Inside a MTD 717-0540 FNR transaxle and possible locker setup

[tractor guy]

First off thanks to doc sprocket for the possible locker solution. I decided to tear into one of my FNR transaxles after seeing a post on ATLTF.com asking for pics of the workings and ideas for locking one. Pic #1 in the top casing you'll see the 14 tooth gear (red arrow) that connects to the pulley. This gear nests between the two 42 tooth shifter gears spinning them in opposite directions. The shifter (orange arrow) moves a gear selector side to side. One side forward, other side reverse, center is of course neutral. This selector uses a key way to turn the shaft and in turn the small 10 tooth drive gear (blue arrow). Pic #2 here you see one of the four, very small, screws (red arrow) that hold the large 72 tooth drive gear to the spider gear housing. Pic #3 here is the large drive gear after removing the spider gear housing. The drive gear spins free of the axle on a brass bushing. In the center is the axle gear. Pic #4 here is the spider gears. The shaft they are on is held in with c clips on both ends. To remove them you remove one clip, the shaft slides through, the spider gears just drop out revealing the axle gear on the other side.

 

[tractor guy]

possible locker?

Doc Sprocket said; "My first impression is that I can't see why a Fozzy Locker wouldn't work. Failing all else, it should be a doable option. If you cannot (or refuse to ) purchase the special gears, you can make your own. I will show an example of a purchased gearset, and a homebrew version.*
I had no intention of locking one of these transaxles (especially after seein how the entire stress of the drivetrain goes through those four dinky screws) but I might do it just to see how much these things can take.

 

[Doc Sprocket]

If there's sufficient clearance, maybe replace said screws with grade 5 bolts?

 

[OzFab]

Hmm, I'm gonna be watching this one, I have the same unit that I'm planning to use in a mini buggy (one day...)

Can you tell us a bit more about the home made locker gears? I'm thinking mild steel would be a bit soft (or, would you want them to be soft?)

If there's sufficient clearance, maybe replace said screws with grade 5 bolts?

Only grade 5?

I could be wrong but, maybe they're only light duty for a reason; maybe they're the weakest link so, if something's gonna go, the screws will break before any of the gearing does... just a thought

 

[katoranger]

I am getting ideas for a UTV build. One of these would make a cheap FNR box with differential.

 

[tractor guy]

they aint known for there strength. you stould try a peerless 820. its multy speed and has a one inch axle.

 

[redlinemotorsportts]

Recently did a fozzy in my 820. fozzy locking results in little more play in the axle, like you can spin one axle like 1/4 turn before the other one spins. left to spaces for teeth incase gears decide to get goobered up.

Fozzy is a great option for this mtd just i worry about the very weak design of the case