[sdunt]

The last time I had the 646 in the shop I noticed that the loader pivot at the dash had a LOT of slop in it, up and down, front to back.. This is a 1973 646 so the hood pivots - hinges ON the loader pivot, and you cannot see anything in there because of the hood in the way. I did note that someone had previously added a full length pipe up behind the battery.

I did not want to disturb or overly flex the hydraulic hoses for the loader, they appear to be original, which makes them 45 years old. Therefore I clamped some angle irons on the loader arms to act as 'legs' and hold them up in line with where they are. The plan was to pull the rod out and move the loader forward 6 inches or so to make room to work. That process actually worked surprisingly well.

(That picture shows the 'bushing' already installed, but not cut off flush yet..)

I had read about all the fun, horror stories actually, about getting the pivot rod out of these tractors. So I took the pins out of the stop collars, took the collars off, then .. I grabbed the rod with vice grips and ??

I just pulled the shaft OUT. No hammers no beating on things, The shaft slid right out of the tractor. It seems that the pipe someone added is just common 3/4" water pipe. The inside diameter of the pipe is .835" with a 3/4" - .750" shaft in it, so lots of space to slop around in there - 085" - Eighty Five THOU. Great how do I tighten this up?

Knowing that I was going to be working on this job and assuming that I would be welding this up and 'turning it down' or some such process to tighten this up, I purchased a 19 MM drill bit which is .748 inch, slightly undersized for ¾ shaft. I also purchased a used .750" fixed reamer to help true things up. I also ordered a 3 foot section of 3/4" stainless steel shaft to use as the replacement pivot shaft.

The 'water' pipe weld job is not terrible, its solid, and I would have made a much bigger mess of things by attempting to remove it. Of course the old shaft was worn as are the outer ends of the 'water' pipe. I decided to keep the 'water pipe' in part because I found some Chinese '1/2" inch' water pipe in the shop that was a good source for a bushing or spacer to reduce that .835" down to .750". I was able to check and verify the size of the 'water pipe' inside past the worn sections by using a cheap 'Telescoping Gauge' These have 4 to 6 inch long handles on them so I could measure the ID of the water pipe 4 inches in from the end, where it was not worn..

So, I chucked up the water pipe in my 100 year old lathe and with the 19 MM drill bit, I bored out the inside of the '1/2" inch pipe' to a depth of about 3 1/2". About as deep as the flutes on the drill went. My lathe is not perfect, and the drill bit isn't either, so the bore I got was almost exactly .750, at least it fit the end of my replacement shaft very tightly. Since what was left of the water pipe is only .040" thick, I knew it would change size when I drove it into the 'water pipe' on the 646. I left about 1/2" inch of untouched pipe on the one end so I could I drive these 'bushings' into place. That's what is sticking out of the frame in the 1st photo.

The water pipe in the tractor has been worn by the shaft turning and moving, making the ends of it 'belled'. IMO there is no way I'm going to arc weld a .040" bushing in place without making a huge mess of it.. So, get out the JB Weld again. An inch or so inside the 'water pipe' it's not worn and the bushing from there in was more of a press fit, but I did want to fill in the wallowed out end of the pipe. JB Weld has a compression rating of a couple thousand PSI, the bushings I made are 3 inches long, one on each side, so ? Who knows we will see that it does.

(The thin bright edge is the 'bushing' surrounded by the previous job done welding the water pipe in )

Once the bushings were driven into the 'water pipe' I cut them off flush with an angle grinder and cutting disk. Then let the JB Weld setup over night. Of course there was enough compression of the bushings that I could not get the new shaft in place and I was NOT going to beat it into place.

Next step was to pull out the 'adjustable blade reamers' and touch up the inside diameter of the 'bushings' so I could get the shaft in place.. My 3/4" Stainless shaft actually measures just a TAD over sized. To get a sliding fit, that means the bore needed to be something like .752" and my fixed .,750" reamer was no help, thus the adjustable reamers.

I took a number of measurements of the width of the loader arms trying to figure out how wide the rear arms where supposed to be spaced and what I finally settled on was adding an 1/8" → 3/16" spacer between the arms and the frame. I cross drilled my new shaft at 26" center to center for ¼" roll pins that hold the stop collars on. I had the shaft in and out a couple of times, I had rounded the end I was putting in first so it would not catch and somehow force the bushing on the other side out. Once I had the stop collars in place I 'parted' off the extra shaft in the lathe.

I have a new short block for the Onan CCK to install. So, while the engine is out, I will be drilling a hole behind the battery box,through the water pipe and the new shaft and putting a roll pin or similar in there to keep the new shaft from turning or moving. But still make it removable if needed.

 

[Bob MacGregor]

My 6018L needs the same repair!
Thank you for the writeup and pics!

 

[Harry]

Scott I repaired mine last year on my 646. I was going to post them when I was done with the project, but I will post some here now. My pivot shaft was bent and was a pita to get out. I ended up cutting it in half to remove it. I noticed the spark pattern on the 3/4" shafting when I was cutting it in half. It certainly was a higher carbon steel than low carbon mild steel. I ended up replacing the shaft with a 1" high carbon one and then rebuild the loader ends to adapt to the 1" shaft. It took me a couple of days to complete the project but will be well worth it in the long run.

I installed grease fittings in the loader arms, and the pivot arms assembly in the loader mast for future maintenance. The complete tractor project is in progress so I have not had a chance to try it out.

Keep the Peace :trink:
Harry

 

[dundee222]

Nice repairs all!!!! Just some food for thought for others loaders out there needing repairs. Now I know that 95% of Case loaders will not see a lot of use per year, but modern loaders use a bronze, easily replaceable thin wall bushing in the arms and pins locked in place with a snap ring on one side and a small flat bar bolted on the other. The bar holds the pin in and from turning in the "ears'. Greased through a hole inside the pin from a zerk at one end they wear quite well. But after a few thousand hours, even with frequent greasing, the bushing and pin wear, BUT are easily replaced with a hammer and cape chisel in half an hour or so.:thumbup: This system is quite adaptable to Cases for anyone thinking about rebuilding their loaders.

 

[sdunt]

dundee, that's interesting.. Pictures or a parts diagram would help me figure that out..

I had wondered about using 'pins' instead of the long shaft. But I wondered about the twisting the tower would get from the short pins vs a pivot that runs from one side to the other.

For now we'll stick with the 303 Stainless since my research tells me its comparable to better steels. And it won't rust inside the fittings and jam up.

pins locked in place with a snap ring on one side and a small flat bar bolted on the other. The bar holds the pin in and from turning in the "ears'.

 

[Eugene Slagell]

Working with stainless in food processing environments, especially in shafting and bearing replacement, I would be concerned about shaft galling. 303 stainless has a Rockwell hardness of 96, so it may not be an issue.

It is just a concern brought by experience when trying to replace a bearing and finding that "get in, get it done, get out" was a pipe dream that was shafted.

 

[dundee222]

dundee, that's interesting.. Pictures or a parts diagram would help me figure that out..

I had wondered about using 'pins' instead of the long shaft. But I wondered about the twisting the tower would get from the short pins vs a pivot that runs from one side to the other.

For now we'll stick with the 303 Stainless since my research tells me its comparable to better steels. And it won't rust inside the fittings and jam up.

I can take some pics tomorrow. Maybe even have the old pins. I'm not sure it would work for the arm pivots on our Cases as you need pin support on both sides of the arm, but works well every where else. The bronze bushing part would excell there though. As far as rusting, never been an issue as the joint is packed with grease and well,,, "it don't sit still for vey long".:canada:

 

[dundee222]

Working with stainless in food processing environments, especially in shafting and bearing replacement, I would be concerned about shaft galling. 303 stainless has a Rockwell hardness of 96, so it may not be an issue.

It is just a concern brought by experience when trying to replace a bearing and finding that "get in, get it done, get out" was a pipe dream that was shafted.

Using stainless for pins would sure work harden the surface in a hurry, no?

 

[Eugene Slagell]

Dundee, I am not sure what will happen with 303 as the shafting I have worked with was and unknown grade. 316 which is a food industry standard is only 3 points rockwell harder than 303, making me wonder if galling will occur before work hardening happens. Is quenching the contact areas of the shaft an option on the 303?

 

[Toolslinger]

I have a love hate deal going with stainless too... Have learned the hard way about the galling since changing industries... (food process, and med research equipment)
In this case I don't think you're going to have too much issue. If you had 303 shaft, in 303 bushings, you'd have issues for sure. Any time we have to have stainless nuts, on stainless bolts, we go with a 303/304 bolt, and 316 nut. That has helped tremendously.
I'm going to have to pull the rod on my older machine that has seen who knows how many hours. When I rebuild, I'll see if I can tell how hard the rod is, but I'd bet it isn't exotic. Think about how much force, and abuse your trailer hitch pin takes, and that's 5/8 I believe. Some 3/4" mild steel will likely work fine in this application.