806 transmission problem?

I have a 66 farmall 806.when I and puting load on it pushing snow or up a hill. It slows down and stops I idle it down when I do it sometimes clunks below my feet and starts to move again. Idk if there is a key stock broke off or a Splin rounded off. It does it cold and warmed up with ta in gaged or not. It does it in high range or low or reverse. Thought maybe the clutch was bad but the clunking noise is what gets me. Just wondering if anyone has heard of this or know a solution I know it s probably going to have to get split. Thanks

Easy things first. The 806 I drove years ago had awful shifting levers. Are you sure the shifting levers are fully engaged?

(quoted from post at 00:06:30 02/25/23) Easy things first. The 806 I drove years ago had awful shifting levers. Are you sure the shifting levers are fully engaged?

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Yes high low and reverse are engaged I just redid the bushings in it 2 years ago 1-4 on the other hand the feel like they are have had some issues with them getting stuck in gear but it does it in 1 or two as far as I can tell it s been getting worse it use to only do it in high and rev now it does it in low as well

Hello JA welcome to YT! Is the TA forward or back
when this happens? Or is the TA out and you are just
using it in direct? Either way you need to adjust the
clutch and TA per the Tractor Vets procedures. If he
does not stop by and fill you in by tomorrow morning I
will post a previous post of his that contains the
process. A clunk followed by movement is likely the
reduction or low side failure of the TA one way clutch.
When you slow the engine down it catches and begins
driving the tractor again.

No splines, keys or gear teeth once stripped are going
to re-engage and provide drive motion. What you are
describing is a symptom of a slipping or failing clutch.
If you worked on it enough to know about replacing
shifter bushings your surely know what clutch pedal
free play is. Tractor Vet says it should be 5/8 inch, so
do you have that? The pedal is the main clutch. There
is also a clutch in the TA that engages hydraulically to
provide Direct or HI side operation. When you pull the
TA back that hydraulic clutch disengages and machine
drive continues through the one way clutch in
reduction or LO side TA. There is also a low side
hydraulic clutch but it only provides engine braking
and has no bearing on drive motion. When you pull the
TA back does it consistently engage into Lo or
reduction even under a pretty good load? Sounds like
it may be in the early stages of complete TA failure.
There are pressure checks that can be done to help
diagnose the TA. Is the hydraulic oil level full? Does the
Tell Tale oil light come on when you push the clutch?

(quoted from post at 01:53:00 02/25/23) Hello JA welcome to YT! Is the TA forward or back
when this happens? Or is the TA out and you are just
using it in direct? Either way you need to adjust the
clutch and TA per the Tractor Vets procedures. If he
does not stop by and fill you in by tomorrow morning I
will post a previous post of his that contains the
process. A clunk followed by movement is likely the
reduction or low side failure of the TA one way clutch.
When you slow the engine down it catches and begins
driving the tractor again.

Click to expand...

It happens in both direct and and ta when it started acting up this summer it was worse in direct. This summer when it started happening it was worse when it got warm no clunks. When it s started acting up I would let it idle then it got better and it would go again. Un till I had to go up a hill. Then it would stop and I would have to put it in low 1 st. I am not to familiar with farmalls can fix most things but it s had when you are unfamiliar with a machine.

(quoted from post at 03:43:36 02/25/23) No splines, keys or gear teeth once stripped are going
to re-engage and provide drive motion. What you are
describing is a symptom of a slipping or failing clutch.
If you worked on it enough to know about replacing
shifter bushings your surely know what clutch pedal
free play is. Tractor Vet says it should be 5/8 inch, so
do you have that? The pedal is the main clutch. There
is also a clutch in the TA that engages hydraulically to
provide Direct or HI side operation. When you pull the
TA back that hydraulic clutch disengages and machine
drive continues through the one way clutch in
reduction or LO side TA. There is also a low side
hydraulic clutch but it only provides engine braking
and has no bearing on drive motion. When you pull the
TA back does it consistently engage into Lo or
reduction even under a pretty good load? Sounds like
it may be in the early stages of complete TA failure.
There are pressure checks that can be done to help
diagnose the TA. Is the hydraulic oil level full? Does the
Tell Tale oil light come on when you push the clutch?

Click to expand...

Yes I have 5/8" free play the clutch ingages on the top of the clutch peddle and I have the hyd oil over full being I have a loader and the amount it leaks from the cylinders.

So you are stopping the tractor with the clutch when
this happens or leaving the clutch out and just idle
back and it kicks in and goes? The steering and
hydraulics work normally?

I know this will not affect the stopping so much but when was the last time you greased the throw out bearing inside. You have to take the bottom cover off to get to it. We put a bulkhead fitting in a hole we drilled to one side and use a grease hose and fitting so we don't have to remove that bottom cover to grease it. IF adjustments to the Clutch and TA don't fix your problem then I think it is to late anyway you will need to do a double split to fix the TA then the main clutch will need work while your there. Check the splined sleeve that goes into the pressure plate as that drives all your hydraulic and PTO on it.

Ah 66 series is 5/8ths 06's are 7/8ths and ya do your checking. setting at the FLOOR PLATE not the top of the clutch pedal. .

Let me ask one question here , does your dash oil pressure tel tale light come on when you depress the clutch pedal???. What does the hyd. filter look like or haven't you looked at it in a while . If you have not then pull it and look to see if it is all sparkly with fine metal or if ya find nice CHUNKY metal pieces layen in the filter housing . , Drop the inspection cover under the bell housing and see what treasures you find there. Then take PICTURES LOTS OF PICTURE an put them up on here so i can see since i am not there checking myself . And i suppose your nowhere close to me where i could come out and look it over myself.

I have greeted the throw out bearing it been awhile but I only put maybe 50 hours a year on it I got it with the farm four years ago and the previous owner did slim to non maintenance change hydro oil and filter two years ago the oil light comes on when I start it but doesn t come on when this happens. And I do push in the clutch when this happens and I still get the clunk not as loud as if I I don t push it in. This summer I did take the bel housing cover off and there was about a quart of oil and a few bolts were loose on the trans side so I tighten them.

Well Humm the Vet did not leave his clutch and TA adjustment process. Apparently he thinks something is lunching out inside, by your description of symptoms it very well could be. Here is a link to one of his run downs, the second to last post is the clutch and TA process and as you see he specified 7/8 inch of free play for an x06. The process higher up is the trans brake adjustment.
Post with adjustment processes

So your saying that you don't see any oil light light up when you push the clutch down HUMMMMMMMM Now if it is not coming on then there must be a short to ground . so we can not say if it is dropping T/A loc upor not . and you don't know if you have any metal filings in the Hyd. filter or not . the only other thing i can think of is the lower counter shaft nut backed off in the speed transmission might be a cause , but to find that ya need to split the tractor at the range transmission and then ya may as well dig into the T/A and clutch and break open the piggy bank . Cause this is going to HURT. And doing your first T/A job can be somewhat over whelming as it is not just and unbolt and drop in deal like some think it is .

After drinking your problem more while working on my Cub Cadet today one more think came to mind here . And thins problem may lay under the range trans mission cover . You just might be missing a couple rollers . Go to the on line Case/ I H parts books and look up range transmission cover and related parts . as there should be tw2o rollers . One in the shifter cam and one on the Hi - Low slide. These get broken from slam shifting when the clutc h , trans brake and the DUMP valve get out of adjustment and people put there big meat hook on the shifter and pull for everything they have to get them out of gear and slam the shifter tryen to get it in gear . And Revers is the one that really takes a beating . If both those puppy's are missing then she is NO going allm the way into gear and thus cause it to Jump out of gear and you said that going up hill it does it more . This now makes sense as when you go into high range the shift collar moves forward and in gauges the main out put shaft coming out of the T/A main shaft with the three sliding gears . When you shift to 4th the shift collar moves back and your now 1to 1 off the flywheel going into the main shaft of the range transmission , so yea when your in high in the range then if that puppy slid back then yes you would FEEL the CLUNK in your feet.

I don t think it s my range I had that apart two years ago and I am know what it feels light when it jumps out of gear not saying it isn t the problem. I check my filter and some of my drain plugs there wasn t to much for metal shavings nothing to be concerned about.I did take my bell housing cover off there wasn t any parts but it looks like there is clutch material stuck to the fly wheel. Thanks for all the help I just really don t want to replace the ta if I don t have to. I don t think it s worth to fix if I have to replace the ta with all the other issues it has