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nelson_thibert53

John Deere LT155 transmission

nelson_thibert53
7 years ago

I replaced the drive belt on my John Deere LT155 transmission. I am unable to set the proper tension. The belt will stay on until I put a load on it i.e.engage the PTO. I have replaced the pulley on the transmission. I have replaced the belt guide. The dealer is telling me that the transmission shaft may have excessive ware or may be bent. Does anyone have any thoughts on this issue?

Comments (17)

  • krnuttle
    7 years ago

    I have a question. You say you changed the "drive belt" on your LT 155. Then you talk about "engage the PTO". I think your tractor may be different than my LT 155 or we are using different terms. The drive belt in my thinking is the belt that runs from the engine shaft back to the transmission. This belt provides the basic power transmission to the rear wheels.

    To me "engage the PTO" means the belt that drives the mower it self. It runs from the engine shaft back to the pulleys on the mower deck.

    If "engage the PTO" is the belt to the mower deck:

    My first question would be, do you have it threaded properly through the pulleys. If it is not then the the belt will not have the proper tension and will be thrown off when you engage the mower.

    To answer what is the proper threading, we would need to know what mower deck you are using. I know there is a 38', 42', and a 48' mower deck.





  • nelson_thibert53
    Original Author
    7 years ago

    It must be the terms.I replaced the engine to transmission drive belt. It will stay connected as long as I am just driving the tractor around.When I engage the mower the engine to transmission drive belt comes off the pulley on top of the transmission. The belt that connects the mower to the engine is fine.

  • exmar zone 7, SE Ohio
    7 years ago

    "Reaching here," wrong belt on the ground drive, or the engine is loose on the frame? If the trans input shaft is excessively worn or bent, you should be able to detect that with the belt off by turning it to see if it's bent and by trying to shake it to see if excessive wear.

  • nelson_thibert53
    Original Author
    7 years ago

    Thanks Exmar.The ground drive belt was replaced last year.It is the same one that I have purchased in the past.I had the tractor taken back to the Deere dealer that was supposed to have fixed the drive belt tension. I will recommend that they try your suggestions. I will keep you informed. Thanks for your time.

  • exmar zone 7, SE Ohio
    7 years ago

    Hmmm, "drive belt tension," That opens up a new area of thought. If the spring is weak or the "tensioner" (typically foot petal and spring, but have seen other's also) is rusted, worn, or not moving smoothly to apply full tension when released that could allow belt to be thrown.

    Typically, throwing drive belts is usually a sign the belt has stretched and it's time for a new one.

  • krnuttle
    7 years ago
    last modified: 7 years ago

    I am faced with this task ether later this season or next so I spent some time researching it.

    In the parts diagram for the LT155 on the John Deere Parts website, it appears there are five pulleys in the system. One is on the transmission and one is on the engine. One is fixed in that it does not move and appears to be bolted to the Frame?.

    The other two are on an assembly the pivots. One of the pulleys on the pivoting assembly is fixed to the assembly. The other, Part #31, is in a slot so it can be adjusted.

    So if the belt is coming off of the pulleys, the probable cause is a weak spring, part #14, on the pivoting assembly or the pulley, Part #31, in the slot needs to be adjusted so there is a little less slack in the belt. .

  • nelson_thibert53
    Original Author
    7 years ago

    I did install a new drive belt. When I removed the #14 spring I spread it too far and deformed it. Apparently I should have replaced it. I bet that is my problem. I adjusted the #31 pulley but should probably check that too. Thank you exmar and krnuttle.I will keep you informed.

  • nelson_thibert53
    Original Author
    7 years ago

    Hey guys. I replaced the tensioning spring (14) and the (31) sheave on the belt tensioner assembly. The good news is the belt stayed on. The bad news is for some reason the two brackets on the front of the transmission snapped. The transmission shifted enough for the belt to move and destroy the cooling fan but not enough to come off the pulley on top of the transmission. What are your thoughts as to why the transmission shifted enough to snap the mounting brackets?

  • nelson_thibert53
    Original Author
    7 years ago

    You present a good point. I will investigate and get back to you.

  • nelson_thibert53
    Original Author
    7 years ago

    Good Morning. Here's the latest on my LT155 drive belt / transmission issue . See photos. Note cracked /split areas at transmission rear mounting points as well as broken front transmission mounting brackets. Do I attempt to weld the cracked split mounting points in the rear and replace the front brackets or is it time for a new tractor?I would probably have to replace the transmission as well. All thoughts on this issue are welcome.


  • krnuttle
    7 years ago
    last modified: 7 years ago

    I suspect that welding is the only options. However, I would contact the local John Deere Dealer and see what they have to say about fixing it. The LT-155 has been our for over 10 years, and I am sure that you are not the only one to experience this problem. So there may be a bulletin on the best way to deal with this problem.

    Based on my experience with the local JD dealer and the broken guide wheels on the mower deck it will probably cost about $80 for the welding plus the cost of pulling the transmission.
    If the two pictures are from opposite sides of the tractor, was the tractor involved is a significant twisting action that would cause the break?

  • nelson_thibert53
    Original Author
    7 years ago
    last modified: 7 years ago

    When I use the free wheel switch and then re-engage it the tractor does not want to move. I have to work the forward /reverse pedals back and forth and rock the tractor to get it to move. This purges the air out of the transmission and generates a lot of torque. It's been that way for about 5 years. I suspect that is how everything split.

  • krnuttle
    7 years ago

    Some where I read that you should never engage the free wheel switch when the engine is running. I guess what you experienced is the reason.


  • nelson_thibert53
    Original Author
    7 years ago

    Sounds about right. I need to decide if I will attempt to repair it, buy a new one and keep it for a backup unit or part it out and make a few bucks on it. There are a lot of good parts on the tractor. It actually runs and mows very well. The unit really owes me nothing. It has been a very good machine for 17 years

  • krnuttle
    7 years ago

    I think you should replace the tractor ONLY if you have been bitten by the new tractor bug. This is good as any to replace the tractor.

    However, the cost of repair say $300 vs the cost of a new tractor $3000 has to be consider. Yes you can get a tractor for less than $3000, but having owned a tractor you are not going to be satisfied with an entry level unit.


  • nelson_thibert53
    Original Author
    7 years ago

    I have about $400 in it now plus another $300 would be $700 although I believe I am able to weld it myself. I know how to do that. I would just have to rent a welder. I have been researching new ones. I have been looking at the X300 with a mulching kit for $3200 out the door. Maybe an overkill for me. I have a half acre and I predominantly just mow. The S240 has the same drive train, pretty much the same features with a little bit lighter frame. I can get that with a mulching kit out the door for $2500. The transmission on mine has got me wondering. I am about 6 bolts away from pulling it. I believe I could change the oil on it and be good to go.The input shaft does not seem sloppy and it has a new pulley on it. Decisions, decisions.