Tech Tips – Residential IHT (w/ integrated reservoir tank) Oil Maintenance

Tuff Torq Oil Service Procedure for Residential IHT  units with Internal Reservoir Tank

Models covered by this procedure:

  • K46 Series
    • Manufacturing ID: K46AA, K46AC, K46AG K46AW, K46BA, K46BC, K46BE, K46BL, K46BM, K46BN, K46BP, K46BR, K46BT, K46C, K46CJ, K4CR, K46CW, K46HD, K46V, K46Z
  • K57 Series
    • Manufacturing ID: K57A & K57F
  • T40A & T40J

Normally the model K46 & T40A transaxles, that are featured in many tractor and rider models, do not require any servicing for the life of the vehicle. If checking the oil level/condition, it may be necessary to remove the transaxle from the vehicle.  This is necessary to access the fill port (black cap) located under the pulley and fan (see diagram below).

After removing the unit from the vehicle, place the transaxle on a level surface and remove the fan and pulley. Then remove the black cap shown in the diagram below.  Maintain the oil level at 20~25 mm (3/4”~1”) below the lip of (black cap) port (see diagram below).

Technical note: Check oil level when oil is at room temperature (20°C or 68° F) and the unit case is level and secure.

Always use the fill port (under the black cap) to drain the oil from your Tuff Torq unit. Do this by removing the cap and inverting transaxle.

Tuff Torq recommends using only using approved Tuff Tech drive fluid when servicing any of our transaxles.  Only use the fill port (covered by the black cap) to refill unit. You will need approximately 2.2 liters of oil to properly refill the unit if completely empty. The amount of oil needed may vary for your service, due to the amount of residual oil remaining in case after draining and the condition/age of the unit you are servicing.

While reinstalling the fan & pulley be sure to place all components on the drive shaft in the reverse order from which they were removed and verify proper torque for each bolt.

Tuff Torq Oil Service Procecdure Diagram

Tuff Torq Oil Service Procecdure Diagram

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    And also how to check if it’s full of oil on the K46BT

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    K46 oil capacity and type of oil pls

  • Mike Simmons says:

    OK, so I got to the “rubbery” black cap with the transaxle still on the mower. How do I get that cap off? Can’t find a “lip” or anything. Undersatnd there is a magnet under it as well?

    • ggraham says:

      a slotted screwdriver “tapped” under the lip of the sealing cap and pry it up using the case as a fulcrum.

  • PIERRE Arnold Jr. says:

    Fluid type and amount for and LX188 John Deere mower.
    Tuff Torq 19154-24122 upper case

  • Ed says:

    Hi, I have a JD L110 (but it has the 20hp vtwin when i bought it) with a K46. I only use it during the winter with a snow blower attachment. It goes forward ok, but has so much less power reversing. im thinking on changing the oil (drop-flip-refill) what would you recommend for oil if it only sees winter service -20F TO 40F mostly in the +20.
    do you think new oil might improve the reverse performance?
    If i see the upper magnet with a lot of metal, i would consider opening it up, so far no evidence of leaks on the shafts

    • ggraham says:

      The best thing to do is check with your John Deere Dealer to find out their oil recommendations. Usually, it is 10W-30 or for a K46 or T40, you could use the John Deere oil their J20C. both of those will work. Fillings on the magnet will indicate that the gears have smoothed off their rough edges unless the shavings are completely burying the magnet it is usually all right. Since in a Tuff Torq, the gear chamber is separate from the hydro chamber the filings will not be a problem. New Oil can help if the oil viscosity is shot and having a hard time holding pressure because of it. It is also a good idea as a starting point because it can be many other things like control lever not being able to move its whole arc that could be an issue as well that you will be able to check when you drop the transmission.

  • Allen Casto says:

    I have a K46 and the serial numbers are unreadable. How to tell what parts to order?

    • ggraham says:

      that is unfortunate. However, you should be able to contact the Original Equipment Manufacturer (OEM) and armed with the serial number of the tractor they should be able to tell you which transmission is installed in that particular tractor.

  • Amador Lopez says:

    Hi I got a K46BN trans and is in neutral cant foward or back ward any help????

    • ggraham says:

      You would want to check all the linkages on the tractor hooking to the transmission and make sure all is well with those. also, check all the pullies on the tractor to make sure those are all working. If everything externally is fine then you would want to change the oil in the transmission and the oil to use is a 5W-50 synthetic. A K46BN holds 2.4 quarts. if it does not get better after the oil change then the wear on the hydraulic parts is too bad for even the thick oil to help. You then would need a repair kit. and you can find that right on the website

  • Roger Kingaby says:

    My 2006 Countax X series (20 ) 4 wheel drive hydrostatic mower is leaking oil from the Tuff torq K574 gearbox, the rubber oil seal needs replacing at the top of the gearbox casing, sealing the shaft assembly under the cooling fan. Can I replace the seal from the top without removing the gearbox ? Can you please advise. I believe the oil seal part no is 187T0134380 Many thanks.

    • ggraham says:

      I do not see these transmissions in the tractor. So I cannot say if you have to remove it or not. You do not need to split the case to change it you can do it right from the top.

  • Timothy Rude says:

    For my Husqvarna YTH21K46 with a K46BT transaxle, could I increase the travel speed by installing a slightly larger pulley on the engine shaft, or would that not work with this type of transaxle?

    • ggraham says:

      I am sorry but I cannot recommend changing the pulley to alter the specs that the transmission is designed to have. I am sure you can understand the liability associated with altering the intended workings of the transmission.

  • James says:

    I have a k46bn much for a rebuild kit?when it gets hot it won’t pull.does fine for a couple hours,then too hot and won’t pull.

  • Tom Cyr says:

    Your table “Fluids and Lubricants” does not specify the type of fluid used in the K46BT trans-axle, could you provide that info? Thanks

    • ggraham says:

      You can use 10W-30 motor oil; or a 5W-50 Synthetic. the best is our Tuff Tech brand of oil and the part number for a 3-liter bottle is 187Q0899000.

  • James Garnes says:

    I rebuilt the rear end in my lt 160 but when you push the petal to go forward it go in reverse what did I do wrong

  • William Mevissen says:

    I realized now that I used the wrong port to fill unit. Can you put in to much oil in the transmission? (K46A2)
    It moves if the wheels are off the ground. But when they touch the ground the tractor will not move.
    I didn’t see what port to use until I looked up on Tuff Torq Oil Procedure.

    • ggraham says:

      If it is acting in that way and you have purged the hydraulic circuit of air then it is probably too much wear on the hydraulic parts that the fresh oil cannot make up for. A repair kit is a hydraulic rebuild and you would need that to get your transmission running like new again.

  • gary kelly says:

    k57r transmission in a husqvarna yta24v48. noticed black gear oil is leaking out of my right rear axle tractor only has 60 hours on it after i replace the axle seal how do i top off the gear oil that leaked out and what weight oil do i use? and what part number is the axle seal.

  • dimitry says:

    hello where can i find parts in Belgium . where can i find more info how to calibrate the fulcrum at the 46 f gear ?

  • Barry Newman says:

    I do not find Tuff Torq transmission oil in the shuswap area. Please tell me the cross reference info so I can use automotive trans fluid.

  • Jerry Stollar Sr. says:

    Can I buy parts to repair my k46 in my jd lt 160 tractor?

  • Carl Ewing says:

    Following the recommended oil change procedure I’ve noticed that when the drive shaft at the top is being turned. clockwise on my K46AC, and the freewheel lever is disengaged I can grasp the turning portion of the axle (right side) and it simply stops in my hand. Is this normal?

    • ggraham says:

      Mr Ewing,
      It is not normal for the axle to just stop. You might have wear on the hydraulic parts which is allowing the oil to escape and lose pressure which is a loss of power, ultimately. it could be you need to replace those parts and a repair kit will be a total hydraulic rebuild. You can find the repair kit on the website: Or you can contact the helpful techs in the service department at 866.572.3441

  • Ben says:

    Could I replace a K46BC with a K56? Are they the same size, with the same mounting points?

    • ggraham says:

      These transmissions are built specifically for the tractors that they are in and swapping can cause all kinds of unforeseen issue. The K56 is a very different transmission than the K46 and no they will not interchange without major modifications.

      • Goose says:

        There is a upgrade kit for the K46 it is a K66 one of the best and heavy duty, way over what you will need and those attachments for your lawn tractor that will ruin your rigg faster than anything the K66 is made for those application. These kits are expensive but includes even new wheels to match the much heavier axle while you can still use your tires

  • William Black says:

    My shop was flooded in Hurricane Harvey. I am afraid water got into the transaxle. The top of the Tuff Torq was under about 8 ” water. Should I split it apart or just drain and put new oil?

  • Javier ibarra says:

    How do you remove the black cap seems to be stuck on? I am trying to refill the fluid because it has been leaking a little bit

  • mike russell says:

    what are the differences between a k46 and a k46ac

    • Hello Mr. Russell. Thanks for your message. While I am happy to help any way I can, you have several questions here that would be best answers by one of our service professionals. You can reach them at or toll-free at (866) 572-3441. The short answer is the “AC” designation describes a particular control logic and specific design set defined by a particular OEM for their tractor application. If you contact our professional service team, they will be able to look up and help you understand the features and specifications of the K46AC model. Hope that is helpful, have a great day!

  • Erki Potisepp says:

    I have Ariens 46″ Lawn & Garden Tractor, 22hp B&S and i would like to change the hand gear to pedal gear (using Husqvarna YTH 20K46 parts)
    I have a question about K46 hydrostatic transmission. Whate are the main differences between K46ba (Ariens) and K46bt (husqvarna) hydrostatic transmissions. Does theoreticaly hand transmission connections fits with pedal transmission parts?

    • Hello Mr. Potisepp. There are several differences that can be designed into each K46 unit Tuff Torq manufacturers for an OEM. The main issue with using non-original parts in a repair is the danger of the non-original unit not having the same “control logic” as the original unit. Meaning, Tuff Torq has the ability to set up a transaxle to have forward/reverse initialized by the control arm in either the “push” or “pull” directions (depending on the need of a specific OEM). Using a transaxle from another OEM may create a situation where initializing your tractor in the forward direction would cause it to actually go backward, and vice versa. So, we do not recommend replacing units with transaxles designed for other vehicles. For more information, I recommend you contact our service team at or give them a call toll-free at +1 (866) 572-3441. Hope this was helpful! Have a great day.

  • I have a tuff Torque K72 High speed transmission, and I would like to know if there is a service manual for this unit that I can get to better help be keep it maintained properly.? It’s in a 2017 Simplicity Prestige tractor. The owners manual that comes with tractor doesn’t cover good technical maintenance.
    Thanks for any info you can give me.

    • Hello Mr. Kraus. I’d recommend you contact our service department. They will be better equipped to find you the information you need to keep your K72 unit working at peak performance. You can reach them via email at or toll-free at +1 (866) 572-3441. Have a great day!

  • Michael Lacy says:

    Wanting to know what the cost of a pump and motor for my K46 transmission would be. I’m doing a rebuild on it as the mower would not move in forward or reverse.

    • Hello Michael,

      Since each model of our K46 transaxles is unique in its specifications outlined by the OEM, it’s probably best that you contact one of our service technicians with your specific model information. They will be happy to assist you with your request. Please feel free to contact them at (866) 572-3441 or via email at Thanks!

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