you could work your way through it yourself.  The basic modifications needed are:

1. Graft the speed control lever off the 7016H onto the B-210.  This requires cutting a chunk out of the donor's frame and grafting it onto the B-210's frame, by either welding or bolting on as I did.  You must also cut a slot in the bottom of the B-210's frame for the lever's linkage arm to move in. 

2.  Bend and reshape the brake linkage rod and speed control linkage rod to fit inside the much smaller frame of the B-210. 

3.  Trim the bulkhead that holds the dashboard, battery, gas tank, etc., to provide clearance for the much longer linkage arm on the Sunstrand's speed control lever.

4.  Installing some type of engagement lever and linkage for the PTO's cone clutch.

5.  Locating and installing a neutral safety switch that prevents starting the tractor unless the speed control is in the neutral location.  You may also want to locate and install the PTO safety switch, which prevents the engine from starting unless the PTO is disengaged.  I chose not to, since the B-210 did not have one originally, and it would have been a challenge, as you'll see below.

Those are the basic modifications, and the details of how I did it accompany the pictures below. First, let me state that I have neither a welder nor a cutting torch and none is required.  The only welding required is to move the location of the metal tab on the speed control lever that contacts the neutral safety switch.  I did the rest of this modification with hand tools, an electric drill and an electric jig saw.


Click each picture for a closer view.

I used the jig saw to cut out the section of the 7016's frame that included the speed control lever's mount, as shown in the picture at the right.   (The specific location is pointed out below.)  The challenge is that the curved top of the lever contacted the dash. I used the original linkage rod that connects the speed control lever to the transmission, and tried shortening it, to move the whole speed control arm back further from the dash.  I did not like this location since it blocked the original parking brake, as shown.  I didn't want to get into the problem of devising a way to mount the hydro's original parking brake, shown.

I had to use a hammer and chisel to knock off the metal tab on the speed control lever that contacts the neutral safety switch.  It was spot welded on, and stuck out too far to the front, hitting the dash.  This tab needs to be welded back on to contact the neutral safety switch in its new position.

I actually tried three different tentative locations for this lever, before I settled on the one shown. This location is actually slightly forward of where it was originally mounted on the 7016H.  I did this so it would angle the control lever back further, gaining a bit more travel before it contacted the dash.  This was still not quite enough, but I'll show the solution to that later.  This position allows use of the original B-210 parking brake.

Next it was time to install the PTO linkage.  This one only took two tries to get it... First, I tried putting it inside the frame tunnel, using the 7016H lever and existing connecting rod, only to discover that this blocked the rear lift rod.  Then, I moved it outside the frame tunnel, and modified a Big Ten handle to mount it as shown, using the 7016H linkage rod.  I had to cut about 3/4" off the back end of the shaft that the knob screws onto.  Note the slight "S" shape bends that I had to make in the previously straight linkage rod.  Still more fine tuning would be required later.

This shows the PTO linkage with the PTO disengaged -- the lever is full forward.  I located the lever in an existing hole that was used to bolt the cover on the tunnel.  (Note that the cover must be notched to clear this bolt, as will be shown later.)  By bending the linkage rod, I could get it to clear the brackets on the cone clutch mounts and the bolt holding the lever on the tractor.  By adjusting the length of the rod, using spacers on the treaded end, I could get it to go "over-center" just enough to withstand the strong spring used on the cone clutch and keep the PTO disengaged.

It's important to trial-fit all the linkage rods.  You'll see just how close things are later, when the hydro lift cylinder and everything is installed.  This picture shows how the brake rods mount -- put them on so the cotter pins go on the inside of the frame -- you need as much clearance from the speed control lever as possible.  Luckily, there's little that needs to be done with the parking brake linkage.  I show more fine-tuning of the linkage rods later.

It was at this point that I decided to go ahead, remove the engine and grille frame and repaint the front end of the tractor.  Note the black inside the bottom of the frame, shown above -- that's rust converter.  When I removed the dash and cover to the frame tunnel, I found about a half gallon of rotted oak leaves and acorns.  This acidic mess had rusted the bottom of the frame almost half through.  Since I had cut a long slot in the bottom of the frame trying all the different mounting positions for the speed control lever, combined with all this rust, I was beginning to question the strength of the frame -- especially since I might want to put a larger engine in it someday.  I had the opportunity to get a B-110 frame that had been used on a pulling tractor that had been cold galvanized and was in great shape -- so I replaced the B-210 frame and started with new freshly cut slot for the arm of the control lever, as shown. 

(That also led to replacing the worn steering gear and sector, front end, etc. -- I'm beginning to think the only thing original on this tractor now is the seat frame...)

This shows the slot cut in the frame, from the top, in relation to the steering sector.  When the speed control arm is full forward, it just contacts the base of the steering sector -- I moved the whole mounting as far forward as I could, to pitch the lever back further from the dash, as described earlier.  Note also how close the arm is to the side wall of the tractor's frame -- that's all the room you have for the brake linkage rod to travel in... The parking brake rod goes lower, below the curve in the arm, and has lots of room in comparison.

This close up view from the bottom shows the location of the slot cut in the frame, in relation to the holes for mounting the steering sector.  If you'll cut the slot here, and mount the lever just in front of the center point of the slot, you'll have it located best to clear the dashboard.  To check it before welding or drilling bolt holes, attach the linkage rod with the bolt centered in the elongated adjustment slot on the transmission, and make sure you can get full travel forward without hitting the base of the steering sector.  Make sure you can go full reverse without hitting the end of the slot.

This view shows how I trimmed and rounded the piece I cut out of the frame of the 7016H.  I didn't want any sharp corners remaining to catch on something.  I think it also gives it a more finished look, without seriously weakening anything -- the tube that the lever's shaft goes through is up flush against the bottom of the tractor. 

By the way, I discovered about this time that the bolt-on mount for the clutch/brake pedal on the B-210 is the same size shaft as used on the hydro speed control lever.  I could have shortened it just a bit and used it instead of sawing the big chunk out of the frame on the 7016H -- saving a lot of "fun" and several jig saw blades.  Oh well, now YOU know...

This view also shows clearly how long the arm is on the speed control linkage -- it sticks up above the frame almost two inches.

These two pictures illustrate the challenge in bending the brake and speed control linkages and getting them to operate without binding.  There are two points that create challenges, as pointed out via the arrows at the right center.  Both rods must be bent because of the curvature in the frame.  But, the speed control linkage rod moves both forward and back of its normal position, while the brake rod moves only forward and then returns to its normal position.  Once they're bent, they don't move parallel to each other at all times -- picture what happens when you apply the brake and move the speed control lever toward reverse. 

Finally, the brake linkage rod must clear the bolts used to hold the cover on the tunnel, so it needs to be down below those holes and as far away from the side wall as possible.

Further, the pin that connects the speed control linkage to the arm on the lever can rub and bind on the brake rod, since both the rods actually move up and down slightly as they travel in the arc of the lever.   I ground the head off on one side of the pin to provide more clearance. 

This picture illustrates how I trimmed the bulkhead, using a jig saw, to provide the clearance for the brake rod and the arm of the speed control.  The shape and curvature was originally a "mirror image" of the other side.  I cut straight across, then straight up on the corner -- well, as straight as I could... ;<)

It also illustrates potential rub points on the top of the bevel gear box.

This picture of the hydrostat's control linkage on the transmission shows how I finally got the speed control lever to work without hitting the dash -- and still provide full forward and full reverse.  I changed the amount of travel needed on the linkage rod by drilling another half-inch hole to mount the linkage rod lower on the control arm at the transmission.  This increases the "leverage" that the rod provides, and it provides more of a change in speed with less movement of the rod.  This made the controls a little more sensitive to operate -- but otherwise they work just fine. 

Note also how I've bent the bracket that holds the  brake linkage rod in as far I can, without causing binding on the speed control linkage.  This helps keep the brake rod away from the side walls of the frame tunnel, and from the bolts used to hold the top on the tunnel.

This picture shows the hydraulic lift and rear lift rod installed.  The frame tunnel is pretty full.  Note that my rear lift rod is slightly larger than stock -- after bending my 1/2" rod using my tiller in my New England rock pile, I had John Scheele make me a 9/16" one out of the tempered steel that he uses for making lift rods.  I don't think it will bend!

Note how little room there would have been to mount the 7016 PTO engagement lever with the linkage rod running inside the frame.  The only possible location would have been just behind the bulkhead in that little corner there -- I would have needed to make a new linkage rod, and then there would still have been the clearance problem with the rear lift rod.  That's why I gave up -- since my B-210 didn't originally have a safety switch that prevents the tractor from starting unless the PTO is disengaged, I didn't bother trying to make the one off the 7016 work...

This view of the frame tunnel shows how little room there is for the rear lift rod already -- the hydraulic lift cylinder must be rotated so that the rod will clear the nut on it.  The rod barely clears the bolt used to mount the PTO engagement lever.

Also note how little room there is for the brake rod to clear the bulkhead.  It's pretty tight quarters in there, especially when these rods are moving and the driveshaft is turning...

The bends in the linkage rods are quite evident also.

This shows the cutout in the sheet metal cover for the frame tunnel.  This is necessary to clear the bolt that I used to hold the PTO engagement lever. Note that I used one of the bolt holes that are used to bolt this cover on, and I cut out where the corresponding caged nut used to be.

This view shows the dash reinstalled.  There's now plenty of room for the speed control lever, without hitting the dash. 

It also shows how the rear lift rod fits in the same little "box" on the PTO clutch arm that the 7016's original lift cable fit in. 

It again points out that the brake rod needs to be as close to the speed control linkage as possible at the rear, so there's as much room as possible to clear mounting bolts on the side of the frame tunnel.

I'm using a thick piece of metal, clamped to the speed control lever with a hose clamp, to make contact with the neutral safety switch, until I can get the original tab welded back on in its new location.

This view down behind the dash shows the new location of the neutral safety switch, down in the lower back corner.  I used the original dual-wire slip-on connector from the 7016 and wired it into the circuit between the ignition switch and the solenoid.

Note also one of my "tricks."  I installed new headlights and moved one of the old ones to become a rear work light.  I like to run the wires for those inside a clear plastic tube to protect them from rubbing and chafing inside the frame tunnel. 

This shows the finished rear of the tractor, with the cover for the hydro's cooling fan reinstalled, the wiring for the work light run and secured with wire ties, and the belt guard from the variable speed reinstalled.

Here's the view from the driver's seat with everything back together.  I used an Allis-Chalmers decal to cover the holes where the gear shift used to be. 

The picture directly below shows a top view of the PTO linkage, and the final bends required to clear the fender.  It still rubs slightly when the PTO is engaged -- i.e. the lever is up.

The pictures below and to the right show the right and left sides of the completed tractor.  At this point, it was ready for a final adjustment of the speed control linkage to stop minor "creeping", then warm it up good and change the hydro fluid and filter.


Here's my 9 year old helper, Eli.  He's now claimed the tractor as his.  I guess if the size of the smiles or the excitement of his first test drive is any indication, then this project was a success....

He's already wanting to know when I'm going to replace the seat and repaint the rear fenders.  Oh well, I guess I'll just have to keep tinkering with these old things... ;)


A special thanks to Sam Ericson who is almost done with a similar conversion.  We swapped ideas throughout this process and he shared his knowledge a lot when I was scratching my head or at a temporary deadend....



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