What I have learned about Saginaw power steering boxes!

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Ever wonder what to do when your power steering box starts leaking at the spud shaft? Below is a pic of the valve body that houses the spud shaft. The valve body consists of the large lock nut, the thrust assembly, the 'barrel', the spud shaft, the small piston, and a couple of rubber seals. The spud shaft sticks through the thrust assembly. A flat rubber seal prevents fluid from leaking out around the spud shaft. The 'small' piston has three sets of teflon seals which overlay three round rubber seals (not visiable). The teflon seals are a little tuff to get on, but boiling them for about 5 minutes helps. That piston and seals are where the high pressure line and return line come in and return to the pump. The small piston does not move back and forth put only rotates. When the steering wheel is turned, the piston turns. On the end of the spud shaft that extends out the bottom of the piston, are two openings and one small groove. The openings and the groove fit onto the worm drive that operates the rotaing circular ball bearings housed in a large piston. Now if fuild is leaking out the spud shaft, it could be just the flat rubber seal on the thrust assembly or the first telon seal. Seal kits, $30 - $60, will have those teflon seals and the underlying rubber seals. The whole valve assembly can be removed from the saginaw box easly and repaired. However, don't ever turn the saginaw box upside down with the valve assembly removed, unless you like dozens of little ball bearings bouncing all over the place ;p
 
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Now for the big piston

This pic shows the large piston with the worm drive that rotates inside the piston. The groves house the little ball bearings (next post for those). This piston is located in the end of all saginaw boxes. The dome shapped cover on the saginaw box is held in place with a steel ovel snap ring. A hole is provided on in the housing to pop the steel ring out. When that ring is out, the dome end cover will pop out. Behind it is a large round rubber seal and the big piston. When the piston is removed, the worm drive will stay in the box becuase it is held in place, and all the little ball bearings will fall out and end up in the botton of the large piston. You can see the bearings in the plastic cup. The large piston also has a large teflon seal with an underlying round rubber seal. Those are pretty easy to install.
 
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Now for the little bearings

Every saginaw power steering box will have these small ball bearings. The number may very from box to box, but they will be inside the box. The Scout box that I used, has 22 ball bearings. As you look at the picture, you can see that 11 bearings are shiny and 11 are grey. They come in different colors because they are different sizes. I have read that the grey bearings are 0.01", 0.005", or 0.003" smaller than the silver bearings. I guess it doesnt really, what is important is that when assembled, they must be put back in by alternating them from one to the other. Looking at the big piston in the other post, two small holes are visiable. The two U shaped half circle halves visiable below are attached to the piston with bolts and a clamp. The purpose of the U shaped 'tube' is to allow ball bearings to exit the piston when the worm drive is rotating to the left, I think. Not real clear on that. The whole purpose of the bearings is to regulate the flow of the steering fulid when the steering wheel is turned. Now the hard part is to get those little bearings inside the piston long enough to insert piston back into the houseing and screw in the worm drive from the other end of the steering box without having any of the littles suckers fall out! :eek: I have read a few writeups on this part where the bearings are coated with grease and pasted to the inside of the piston in the proper order. OK, now this is were I am stuck. As you can see, I have my piston, bearings, and grease and worm drive all ready to go. If you have done this part, please speak up and clarify this part for me. :D
 
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Isn't it that you feed the balls into the piston from each side while screwing in the worm shaft so that as the wormshaft goes in in makes room for the next balls?
 

dgangle

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You are exactly to the point at which I threw it all in the trash and went to the bone yard for another $30 box that didn't leak. Good luck!!
 
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The MOTOR manual calls for a tool to substitute for the worm drive shaft while you put the balls in. Then as you install the worm drive the tool slips out the other side. I made mine from wood and didn't have a problem with assembly.

My problem was I had the wrong rebuild kit and had to reuse the Teflon seals. They blew out and I ended up with another wrecking yard box, just like you. Paid $30 too! :)
 
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What other side? Do you take the end of the piston off ? I have heard that 1/2" socket extension will work also?
 

krzyabncanuck

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I ahve rebuilt one in both a dodge and a chevy and i can tell you from experience that you want to make sure that it is completly back together before you go to turn it at all. If not you will be doing it all over again.
 
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krzyabncanuck said:
I ahve rebuilt one in both a dodge and a chevy and i can tell you from experience that you want to make sure that it is completly back together before you go to turn it at all. If not you will be doing it all over again.
So, if you have rebuilt 2 can you tell how to get the ball bearings back in the piston? I have removed the bolt from the end of the piston. I can see how a tool could be used to get the bearings in with a little bit of grease as glue.
 
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Har Har Har!! The actually parts are not that difficult. Replacing the seals is not difficult at all. It's the 'little' bearings that are the killer.

Update, the larg nut on the end of the big piston comes off to assist in the placement of the bearings.
 
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cardinal fang said:
It's the 'little' bearings that are the killer.
Here's what I remember from 2 years ago when I did this. I'll check the manual if I remember, or hit me back if you think I'm doping it up somehow.

The "tool" is just a wooden dowel that I turned down on one end to the same diameter as the shaft. With the tool in place, lay the bearings in, alternating sizes like you already know, until the cavity is filled. You can "plant" the few remaining balls in the u-shaped retainer with grease and put that in place.

Then install the shaft. It should first contact the end of the wooden tool, then push the tool out the end as it goes in. Supposed to be a smooth transition from the tool holding the balls in place to the shaft holding them. Took me a couple tries but it worked fine.

Like I said, I might have a detail or two mixed up.
 
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theo said:
Here's what I remember from 2 years ago when I did this. I'll check the manual if I remember, or hit me back if you think I'm doping it up somehow.

The "tool" is just a wooden dowel that I turned down on one end to the same diameter as the shaft. With the tool in place, lay the bearings in, alternating sizes like you already know, until the cavity is filled. You can "plant" the few remaining balls in the u-shaped retainer with grease and put that in place.

Then install the shaft. It should first contact the end of the wooden tool, then push the tool out the end as it goes in. Supposed to be a smooth transition from the tool holding the balls in place to the shaft holding them. Took me a couple tries but it worked fine.

Like I said, I might have a detail or two mixed up.
Yes, I was thinking of getting a dowl to use. After the bearings are installed in the piston, doesn't the piston need to be installed in the gear box, then insert the worm drive and turn out the dowel? There is a divider in the gear box that the worm drive must pass through before screwing into the piston on the other side of the divider. Well, that is what I am seeing it do. Is that correct? Thanks for the feed back :)
 
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As usual, I messed up my description because my memory, like my eyes, is failing!

You're right. The dowel is to hold the worm in place in the rack-piston as you install the assembly into the housing.

Sorry for trying to confuse you. I do it well, though. ;) A '70s vintage MOTOR manual has detailed descriptions for every aspect of servicing these gear boxes. I could photocopy some pages for you but I'm leaving tomorrow or Saturday for a week and a half. PM me if you want them when I get back and I'll do it.

t
 
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Here's a quicky of the dowel I used. 1" OD on the fat end. ~19/32" on the thin end.
saginaw dowel.jpg
 
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