What kind of transmission do I have?

Hey y’all. Sorry if someone has talked about this before but I looked and couldn’t find any. I was curious what kind of transmission is in my craftsman lawn tractor. All I could find on it was Spicer and it is a 6 speed with 3/4” axles. The model number on my machine is 917.252700 if that helps. If any of you know, what kind of abuse can this transmission take?

Depends on who you talk to, but I would call the Spicer you have the equivalent to a MST206.  Abuse?  As long as there are not a lot of clutch dumps and not bouncing it off every rock on the trail.  It should work pretty well.  You treat it well, it will treat you well.

hehe i know spicers dont like clutch dumps and down shifting lol

Budget_gokart wrote:

hehe i know spicers dont like clutch dumps and down shifting lol

Well that’s not good cuz I don’t have any brakes and I been downshifting. Do you know if there’s any work that can be done to beef them up? I think I’m going to weld mine so I can run less aggressive tread tires and a pinion brake. Is there a way to put bearings on the axles?

MightyRaze wrote:

Depends on who you talk to, but I would call the Spicer you have the equivalent to a MST206.  Abuse?  As long as there are not a lot of clutch dumps and not bouncing it off every rock on the trail.  It should work pretty well.  You treat it well, it will treat you well.

Thanks for the input. Do you think it will hold up with a welded diff on some ag tires or holeshots? And a pinion brake? I also pull a trailer pretty often loaded up with equipment or dirt.

I would be concerned with the trailer weight with a welded dif.  It could bust the transaxle at the diff.  You could get some more axle strength with a doc locker possibly.

Okay so I did a little reading on transaxle modification but there is not a whole lot on spicers. Seems like I should mst or peerless swap but I’ll run this one till it blows. I would ideally like to be able to pull a trailer, not on the trail but on the road and around the yard. I might go with a doc locker, I can get a axle for pretty cheap. My questions are:

Does the spicer have places for bearings for the axles? It looks like it does but they might not be cut out.

Should I seal the transmission and run oil, or just stick with grease. I’m aiming for 20mph tops. If I do seal it, could I drill and tap pipe thread holes for plugs on the top and bottom to drain and fill?

When a transmission does “blow” where does it typically break? The Diff, the case, the pinion?

Would you go with more aggressive tires and an open diff or less aggressive tires and a locked diff? Less aggressive to avoid blowing the diff. I ride on hardpack, mud, road, tight trails and open trails.

Sorry if I’m asking too much but I’m not sure what I should do with my transaxle.

Okay I went ahead and dropped the transmission and opened it up. Everything looks to be in pretty good condition, maybe a little more slop than stock but nothing I’m worried about. The chain is a little loose. The axles do have some play in the case which I’m not exactly thrilled about. The cases don’t really have a place for oil seals, just little rubber wipers I guess you would call them. They’re worn out. There are cutouts for a bearing in the lower case but not in the upper. I could get them machined out, I have a good shop by me.

I read the write up on the doc locker and this spicer has a smaller spider gear pin than the one he showed. The pin that engages the big gear. That kinda makes me question strength.

There should be some end play in the factory axles, as should there be when any type of locker is installed. I'm not familiar with Spicer internals but would imagine there should be a little chain slack to keep from binding or "loading." As far as oil conversion... without oil seals or a bearing acting as an oil seal, I'm not sure the oil would stay inside for long and may allow water in. You can drill and tap the case and this would allow you to drain and inspect for water and refill. I hope someone who has done one can speak on experience for you.

In a Doc locker, the pin you speak of gets removed and replaced with the hub and key stock to engage the bull gear. It is a much stronger engagement than the factory pin because there is much more surface area contacting the bull gear. The Doc locker video says the pin in the Peerless MST will be 1/2". I have opened 3 and Doc locked 2. One of them was actually a 5/8" pin.

Double check the Doc locker write-up or video for the dimensions of the hub used as I can't recall offhand. It's a 3/4" bore "x-series" hub but they come in two different diameters.

For the record, ALL 3/4" axles are subject to breakage in the same weak point: aluminum case
Your Spicer will be OK with aggressive tires up to 22" as long as they're not super deep lug swampers.

Food for thought... you could find a Peerless MST to Doc lock as you have time (to have the oil capability and bearings) and in the meantime either run your Spicer as is, or weld it, or "fozzy lock," and run it until it breaks or you finish building an upgrade. Best of both worlds with minimal downtime.

I hope this helps

PS- When considering "should I lock my transaxle..."

If you often find yourself stuck because one wheel is spinning and you would be able to go if that other wheel would just grab, then lock it because tires can only do so much if they are free to spin

If you are doing a lot of hill climbing. Locking is a must for safety.  Especially if pulling a trailer.

Alright y’all have convinced me to lock it. Y’all would go with the doc locker 2.0? I think I’ll get a 3/4 axle with a keyway, the hub and everything needed to lock it and I’ll take it down to my local machine shop and get the cases machined for bearings, the hub cut keys cut, and slots cut on the axle for e-clips to hold the wheels. I’ll leave it grease filled but replace the wipers. Maybe put a couple grease fittings in a couple places on the case. I can also get 3/4 bore 4” x 4” wheel hubs which opens up a whole new world for tires since I can get bigger wheels. Do you think the doc locker and bearings will be good for towing a trailer? And any opinions on kind of grease? Could I run outboard pillowblocks on the axle that are mounted to the frame to take the abuse rather than the cases?

Btw, the play in the axles isn’t end play, it’s up and down in the cases.

EC carburators sells billet 4 on 4 hubs for 3/4 axles

How much weight is going to be at the tongue on the trailer, and how much are you towing?

Budget_gokart wrote:

EC carburators sells billet 4 on 4 hubs for 3/4 axles

I can get 4 on 4 3/4 hubs from GoPowerSports with lugs for $20 a piece.

Rustbucket Garage wrote:

How much weight is going to be at the tongue on the trailer, and how much are you towing?

I have no idea. Trailer with a push mower, weedeater, blower, edger, and gas. Trailer of dirt. Maybe a couple people. I don’t need to pull a trailer of dirt but I definitely want to pull equipment or be able to take atleast one person for a ride.

How much dirt? I wouldn't go past 8 cubic feet, or basically a dump cart filled to the brim and not heaped. Bear in mind that when you are towing heavy loads with a tractor, it's more than "how much can the transmission withstand" but rather "how much can I stop safely". Most gts will tow a 1/2 ton, but heaven help you if you try and go down hill like that. To sum it up with some lyrics from Smokey and the Bandit, "He started down the grade when he lost a gear, hit them brakes, found he had no air, the Monteagle grade is steep and long and everybody that seen it thought the Bandit was gone."

The equipment side of things you should be definitely fine, as is putting a buddy or two and carting them around.

So as it turns out, my Murray select, which I use to cut grass, has a MST-205 in it. She’s gettin worn out and I’m considering running it for another season but I really want to do a race build on it. Would it be worth it for me to swap the transmissions? How much stronger is the mst over the spicer? And would it be worth the effort for the gain? The only thing I see from a quick glance is that that shift shaft is longer (taller) than the spicer.

If you have slop in your axles then the case is wearing. It might not be worth putting all that work and money into machining bearings into it. There are different views on which would be stronger. You could just lock your current transaxle and run it. If it breaks, just transfer your locker and axle into whatever trans you find. Or until you build something better. Converting your machine to accept an mst will require some fabrication skills. Not only shift shaft but brake alignment/config, and input pulley height as well. I dont know from experience what differences they have in these respects (mst compared to spicer)

I say lock it and enjoy it. while you think about the next upgrade, it will buy some time to find parts and assemble something you will be happier with. Maybe a built peerless 820 built over time and installed when you're ready for it

The slop was there when I got it so it’s not being caused by abuse but I definitely don’t like it. I have the opportunity to buy a lt1000 that needs a transmission but other than that its in good condition. I plan on using it as a mower. I was thinking I may be able to take the spicer I have and put it in that mower and then upgrade the transmission in my mudder. So my question is what will swap in that is an upgrade? I know an 820 will but that’s an expensive swap. MST-206? 930?

Any MST, 800, or 900 series peerless. The 820 doesn't need to be an expensive endeavor. I scored a non running Toro Wheelhorse (vertical shaft, light garden tractor model 264) with one in it for $50. I also scored one out of a parts machine locally for $20. I know this is seems like a rare find but I've only been hunting tractors for a year now. This is why I say to roll with what you have while you hunt. Of course swapping your current trans into a mower duty tractor can take place anytime you're ready to upgrade. Swap them all out once your built trans is ready. This way you don't get any downtime waiting to find a trans to build

i think ive got an aws peerless 820 i just need to get the difflock and chop the factory pully off its rusted on. the difflock thats billet on ec carburators seems like a good one considering i think the 820s are reverse gear it should be good mof my craftsman