JD 850 needs a clutch

[PHIL850]

My JD 850 needs a clutch replacement. I have replaced Clutchs on small trucks before, but I am unsure about splitting a tractor in half to do the same. Bottom line, my PTO will not disengage, however the main drive clutch is fine. The tractor was originaly used as a loader mostly, and I suspect ware on the drive clutch has made the PTO clutch inoperatable. If you take up on the clutch rod adjustment you can get the PTO clutch to disengage, however at that point in the adjustment, the main drive clutch will fail to engage! So here I sit with out being able to brushhog my field. JD dealer mentioned a cost in excess of $2k to replace the same. Has anyone done such a job and can it be done without the use of the various special tools mentioned in the technical manual.

regards, Phil C.

 

[crashz]

Not sure Phil, but I'll be watching your thread closely as I forsee a clutch job in the next year or two.

 

[chriswheeler]

I have the manual. My 950 is covered with the same one. It is just a standard seperation, no special tools. You will have to seperate the tractor at the bell housing blocking the transmission and walk the front half of the tractor on a floor jack. I would highly recomend you get the manual to see what you need to do, also contains specs you could only guess at. Cost in the $125 range. Did mine in 6-8 hours, but I have a gantry crane to use with the floor jack for the seperation. Use the drive line with the splines to align the clutch to the flywheel when tightening the pressure plate. Not that hard of a job, but special caution needs to be used to keep both halfs of the tractor level, aligned. If something moves on blocks and falls, could be a big safety problem. Buy the book, well worth the investment.
Chris

 

[arrow]

I had to split my 750 in half and I've built race engines for a good long while. Although somewhat mechanically inclined, this job just about made me nuts. Every thing that could go wrong did. I am no where in the same ball park as Chriswheeler nor was I set up like him not that it would make much difference. Just didn't have the temperment for it and admire very much the guys that do. Even though it may cost me 2 grand to do it next time, I will gladly pay the money and save my brain. And yes I had the manual and had to make special tools. If you have a short attention span and somewhat firery temperment with a short patience limit such as myself, it is not a job for the inexperienced in my mind. I'll make 2 grand extra somewhere and then give service the tractor. They'll have it done in 3 days where it took me off and on 3 weeks. If everything goes right, I guess its a simple job for an adept person. Oh yeah, I now have a noise coming from the PTO I never had before but will I tear it apart again?... not in this life time.

 

[chriswheeler]

One thing I forgot to mention is plan on replaceing your throw out bearing, pilot bearing, and springs. All of these are cheap parts, you wouldn't want to have to split the tractor again to replace these. This isn't a hard job at all, you just need a flat place to work, some tools, the manual, and the right temperment. Most folks will do just fine. Buy the book first, look at the job, decide what to do. For $2000 you could do this job 4 times or pocket $1500.
Chris

 

[PHIL850]

I have the Technical Manual for the Tractor. It shows two special tools, one is the alignment tool for the clutch plates. I suppose I could use the Transmissions input spline to do the same, if it is no big deal to remove it from the tranny. The second tool is a gauge for setting the clutch fingers to a certain height I believe. I don't have the manual in front of me as it is north at my place in VT along witht the Tractor. Oh ya did I mention that I visit this place on mostly weekends, and this project would have to be done then.
My tractor is also 4 wheel drive, adding a little more work to the split. A crane or chainfall seems like a must in this case as I can't imagine balancing two halfs on a bunch of wooden blocks and floorjacks. What I realy should do is trade it in on a replacement, but money supplies prohibit such a deal at this time. Besides I have had two separate JD Dealerships tell me that these models (750, 850, 950, 1050) are great tractors (made by Yanmar). OK, so I am still on the fence on this one. Guess I will have to study the Manual a little more and think this one through.

Phil C, sometimes in mass, and some times in the North east kingdom of Vt.

 

[sixdogs]

I split a Ford 10 years ago and paid "a guy that fixes tractors on the side" to help me. I was the brawn and he was the brain. Cost me $100 for his time.
Keep the two pieces aligned.
Go for it.

 

[PHIL850]

Well I did some more research on this. I priced out a replacement clutch from John Deere on line. Part# AM878710 cost $1976.27 not including shipping and handeling!!! This is for the entire clutch minus things like throwout bearings and assorted stuff that should probably be replaced at the same time (OUCH). To replace just the Drive Disk P/N M802499 they qoute $275, and for the PTO Disk P/N M804454 another $295. Now I would hate to cheap out on this and only replace the Disk/s to later have additional clutch issues in the future. Lets face it, the labor to split this thing has got be a sizeable chunk as well. I guess this is what happens when purchasing used. I will think this through some more. ANyone know of a good Tractor Mechanic that hangs his/her shingel in Nrothern Vermont?

Ciao, Phil

 

[JerryG]

Phil.
What you need to do on the parts is to find a clutch rebuilder. You can either send you clutches and pressure plate off to them for rebuild or exchange with them for a set that has already been rebuilt. I have split a lot of tractors in my life and I have never used anything but rebuilt units.
I have always used two floor jacks to do the split but you can use one floor jack and a cherry picker, an A-frame or over head gantry. Be sure to put a wood wedge on each side of the front axle so that the engine assembly won't fall over. The special tools that you will need are: a input shaft with both clutch shaft diameters and then a finger adjustment gauge.
Good luck.

 

[PHIL850]

I have found a rebuilt clutch for little less than half of a new one. (now things are getting a llittle more reasonable). But I still need to locate the special tools needed, the Clutch disk alignment tool and Finger height alignment tool. I could probably just turn down a piece of shaft on the lathe for the disk alignment tool and mimic the transmission input shafting, however I am unsure of the Finger alignment tool. This too could be made pretty easily, if I had the proper demensions. JD parts on line list these puppies out at $63.53 and $72.17 (not in stock either!). Not trying to Cheap out here, it's just that this project was not in this year's budget, So I need to keep it as low as possible before presenting this to the family Finance officer, if you catch my drift.

regards,Phil C.

 

[chriswheeler]

The job I did on mine was a couple of years ago but I used both the inner and outer drive lines as the alignment tools, worked perfectly. Removed these to change the throw out bearing and springs anyway. Setting the fingers on the pressure plates was done with a square and, again, turned out perfectly, no special tools needed. Yes, I did get my clutches and pressure plates rebuilt localy and it seams I paid less than $130 for all. Time has a way of changing prices though. Even if you buy a alignment tool and a setting ring you will still be way under the cost of having someone else do the job and you will have the tools for the next clutch change. Think that will be many years in the future though. If your tools are limited or you don't have a place to work, might want to think about paying for the work. Good luck,
Chris

 

[moeh1]

I helped my neighbor with a large 85hp tractor. He bought a "universal" alignment tool from one of the local auto parts or Napa stores for lining up the clutch. It had a bunch of bushings and a spring loaded conical section. It was cheaper that the prices you are looking at.
We blocked the motor the front wheels and the front half of the tractor right ahead of the split and used a special cart to roll the back half away.
The cart is not that hard to fab if you have some metal skills. The base is T shaped with 3 wheels on it (one at each end point). The "bottom" of the T is lined up under the back pumpkin and is blocked there. At both ends of the top of the tee is a height adjustable riser which get bolted to the tractor casting where an attachement point permits. Put a bit of upward tension on these, unbolt the halves and roll back.
I've done a smaller tractor the harder way and this cart was well worth making.

 

[PHIL850]

The suggestion on the Cart is a great idea. I have some heavy duty angel iron available and will see about welding up something. I broke down and ordered a rebuilt clutch from a supplier. Haven't seen delivery on it yet. I still need to order up bearings and springs to complete the parts needed. I am not sure when I will start this project due to the distant location, however when I do I will attempt to document it with pictures and verbage.

regards, Phil C.

 

[Keoke]

Hi Phil,
It looks like your pto clutch disk is rusted on to it's drive and driven plates from none use over a long period of time. This is not unusual on tractors, especially the Yanmar built JD's. A lot of clutch disk's have metallic wire woven lining's that simply rust up to their drive plates with a little bit of moisture.
Before splitting tractor try to break disk free by doing what you did earlier
(running down t/o bearing adjustment all the way). Then put on a pto drive shaft (bush hog, etc.) and finding a way to lock the shaft up (long pipe wrench etc.). The next step is to bump the starter and hope that this will break disk loose. And even better way is set tractor, with bush hog over a large grass clump and then lower hog unto the the clump while holding clutch pedal all the way down. Hopefully this high shear load on disk may break it free.
Also, when lining up tractor bell housing to engine it is helpful to get at least 4 extra long coupling bolts, cut their heads off and use them as dowels for lining up the two faces. Chamfer ends and put two blades on hacksaw and cut a screwdriver slot on dowels for removal. This will make the job much easier. Be sure to keep the two flanges equally parallel all the way around housing while bringing it together.
On height adjusting tool, be sure to measure finger height on old clutch before disassembling and set new one the same or close (new disk will have less) and you should be ok.
On the spline alignment tool, universal clutch alignment tools are made by Snap On and others which use variable tapered nose's. These are not as good an OEM pilot tool or shaft but will do most of the time.

Phil, lots of luck

 

[PHIL850]

First I tried lowering the Brushhog on to a few maple trees while holding the clutch all the way in. This attempt did not break the clutch loose.
I was able to disengage the PTO clutch by over adjusting the clutch pedal linkage. Unfortunetly, with the linkage over adjusted the driven clutch was disengaged all the time. I did this to make sure that the PTO clutch disk was not frozen to the fly wheel. When I bought the tractor (used) I was told that it was mainly used as a loader. I suspect that the driven clutch disk is well warn from this use and has been adjusted out to its limit. Your suggestion on the extra long bolts used as dowels is a good idea. I'll have to remove one of the bellhousing bolts as a sample and go visit my local metric bolt supplier.

 

[cmoo]

I have found a rebuilt clutch for little less than half of a new one. (now things are getting a llittle more reasonable). But I still need to locate the special tools needed, the Clutch disk alignment tool and Finger height alignment tool. I could probably just turn down a piece of shaft on the lathe for the disk alignment tool and mimic the transmission input shafting, however I am unsure of the Finger alignment tool. This too could be made pretty easily, if I had the proper demensions. JD parts on line list these puppies out at $63.53 and $72.17 (not in stock either!). Not trying to Cheap out here, it's just that this project was not in this year's budget, So I need to keep it as low as possible before presenting this to the family Finance officer, if you catch my drift.

regards,Phil C.

This post is a little old, curious how it worked out since I have a JD 850 2 Wheel Drive with a 2 stage clutch. Anything to share?

 

[Evets Tsorf]

My 750 has a dragging clutch problem and I have been looking at options. For anyone facing this I suggest going to the Hoye tractor site, there is a clutch replacement video that walks you through the process. Our JD’s being green Yanmar should make this info pertinent to ours as well. Ebay shows clutch, pressure plate, through out bearing, pilot bearing and alignment tool for under 200 bucks.

 

[PHIL850]

This post is a little old, curious how it worked out since I have a JD 850 2 Wheel Drive with a 2 stage clutch. Anything to share?

I traded with a local guy to replace the clutch. So far it has been fine. The old clutch wasn稚 really warm out badly, but the tractor had been used a lot as a loader so the drive disc wore much quicker than the PTO portion