Anyone Spool an F-N-R

I have a 1996 Yard Machines that just blew the FNR transaxle case to pieces.

I already sourced, cleaned out, rebuilt and installed a replacement 618-0163. While I had it open, I thought of locking it. I was going to do a Doc Locker, but can't find a weld hub with large enough diameter to mount the ring gear directly to. I considered getting a weld hub, weld a large enough sprocket to it to then mount the ring gear. And then... (here comes the dangerous part)

I had a thought; instead of a diff carrier of stamped steel filled with sintered gears, how about I mount the ring gear to a wheel hub, and replace the floppy halfshafts with a solid axle?

I like the idea well enough, and I know it'll work, I'm just surprised I haven't seen  it on youtube. Is there a fatal flaw in such a setup? Is a gopowersports 3/4" steel hub skookum enough for it? Am I going to bust the tranny again? Has anyone else done this on here and keeping their secret, well, secret?

Before I buttoned up the case, I did go ahead and lock it by adding spider gear from the broken tranny. I just hope I don't bust the case again before my parts come in...

I have not heard of this but try look around at some transaxle bracing or beefing up.  All the fnr's I have seen do look a little "fragile".

Not sure there's a spool for a FNR, they're made for other Peerless trans'  but they're not cheap. **EDIT** Maybe they could work on a FNR, here's a link to one i saw on eBay a few days ago Peerless no-weld mini spool

A Doc Locker really is an excellent, basic and cheap way to go, strong as well as long as the welds are good!

Another way is to do what this guy did,  that will allow you to mess with the ratios a bit as well and will be really strong. I see myself doing this possibly this year.

There's several ways to go about it, here's a link to the thread here outlining them all in case you haven't come across it yet Rear Axle Locking Methods

BTW Welcome to the ATLTF!

I didn't mention that I don't have a welder, so that's a key factor for me. I'd have to take any welding work to sparky for some of that good ol' lincoln hot glue, as I did when I swapped out the stock engine pulley with a weld hub and six inch pulley. Man, I really need to get a small welder so I don't have to send that sort of stuff out...

Anyways, I've seen a video or two of that mini spool and the snapped-off axles that may come, so that's why I think a full spool and solid axle are the way to go. Also, the mini spool is only useful with the splined halfshafts; with the full spool and solid axle idea, if I later upgrade to a better transaxle, I can repurpose them for another project. The only safe place I'm ever going to put the old halfshafts is the scrap metal bin.

I have considered using some angle iron to brace up the transaxle case. Even small angle iron would do a lot to tie the case together better, and a little protection that would keep the bulbous bottom half off the rocks would be awesome. Again, I think I need to get a welder...

I see where this winds up; I get a welder, then a rotoshift transaxle, then I start going out to the OHV trails, then I find the wife got fed up and left while I wasn't paying attention....
What could possibly go wrong?

Let's start over... lol.

What's your goal speed wise? Want to keep the stock-ish speed or do you want crank it up some? What are you planning to use your rig for, offroad or racing?

The way the guy does it in the first video I think is brilliant. Simple, effective, relatively cheap and looks pretty strong to me. You can indeed buy 3/4" sprockets already welded together so no more worry about that! The gear ratio he's using would make the machine about 4 times faster but there's some flexibility in there as well as there's some room to change the sprocket sizes around.

Does your ring gear and diff look like his where the carrier bolts onto the ring gear or is it more like in the Doc Locker video with the pin inside of the ring gear/Bull gear (whatever it's called)? I have ideas for both styles that would be no weld.

If you want to keep the VariDrive or ditch it would dictate whether to keep your ring gear or replace it with gear and sprockets. I've already ran the calculations for myself and should be able to hit my speed goal of 35mph by ditching the VariDrive, 6" pulley up front, 5" in the rear and a slightly different ratio than the guy in the video.

Really you couldn't have picked a better time to have asked as I've been chewing away at this for 2-3 weeks and will be getting to work soon.

I'll play with some parts today to show you my no-weld spool ideas.

Sorry for the long winded post! Lol

I'll see your long-winded post and raise you another one

I had seen the chain drive setup before, and I'd probably do that if I was looking to change the final drive ratio, but the speed is ok already with a 6 inch up front and the stock transaxle pulley around back. It's every bit of 16 mph or so now, with 22x11-8 knobby tires, and that's fast enough for the crappy steering it still has from the factory. I had recently thought of going back to a smaller crank pulley, as I use it to drag fallen trees and whatnot about the yard, but it does pull okay with the stock FDR and an open diff on flat ground. It's crawling over the rocks and fallen tree trunks in my yard that necessitate less differential action and more traction.

The diff is a stamped steel carrier, bolted to the ring/bull gear. I've seen people mention rivets, but the two I ripped apart both had socket/torx head screws that were then peened/pressed like a rivet to keep them from backing out, so I just drilled out the socket heads with a 1/4" bit until the head came off, then screw the remainder out from the backside of the ring gear. The cross pin on both units was loose. Well, the carrier was worn out so no real repair without, you guessed it, a welder...

Come to think of it, I may have hurt the trans while trying to pull some large rocks around to pile them up, just a day or so ahead of when the case broke open on me and gears started growling and popping.

I haven't gotten on it since I put it together the other night, as I've got my back all torqued up again from working on the floor and fighting while the transaxle was hanging up on things going back in.

I need to take some pics and make a post showing what I've done to the rig so far. It's in it's second reincarnation now, with a hood from a 2000-something yard machines, GPS hubs and golf car wheels up front. Oh, and I scrapped the old B&S 14.5 that ate keys for breakfast. Maybe bent crank, didn't care enough to find out because I had a 22 horse Kohler laying in wait. For Christmas my brother got me some wanda 18x8.5-8 tires for the front. I also got a small winch, but I won't be able to put that on until.... you know the deal

I really need to just break down and buy a welder.

Lol good one!

The good news is even if you harmed yours they're generally really cheap and easy to come across. If you want to handle extra towing capacity I'd highly recommend you drill out all the threaded case-half screws and replace them with bolts/nuts and brace the chassis, they definitely twist, even the tunnel framed MTDs. I made a nasty offroader from one, check out The Warhorse (link in my signature/my profile pic).It has an open diff as well but with a MST203 and it does really well over obstacles also.

As for the spool... I'm sorry I don't have the ACTUAL sprocket on hand but use your imagination and follow along! This is going to be really cheap and easy to do...

You're going to get a sprocket where the teeth are larger than the carrier pocket so you carefully grind them off to keep it cocentric and bring the diameter down to what you need, I've shown what I'd have to do to mine. Drill the threads out of the ring gear, drill holes in your new spool to match, bolt them together, reassemble and you're done!

Really all you need is a large sprocket with a 3/4 bore, a 3/4" keyed axle, 3/16" keystock, 2 or 3 3/4" shaft collars and maybe a couple 3/4" shim washers (available at Home Depot) just in case. I think it'll be REALLY strong and that it can be done for under $100.

Want to beef it up even more? Add 6203-3/4-2RS bearings in the outer axle pockets if you have them and make a brace that goes from one (chassis) mounting point to the other side!

Yes my carrier was held by screws with green loctite and I broke my impact driver bit on the first one.... a propane torch and good vise grips got them out with no problems!

Oh yes you definitely should start a build thread and show us what you've got and are up to, we love pictures around here!

@Brianator that looks likemy ring/bull gear, only difference is that the holes are clocked differently, placing the threaded holes much closer to the big holes. I thought about doing it that way but the hub of the sprockets at the local farm stores are awfully short, maybe an inch long, and I worried they weren't skookum enough. Granted, they are made specifically for power transmission, but they looked a little skinny to me. If the gps wheel hub doesn't hold up, and I don't decide to bin the FNR altogether and go with something a little less dainty, I might end up using a readymade sprocket with hub.

@MightyRaze Yes, fragile indeed. I started tinkering with this thing in 2017 when we cleaned out my brother's stuff, and I'm surprised that it hadn't broken before now. I've dragged a lot of loblolly pines around my yard, climbed the logs on the burn pile, bounced over big rocks, dragged trailers with two flat tires, and it it has held up until recently. I'm in central AR, not too far from OK. Whereabout OK are you?

Sarge wrote:

@MightyRaze Yes, fragile indeed. I started tinkering with this thing in 2017 when we cleaned out my brother's stuff, and I'm surprised that it hadn't broken before now. I've dragged a lot of loblolly pines around my yard, climbed the logs on the burn pile, bounced over big rocks, dragged trailers with two flat tires, and it it has held up until recently. I'm in central AR, not too far from OK. Whereabout OK are you?

East side of Oklahoma City.

@Sarge the hubs on the sprockets you speak of sound like what I'd get and use with little to no worry. I also wouldn't be concerned about the bolt spacing, they are where they are and have held up fine so far right? Drill them out (just the threads), use washers on both sides for the extra clamping force with grace 8 bolts/ nuts and I bet they'll be fine.

@Brianator I'm glad for that. If I do have to use them I won't worry about it, then. As for the bolts, I was considering a bump in size. The ring gear is made to fit to the four tabs on the carrier, and looks to me that's where the torque is transferred, so the screws only clamp the tabs into the ring gear; since I'll be losing that 3-D interface by mounting the ring gear to a flat surface, do you think I should move up from the 1/4-28 bolts to 5/16-24, or perhaps even larger?

@MightyRaze that's weekend trip range from here. If you're getting a group ride together sometime this year I'd be up for it. I still haven't hit any trails with it, just romping and working around the yard, but I've been wanting to for a while now. I'm definitely gonna have to cobble together some armor for the transaxle, though.

I think the straight axle and hub should be here this week, so I'll probably be covered in 00 grease this weekend.

Oh well, now you're just getting carried away! Lol. I'd definitely go up a size if safe to do so. I look forward to seeing you make all this happen!

Still waiting on the sprocket hub to arrive, so not much happening. I did get another lower case half in, cleaned up both halves and painted them just for giggles.

My thoughts now are about the screws that hold the case together. Obviously I'd want to through-bolt anywhere I can, but there are only a few bolt holes that have anything close to a flat perch on the underside for a nut to bear against. If I were to drill the others through, I'm not sure whether they'd be an improvement or not. Studs are probably a good improvement over screws, so I was thinking I could through-bolt where reasonable and install studs everywhere else.

I hadn't seen much specifications on the FNR transaxle, so I checked the gear ratio to be sure what it is. The input gear set is 14 teeth running on 42, so a 3:1 ratio; the final drive set is 8 teeth running on 58, a 7.25:1 ratio; together, these give the transaxle an overall ratio of 21.75:1.

So I reckon that makes around 700 lb ft at the axle with the SV591.
What could possibly go wrong?

UPDATE: 21 Jan '23
I got the hub in. Carefully marked and notched, it fits to the ring gear nicely.


I drilled and through-bolted the case, eliminating 12 of the 13 blind holes and self-tapping screws. The final one lines up with the rear brake mounting screw, so it stays as-is.

Since the transaxle bears the weight of the mower, I decided to make a girdle that will  reinforce it, protect it from impact, and sturdy up the chassis. I have 3/16" steel marked and drilled, just needs cut and welded up.

UPDATE: 31 Jan '23
I got the belly plate welded up, working on similar brace for the topside. I need to mount the pulley so I can work out height of it. Considering extending the brace forward with some 1/8"x.75" flat steel to tie in the front half of the transaxle on both top and bottom. Here's how it sits right now...


I decided to install a grease fitting in one of the unused holes for the left side brake mount.



We don't get a lot of wintry precip here in AR, but we've had two winter weather events while this thing has been on jackstands, and I don't wanna miss another snow romp if I can help it. IDK if we'll have another snow this year, but if our Canuck friends can send some after I get it together that'd be feckin' awesome!

I made a little progress on the tranny's exoskeleton yesterday. I have a few more things I want to do before I call it done, but it's coming together...

I haven't had much time or will to tinker lately, but last time I was under The Hummer I noticed I'd have to make an adjustment to the upper brace. I wound up narrowing the hoop part of it to make room for the variator control/speed selector, which I'd somehow not looked very closely at before. I also added bracing on top that goes forward to the narrow section of the transaxle, as well.



This morning I woke up not feeling quite as hobbled up as I have been lately, so I bolted in the braced-up tranny, cut the axles to length, and set out to haul the garbage can up to the curb. Well, whilst hauling the can up to the street I snagged a small stump at roughly walking speed. It wouldn't hop over with prodding, so I tried to back up and straighten the wheels to go around, and...  No. Dang. Drive.

It appears the 1.5" 3/4" long 3/16 key mating the center hub to the axle gave up the ghost on it's first ride. I have the axle out now, will clean it up and have a closer look later. Though I don't recall whether the key that sheared came with the hub or if it was one I'd gotten from TSC along the way, I happened to notice that my bag o' keys from said retailer doesn't stick terribly hard to a magnet. It sticks, just noticeably less than mild steel or cast iron do. I have no idea what alloy the keys tend to be, but I'm hoping I don't have to start cutting up good screwdrivers to make new keys.

You can buy lengths of steel keystock at alot of hardware stores, then you just cut off how much you need and shelve the rest for later.

I did find a reference to key material. It seems stainless isn't uncommon as key stock, especially in harsh environs or food production, but I think the problem actually lies elsewhere...

I did some measuring...
I measured the keyway in the GPS hubs. It's about .002 over dimension.
The keys I have on-hand are about .0015 under dimension.
The keyway in the shaft is about .002" over.
This adds up to nearly to .006" of backlash, and I haven't even cleaned and measured the center hub's keyway yet. It seems a bit much. A sliver of beer can (~.005") fits cleanly between the key, shaft, and wheel hub when assembled. I'm not sure about stuffing the keyed connections with beer can shims. Could one loctite a keyed connection to shore up backlash?

You could do the beer can shim thing but personally I would drill and tap the hub at the keyway for a set screw or a bolt so it tightens down on the key just like how a keyed sprocket does.

Slop in keyways will shear keys, and a set screw will absolutely help. As for the magnetism of the steel, higher carbon alloys will be less magnetic, especially when hard. Though most key stock is really soft. If you could get a piece of 3/16” pre-hard 4140 it would be tough enough without hurting anything around it.

@sadeoo7 had trouble with the straight axles in his transmissions, I think his yardman mower. He sheared a key or two and then ended up welding his axle to the hub. I chamfered the hell out of the hub on my 820 and welded it solid, haven’t had problems with it yet. I think that is the best solution.

The center hub key is sheared and the keyways are now opposite one another, so getting the hub to move laterally along the shaft will be fun. The halves of the sheared key are still there, and have the hub fairly well bound up on the shaft. When the ol' lady goes to work tonight I can work (and cuss) much louder, so I should be able to finish disassembly of the axle then.

I picked up some oversize key stock at Fastenal, and will try to find some Loctite 660 or similar. The key stock is only .001" over, but that'll at least take up half the slack given by the seemingly wide tolerances on everything. I'm hoping the retaining compound will get it the rest of the way there. Of course, all this is predicated on the serviceability of the shaft and hub once I get them separated.

I thought about welding the hub and axle, but that's a few years welding experience down the road, I think. If the axle is boogered up bad enough when I get the hub off it that may be the only choice left, and I'd let a pro put the stickum to it.

I wish I'd started this project with a plain shaft and clamping hubs instead of keyed, but you know what they say about hindsight. With two setscrews, one behind and one 90 deg off the key, I thought this hub would be skookum enough. It might have been if the shaft, key, and hub fit tighter. Maybe..

After some cussin', heating, beating, and more cussin' I got the center hub off the axle. It's pretty gnarly, as is the axle. I should've taken a pic of it before, showing how the key tried to squirt out from under the hub before shearing. It probably would've lasted longer if the key hadn't moved, but with the slop-fit probably not a whole helluva lot longer.