MTD Yardman Transmission trouble

I just got an MTD Yardman mower a neighbor told me he bought new for his son several years ago. Not long after getting it his son threw it into reverse from a forward gear and "locked" the transmission up. The machine has been sitting in the garage since then until my neighbor brought it to me the other day. The weather has been too cold and wet for me to even attempt to get it started. That may have to wait for awhile longer before I'm able to get outside. Can anyone give me any ideas as to what kind of repairs I may be looking at to get the transmission going again?

Mrbill1 said:

I just got an MTD Yardman mower a neighbor told me he bought new for his son several years ago. Not long after getting it his son threw it into reverse from a forward gear and "locked" the transmission up. The machine has been sitting in the garage since then until my neighbor brought it to me the other day. The weather has been too cold and wet for me to even attempt to get it started. That may have to wait for awhile longer before I'm able to get outside. Can anyone give me any ideas as to what kind of repairs I may be looking at to get the transmission going again?

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:welcome:

Going to need a lot more information to give you any meaningful answers
Several types of trannys will have different problems.
Anything from chain jumped on a sprocket, through to broken shift keys to a jambed pinion on varidrive models.
So full mower number from the tag under the seat.
Same for the engine
have a look underneath and see if there is a tag on the tranny ( usually facing backwards on both sides near where the tranny axel bolts to the mower.
Full model number of the mower and it's name
Plus anything like Autodrive, varidrive, shift on the fly etc etc.

Hopefully, this is the correct info needed:


Mod# 13AM772G755 Engine # 0606082D68504 Trans # 618-04381 SN# 2B197Q1 1496 7 spd manual transmission

Mrbill1 said:

Hopefully, this is the correct info needed:


Mod# 13AM772G755 Engine # 0606082D68504 Trans # 618-04381 SN# 2B197Q1 1496 7 spd manual transmission

Click to expand...

OK Bill.
Thank you they are the numbers we need & you will also be needing from now on.
Now you have told us your are looking at repairing mowers, it is teach a man fish time.
So get on line & go to parts tree or Jacks Small Engines.
There are other sites but I find these to be the best.
They both subscribe to a third party ( ARD ) they hosts all the parts diagrams for nearly everything.
Assuming you are at parts tree, in the model number section start typing in the model number ( the one that start with 13).
As you do that a drop down will appear to show variations and usually you will see your full number there so click on it.
That will bring up a page with folder icons down the left side, naming what section of the mower they have the diagram for.
Hint, Left click to bring up that diagram in a new tab which will make it easier to go back & forth because some parts are not where you think they should be.
Your broken spring ( from another post ) is a perfect example.
It is in the Drive Diagram ( I think ) either part # 22 or # 23.
If either of these is broken then the mower won't go.

22 helps control the rod # 2 which controls the rod # 27 down the bottom of the diagram.

Now from the "Transmission" diagram you will see the shift fork # 20
The rod pushes or pulls the fork which moved the dog # 16 into either one of the 2 crown wheels selecting either forward or reverse.
So if the rod can not move the fork you are not going anywhere

This is one possibility


The other is the broken spring is part # 23 back in the drive diagram.
That spring pulls against the idler pulley # 62 which tensions the drive belt.
So same story.
If that belt is loose, the pulleys don't turn and you are still going nowhere.

So easy check first, is the belt tight ?
If it feels a bit loose the start the mower using jumper leads so you can see the pulleys.
If the big one is not turning then you have found a problem. there might be others.

The drive on these tractors is called "Vari Drive" and it works by having 2 belts on either end of the same pulley
The middle of the pulley can move up or down so the effective diameter of the top & bottom changes which changes the speed.
It is exactly the same principle as a stepped pulley system used on lathes & pedistal drills except the pulleys change size rather than the belt moving form one pair to the other.

MTD put out a manual which is a free download called the "Must have manual of outdoor equipment" in 4 volumes which covers everything they made prior to 2000.
Your mower is in book 2
There is also a "professional Shop manual for 700 series tractors which also covers the vari drive but not as completely as the must have.
It is also a free download.
You will also need to know how to decode MTD model numbers as they make a lot of mowers under different brands
13= lawn tractor
A = how it got sold ( not important )
M = Engine handy to know
7 = frame size ( ie 700 series tractor )
7 = transmission (vari speed with 7 speed notches)
2 = styling number ( colour & shape of hood etc ) not important to you
G = deck type & size, very important ,42" side discharge.
775 = customer code , no idea but not important for repairs.

Getting back to your mower,
Note that the spring # 23 in the drive diagram has the letter B at one end.
Then the frame drawing also ha the letter B at a hole
This tells you that the spring # 23 goes from the tensioning arm # 53 to the frame at B.
Some times they lie a little as the diagram looks like the spring is on the end of the bolt that mounts the pulley.
All the ones I have seen the spring has it's own little hole in the arm, which get torn through by the spring so if that is your spring expect to replace the arm as well or at least weld it.

Thank you. You gave me a lot of good information to absorb. Yes, I had looked at the diagram another member had posted for me and saw the two springs. It looks just like those and looks like it connects to the right spot. I suspect it is #22. I will have to look closer at the mower now that I have that info. Perhaps this repair will turn out to be pretty simple and inexpensive. That would be great!
I will save your post in my downloads so I can refer back to it later. My memory isn't what it should be. Those downloads for the manuals will be a wealth of information as well.

Mrbill1 said:

Thank you. You gave me a lot of good information to absorb. Yes, I had looked at the diagram another member had posted for me and saw the two springs. It looks just like those and looks like it connects to the right spot. I suspect it is #22. I will have to look closer at the mower now that I have that info. Perhaps this repair will turn out to be pretty simple and inexpensive. That would be great!
I will save your post in my downloads so I can refer back to it later. My memory isn't what it should be. Those downloads for the manuals will be a wealth of information as well.

Click to expand...

While it looks like 22 in the diagram , those springs are under the guard so not likely to end up under the battery.
Spring 23 lives under the battery so it gets elevated to the prime suspect.

As previously mentioned either one can leave you with no drive.
The way the F-R shift works is bit quirky, but you can easily check it by removing the shift rod grabbing the end of the shift fork and moving it back & forth.
This is a lot harder to do than you would think.

The two #22 springs were missing and the rod is loose. I went ahead and ordered those springs from my local repair shop. The diagram shows two #22 springs so that was what I ordered. I'm guessing it uses two springs for added tension. Seems like they should have just used one spring that had more tension. Maybe they figured they could make more money by selling two springs instead of one. I had a drs appointment today so wasn't able to get the engine started yet. Looks like the weather will be nice tomorrow so I'll get it running and check the drive system out further.
Just a note of more explanation about where I found the broken spring. It was not under the battery compartment. It was hooked at the front of the compartment attached to the compartment housing.

Mrbill1 said:

The two #22 springs were missing and the rod is loose. I went ahead and ordered those springs from my local repair shop. The diagram shows two #22 springs so that was what I ordered. I'm guessing it uses two springs for added tension. Seems like they should have just used one spring that had more tension. Maybe they figured they could make more money by selling two springs instead of one. I had a drs appointment today so wasn't able to get the engine started yet. Looks like the weather will be nice tomorrow so I'll get it running and check the drive system out further.
Just a note of more explanation about where I found the broken spring. It was not under the battery compartment. It was hooked at the front of the compartment attached to the compartment housing.

Click to expand...

I don't think they made 2 models with the same arrangement for the F-R shift lever.

I went through some of my "spare Parts" stuff and found a spring that was quite a bit heavier duty, and slightly longer, but I bent one end to make it the length that I needed it to be. I still have the original part on order, but for now this spring will work.
I also had to take the carburetor apart and clean it. The jets were clogged and the needle valve was frozen solid. I had to pry it out. The electric shut-off selenoid was also stuck. After a thorough cleaning all parts worked fine and the engine cranked.
Then the two blade spindles were frozen up. Got those freed. The mower is working fine now
Thanks for all the input help.

Excellent.
Thanks for the final post so the thread has some final answers.
This makes it really handy for others who might read the post latter on.