Buying Advice Jinma 354 reverse gear removal advice needed please

[ghidley]

I have a year old Jinma 354 with the new EPA 4 cylindar engine. My reverse gears lost some teeth and upon inspection I found the culprit was a 14mm bolt about 1.5 inches long which apparently had been dropped in during assembly (it was very mangled) and had finally found its ways through the gear mesh.

I have split the tractor intending to replace the two reverse gears and was able to remove the one on the separate short shaft. But I have yet to figure out how to remove the primary shaft (through the front I assume) so I can remove the other reverse gear. I have removed the circlips on the front of the shaft and the shift rods and forks. But the shaft does not budget forward. Do I need some special tool? Do I need to remove the large bearing at the front of the shaft where it penetrates the front of the housing (I assume some special tool may be needed for that as well). Any advice is appreciated ... my tractor has been off the job for almost a month now trying to figure this out and I am getting desperate.

thanks!
greg

ghidley@ucsd.edu

 

[greg_g]

They usually have to be tapped out. Safest is to tap out the bearing race with a socket of approximately the same diameter. If that's not possible, tap on the shaft. But to do that you'll need a brass rod about the same diameter as the shaft. Place the rod on the shaft end, use the hammer or mallet only on the brass rod. This will prevent steel-on-steel damage to the shaft end.

Tapping on the shaft often means leaving a strategic clip in place so it will take the bearing with it. It's important to replace it with a new clip during reassembly..

//greg//

 

[ghidley]

Thanks for the advice. I will give this a try ... it wasn't clear I could get "behind" the primary shaft to drive it (and the front bearing) forward and out the front. I'll take a closer look.

greg

 

[Soundguy]

Spare parts.. don't you love them!! And don't you wish the chinese engineers would find a safer place to store them.. vs a gearbox!!

seriously though.. good luck on the repair...

Soundguy

My reverse gears lost some teeth and upon inspection I found the culprit was a 14mm bolt about 1.5 inches long which apparently had been dropped in during assembly (it was very mangled) and had finally found its ways through the gear mesh.


ghidley@ucsd.edu

 

[3RRL]

Spare parts.. don't you love them!! And don't you wish the chinese engineers would find a safer place to store them.. vs a gearbox!!

seriously though.. good luck on the repair...

Soundguy

All those spare parts...
I found roll pin in my transmission that didn't go any where. Probably just dropped. Hey, THAT'S why our tractors are so expensive!

 

[ghidley]

They usually have to be tapped out. Safest is to tap out the bearing race with a socket of approximately the same diameter. If that's not possible, tap on the shaft. But to do that you'll need a brass rod about the same diameter as the shaft. Place the rod on the shaft end, use the hammer or mallet only on the brass rod. This will prevent steel-on-steel damage to the shaft end.

Tapping on the shaft often means leaving a strategic clip in place so it will take the bearing with it. It's important to replace it with a new clip during reassembly..

//greg//

I looked over the transmission carefully and to get at the rear of the primary shaft (to drive it and the front main bearing forward) I need to remove the rear BH oil pump takeoff shaft that is driven in line by the main shaft. It's removal is also hampered by a large bearing in the rear of the case. It looks like I need to focus on getting the front bearing out. I am hoping a run to NAPA or Pep Boys will result in my finding a bearing or gear removal tool that can pull from the front by grabbing on to the inside of the bearing outer race (there are 5/16 inch gaps between the balls where I might be able to get a small enough puller arm in there to grab the race). If that fails, then I may have to drive the bearing out from the inside with a punch of some sort (probably resulting in the bearings destruction). I guess heating the case around the bearing with a propane torch may help with the bearing removal as well.

If anyone has other tips, they are appreciated in advance!

thanks
greg

 

[schmalts]

If you need to get that backhoe pump shaft out here is a trick that works well on the 254 jinmas and may possibly work on your application but I am just assuming it may be the same. Take off the cover ( i assume you did already) and look at the shaft, it may be center drilled on the end. Use that center drill and drill it out even further and tap the hole and then use a bolt and makeshift u-shaped puller to bridge the bearing. (you will use the bolt with a nut drawn up to the puller to pull out the shaft and bearing together with the u-shaped piece resting on the case) you can make up a puller with some small pieces of steel and some threaded rod or better yet a long grade 5 bolt. I have done this a few times on Jinmas and it works great. Should take less than an hour to rig it up and get it done if the application allows.