806 Range selector quit engaging today

[Luther D]

Our 806 diesel (no TA) has had a hard time shifting into reverse since I don't know how long. I started working at this farm 4 years ago and it took a lot of back and forth to get it into reverse then, and has naturally gotten worse over time. Today running the 12 row cultivator the range shifter went pretty loose and the tractor won't move at all.

I can still feel it slotting into the detents, but it's not engaging somewhere. Its been taking a bit of grinding to get into low and high since ive known the machine. Got the side cover off and am ready to pull the top cover on the range transmission, just wondering what to expect once I get in there.

 

[used red MN]

Hello Luther welcome to YT! Make sure you check
back in the morning. The posters who know those old
tractors often view the forums early in the morning.

 

[Absent Minded Farmer]

There's a couple adjustments for the linkage close to that shifter lever, behind the dash. Check to see if they are worn.

Mike

 

[caterpillar guy]

To pull the top cover on the range you need to disconnect the parking brake, and put a nut under the pin so it stays in the up position. The rod running vertically. Then with the linkage and bolts out you should be able to work a thin putty knife in the gasket crack to work it loose. I would look at the pins in the vertical shaft on the right side where they come down from the levers above there is a couple roll pins there that can break if they do it will not shift and be difficult to sift if it does happen to catch. When you get it all back together there is a clutch brake in the bottom. That is the rod you see down on the right side. Also check the wiggle on the top cam shaft through the cover. IF it has any wiggle it is time for a new lid/bored and bushed to fit nice and snugly yet be moveable. Then watch for the roller that sets on the top of the shift fork they break or get out of place when assembled so they are sloppy to not shifting. And the key in the reverse fork which is down on the left side behind that cover with the corner clipped off. You will want that off when pulling the cover so you don't drop the reverse fork in the transmission or the key. Look for the ends of the reverse fork for breakage and the hole being wallered out. Then when you have all this done look at the shaft that goes into the reverse fork with the key see that the slot in the arm is not all sloppy and loose that will affect shifting into reverse as well as the track for the cam of the shifting fork on top. When disassembling the top cover there is a rool pin through the triangle shapped casting that has to come out to chang e that if it is worn severly or the roller is broke on the detent arm. I use some grease to hold some of those things together on assembly. IF any of this is worn broken or missing it will cause it to be sloppy and hard to shift. Also if the keyway is worn and sloppy in the vertical shaft to the reverse fork it will be next ti impossible to get it into reverse. IF you have more questions post them. When T.V. comes on he will probably have more information on the adjustments since he has forgotten more than most of us will ever know about them. Since I still own one I have had them apart some and know my way around it pretty good. I bought it rigth out of high school and still have it 40 some years later. By the way you can also convert it to the shifting mechanism of the 56 series pretty easy too if you want to go that way. I did that to my 806 several years ago. IT give you a rod to both the forward gears and a seperate one for the reverse rso it is adjustable to help with some of the slop. You have to chnage the rods and levers up on the side to shift with.

 

[Donald in MN]

take the cover off between the clutch and brake pedals . move the lever and check for a broken or missing roll pin in the shaft that moves the fork
that goes to the transmission first. i put a wire through the roll pin to keep it in place on the 856. i had to put a hose clamp on the 706 many years
ago as the wire kept breaking

 

[Luther D]

(quoted from post at 23:14:51 06/09/23) There's a couple adjustments for the linkage close to that shifter lever, behind the dash. Check to see if they are worn.

Mike

Those all seem nice and tight, I know we had them done by a neighbor who knows these old farmall pretty well a couple years back. He's going to stop by to help me with this too thankfully. Thank you for your input on it I'm very appreciative of the help.

 

[Luther D]

Thank you so much. We've got the parking brake disconnected but I didn't have a nut on it to hold it up, I'll get that set right before continuing. I'm thinking a new cover is in order, there's a lot of slop on that top cam coming out of the cover. I can even see its all wallered out with it in place still. Very much appreciate your input. This is my first time in a transmission so I've been proceeding rather cautiously. We have a neighbor who knows these pretty well who's going to stop by and give me some advice as well.

I've only been working out here 4 years but this tractors been on the farm since it was new, and it's still an important part of the operation. Im very lucky to get to learn to do this work and keep it in the field.

This post was edited by Luther D on 06/10/2023 at 06:20 am.

 

[caterpillar guy]

Those lids new are pretty pricey for what they are. IF you can bore it and put a new bushing in there would possibly be cheaper. Look at the wear on the cam where the roller rides. they wear some also. those rollers don't amount to much but if they break it sure does let the slop open up then. The one on the top of the high low fork is pretty easy to see and change right on top. The one in behind the cam on the lid is a different story also is harder to hold in place since it works as the roller to the detent.

 

[Luther D]

Welp we are all apart here, turns out the shaft running through the high low fork (the one that's bolted in) snapped clean half in two. I don't know what I was expecting but it wasn't that. Roll pin also sheared on the vertical shaft going to the cam. Everything else looks good thankfully, not a lot of wear in the detents or anything.

My real problem now is how on earth am I going to get the replacement in? Can I pull the rear end top cover the seat sits on?

An update- going to pull the rear end top cover and slide the shaft in from the back there. Then hopefully just clean everything up and start reassembly.

This post was edited by Luther D on 06/12/2023 at 02:56 pm.