The Tech Page
Corrections to boo-boos in the manuals, suggestions, and anything else weird!
PTO Clutch adjustment, Model 80 vs 820 Service, Loose Rear Hubs, 3 Point Hitch, Service Bulletins
PTO Clutch Adjustment for the 80, 820, and 830
If you have a new reprint (or maybe even original) John Deere-made service manual or operators manual, beware that the illustration for the PTO Clutch adjustment may be WRONG! However, if you have the Intertec (I+T) manual JD-17, for the 80, 820, 830 it appears to have the correct illustration.
If you'll note in the image below (Which is a scan from my 80 operators manual), the text says if tightening the clutch, to rotate the adjustment cam counterclockwise (viewed from the rear). The illustration; however, shows you to rotate the cam clockwise. The illustration is WRONG, and the text is CORRECT.
Here is a corrected illustation:
Model 80 vs 820 Service changes
Since the model 80 did not have a service manual of it's own, owners are forced to use the model 820 Service Manual (SM2021). The manual itself says "Although this manual is prepared specifically as an aid to proper maintenance of the "820" Series Diesel Tractor, much of the information it contains applies equally (with minor variations) to the Model "80" Tractor. It can be used to advantage when maintenance problems concerning the Model "80" Tractor arise."
I've noticed a few maintenance and service details that are different between the two tractors, and will list them here as I find them.
#1 The 820 service manual advises you to grease the cranking engine clutch release collar every 500 hours. However, 80s did not have a greaseable collar until #8001700 and onward. Beware that an earlier unit could have been updated to have the greaseable collar. Source for service info: SM2021, page 20-10-12. Source for serial number of change, PC766, page 85-25, Key number 28A and 28B.
#2 The 820 service manual notes the speeds of the cranking engine as:
Load........4500RPM
Fast Idle...5000RPM
Slow Idle...4000RPM
However, the 80 Operators Manual lists the cranking engine speeds as:
Load........5500RPM
Fast Idle...6000RPM
Slow Idle...5000RPM
Note the 1000RPM difference! However, I don't think it will matter whether you set your engine to run at 5000 or 6000 RPM. Slowing it down might be a good idea anyway!
Loose Rear Hubs?
I've heard of a few instances of rear hubs working loose on an R, 80, 820, or 830. If your axle splines and hub splines are still in good shape, it may be fixable without replacing major parts. Here is an illustration of how the rear hubs and axles are supposed to go together:
Note the gap between the retainer and the end of the axle. This gap allows the retainer to wedge the hub in place. However, I've heard that sometimes the retainer can end up butting up against the axle, leaving the hub with little or no pressure holding it in place. The solution for this would be to machine the inside of the retainer to open up a gap. Then hopefully your wheels will remain tight!
Three Point Hitch?
No there was never a factory Three Point hitch for the R through 830, nor do I know of a mass produced aftermarket hitch. However, I just happened to see these pictures of a homemade hitch on Ebay, and thought they might be interesting for others to see! I for one do not recommend trying such a setup, but what you try is your business!
The setup appears to require two remote cylinders to operate the two lower arms. It looks pretty beefy, but I don't know if I'd try to lift very much with it. Interesting nonetheless.
Here is a sketch I made that is probably what the final assembled hitch would look like. I didn't even attempt to route hydraulic lines!
Service Bulletins
Every so often, John Deere would send out a service bulletin to show solutions to problems that showed up after tractors left the factory. Here I will list various service bulletins that I find that pertain to the R through 840. This definitely isn't a complete collection!
Diesel Crankcase Dilution
Diesel Crankcase Dilution, part 2
Model R rear axle bearing lubrication problem
Clutch Dog Toggle lubrication change
840 Wiring Harness update
50, 60, 70, and R Warning Light Installation
