JD750 MFWD

[DeereDoug]

I noticed just recently that the MFWD does not function on my tractor now. I looked around the control arm and drop housing and saw nothing of interest, I unscrewed the drive shaft retainer cover and yanked back on that and the connection seems to be ok, when I rock the shaft with hand I can feel it working the front wheels. So that leads me to believe that there is something wrong internally in the drop housing.

Whats parts would be expected to break to the drop housing?

Also, could someone explain to me, how MFWD drive shaft engages to the transmission? The TM I have is not too description so I am trying to envision it in my mind.

Thanks.

 

[4310]

John Deere - Parts Catalog
Here's a link to the john Deere parts site. Just do a search for your 750 and then look for transmission or whatever they have it listed under. There will be an exploded view of all the parts and how they go together.
Sorry I can't help any more than that.

 

[Zebrafive]

It appears gear 25 slides to engage gear 3. First I would check and see if pin 19 has sheared.

 

[prs]

DearDoug;

Been thee and dun it. There is a part that Deere lists as a "device" that is at the end of the FWD engage lever INSIDE the tranny case. The case halves have to be split to replace it. It is an obsolete part, but I saw a device on ebay not too long ago. A machine shop would have not trouble making one. Retrieve the broken tab from your tranny. Pizz-poor design that device is.

prs

 

[DeereDoug]

Ok, I got around to looking at tractor as NOT having 4-wheel drive sucks.

I yanked back the covers on the MFWD drive-shaft and the front looks fine other then some leakage. The rear was just as messy as well, but I noticed that there was 5 ball bearings sitting inside the cover, so this probably explains why the front wheel drive is not engaging.

Question: Do I need to remove the front axle to remove the drive shaft?

I am also guessing at this juncture the drop housing should be pulled for inspection.

D.

 

[DeereDoug]

PRS, are you referring to part #14?

http://jdpc.deere.com/pimages/RP16/RP1653_________UN01JAN94.gif

 

[Barry 1]

Slide the covers together and back. On the front of the shaft is a spring you have to compress a little,and pull the cotter pin,then you can slide the coupler back and remove the shaft.Should be 6 balls in the couplers- front and back of shaft.
I use jdparts.deere.com to look things up.
You have to slide those rubber boots off of the couplers a little too.

 

[DeereDoug]

Barry, thanks! I will start on that portion tomorrow, there is one ball in the front coupler and I recovered 5 in the back portion. So I will need to order the missing ones.

Question: When the lever is moved downward to engage 4-wheel drive, does the driveshaft move forward to engage the front axle and the spring cotter pin arrangement pushes it back when you disengage the lever? Also, what is the purpose of the ball bearings as they are not inside a bearing housing?




D.

 

[prs]

That looks like a device to me. ;-)

prs

 

[Barry 1]

When you get it apart,you will see the slots the balls fit in.They lock the coupler to the shaft,and the spring keeps the coupler from sliding back and falling apart. When you move the lever,it slides a gear into place. Use a heavy grease to hold the balls in the slots when you put it back together.

 

[Barry 1]

Some pictures that show the ball slots in the coupler and ball grooves in the shafts.

 

[DeereDoug]

Ahhhh ok.... so from what I know now. My problems stems something being broken in the drop-housing and the missing drive shaft coupling balls. I did notice the grease had a bright grey color to it, so I wonder if they got ground up. If that is the case and depending on the metal hardness, the coupling's may be damaged as well.

 

[DeereDoug]

Well, I got everything disconnected from the tractor and it seems to me that the coupling bearings got ground up, as I am missing 75% of the twelve that are supposed to be there. Also, the cam that slides the drift gear rearward is intact, but I am going to replace that as well, along with some seals and packings. Wish me luck!

 

[DeereDoug]

View attachment 431648View attachment 431649View attachment 431650View attachment 431651View attachment 431652

 

[DeereDoug]

View attachment 431656View attachment 431655View attachment 431654View attachment 431653View attachment 431657

 

[prs]

From where are you sourcing the parts? Always looking for sources to keep my JD on the job. 1982 model 650. Regarding prevention of such wear once the repair is done, NEVER shift MFD in or out on the fly. Stop, gently lever the shift, if resistance let tractor roll back a tiny bit and try again and then forward and try again.

prs

 

[DeereDoug]

I have yet to decide on where to purchase said parts. Yes, I know about engaging the 4WD, as this is a used tractor there have been at least 2-3 previous owners. The cam in the drop-housing shows that someone did do just that!

 

[DeereDoug]

Is 15 images too much for the server? some of the previous images are showing as invalid now.

 

[DeereDoug]

Well it appears that I can order all of the parts I will need, jdparts seems reasonable, however I do not need to go through a dealer to order parts, I can do that myself!! John Deere needs to create a Amazon like website for its parts center. If I wait on my dealer, my tractor will be down for weeks.

 

[DeereDoug]

I provided a IMGUR link of all the previousl images for future reference: John Deere 750 MFWD - Album on Imgur