704 3 speed to 8 Speed Swap

[DBlackston 298]

Hello all!

 

I have a 704 that when I purchased it the transmission was locked up solid.

 

 

I tore it apart but the inside was rusted quite badly and was in need of all new bearings and seals. 

 

 

I was going to buy a rebuild kit and tear into it, but a friend had a good transmission out of a C-111 that just needed seals.

 

 

 

I have some questions though about this swap, and this is my first Wheel Horse Resto so I wasn't sure about a few things. 

 

I found this chart and found out that the 704 had a 5046 transmission and the C-111 had a 103916 transmission.

 

 

I do have the hubs off of the C-111 transmission, and they are different than the 704 hubs. They are 5 hole instead of 3 hole but the same bolt pattern I think.  The main difference I can tell is that the axle shafts are bigger at 1- 1/8" on the C-111 transmission than the 1" on the 704 transmission which I like since I plan on putting a set of dual ags on the tractor and filling them with washer fluid.

 

The input pulley is also different, which I wondered if it would cause any issues. Unfortunately I started this swap about 2 years ago and life got in the way. I no longer have the 704 input pulley and don't know what size it was. 

 

The easiest option would be to just keep the C-111 input pulley but it may be too big for the belt cover on the 704, I also am not sure if the K161 motor has a different RPM than the C-111 motor and I might end up with a slow tractor or a hotrod out of the deal. I think I had originally planned to put the 704 input pulley on the C-111 transmission but I broke it when removing it from the transmission. I seem to recall them being different shaft sizes too. Is there a pulley that would fit the C-111 shaft and be the right size for and input for the K-161 motor?

 

I did check tonight and found the frame attach bolt pattern to be the same between the 794 frame and C-111 transmission which I was worried about. My frame is cracked though. I need to grind the cracks and weld them. I think I will buzz a 3/8" plate out on our waterjet and weld it to the inside of the frame to better support the frame in that area and prevent future cracking. I will buy some longer studs to accomodate that. 

 

The last thing I was concerned about was the brake linkage as I think the C-111 has the brake drum in a different location than the 704 does. If I recall though I bought either a Raider 12 brake linkage or a Raider 10 that should be correct to put an 8 speed in a short frame tractor.

 

The last thing I will need to do once I have the tranny in is make new shifter levers, a new cover plate to accomodate the high low shifter, and then have VinylGuy make me a custom shift pattern sticker. 

 

Is there anything else I am missing to make this swap work?

 

 

[Pullstart 62,851]

I just noted some swap details in my 502 thread.  The larger trans input pulley was because the C-111 had a larger engine pulley.  You’ll be crawling if you leave the 8 speed pulley on there.., and the belt groove is wider than your stock 4L belt.

 

check out the details here:

 

https://www.wheelhorseforum.com/topic/73794-502-worker-refresh/?page=6&tab=comments#comment-1086840

 

[953 nut 55,222]

7 hours ago, DBlackston said:

 

I do have the hubs off of the C-111 transmission, and they are different than the 704 hubs. They are 5 hole instead of 3 hole but the same bolt pattern I think.  The main difference I can tell is that the axle shafts are bigger at 1- 1/8" on the C-111 transmission than the 1" on the 704 transmission which I like since I plan on putting a set of dual ags on the tractor and filling them with washer fluid. The hubs are no problem but if you are running dual rear tires do not fill the outer set and keep the inflation down to 2 or 3 PSI so they can flex rather than putting too much pressure on you axles and hubs.

 

The input pulley is also different, which I wondered if it would cause any issues. Unfortunately I started this swap about 2 years ago and life got in the way. I no longer have the 704 input pulley and don't know what size it was. Stick with what you have and go for a 5/8" wide engine pulley the same size as the C-111 had.

 

The easiest option would be to just keep the C-111 input pulley but it may be too big for the belt cover on the 704, I also am not sure if the K161 motor has a different RPM than the C-111 motor and I might end up with a slow tractor or a hotrod out of the deal. I think I had originally planned to put the 704 input pulley on the C-111 transmission but I broke it when removing it from the transmission. I seem to recall them being different shaft sizes too. Is there a pulley that would fit the C-111 shaft and be the right size for and input for the K-161 motor?   Just have to get measurements and buy a new one or stick with what you have. A smaller input pully will increase speed.

 

I did check tonight and found the frame attach bolt pattern to be the same between the 794 frame and C-111 transmission which I was worried about. My frame is cracked though. I need to grind the cracks and weld them. I think I will buzz a 3/8" plate out on our waterjet and weld it to the inside of the frame to better support the frame in that area and prevent future cracking. I will buy some longer studs to accomodate that. 

 

The last thing I was concerned about was the brake linkage as I think the C-111 has the brake drum in a different location than the 704 does. If I recall though I bought either a Raider 12 brake linkage or a Raider 10 that should be correct to put an 8 speed in a short frame tractor.   Keep the clutch linkage as is and adapt the brake linkage from it.

 

The last thing I will need to do once I have the tranny in is make new shifter levers, a new cover plate to accomodate the high low shifter, and then have VinylGuy make me a custom shift pattern sticker. 

 

Is there anything else I am missing to make this swap work?

 

[ri702bill 8,319]

Good project - Kevin, as mentioned above and @Handy Don have done similar swaps. Don used a 6 speed - no issue with either the input or the brake.

I did a similar to your swap on my 854 using the Unidrive from a 1979 C81 donor....

Got a new input pulley of similar diameter as the 704 but with the 5/8" bore from McMaster - the groove is a tad deeper - used a 69 inch belt, not the original 70 inch one.

You need to shorten the dipstick and tube an equal amount to not only clear the seat, bur allow removing the dipstick with the fixed seat above. I found it easier to do this as a last item - remove the seat, install the uncut tube and dipstick and fill the Unidrive UP TO the full mark on the dipstick. Then cut the tube and dipstick, reinstall them the top of the fluid mark is your new "full" mark - just use a triangular hand file to add the line - do not use a Dremel!!

Have not figured how to hook up the parking brake - but in first gear, lo range it stays put!

Shift pattern - the C81 came with the flat top shift knobs, just cleaned them up for a couple coats of black vinyl interior paint and new decals from Terry....

 

Edited October 3, 2022 by ri702bill

[Pullstart 62,851]

@953 nut I rarely disagree with you, but as wouldn’t suggest increasing the front pulley, because that’ll require a hefty amount of belt guard remaking.  I believe my 502 has a 3.5” or 4” pulley stock.  Running my 5/8x3/4” shaft sleeve, I still have my stock pulley set, stock belt and guard as well.  The input speed never changed and my final drive is still the same 

[Pullstart 62,851]

I also haven’t ever found it to be lacking of belt grip.

 

 

[ri702bill 8,319]

8 hours ago, DBlackston said:

I did check tonight and found the frame attach bolt pattern to be the same between the 794 frame and C-111 transmission which I was worried about. My frame is cracked though. I need to grind the cracks and weld them. I think I will buzz a 3/8" plate out on our waterjet and weld it to the inside of the frame to better support the frame in that area and prevent future cracking. I will buy some longer studs to accomodate that. 

 

I think 3/8 may be too thick because of the limited clearance on the top fasteners being partially hidden by the clutch cross shaft. I have used !/4 HRS plate to repair a few. Some advise - waterjet the shape and add the 4 clearance holes in the rectangular pattern at the same time. Gouge out the cracks of the frame from the back, weld them up and grind the entire back side smooth. Drill eight or more 5/16 to 3/8 holes thru the frame plate - away from the mounting holes - to allow plug welding. Nut & bolt your plate FROM the INSIDE of the frame in place - this keeps the belt length normal. Clamp any areas together if you see the plate is not right up against the frame and plug weld up all the holes. Remove the fasteners and grind the plate smooth - prime & paint.

Hope yours does not look as bad as this 854 I picked up - 3 of the 4 cracked out... and a 1/4" twist in the frame...

 

Edited October 3, 2022 by ri702bill

[oliver2-44 9,746]

Save this old transmission for the future, or for parts for someone else.  It will clean up in an Etank or with a bead blaster.  

It looks better than some I have cleaned up.

 

[DBlackston 298]

5 hours ago, Pullstart said:

Running my 5/8x3/4” shaft sleeve, I still have my stock pulley set, stock belt and guard as well.  The input speed never changed and my final drive is still the same 

 

I never even knew a shaft sleeve was a thing! I think I will take this route. I remember my input pulley broke when removing it from my 3 speed so I will just source one of those and a shaft sleeve. 

 

6 hours ago, Pullstart said:

 You’ll be crawling if you leave the 8 speed pulley on there..

 

 

I did just pick up this unit for my 854 with a tiller. Maybe I need to put this on there and go super slow?

 

[Pullstart 62,851]

That’s a pretty rare speed reduction kit!

 

nice!

[Handy Don 12,217]

7 hours ago, ri702bill said:

I think 3/8 may be too thick because of the limited clearance on the top fasteners being partially hidden by the clutch cross shaft. I have used !/4 HRS plate to repair a few. Some advise - waterjet the shape and add the 4 clearance holes in the rectangular pattern at the same time. Gouge out the cracks of the frame from the back, weld them up and grind the entire back side smooth. Drill eight or more 5/16 to 3/8 holes thru the frame plate - away from the mounting holes - to allow plug welding. Nut & bolt your plate FROM the INSIDE of the frame in place - this keeps the belt length normal. Clamp any areas together if you see the plate is not right up against the frame and plug weld up all the holes. Remove the fasteners and grind the plate smooth - prime & paint.

Hope yours does not look as bad as this 854 I picked up - 3 of the 4 cracked out... and a 1/4" twist in the frame...

Seconding Bill's guidance here. I fixed my 854 in similar fashion with a piece of, I think, 5 ga steel. Big C-clamps held it all flat (checked with a square) during the welding--the locking pliers were ok around the edges but the deep-throat C's were essential since we didn't use bolts and nuts as Bill does.

It's really tight inside that F plate, so you'll need a small grinder it you need to smooth those welds!

Edited October 3, 2022 by Handy Don

[Handy Don 12,217]

2 hours ago, DBlackston said:

 did just pick up this unit for my 854 with a tiller. Maybe I need to put this on there and go super slow?

 

Putting this on the 854 will be similar to having a 6- or 8-speed transmission locked in low range. It was intended for setting up a dedicated ground-engaging tractor that'll always go slow and pull hard. You cannot quickly shift from "low" to "high".

As noted by @ri702bill and @Pullstart (and me ) having a newer transmission gives you the low range AND the high range. I can recommend finding and using a 6-speed as it makes the swap very easy (only a little bit of sheet metal drill/cutting for the low/high range lever shaft). 8-speeds are more plentiful and so much easier to come by (and less $$), but they do require re-doing the brake linkage and accommodating the dipstick as Bill mentioned.

[Pullstart 62,851]

@Handy Don it would be cool to see how slow low/low would be!

[Handy Don 12,217]

12 minutes ago, Pullstart said:

@Handy Don it would be cool to see how slow low/low would be!

Hard to comprehend.

Usual low/low is ~0.5 mph and the reducer used a 7.5" transaxle pulley instead of the usual 4" so 4 / 7.5 * .5 = .27 mph or 24 feet per minute. 

In my house, kitchen to front door or back to front of the garage in ONE MINUTE.

Edited October 3, 2022 by Handy Don

[ri702bill 8,319]

I think it would allow for at least 3X the nornal AM cycle - a coffee and a wee, before that thing moves 15 feet!!!

Seriously, you could go thru a tank of gas and a drive belt before any appreciatable work is done!!

[DBlackston 298]

14 hours ago, ri702bill said:

I think 3/8 may be too thick because of the limited clearance on the top fasteners being partially hidden by the clutch cross shaft. I have used !/4 HRS plate to repair a few. Some advise - waterjet the shape and add the 4 clearance holes in the rectangular pattern at the same time. Gouge out the cracks of the frame from the back, weld them up and grind the entire back side smooth. Drill eight or more 5/16 to 3/8 holes thru the frame plate - away from the mounting holes - to allow plug welding. Nut & bolt your plate FROM the INSIDE of the frame in place - this keeps the belt length normal. Clamp any areas together if you see the plate is not right up against the frame and plug weld up all the holes. Remove the fasteners and grind the plate smooth - prime & paint.

 

Bill this is pretty much the exact path I intend to take. I will let you know how it turns out.  

 

 

6 hours ago, Handy Don said:

Putting this on the 854 will be similar to having a 6- or 8-speed transmission locked in low range. It was intended for setting up a dedicated ground-engaging tractor that'll always go slow and pull hard.

 

@Handy Don that's the exact reason I originally started looking for a speed reducer kit. I have a WT-244 tiller I want to restore and at the time I didn't have any aspirations of getting a 6 or 8 speed tractor.  I also have a 7-1111 mid mount belly blade I want to use, as well as a set of the AC- 673 cultivators. 

 

Even in 1st gear I found the 854 a bit fast for my liking for working in the garden around plants with the cultivator, and also using the belly blade. 

 

The usual solution of slowing down by slowing the motor RPM didn't help me alot though as then my HY-3 is slow to react. I also didn't like running the motor at low RPM.

 

Lastly I plan on letting my niece run this tractor and not letting her have high gears would be handy. 

 

6 hours ago, Pullstart said:

@Handy Don it would be cool to see how slow low/low would be!

 

6 hours ago, Handy Don said:

Hard to comprehend.

Usual low/low is ~0.5 mph and the reducer used a 7.5" transaxle pulley instead of the usual 4" so 4 / 7.5 * .5 = .27 mph or 24 feet per minute. 

In my house, kitchen to front door or back to front of the garage in ONE MINUTE.

 

@Pullstart and @Handy Don I am pretty sure I am going to have to make this happen. 

 

I will get a video if I do.

 

An 8 speed transmission, low 1st gear, speed reducer kit, and full RPM sounds too fun to see!

 

Surprised nobody ever did it for the big show "race".