perhaps you may have to be a member to open??, it just opened for me , so I did copy it so that there is no problem
For those of you considering using a late model power steering box on your early
trucks, I would like to mention a few things. First is, this is a really great
way to upgrade your truck. There are a few ways I've seen this done. The first
is probably the worst way, and you wouldn't believe how many times I've seen it
done. Some people have used nuts or washers to shim out the steering gear box so
it will mount on the flat frame.
For those of you that aren't familiar with these, I need to point out that the
saginaw 800 series steering box does not mount on a flat frame. If you have ever
taken one off of a '67 or newer truck, you may have noticed that the frame is
"sculpted" to match the contour of the steering box. There is a company that
makes a bracket that will allow you to mount this box on the flat frames of the
60 to 66 trucks, but, the drawback to this, and the other method I previously
mentioned is that they both move the steering box and therefore the pitman arm
outwards from the frame. In doing this, you change the steering geometry, and
the number of turns it takes to go from having the wheels centered to full lock
on either the left or right turn. The problem is that because the shaft is not
in the original location, it will take {approx}2 turns to go to full left, but
take {approx}4 turns to go to full right turn. { I say it's approxamately that
many turns because
some of the steering boxes have different ratios, therefore take more or less
rotations to go from left to right.} This is of course if you center the
steering box first, meaning the same amount of turns to full left or right, and
adjust the tierod linkage to match. If you look at the linkage after you've done
it this way, the tierod ends on the center link are not centered evenly on the
frame, they are both moved to the left to compensate for the steering box
position, and your right tierod will be longer than the left. You will also
experience bump steer in this case.
Another way to do this using the mounting bracket is to try to compensate by
centering the center link between the pitman and idler arms, neither of them
will be aimed straight back then, but both are aimed slightly inward towards the
center of the truck. This throws the steering box off center. Again, with the
wheels aimed forward, you will wind up with a left turn steering wheel rotation
count higher than the right turn count. And this is if the steering box internal
stops are not met before the spindle stops are met.
The third way to use the mounting bracket is to keep the center link in it's
proper location, centered between the wheels evenly, and take up the difference
in distance by turning the steering box to the right. In doing this, because of
the arc of rotation, the end of the pitman arm comes forward some and pulls the
center link forward as well, again, changing your steerng geometry slightly.
This way changes things only slightly, but it also throws off your gear box
center the most, meaning now the possibility of hitting the internal stop in the
gear box before the wheels are turned completely on a right turn is much more
likely.
When the steering box is sitting in the proper location, the pitman arm and the
idler arm should both be pointing straight back when the wheels are aimed
straight forward. Think of the pitman and idler as pointing to 12:00 o clock if
you are standing in front of the truck. Now if you move the steering box
outwards {to the right} without moving anything else, the pitman arm will begin
to point in the 11:00 position. This also has the effect of pulling the center
link towards the front of the truck because of the arc of rotation, changing the
steering geometry. The further out the pitman/gearbox is moved, the further the
geometry is changed. In the correct position, the center link can be thought of
as going from the 9:00 o clock to the 3:00 o clock position, left to right. As
you move the pitman out, the center link goes from 9 to 3, to 9 to 4, if nothing
else is adjusted. Now if the center link is kept parallel by moving it to the
right to compensate
for the gearbox position, this will turn the idler to the right as well, and to
keep the wheels pointed forward, the right tierod would have to be made longer,
and the left one shorter. This is when you will get a bump steer condition.
Now, the only way I have been able to keep all the components in the right
locations and the steering geometry correct, is to do a frame graft at the
gearbox mounting location. I take a piece of the '67 to '72 frame where the
steering gearbox mounts, and graft it into the '63 to '66 frames. This gives you
the "sculpted" frame mount and keeps the pitman shaft/arm in the proper
alignment. I've done this to 4 trucks so far, and it works great. But it's also
not something that just anyone should try without knowing first, how to weld,
and second, how to align the frame sections. There are 3 bolts that hold the
original steering box to the frame, but the power box uses 4. Only one of those
4 bolts will line up with any of the original holes and keep the gearbox in the
right location. In doing the frame graft, I've kept the pitman shaft location
close to the frame, just as the original one is. You do have to cut out part of
the frame rail, the side and just a
small part of the top and bottom lips where the gearbox will mount. This is so
that as you put in the new piece, it will go in far enough. I also then make a
back up plate to help reinforce the frame in this location and weld it into
place.
I have to do this to my 1 ton in the near future, and I'll take some pictures
of the process as I do it so that if anyone else is interested in doing it, you
will have something to follow. I'll also try to take some picture of my two
trucks I've already done. The other two belonged to someone else and are down
the road killing bugs now. I don't know how much will be visible n the two I've
already done. One is all painted black, and the other is all covered in surface
rust.
But if anyone has any questions about this, feel free to contact me. I'd be
glad to answer any questions you may have.
Rick Cook
Sierra Vista, Arizona.
