I have a clutch abuse issue. So I had to design a new 820 locker. The typical 820 doc locker does not work for me as it does not provide enough axle key engagement. If you actually go and build this thing, please post yours. I'd love to see it. I will post pics of mine once it's completed.
Little tykes assembly
Here's the locker hub itself. You will want to use a full length 1/4" key for the axle. The two keys that transfer the load from the bull gear to the hub are 5/8" tall by 3/4" wide by about 1.3" long. I would have gone 3/4x3/4 but i didn't like how the bottom of the keyway got down into the 2" diameter.
It would probably be a good idea to tap a few set screw holes to stop the axle from sliding around in the case/locker. I would recommend tapping them where they will wind up underneath the side plates, so if they loosen up they can't really go anywhere.
Front view of the hub. Those two dimensions should be the same but mastercam is goofy and rounds things different ways. .0001" isnt an issue either way.
Here's the print for the keys, how I did them. I screwed up and made my hub too narrow and had to bolt the keys into the slots to center the hub in the carrier. Drill and tap hub for 1/4" socket head capscrews, and drill .1875" (3/16) for roll pin. Spacing same as key and centered on the center section of the hub. It's a nice idea to bolt the keys in but not necessary at all. You can just cut a piece of 5/8x3/4 about 1.3" long and stick it in the key slots
Personally I bored my factory side plates up to 2" to fit the locker, but I drew up new side plates anyway. NOTE that two of these are required, one with tapped holes and one with clearance holes.
Front view. The only thing critical in terms of thickness is the .094" dimension, it sets your side play for the bull gear.
Just for fun, here's some dimensions on the bull gear. 7DP is an odd pitch for gears, I figure the designers used it just because that's what tooth count they needed in a certain diameter to fit in the transaxle.
Literally the first thing I did post locker. I don't think I changed the couple around the brake cutouts or not, but all the other were, and I did also install nuts on the opposite side. I splurged a bit and used full threaded stainless bolts.
Figured I’d put all the build pics I got into one post.
First side drilled and outside turned
Boring first side
Second side in progress
Lathe work done
Truing up cast surface of side plate so I can hold onto them better
One bored side plate
Another side plate bored and what’s left of the original centers
Cut flats on the hub so I have something nice to hold onto and can just flip the part to do keyways 180* apart
Both keyways cut
Key bolted into bull gear with 1/4-28 SHCS with hole for roll pin in center
Center keyway cut in my shaper
Here you can see the tapped holes and roll pin hole for the key, as well as 4 of the 6 set screw holes. Two of these holes are over the keyway.
If you are building something this complicated for a mower you may have undiagnosed autism.
May as well leave my signature
In case with axle
Bonus information. There’s about .15” extra space between the hub and bearings. This also applies for the stock carrier setup. A pair of .07” thrust washers would leave .01” side play, but a pair of .0625” (1/16”) is probably more common and would leave a still reasonable .025” of play. Don’t shoot for 0 play, there has to be something.
The 820 case is right around 19 5/8” wide, this will hopefully help whoever is looking to figure the straight axle length they want.
Thanks @Crazy_Carl I’m not in a hurry for once so I figured I may as well try to do a nice job of something lol.
@JB_4x4 glad that cleared something up for you. If you or anybody else wants any clarification on things don’t be afraid to ask. My drafting skills are just meh haha. I wouldn’t have even tried to draw all this stuff up if I didn’t want to share it with you guys. I’ve done more complicated stuff just off the top of my head working from memory hahaha.