18 Auto Drive Issue

["Manic-Mechanic" 1,194]

I have been working on my finish mower so the tractor is getting more action than usual. I will be moving along in forward/reverse and an abrupt stop with occur! Like a wrench was thrown into a gear! No movement in either direction and the pump charges up normal all other hydro works. I first thought the clip came off in the hydro motor, but then if I rock it gently to reverse there is a mild slip and then she will move forward/reverse. I gently brought her back to the shop as sudden movement and it'll lock up, which I hate terribly! The parking pawl never worked since I have owned this, so now am wondering if it in fact is just loose in the tranny getting into gears! Never worked now wants to start locking things up!

[953 nut 55,291]

You didn't mention what model  you are working with. It does sound like the problem is in the transaxle final drive rather than the Hydro portion.

[daveoman1966 3,752]

Reads to me as if your dfferential is or has exploded....sheared off one of the 4 bolts that is.  This is not as uncommon as you may think...same thing happened on my C-120 years ago...pretty much the same gearbox.     

["Manic-Mechanic" 1,194]

28 minutes ago, 953 nut said:

You didn't mention what model  you are working with. It does sound like the problem is in the transaxle final drive rather than the Hydro portion.

18 Auto 1-0600. I agree. One enthusiast tried to say there is no pawl in the rear on an 18 Auto and went on to explain the whole hydro, which is nice and all but not the area in question.

Edited July 16, 2022 by "Manic-Mechanic"

["Manic-Mechanic" 1,194]

3 minutes ago, daveoman1966 said:

Reads to me as if your dfferential is or has exploded....sheared off one of the 4 bolts that is.  This is not as uncommon as you may think...same thing happened on my C-120 years ago...pretty much the same gearbox.     

I believe it is in this section as was just mentioned by 953 nut as well. Either way it has to come apart again and might as well rebuild the pump and motor, check the hoses & manifold. A lot of work...

["Manic-Mechanic" 1,194]

1 hour ago, daveoman1966 said:

Reads to me as if your dfferential is or has exploded....sheared off one of the 4 bolts that is.  This is not as uncommon as you may think...same thing happened on my C-120 years ago...pretty much the same gearbox.     

So, you could still run it even with the risk involved, just didn't do so?

[oldlineman 1,481]

I had the same issue with a 1989 414 8 one of the diff bolts  broke and was contacting the diff case inside bending the bolt. It would lock up then I could rock it back and forth and it would free up. I think you need to split the case and see what's up. Here's what I found only other damage was one of the diff. ends ( 4-19 ) was cracked were the bolts go through the differential. Good luck Bob

["Manic-Mechanic" 1,194]

39 minutes ago, oldlineman said:

I had the same issue with a 1989 414 8 one of the diff bolts  broke and was contacting the diff case inside bending the bolt. It would lock up then I could rock it back and forth and it would free up. I think you need to split the case and see what's up. Here's what I found only other damage was one of the diff. ends ( 4-19 ) was cracked were the bolts go through the differential. Good luck Bob

scary thoughts running all through my mind! Lol

[oldlineman 1,481]

Wasn't a difficult repair with the help of great people here. As your saying goes, Never give up, I believe that Phil. 4:13 is very true! Bob  

[pfrederi 17,741]

Do NOT run it  If there is a broken bolt it can get caught between the bull gear and the case and may crack the casing....

["Manic-Mechanic" 1,194]

10 hours ago, pfrederi said:

Do NOT run it  If there is a broken bolt it can get caught between the bull gear and the case and may crack the casing....

She's put up in the stall for some TLC.