4020 syncro shifting issue-galled gears?

Derick in MN

New User
While I have been reading this forum for a number of years now, this will be my first post. I have gleaned a lot of useful knowledge from this site and am glad that something like this exists. Anyways, here is the issue. While picking up round bales with our 1967 4020 gas syncro (approx. 12,000 hrs) the other day, dad was facing uphill with the transmission in first gear. He pushed the clutch in and coasted backwards down the hill maybe 35-40 feet. I am not sure how "fast" he coasted, but when he got to the bottom of the hill he let the clutch out and nothing happened. The tractor acted like it was in nuetral. He pulled on the shifter to try to get it into 3rd gear, but the shifter is stuck in the 1st gear position. Try as we might we cannot get it out of 1st gear. No grinding, nothing. We did some investigating and took the shifting rod off the top shaft of the transmission which is by the right hand battery box. The gear selector on the dash then moves freely, but the shaft still does not want to move. Tractor rolls freely forwards and backwards even with the clutch out, just like it is in nuetral. Does this mean the transmission top shaft has a gear galled to it? I was under the impression that if a gear has galled to the shaft (such as what might happen if a syncro is towed while transmission is not in the "tow" position) that the tractor wouldn't be able to move and would choke when you let the clutch out. Any ideas or thoughts on this?
 
Welcome to YT! There are a lot of helpful and informed people on here that will be able to help you out.....I am not one of them, LOL.
I am thinking though that the front shift collar (JD Parts catalog terminology) has split and is allowing the top shaft to spin freely.Even though I am saying this I can't think of why you can't shift out of first gear unless the syncro drum has taken a hit and is bound up against the shift collar.
Wait for Tim S or Tx Jim to chime in with more informed input.
Regardless you will be going into the top of the transmission I am afraid.
 
When a gear galls to the topshaft in those transmissions, it locks it to whatever speed the gear is that galled. If in any other gear or park, transmission will be stuck and kill the engine if the clutch is engaged.

The shift collar, itself, isn't what galls, so it seems unlikely for the shifting part to be galled/stuck.

Possibly, the synchronizer grenaded, and may have blown up the lined clutch disc as well???
 

I agree with others that state that more than likely problem is in synchronizer failure not galled gear. I'd suggest to remove floorboard & trans top cover and inspect top trans shaft. 1st & 3rd gear(parts key 5) are on pinion shaft

38005.jpg
 
My first thought is you have slung the clutch lining off the clutch disc ,and then also have a shift issue,
remove the bottom cover under the clutch housing and take a look, also try to engage the PTO,, and then tell
us what you find. If a gear gaulded it would ether move the tractor in that gear or kill the engine from being
in 2 gears. I get at least 1 tractor a year in here for having the clutch lining slung off from coasting with
the pedal down while in gear, the centrifugal pressure on the lining can't deal with the speed developed with
out the clutch pressing on the disc.
 
Well fist let me commend you on being one of a VERY small group (myself included) that still has a gas 4020 running around. I'm surprised none of the previous answers included instructions on how to convert it to a diesel ? LOL.

Not sure what all was damaged but I'd start at the clutch. I have repaired smaller tractors that were in gear coasting opposite direction and then owner dumps the clutch back out either rips the lining off the plate or tears the splined hub out of it.
 

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