I have recently purchased a 2008 Deere X304 4WS model that was used commercially with 1557 hours use. Needless to say, the K46 is toast, only will pull for five minutes and groaned loudly. I looked around and decided to upgrade it to the K58. Given all the negative talk about the K46, I can't believe this is the original transmission in the mower. The dealer that took it as trade in didn't have any records to share.
So the first thing needed was to upgrade the rear universal joints to fit the 1 inch axle diameter (Pricey at $140 each). The second thing is that there aren't any good pictures of the short stubby axles needed by the X304. Rather than a circlip and keyway, the axles were shorter and had the last 1.5 inches splined, which fit the universal joints. Other than that, the front transmission mount was located differently as the casing is at least an inch further to the front of the mower than the K46. The three control rods connecting to the transmission are the same, or can be adjusted to fit easily. the forward/reverse rod had to be rotated to fit on the opposite side of the transmission arm due to space since it is closer to the frame than the K46.
Not knowing better, I bought a K58A transmission for $500 delivered from a vendor on eb*y. The Deere parts diagrams and the Tuff Torq diagrams show the standard keyed/circlipped axles for the K58B. They are wrong. Fortunately, there is a photo on TT's parts site that shows the short stubby axles. Replacement axles are not available from Deere, you have to go to TT. The axles, seals and gasket material and new caps and shipping ran about $150. I purchased the Tuff Torq oil drain plugs, too. Do not be confused, they call one screw and sealing washer a Kit, so you need two kits to do the job.
There is a K46 axle replacement PDF document and I figured it would apply (after studying the parts diagrams of the K58).Open the bottom case, pull two clips on one side, change seal (if necessary), change axle, and put clips back in. Repeat for other side. Easy as pie. Not.
First, there are only one set of K58 internal pictures on the internet. Casual inspection makes you think the case is identical to the K46, with upgraded components. Not quite. I removed the plastic caps and drained the oil out and then removed the 16 bolts holding the lower case to the upper. First, the lower cover did not want to come off easily. I rocked and wiggled it and finally it came off, with the middle gear shaft stuck to the lower case lid. This isn't supposed to happen. To make things worse, parts started falling off the lower case.
I got the reduction gears, washers and shaft off the lower case. When I was done, I had four dark brown steel blocks. Two were rectangular with little nubs on one end and a half moon bearing on the other. TT calls these support bushings. The nubs sit in mating holes in the upper case and basically raise the shaft up from the motor and differential. The reason is that the K58 reduction gear has more teeth. With fixed spacing, this makes a larger diameter gear, needing the bearing to be raised above the aluminum of the upper case. the lower case has the other half moon bearing molded into it and the steel blocks fit semi-snugly into recesses in the aluminum. The shaft stuck to the lower case lid because excess gasket material leaked into the area where the metal blocks went, gluing them and the reduction shaft, temporarily in place.
The other two blocks turned out to be the two pads of the internal disc brake. Not too many pictures show these parts clearly and the parts diagram does not show the disc in between the two parts. The final issue is that in trial fitting the lower cover back on, it did not fit closed. One of the two steel reduction shaft blocks was turned around.
The axle change was easy as expected once the loose parts issue was sorted. I lubed the axles and they didn't nick the seals coming out or going in, so I didn't have to change seals, although I have them if ever need them.
The K58 has four magnets. Many K46s have only two and TT offers an additional two near the filter as an upgrade for the center housing. One at the upper fill port, one near the differential, and two next to the filter for the hydraulics. These are pretty weak ceramic magnets. I figured that if more magnets are better, then stronger magnets are better yet. I put two 1 inch x .25 inch 20 lb magnets next to the filter under the bracket. Slightly too big, they still fit and won't hit the case when it is closed. I put one 1 inch by 1/8 inch 14 lb magnet at the oil fill (fits the bracket perfectly) and one in the case. This should capture more and finer iron debris and should help prolong the life of the transmission. The neobdynum magnets are temperature sensitive and can start to lose magnetism starting at 180F. In theory, the oil could get that hot, but not much more. Since these magnets are 4 to 5 times the strength of the factory magnets, I am not worrying too much. In addition, I used Castrol Edge 5W50 oil, which should knock some of the temperatures (and will pay attention to keeping the transmission case and fan clean).
Oh, one other thing to note: All K58s have the narrow part of the triangular wedge pointing out of the case (up looking down at the upper case). For those considering a K58 upgrade, the front transmission mount and the direction of the wedge may come into play. And of course the 1 inch versus 3/4 inch axles will require new rims or hubs, depending on your wheel attachment.
With nearly 1600 hours, you can image that the rest of the mower is worn out. I stripped, painted and replaced all moving parts on the deck. painted the fenderdeck, cleaned inches of trapped grass and dirt muck under the fenderdeck, and will be putting a new Kawasaki engine on this weekend, and replaced right front tie rod ends. I changed to new tires and painted the rims. The restoration finishes with a new hood, headlight lens and lower plastic bumper. It looks almost new.
So the first thing needed was to upgrade the rear universal joints to fit the 1 inch axle diameter (Pricey at $140 each). The second thing is that there aren't any good pictures of the short stubby axles needed by the X304. Rather than a circlip and keyway, the axles were shorter and had the last 1.5 inches splined, which fit the universal joints. Other than that, the front transmission mount was located differently as the casing is at least an inch further to the front of the mower than the K46. The three control rods connecting to the transmission are the same, or can be adjusted to fit easily. the forward/reverse rod had to be rotated to fit on the opposite side of the transmission arm due to space since it is closer to the frame than the K46.
Not knowing better, I bought a K58A transmission for $500 delivered from a vendor on eb*y. The Deere parts diagrams and the Tuff Torq diagrams show the standard keyed/circlipped axles for the K58B. They are wrong. Fortunately, there is a photo on TT's parts site that shows the short stubby axles. Replacement axles are not available from Deere, you have to go to TT. The axles, seals and gasket material and new caps and shipping ran about $150. I purchased the Tuff Torq oil drain plugs, too. Do not be confused, they call one screw and sealing washer a Kit, so you need two kits to do the job.
There is a K46 axle replacement PDF document and I figured it would apply (after studying the parts diagrams of the K58).Open the bottom case, pull two clips on one side, change seal (if necessary), change axle, and put clips back in. Repeat for other side. Easy as pie. Not.
First, there are only one set of K58 internal pictures on the internet. Casual inspection makes you think the case is identical to the K46, with upgraded components. Not quite. I removed the plastic caps and drained the oil out and then removed the 16 bolts holding the lower case to the upper. First, the lower cover did not want to come off easily. I rocked and wiggled it and finally it came off, with the middle gear shaft stuck to the lower case lid. This isn't supposed to happen. To make things worse, parts started falling off the lower case.
I got the reduction gears, washers and shaft off the lower case. When I was done, I had four dark brown steel blocks. Two were rectangular with little nubs on one end and a half moon bearing on the other. TT calls these support bushings. The nubs sit in mating holes in the upper case and basically raise the shaft up from the motor and differential. The reason is that the K58 reduction gear has more teeth. With fixed spacing, this makes a larger diameter gear, needing the bearing to be raised above the aluminum of the upper case. the lower case has the other half moon bearing molded into it and the steel blocks fit semi-snugly into recesses in the aluminum. The shaft stuck to the lower case lid because excess gasket material leaked into the area where the metal blocks went, gluing them and the reduction shaft, temporarily in place.
The other two blocks turned out to be the two pads of the internal disc brake. Not too many pictures show these parts clearly and the parts diagram does not show the disc in between the two parts. The final issue is that in trial fitting the lower cover back on, it did not fit closed. One of the two steel reduction shaft blocks was turned around.
The axle change was easy as expected once the loose parts issue was sorted. I lubed the axles and they didn't nick the seals coming out or going in, so I didn't have to change seals, although I have them if ever need them.
The K58 has four magnets. Many K46s have only two and TT offers an additional two near the filter as an upgrade for the center housing. One at the upper fill port, one near the differential, and two next to the filter for the hydraulics. These are pretty weak ceramic magnets. I figured that if more magnets are better, then stronger magnets are better yet. I put two 1 inch x .25 inch 20 lb magnets next to the filter under the bracket. Slightly too big, they still fit and won't hit the case when it is closed. I put one 1 inch by 1/8 inch 14 lb magnet at the oil fill (fits the bracket perfectly) and one in the case. This should capture more and finer iron debris and should help prolong the life of the transmission. The neobdynum magnets are temperature sensitive and can start to lose magnetism starting at 180F. In theory, the oil could get that hot, but not much more. Since these magnets are 4 to 5 times the strength of the factory magnets, I am not worrying too much. In addition, I used Castrol Edge 5W50 oil, which should knock some of the temperatures (and will pay attention to keeping the transmission case and fan clean).
Oh, one other thing to note: All K58s have the narrow part of the triangular wedge pointing out of the case (up looking down at the upper case). For those considering a K58 upgrade, the front transmission mount and the direction of the wedge may come into play. And of course the 1 inch versus 3/4 inch axles will require new rims or hubs, depending on your wheel attachment.
With nearly 1600 hours, you can image that the rest of the mower is worn out. I stripped, painted and replaced all moving parts on the deck. painted the fenderdeck, cleaned inches of trapped grass and dirt muck under the fenderdeck, and will be putting a new Kawasaki engine on this weekend, and replaced right front tie rod ends. I changed to new tires and painted the rims. The restoration finishes with a new hood, headlight lens and lower plastic bumper. It looks almost new.
