Another location of frame damage on the Onan powered tractors is found
right under the engine bolts. You will find that 30 years of vibration
between the engine and the frame wears BOTH the engine oil pan and the
frame thin. You must first weld up the gouges in the frame, then grind
the welds down smooth to the point that placing a straight edge across
the rails in all directions indicates a flat plane. Failing to do so
can allow the oil pans front "feet" to break off down the road.
Before I started to strip the original paint, I went on to other
mechanical repair/modifications. One thing I always found lacking was
the Case steering in general. I knew I wanted things much tighter than
what I was finding on these 30 year old tractors, so, I figured if I
just got it back to the clearance specs of when it was new, I would be
happy. The first step was to repair the slopped out main pin openings
for the front axle. This simply consisted of welding a shaft collar on
each side of the existing frame portions. I "thinned out" my collars on
my lathe so they were not as thick. I certainly did not want any
clearance problems withe the deck/snowcaster v-belt. The following
photos should be self explanatory.... but there is a little more to the
project if you want to do it right. First, you have to pull the two
supports together to be parallel, then with a new pin, you can tack the
collars in place. BUT, you should tack them only after you have the
axle installed so proper alignment can be achieved. That in itself is a
loaded statement, because every 30 year old front axle no longer has an
accurate main pin hole anymore !
So, before you can get carried away with the new main pin and collars,
you have to clean up the pin bore and install a new bushing. Before you
can properly bore the pin hole, you have to true up the axle wear
bosses that were cast into the axle so the axle can be clamped true to
a mill. Below, you can see that the bosses both top and bottom were
"flown off" with an end mill.
With that work done, you can move on top boring the hole. I set up the
bore for the thinnest steel liner I could find. Lucky me, Mcmaster has
a PTFE line bushing that is the perfect answer. The steel shell makes
it tough enough to press in, and the PTFE makes it slippery for the pin
Here is the liner sitting on the bored hole ready to be pressed in. I
will install one liner from each side, leaving a "grease gap" in the
middle just like the factory had.
The axle work doesn't end there though. If you really want to bring a
tractor back to new/better than new condition, you also have to examine
your kingpin bores and spindle shafts. I failed to get photos, but I
sent this axle to a machine shop that had a mill large enough to bore
the 5 plus inch long kingpin holes on each end for the same type of
bushing. The good news here is that the steel spindles seem to wear
less than the cast iron axle, so the spindles did not need any work.
They measured up such that once the new liners were in each end of the
axle, there would be .003"-.004" of clearance, which is probably a lot
tighter than they were new.
To make the tractor steer better than the way it did from the factory,
I will also install the "poor man's power steering", which, is nothing
more than actual thrust needle bearings between the spindles and the
axles when they are installed. You can search Google for that term and
find it discussed in various tractor forums. It really DOES make quite
a difference, though, true power steering its NOT !
Once the main axle bore has been restored, you can move forward with
the frame repair. Here is the new pin with collars tack welded in
place, with the exact location determined by having the axle mounted
while tacking it.
Finally, you weld it all up. Note that when you do reinstall the axle,
you typically need to install some thrust washers in between the axle
and the frame on the front side to tighten things back up from having
too much front to rear travel on the main pin. The amount of shim will
depend on how much of the boss you had to fly off to true things up as
shown in an earlier photo.
Tight steering doesn't end here however. If you stop and take a good
look at your steering gear, you'll likely find that it is also in need
of some effort to bring it back into specifications. First off, you'll
want to make darn sure that you have a worthy quadrant gear to start
with. You need to look at each tooth to make sure it is worth using. If
yours looks like the gears have jumped one too many times, you might
want to look for a better used one. I say USED ONE, because the newer
replacement quadrant gears are stamped steel, not cast like they used
to be. The steel ones would be fine, however, the gear surface area is
not even half of what the cast quadrants offered. I would stick with a
good old one rather than the new style if at all possible.
In any event, here too, we find that the bore for the quadrant is
usually worn, whereas the steel pin is quite reusable. So, the quadrant
needs to be bored and sleeved just like the axle bores were. Here is a
photo of the main steering gear mount bracket. The center bore and
sleeve is to tighten the lower steering shaft (and gear) from being
sloppy. Unlike the other locations where the Pin portion is reusable,
that is usually not the case here. Every old steering shaft I have come
across has worn excessively wear it rides in the mount. This is because
once you look at it apart, you find that the steering shaft rides on
very little surface area of the mount. So, the shaft gets grooves worn
in it. If your steering shaft has mild grooves, you might get away
using it because you can put in a conventional oil impregnated bronze
bushing like I did, and the new bushing will bridge some of those gaps.
When you do put a new bushing down there, be sure to drill thru the
bushing so the grease zerk allows grease to go where its necessary !
Note in the above photo too, that I opted to bore and sleeve out the
bottom area for the travel control lever and the lift lever while it
was mounted on the milling machine. Doing so will tighten up all of
that associated linkage to be better than new as well.
Below you can see where I bored and sleeved the quadrant gear. One of
the important things to watch for here is that you want to spend enough
time to make sure you align the boring head properly to that existing
bore. If you bore in the wrong spot, you will mess up your ability to
use shims to adjust pinion clearance.
At this point, upon reassembly, if you would also install a new bushing
in the top of the steering column, and put in a steering shaft that is
in good condition, you would probably have steering that is far better
than it was originally, but also steering that will stay within
specifications a lot longer than the original did because you now have
more surface area between the various pins and bores. But, frankly,
that's not quite good enough for me :-)
One last frame modification though I have no photo available of it, is
you have to drill new holes for the integral holding/travel valve,
exactly 11/16" farther back than the original holes, then weld up the
old ones. Doing so allows the new valve to mount exactly where
everything lines up...
Hydraulic lines front, bottom and the control rods all work perfectly
Next, I will show you the next level of steering modifications that
work very well on a Case garden tractor, "power steering" without the
hassles of fitting more hydraulics into an already challenging to work
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