Uni System Transmission issue

We recently resurrected an old 703 power unit with a combine attached to it. We ve actually had pretty good luck with Combine, and have been learning how to set up and operate it. It is a good machine to handle weedy crops.
I just ran into a problem, that I am hoping someone can help me.
We had issues with the clutch master cylinder, that was causing it to shift pretty hard. I was able to replace clutch master cylinder and cure that issue. My problem now is, I cannot get it into reverse. I disconnected the linkage from the transmission, to make sure the linkage was not binding up, and it was free. It acts like it starts to go into reverse, but the gears will just grind. The shifter probably moves one forth the distance necessary to go into reverse.
if someone can enlighten me on what to look for, or suggest someone else that I can talk to I would appreciate it.
Thank you! Jim

Hello Jim welcome to YT! I know nothing about your
machine. What I will add is there is a Minneapolis
Moline topic section here as well. This is one of the
lesser viewed topics here. If you do not get a reply
here in a day or so I would post this on the MM board.
If you do not know how to find it the following will
describe one way. Depending what ..View.. you are in if
you use the ..Jump to.. or ..Hop to.. drop down box
seen below when viewing your post you can navigate
to those topic sections. Clicking in them will bring up
the ..Topic section.. list for you to choose from. There
are other ways to navigate to the other topic sections.
If you hang around here long enough you will figure
them out. This seems to me to be the easiest to
explain.

Thanks!
I forgot they were built by MM before New Idea. I will post the question there.

Not sure if there's one or two shift
levers besides the reverse lever on the
transmission, but unless the other gear
shifters are completely centered in
''neutral'' the internal shift interlock
mechanism MAY be blocking ''reverse''.

Dad had a MM unit that really didnt have a transmission clutch, it had the big belt pulley. So cant help you but hope you get it figured out. Dad bought the unit to pick ear corn, but with that belt setup instead of a real clutch, going down our rolling hills farm with a load of ear corn behind, it got pretty squirrely he ended up likening the bean combine part better than the picker part.

Paul

If you've got all the linkage completely off the transmission, it about has to be a fork I'd think. I got inside of one on a 701
once, but that was 35 years ago. I don't remember them being anything complicated.

Thanks for responding.
On the transmission there are 2 shift levers operating 2 plungers. One lever pushes a plunger in for first gear and pulls it out for reverse. The other plunger is in for 3rd gear and out for 2nd. Center position on the plungers is neutral. I disconnected linkages. I put the 2nd / 3rd gear plunger in neutral, I could physically push the other plunger to engage first gear, when I go to pull it out to engage reverse, it will pull past the neutral detent slightly, but not fully engage into reverse. With the 1st / Reverse plunger in neutral, 2nd and 3rd gear shift easily.
Something is preventing it from fully engaging in reverse.

Thanks for the response,
I was wondering if it might be something like that. My next step is to open up the side of the transmission. It looks fairly accessible, and the bolts show evidence of being removed in the past. When I get things opened up, I will see if I can post a few pictures.

(quoted from post at 07:43:53 09/11/22) Thanks for the response,
I was wondering if it might be something like that. My next step is to open up the side of the transmission. It looks fairly accessible, and the bolts show evidence of being removed in the past. When I get things opened up, I will see if I can post a few pictures.

Click to expand...

Here it is a few months later:

I finally got the Transmission out and thought I would update what I found and try to include some pictures.
As I mentioned originally, the clutch had issues and gears were being jammed pretty hard. After removing the transmission and opening it up, I found the teeth on the side of the reverse gear were burred up pretty severely, not allowing the sliding gear (For 1st and reverse) to engage. After getting the gear pulled out, I used a Dremel with a small cutoff wheel to clean up the burred edge. It probably took only 15 minutes to clean the gear. I cleaned all metal shavings out of the transmission case, cleaned and inspected all bearings. I did fond one of the Main Timkin bearings for the Right side output shaft had a lot of galling in the outer race. I replaced that race and bearing, and two seals. I also replaced the parking brake pads (Same as a Hyster Forklift) It took a
bout 12 to 16 hours total time to disassemble, fix the gear, clean and reassemble to transmission. All went well and we were able to combine some beans!




[video play=false:741efc8ed9]https://forums.yesterdaystractors.com/videos/mvvideo100235.mp4[/video:741efc8ed9]