John Deere 820 (3 cylinder diesel) Transmission Problem

[rocketscientist]

I inherited my Dad's old John deere 820 3-cylinder diesel utility tractor after he passed away four years ago. It was manufactured in Manheim, Germany. I have been working on it for months restoring and painting it. I drove it new off the truck when I was 10 years old in 1970 so I'm kind of attached to it. I have it looking and running well except for one thing at this point. It has the 8 speed forward, 4 speed reverse, collar shift transmission. The left shifter lever has the Park detent on the upper left. The lever used to be spring loaded to the right into the parking position but now just flops around, although it will go into park. So, I figured the park spring was missing or broken. I removed the transmission top cover and shift levers and discovered that the high-range shifter shaft (P/N AT29387) has a broken and missing forward tab on it. The forward tab retained one end of the parking detent spring (P/N T28680). I assume the broken tab and the spring fell to the transmission sump. In any event, I am wondering what is involved with replacing the high range shifter shaft. Can it be done without splitting the transmisison? It appears that it might be possible to remove he rockshaft housing--just aft of the transmission top cover--to access the high range shifter shaft but I really don't know. I don't have a technical manual. Can anyone advise what is involved in this repair?

[Tx Jim]

You're correct that the shifter fork set screw can be accessed by removing RS cover but the tractor will have to be split between clutch & trans housings to R&R shifter rail. Have you considered fishing broken piece & spring out with a magnet and welding piece back in place?? I've seen this done on other JD utility tractors with a shift rail tab problem.

[rocketscientist]

I was afraid of that. I'm refurbishing this thing in my garage and don't have an overhead crane or enough shoring--or perhaps even boldness to try--splitting the tractor in two. I think I'd opt to take it to a shop and pay to have it done if it came to that, although I'm sure it would be quite expensive. I am going to try and fish the broken tab and spring--whatever is left of it--out as soon as I can go buy a magnet. It will be good to get them out of the transmission. I'm worried about welding in the transmission though as it could catch fire. Plus, my other concern is how long a welded tab would hold. I'm assuming that the slide I'd be welding is heat treated steel, although it looks like it is perhaps cast. The fracture looks like pretty typical low cycle fatigue, likely from years of putting it into and out of park. I do notice there have been several part numbers so I'm sure it has been a problem component. I am thinking of checking the clearances, taking some measurements, and perhaps getting a machined piece in there that would be retained by a small hole I found on the forward end of the slider. I could get a small piece of stainless machined to retain that end of the spring if there is enough clearance with the cover and front of the slider.

By the way, I have another general question you might be able to answer. The 820, 930, and 1020 tractors--and perhaps some other models in there, appear to have the same engines, same bore, stroke, displacement, compression ratio, etc. I'm wondering how the 930 and 1020 derive a few more horepower. Is it the fuel injection system? I notice that the 930 and 1020 have a different fuel injector pump. The 820 has a Rosa master injection pump.

[Zebrafive]

My 2030 alos had that part broken. It took splitting the tractor to repair. That was in 2001 and still good (knock on wood)

[Tx Jim]

Broken shift tab is steel not cast. The tab was welded to shift rail at the factory. There's nothing I remember in clutch housing cavity to catch on fire. A good weld is as substantial as non welded material. According to Tractordata.com 820 was rated at 32 pto hp @ 2100 rpm & 1020D was rated at 38 pto HP @ 2500 rpm

[rocketscientist]

So, I got a nice fishing magnet and dabbled around in the transmission fluid below the area of the shifter and retrieved both the spring and the broken tab. Based on the way it looks and my stick welder sitting nearby, I'm tempted to weld it back. There is transmission/hydraulic fluid beneath this area. Is that stuff very flammable or would it be sufficient to put a heavy shop cloth under the slide when welding in the area? Also, what welding rod would you recommend? 6011, 7810, something else?

[Tx Jim]

I was thinking there was no hyd fliud under that section of the shift rails BUT it's been many yrs since I looked down in that area. Yes hyd fluid is flammable of coarse not to the same extent as gasoline or diesel. I would put something non-flammable under the shift rail and my welder of choice would be a wire welder not stick.

[Zebrafive]

So, I got a nice fishing magnet and dabbled around in the transmission fluid below the area of the shifter and retrieved both the spring and the broken tab. Based on the way it looks and my stick welder sitting nearby, I'm tempted to weld it back. There is transmission/hydraulic fluid beneath this area. Is that stuff very flammable or would it be sufficient to put a heavy shop cloth under the slide when welding in the area? Also, what welding rod would you recommend? 6011, 7810, something else?

I think you mean 7018. That would be my rod choice for nice clean metal, save the 6011 for rusty stuff.

[rocketscientist]

Yes, I meant 7018. I thought that would be the best. Of course MIG would be the best but I only have a stick welder. I'll probably cut off some rods shorter so I can hold them steady. It really won't take very much as the piece is pretty small. I just need to get good penetration on it. Just as a precaution, I'm going to go ahead and drain the hydraulic fluid into a clean bucket (unfortunately, I just changed it) so that, even if it did catch on fire, it wouldn't have much fuel. I have enough room under the shifter slides to get a good thick welding shield of some kind and I'll cover the whole area too. And, of course, I'll have a fire extinguisher handy. I'd really hate for something to happen as I have a lot of sweat equity in it now! I feel pretty confident though. I'll post back how it goes when I'm finished this weekend.

[jenkinsph]

Post some pics when you get it back together, would like to see it. I have a 73 820 and it has been a nice tractor.