Difference Between Transaxles

The K57 is based on, and just as serviceable as, the K46. It will last longer because the charge pump takes over the duty of pulling fluid from the reservoir to replenish losses in the hydro pump and motor. In the process, it improves the performance of the hydro by a very slight margin.

It's still inadequate for slopes for a long life expectancy, as is the K58 which is serviceable, has a more robust final drive, and has the options of a filter and implement lift hydraulics.

All 3 hydros use the same small size pumps and motors which means that pressures are going to be high when dealing with slopes, and high pressure means high heat generation and increased wear.

K46, 7cc pump/10cc motor, 3/4" axle, 171 lbft torq rating,
K57, 7cc pump/10cc motor, charge pump, 3/4" axle, 188 lbft torq rating,
K58, 7cc pump/10cc motor, charge pump, 1" axle, 218 lbft torq rating

So, as you can see the biggest difference between a K46 and a K58 is the 1" axle and heavier differential, as Tudor said. How close is a K46 to a K57? Well if you choose, TuffTorq will sell you the charge pump and parts to make a k57 out of your K46.

Put another way, the K57 is a K46 with a charge pump, the K58 is a k57 with 1" axles

JD makes some K58s serviceable, X310, X360, and some that are not serviceable, X320, X324. Difference is if you have external hydraulics from the tranny, power steering, power deck lift, you'll get a serviceable unit with external filters and drain/fill provisions.

steve

Be careful with torque rating comparisons. Different axle ratios have different torque ratings. The K57 with the same axle ratio as the K46 is rated at 174 lb/ft. The K58 has a different axle ratio.

There are 2 axle ratios shared by the K46 and K57. In addition, the K57 has a third axle ratio that compares closely to the one axle ratio in the K58. I surmise that the larger, more robust, gears themselves in the K58 may also have an effect on the torque rating, otherwise logic would say that the K57 should have a torque rating closer to the K58. Or, more likely, the rating for the K58 may be a misprint.

In any event, crunching a few numbers indicates that the 218 lb/ft for the K58 to be somewhat optimistic based on gear ratios alone. An increase in peak pressure could account for the discrepancy.

TUDOR said:

The K57 is based on, and just as serviceable as, the K46. It will last longer because the charge pump takes over the duty of pulling fluid from the reservoir to replenish losses in the hydro pump and motor. In the process, it improves the performance of the hydro by a very slight margin.

It's still inadequate for slopes for a long life expectancy, as is the K58 which is serviceable, has a more robust final drive, and has the options of a filter and implement lift hydraulics.

All 3 hydros use the same small size pumps and motors which means that pressures are going to be high when dealing with slopes, and high pressure means high heat generation and increased wear.

Click to expand...

Thanks, this helps.

So, in my situation, I have a very flat lot, but I put about 60 hours a year on my tractor from simply cutting the lawn. I stripe every time, so there is a lot of backing up. Every now and then will pull a trailer with about 300lbs of fertilizer, throw me on the seat and the tractor is pulling 470lbs. It sounds like the K57 is a small upgrade over the K46, but not much. However, it should last me the life of the tractor. Yes?

Just to add one more question, would a K62 High Speed tranny be worth an extra $800? There are some other upgrades too, but this is the one I care about.