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Ryobi Powered Snapper Riding Mower Conversion

1646 Views 12 Replies 4 Participants Last post by  Sylence
I've been collecting parts for about a year and am finally ready to start building.

Donor mowers:
Snapper SPX 2242 (Pretty standard MTD hydrostatic riding mower from 2015-ish)
3 Ryobi 40V Brushless Push Mowers (2x RY401011 and 1 self-propelled RY401012)

The plan:
My father-in-law acquired the riding mower for free and only planned on scavenging the ICE from it. I got 4 of the Ryobi mowers in a lot for about $200.

I plan to integrate the riding mower and push mower safety systems while keeping the riding mower looking at stock as possible. The drive motor will be wired to be started with the key switch. The riding mower utilized an electric clutch for the mowing deck, so I'll wire that switch to start the mowing deck. The existing seat switch will be wired into the push mower's safety circuit to cut power to the blades. The deck will still be removable and power will be delivered via a "standard" household 3 prong locking plug and outlet. The push mower LED headlights are usually on anytime a handle switch is depressed, but I'll wire them through the riding mower's existing headlight switch because it's there.

Power:
I've been waffling back and forth for months on how I wanted to power this 36/40V system. Did I want to use 3 12V deep cycle lead-acid batteries, 3 12V 30+Ah lithium packs, or a single large 36V lithium pack? I had dismissed the stock push mower batteries early on, but after finding a similar build online, I have come back around to the idea. I may still move to a higher capacity lithium pack in the future, but the Ryobi batteries should get me started.

A similar build:
While researching lithium batteries to use in this project I came across this YouTube video posted only a month ago where he built basically the exact same build as I have planned. His Yard Machines is another MTD re-brand, and he is using the same 40V Ryobi motors as me. His build inspired me to use the stock Ryobi batteries instead of something more elaborate. One difference between our builds, he installed a speed controller on his drive motor to control the speed instead of running it full speed and using the transmission to control the speed. As a bonus, his videos serve as validation that my plan to use the push mower as a drive motor will/should work ;)

Walk-through video:
Real-time battery life test (~43 minutes):

Donor Equipment Pictures:
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Discussion Starter · #3 · (Edited)
One drive motor from a walk-behind mower to drive a ride-on just seems horribly inadequate. Even two seems marginal.
I realize I didn’t specifically say, but each of the two blades will have its own motor in a direct drive configuration. The third push mower motor will only need to run the hydrostatic transmission.

The push mower motors should do fine running the blades and if the drive motor ends up being underpowered I can always find something bigger. The three smaller motors should be quieter than one large one and there won’t be any belt/pulley noise or vibration.

Edit: I recognize this plan flies in the face of nearly everything I’ve read in these forums. This is a big reason why I’ve sat on this project for so long.
 

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Discussion Starter · #4 · (Edited)
This afternoon I spent a couple hours in the 90+ degree heat cleaning up the riding mower and deck. Removing the last greasy remnants of the gas motor and 8 years of grass and dust. I still need to take a power brush to the bottom of the mowing deck to remove the more stubborn debris. I want to give the bottom a coat of paint and a coat of silicone protectant. Some metal was flaking off in places where it was rusting.

Clean body (fixed the tire after taking the picture)
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Deck before: almost forgot to take the picture so I had already started on the right half
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Deck after
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Discussion Starter · #6 ·
i've been using a ryobi 40V mower since 2015 and really like pushing it, but fyi the battery packs only last about :30 on a charge.
I have to agree. I’ve been using one of the mowers from the lot I bought since the end of the last cutting season. From maintenance cuts in the front yard to knocking down some tall grasses in the back it’s done a great job. I’ll keep it around for the smaller jobs.

I have a 6Ah battery and I have been getting about 40-45 minutes. I’m guessing you have the 4Ah battery? Even 30 minutes from 3 pounds of batteries is amazing! When cutting 40-42” at a time with a rider instead of 20” pushing, I should be able to double how much I can mow on a charge.
 

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I realize I didn’t specifically say, but each of the two blades will have its own motor in a direct drive configuration.
Yes, that's what I assumed.

The third push mower motor will only need to run the hydrostatic transmission.
I assumed that the idea was to use the drive motor (not blade motor) from a self-propelled mower, but the motor that drives the blades might have suitable power output. (y):)

The push mower motors should do fine running the blades and if the drive motor ends up being underpowered I can always find something bigger.
Good. You could also try driving the hydrostatic transmission with two motors.
 

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Discussion Starter · #8 ·
I assumed that the idea was to use the drive motor (not blade motor) from a self-propelled mower, but the motor that drives the blades might have suitable power output. (y):)
I see how you could get there from my wording. Definitely going to use a third blade motor :)

I was trying to think of a way to utilize the self-propel motor. Maybe, some sort of electric PTO? I wasn’t coming up with any brilliant ideas. Maybe a towable de-thatcher? Or, use it separately for a light duty powered wheelbarrow?
 

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Discussion Starter · #9 ·
Progress:
I was able to 3D print a temporary set of lovejoy couplers to drive the transmission. There is plenty of room under the seat for the motor to directly drive the transmission, but I do need to figure out how to mount the motor.
The batteries I ordered and a couple extra chargers arrived today as well.

I’m excited to get building this weekend!

Side project: Was going through the garage and saw our Radio Flyer ATW (All terrain wagon). This might be fun way to use the excess self-propel hardware.
 

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Discussion Starter · #10 ·
I cleaned the bottom of the mowing deck a bit more and coated the inside with Rust-oleum Rust Reformer and spot treated parts of the top. I’ll need to get some matching red paint to touch up the treated portions of the top of the deck.

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I burned through a couple drill bits drilling new holes in the deck’s reinforcement plates for the electric blade motors. As Adam Savage would say, “use more cooling fluid.” I tried to push too hard and didn’t use enough lubricant. They also got a rust converter treatment/primer. I’ll reattach the plates and drill new holes in the thinner and softer mowing deck tomorrow.

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The initial lovejoy couplers didn’t work out, I mis-measured and didn’t account for the splined shaft on the transmission. I designed a custom coupler, though this first revision requires a lot of pressure and perfect alignment to keep the 3mm deep “gear” engaged. The holes on the perimeter engage the transmission cooling fan, as did the stock pulley
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After a little bit of shaft clearance adjustment, I was able to attach the coupler to the motor and test fit to and run the transmission
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I ran the transmission in neutral then, I briefly engaged the drive before running out of limbs to engage the motor switches, manually hold the motor in place, engage the throttle, and not fall down. Once I can secure the motor, I’ll record a proper test drive for you all.

WTF Moment of the week:
The donor electric mowers advertise a 20” cut, so I bought a couple 21” Kobalt electric mower blades to better fit the Snapper’s 42” deck. (I assume Homelite/Ryobi builds Kobalt mowers for Lowe’s as the blades appear identical.) It wasn’t until after opening the blades that I realized that these “21 inch” blades are barely 19” long!? We’ll see how they fit when I get the motors and blades mounted to the deck. We’ll see how it affects the cutting once it’s all together.
 

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Discussion Starter · #11 · (Edited)
Today, re-attached the plates and drilled new holes in the deck for the motors. I then test fit a motor in each position. The first one fit perfectly. I attached a blade and found some interference with a bolt that isn’t used anymore so I removed it. As for the second position, my template must have shifted after I drilled the first two holes as the second two are off by half the width of the hole. I mounted the motor anyway with just the two bolts for a fit and clearance check. The bracket that holds the side discharge flap is a little bent and sat a little low and would interfere with the blade. I wanted to convert it to mulching anyway, so “Bye bye bracket.”

High temperatures and humidity are back so, I’ll fix the holes tomorrow.
 

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WTF Moment of the week:
The donor electric mowers advertise a 20” cut, so I bought a couple 21” Kobalt electric mower blades to better fit the Snapper’s 42” deck. (I assume Homelite/Ryobi builds Kobalt mowers for Lowe’s as the blades appear identical.) It wasn’t until after opening the blades that I realized that these “21 inch” blades are barely 19” long!? We’ll see how they fit when I get the motors and blades mounted to the deck. We’ll see how it affects the cutting once it’s all together.
This will probably give you, as brian might say, a horrible Mohawk cut to your grass -with a strip of uncut grass in the middle of the cut. A 2 blade mower deck, like yours, is usually twisted away from the center line of the rest of the mower to generate(within limits) some overlapping cut to prevent this. I ran into this blade length problem as I was playing with these Ryobi mowers. Different models have somewhat different length blades.
 

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Discussion Starter · #13 ·
This will probably give you, as brian might say, a horrible Mohawk cut to your grass -with a strip of uncut grass in the middle of the cut. A 2 blade mower deck, like yours, is usually twisted away from the center line of the rest of the mower to generate(within limits) some overlapping cut to prevent this. I ran into this blade length problem as I was playing with these Ryobi mowers. Different models have somewhat different length blades.
I’m expecting as much, but at this stage, I’m hoping it won’t be too bad and I’ll settle for a completed build that I can use while tweaking over time. Fingers crossed 🤞
 
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