First time, long time ....

I have a 2014 John Deere X320 tractor with a Tuff Torq K58 transmission installed. It has about 405 hours of operation. I mow about 1.5 acres of which 0.1 acre is a 17% hill (which I do half downhill and half uphill).

Last summer, for the first time, the transmission in my tractor started overheating after a few passes up that hill (it usually takes about 8 passes up the hill to mow it). I’d let it sit for a while to cool off, and then I’d do a little more. This spring, I changed out the transmission fluid as was recommended by Tuff Torq and also seeing the same recommendation in this forum. Unfortunately, that did not help the situation so now I find myself considering replacing the transmission (I’m not mechanical enough for a rebuild).

My previous tractor was a Toro 267H. I looked that up and it had a Tuff Torq K61 transmission which, interestingly enough, has the same rated torque as my current K58. The Toro lasted at least 15 years on the same hill with no problem, so I'm wondering if my current transmission is a lemon and I should just get a new K58 (now with periodic transmission fluid changes!) or should I upgrade to a K66 transmission for which I see kits available online.

Does anyone have experience replacing the K58 with a K66? Any advice or things I should look for? In particular, I’m worried about the axle bolt holes lining up, whether the splines on the axle are the same, and whether or not the existing transmission drive belt for the K58 could be reused for the K66.

Also, after I got the transmission exposed to allow me to change out the fluid, I thought I’d go further and remove it from the tractor to turn it upside down for a complete drain. However, when I removed the spring pin that holds the tractor brake rod, I couldn’t push the brake rod up to get it out of the brake lever on the transmission. Is there a trick for removing the tractor brake rod from the transmission?

Thanks for your help!

Here is a thread That can help with a K66 Upgrade John Deere X300 K66 Upgrade project from a former site staff Member

 

Thanks Sergant - that's a great resource. I breezed through it, now i have to back and study it!

 

I have done the same to my X300. I replaced a K46 with a K66. I sourced my K66 from Surplus Center - an online supplier. My X300 had only 68 hours when I replaced the K46. It was still working good when I did the swap. Now the X300 is over 300 hours. Working great.My experience was also posted on this forum.

 

I find myself considering replacing the transmission (I’m not mechanical enough for a rebuild).

A rebuild is surprisingly easy and you don't have to go very deep into the unit to replace the pump and motor. If you are comfortable pulling the transaxle, you can do the rebuild.

 

Aluvaboy - Thanks for the info. I looked up your post - great pix! I'll have to study that one too.

denverguy - Thanks for your vote of confidence! I've looked at some videos of rebuilds and I'm haunted by little springs and spacers popping out and "make sure you get this in the right way" and such. Also, this is my only tractor and I can't afford to have it out of service very long. I'm thinking I could do a swap in day, maybe 2 at the most, but I don't know how long a rebuild would take me.

 

Also, from my internet research, it appears that there are several versions (?) (models?) of both the K58 and K66 transmissions. But i can't find any documentation as to what they are. Is there a reference list available somewhere listing the different versions and what their features are?

 

17% or 17°
17% is less than 10°, so that is not a lot

It looks like the K58 has 1" axles, which is good if you want to swap to a K66. But, the days of the cheap K66Y's are long gone.

But this rebuilt one looks interesting:

Tuff Torq k66 transaxle for Simplicity | eBay

Find many great new & used options and get the best deals for Tuff Torq k66 transaxle for Simplicity at the best online prices at eBay! Free shipping for many products!

www.ebay.com

A new one is probably in the $1K range these days.

Looks like a K58 is in the $800-1200 range

There are lots of differences, but most are probably not visible and probably don't matter. Go pedal direction and axle length/ends matter the most. Getting one that is close is easy, as they all are, and can generally be modified with enough skill.

 

I measured the slope with my GPS. It said I walked 129 ft with an elevation change of 22 ft - so yeah that works out to 10°. Thinking about my protractor, it seems steeper than that!

One of my big concerns is if the K66 axle will bolt into the same location as the K58 does on my tractor (ie - is the bolting pattern the same for both of them). I've written to Tuff Torq asking them that, but I haven't heard back yet. Neither of the two K46 to K66 upgrade projects referenced above indicated any problem with that, so maybe I don't need to worry about it.

 

They typically have multiple sets of mounting holes on them. So, it should just bolt up. But, the sizes of everything else can be different enough that adaptation might be required.

If you want one that is sure to bolt right up with no modifications necessary, buy the exact same model number that Deere uses. Any other one is likely to require more time and some to a lot of head scratching and therefore more machine down time.

 

Not sure where you are located but DH Marvin, a small Deere dealer in Colchester CT has brand new K58M transmissions on their website for $400. Deere part # MIA12579.

May bolt right up and be the easiest/lowest cost solution. I'm sure they could ship it to you.

Nice people. I live on the other side.of CT but have purchased smaller items from them when visiting friends in that part of the state.

 

USED EQUIPMENT FOR SALE - DH Marvin

John Deere 45 Loader for X700 Series Tractor Fits 2012 and Older Tractor Also includes Heavy Duty Tooth Bar and Mounting Frame Consignment Unit

dhmarvin.com

That's the link, but they say the transaxle(s) are new. That will be your cheapest and quickest way. Even if you are not close, they should be able to ship it to you for around $100. You got 8 years out of the original. This would last longer if you change the fluid regularly. I don't think I would spend twice this price for something not that much better. But, I might buy the transaxle fix the machine and then be on the lookout for an X500 series class machine that has easily changeable fluid on a much heavier duty transaxle.

 

Don't get excited about the 45 loader above. That seems to be gone, probably long gone.

 

Forgmore, Fcarp - Thanks for the input! Looking up that part number on the JD website says that a K58W is a substitute for it. What's the difference between the K58W and the K58M (which is what I've figured out is the version installed in my X320)? I'll give a call to the Marvin folks on Monday and see if they know. I'm about a 2.5 hour drive from them so I hope the shipping cost is reasonable.

 

Glad to help 👍

When you call give them your model and serial number and see what they say. It may just be some internal change in the transmission itself but otherwise the same mounting, pulley location, linkage, etc.

Let us.know how you make out!

 

Shipping would likely be around $100 assuming it isn't a profit center for them.

I am seeing K58M as the transaxle for the X320.

https://partscatalog.deere.com/jdrc/partdetails/partnum/MIA11860

I think the part number that was there originally was replaced.

 

Update - Today I bought a K58M transmission from DH Marvin. I'm going down to pick it up on Wednesday (spend about $50 in gas to save $95 shipping fee). They're about 2-1/2 hrs from my house so my wife and I will take our bikes along and hit 1 bike trail on the way down and 1 on the way back. It's supposed to be a nice day so it should be fun!

I really wanted a K66 for the extra torque and the much easier serviceability. So, why did I choose the K58?. Here are several things I thought about in no particular order -

1. Cost - this unit is costing me $400 which I'\m sure is a steal (many many thanks to Fcarp for his tip). The next cheapest I saw for a K58M was $800 from Mulligan Parts Co. The cheapest I saw for a K66 was $1200 also from Mulligan Parts. I don't know if Mulligan Parts had either of those units in stock.

2. Which K66 version to get - an interesting website I ran across was ecrater.com, They were offering a K66Y for Husqvarna, Craftsman, and others. They had the most detailed description of the unit by orders of magnitude. They listed many dimensional details from which I became very confident that the K66 would bolt in the frame the same as the K58. However, they also said the K66Y may not work in a John Deere - they stated that the K66R was made for Deere and recommended contacting rjrtractor.com. I called RJR Tractor and asked about the transmission version. At first, the guy said R, but then he changed it to Y. I probably should have questioned further but I did not, sorry.

3. I had already looked at the RJR Tractor site since they have K66 upgrade kits (for around $2400). When I looked at the kits, I saw a new transmission belt, a bunch of parts for wheels (which I didn't think I needed since the X320 already has 1" axles), new idler pulleys (which probably really don't need), and a new freewheeling rod. I was concerned about installing a new transmission belt. I had seen a video of replacing an X320 transmission belt and it was involved. I also saw a thread on another forum about a transmission upgrade and replacing the belt was glossed over (just remove the steering rods). However this thread had a preface which stated that the job was intuitive so I'm sure something that was not a big deal for him would be a big deal for me. On the RJR Tractor site, they sell the belt as a separate item - their picture identified it as 89" long. I looked up my current transmission belt on the Deere website and it is 91.89" long - sigh.

4. Looking at photos of the K66, I realized that the freewheeling rod for my K58 wouldn't work for the K66 because the fluid reservoir would be in the way. I would need to build or buy a new rod. Building might be problematic for me. I asked RJR Tractor if I could buy the rod as a separate item - they said no.

5. I also told RJR Tractor I wouldn't need any of the wheel parts. They said that I would have to modify my OEM wheels - they have instructions in their manual (the kit includes an illustrated manual, I'm sure it's very good - I was going to get that too if they would have sold it to me), but I would save $200 if I did the modification myself.

6. What transmission pully should I use - I don't know if the K58 pulley and the K66 pulley are the same. Fortunately, both transmissions are designed for 3400 RPM input so i reasoned that I should probably use the K58 pulley since I know it's sized to give 3400 RPM input based on the engine output RPM. I assume that the K58 pulley will fit on the K66 input shaft but I don't know for sure.

7. As stated in one of my previous posts - I'm looking for a 1 or 2 day transplant since this is my only tractor. Looking at potential issues with the transmission belt and the freewheeling rod, I am concerned about exceeding that timetable. Actually, I could probably go 5-7 days, but I wouldn't be happy and I have other things I want to do.

8. Do I really need a K66 - despite my ignorance on maintenance (I believed the Deere Owner's Manual), I got 6 good years and 1 partial year out of my current K58. Now that I'm smarter and would actually do proper maintenance, I think I can do better with a new K58. At that point, my tractor would be at least 15 years old and I would feel better about having "got my money's worth" (I understand that everyone's idea of "their money's worth" may be different).

I guess the big hitters in this list are Points 1, 7, and 8 - combined they lead me to taking the surest (and least expensive) way out. I've learned a lot from this experience. I want to thank everyone here and other many other posters that I've read for sharing their knowledge and experience. I'll probably update the project as I do it, but it probably won't be too exciting (at least I hope not!).

Side note - I wrote to Tuff Torq about this issue and I noted that the transmission in my previous tractor had been a K61 (which has the same torque rating as the K58) that had gone 15+ years on the same hill with no problems. I asked "Is there any reason you know of that the K61 is more robust than the K58?" Here is their answer - "Yes, it is a bigger transaxle larger oil capacity. Plus the K61 will handle hills better than a K58."
Great - they don't make the K61 anymore - they don't build them like they used to!

 

You can think of the K66 as a better K61 and the K58 as a better K46-57. Or you can think of the K61 as a better K58. It is all a matter of perspective. They do build things both better and also cheaper (but not necessarily better than before). There is a desire for most people to pay less. Manufacturers meet that need by making things cheaper. That usually means there is nothing extra. Some times they go too far and the quality suffers too much. With Deere you generally have the option to pay more to get something better. Most people choose the cheaper option at Deere or otherwise.

 

I totally agree that people have a desire to pay less and that quality may suffer to meet the cost goals. Still, I'm a little disappointed with this tractor. I paid $4200 for this tractor 9 years ago. I didn't buy an L Series tractor because I knew I had a big yard and a big hill and the L Series wouldn't cut it (pardon the pun!). This tractor has basically the same characteristics as my previous Toro which went 15+ years - similar engine size, similar frame and physical size, same torque rating for the transmission (although that was not something I checked at the time - I didn't even know what the torque rating was for either of them until I started doing this). How much more expensive could the K61 transmission be for Deere to install instead of the K58? Even for $200 or $300 wouldn't have deterred me from buying this tractor. And now I'm spending $400 (and thankfully only that much more) to get to the same place as my previous tractor and I'm going to do more maintenance to get there (periodic transmission fluid change outs which I didn't do on the Toro - Toro also said no service required on the transmission). I expected to get at least the same life as the Toro - actually more - this is a John Deere! (although when we moved here 40 years ago, my neighbor recommended Wheel Horse which is what my first 2 tractors were before Toro bought WH) Obviously, if I ever buy another tractor, I'm going to be paying a lot more attention to the transmission in it!

 

You realize you have a sample size of one for each of the K61 and K58? With that small of a sample size you can't make any statements of goodness with ANY statistical validity. The K61 and K58 are pretty much the same from a capability and reliability point of view. You had different experiences with them and that sucks. I have had that experience. I have also had the opposite. My K46 is still working fine after 15 years. That doesn't help you are all. There was someone else here that had to rebuild a K72 with fewer hours than yours. That REALLY sucks, but once rebuilt it was fine. Maybe that will make you feel better that you didn't spend twice the amount you did and still end up with a bad transaxle.

Maybe your hill is bigger than mine. Maybe you mow in temperatures that are hotter for longer than I do. Maybe you got a "bad" one. Maybe I got a "good" one. I think once you get the new K58M installed, you will be back to being happy. I know I spent a decade worrying about the K46 in my X300. But it would never die. I finally gave up on that happening and got the X534 that I really wanted. I like it so much I also got an X749. Each has its advantages and disadvantages, but I like them all.

 

Your absolutely right about the small sample size - the baseball forum I follow brings this up all the time! As i said in my first post, I may have got a lemon - one of them has to be below average - otherwise the average would be better. I expect the new transmission to be better than the one I've got. And since I'll take better care of it, it will be better.

 

@wwebbiee, how is the transplant going?

 

The transplant is scheduled for today. Hopefully there will be a full report of a successful transplant later

 

My tractor underwent transmission transplant surgery today. The procedure took about 4.25 hours. I ran the tractor up and down our hill and around a larger field for about 2 hours and then it charged back up the steepest part of our hill. I'd say the patient has made a full and complete recovery!

Some details - The pdf file below is the instructions I used to do this - they're from the John Deere X300 Series Technical Manual I bought online. (if they post, otherwise see next post)
In a previous post I noted that the John Deere part number on the transmission I bought (was considering at the time of the post) matched up to a K58W transmission. As Fcarp posted previously, there may be some internal differences. Externally, the big difference is that the pulley is on top of the fan (see the first 2 pictures) - in my OEM transmission, it is the other way around. So I needed to change the configuration otherwise the transmission drive belt would not work. This was easier said than done. On my old transmission, I was able to hold the fan to keep the shaft from turning while I loosened the nut. The nut on the new transmission was much tighter, I couldn't hold the pulley to keep the shaft from turning. I tried using some vice-grips on the shaft to hold it. To my surprise (and disappointment), that didn't work either. I finally realized that the holes in the pulley you can see in the top view are there for a reason. The holes are 5/16" diameter. I drilled 2 holes in a 3 foot piece of plywood to match the holes in the pulley and used 2 5/16" drill bits fit through the holes in the plywood and the holes in the pulley. I held the board, my brother was on the socket wrench, and my son held the axle to prevent the rest of the transmission from moving, and, with the help of a cheater bar on the wrench, we got the nut off (see the third picture). You could probably do it with 2 people.
The only other issue I had was removal of the brake rod. The instructions called for its removal, but didn't say how. I removed the spring clip, but we couldn't physically move the rod up to clear the transmission lever because it was constrained by the tractor frame. After mulling it over a few minutes, I decided that when we lowered the transmission to remove it, the rod would come out then. So that's what we did - I had the transmission on a jack, we were able to lower it slowly and the rod came out, we might have helped it along with a few gentle taps with a hammer.
The instructions call to disconnect some fuel lines and remove the fuel tank. I didn't do that, I just moved the tank out of the way - there's enough play in the lines to do that (see the fourth picture).
One other tip - to remove the fender deck, you have to remove the deck height adjustment knob. It is a friction fit but it is very difficult to remove. The first time I did it, I wound up taking off the left rear tire to get better access and using a pry bar. When you get it out, you'll notice it has 2 washers which provide the friction fit. I removed one of the washers when I reinstalled it. When I went to remove it for this job, I was just able to pull it out - much easier and it's not going to get loose when it's installed.

So that's it. Again, thanks to all who helped out on this and I hope this helps someone else in the future.

 

Great write up. Glad you got it working. You should get an impact wrench. I have one of the inexpensive ones and it works fine for some things. I have an IR one that is about as good as an air powered impact. I bought it to loosen the nuts on my chipper blades that have a 300-ish lb-ft torque spec. With that, you can just hold the fan and remove the nut from the transaxle easily.

 

Glad to hear this worked out for you. Now that you figured out how to remove the old one, it will be much easier to change the oil in the new one 50 hours from now.

If you do that, odds are this tranny will last the life of the machine.

 

Yep - that's the plan. I already bought some synthetic 5W50 because i wasn't sure if the new tranny would come with oil (it did). And after that first change, how often then - 100 hrs or 200 hrs? I've seen both.