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Discussion Starter #1
As before, this information was compiled while working on my 1970 Chevelle SS, but is relative and applicable to 3rd, 4th and 5th Gen El Caminos.

While cleaning and painting the front clip of my Chevelle earlier this year, I decided to go deeper into the engine bay and give her the cleaning and detailing that I've been meaning to do since 1998. The first major component, as I work my way towards the firewall, was the Saginaw power steering gear box. In the past someone painted mine blue, I'm assuming to match the exterior color. I had had a leaking PS resevior, cracked at the return hose fitting, which has been replaced and have replaced the hoses, so I thought a rebuild of the gearbox was in order. After looking at the overhaul manual and doing some net reading, I came across a GOLDMINE of information on YouTube Many thanks to hutchhiperf on YouTube for this series of videos concerning the rebuild and adjustment of a Saginaw Power Steering Gearbox:

Tear Down
https://youtu.be/WX119EtadWM?list=PLvTshlwDi1UF8ueUn-v_YUyqPWJa3Ser-

Installing Seals
https://youtu.be/iqqqdQMljm0?list=PLvTshlwDi1UF8ueUn-v_YUyqPWJa3Ser-

Rack Piston
https://youtu.be/l3GAggBjHJU?list=PLvTshlwDi1UF8ueUn-v_YUyqPWJa3Ser-

Final assembly
https://youtu.be/0F2eHlRnZfk?list=PLvTshlwDi1UF8ueUn-v_YUyqPWJa3Ser-

Adjustments
https://youtu.be/UJ-89YhvAXU?list=PLvTshlwDi1UF8ueUn-v_YUyqPWJa3Ser-

There are two types of kit you can buy, one is a kit of seals, for a lower level refresh, and the other is more a intensive, full-on rebuild kit which includes seals and replacement bearings. I opted for the full rebuild kit to do my job.

All in all the process isn't terribly difficult. I will call out a few areas that I found were different than Hutchhiperf's video series and things that found made my job easier.

My results:


You can also view the gallery of photos I took of my own work, with descriptive and hopeful helpful captions here:

https://picasaweb.google.com/106242937059319515061/ChevellePowerSteeringRebuild#6186708719696996050
 

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Discussion Starter #2 (Edited)
Special Tools

All in all the process isn't terribly difficult. I will call out a few areas that I found were different than Hutchhiperf's video series and things that found made my job easier.

Firstly, make your own spanner wrench. Hutchhiperf uses needle nose pliers, which is a bit unwieldy for me. I used two pieces of metal bracket/strapping with three bolts. One to hold it together and two longer ones which will act as your tool's grippers. Be sure the long bolts you use fit into the ports on the plug. You can see my spanner wrench here:



I also ad-libbed a tool to keep all of the ball bearings in place along the insides of the rack piston during assembly. I used a 1/4" drive 7/16" deep socket on an extension to fill the space, which fit perfectly and held everything in place.

 

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Differences in details from the YouTube videos

If you're working on a gearbox of similar vintage to mine, don't be alarmed that you only find 22 ball bearings inside the rack piston. That's what I and other people have had as well. It is vitally important to identify the "dark" balls from the "chrome" balls. The darks are slightly smaller (by like less than a .001") and you have to reassemble in alternating fashion: dark-chrome-dark-chrome-etc. Failure to do this will cause excessive wear and damage as two or more similarly sized/coated balls will wear against each other.

My work went almost exactly like what is shown in the videos, except for when I got to the valve spool, as seen towards the end of the teardown video and especially in the Installing Seals video. On my 70 Chevelle, the valve spool is held in place on to the stub shaft with a coil spring. The diameter of the coil spring has to be expanded to get it over a lip on the plug shaft to get it off and to release the valve spool.

Assembly of the valve body is extremely tricky and can jam easily. I needed to clean both the interior of the valve body and the exterior of the valve spool many times and heavily lubricate with power steering fluid. I assembled the spool into body first, the the plug shaft into valve body THEN get the spring back over the plug shaft to hold the valve spool in place. That is not as easy as it sounds.
 

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Discussion Starter #4
Tips For Rebuilding Rack Piston

Rack Piston Seal
Replace all rack piston seals before installing ball bearings!

I had to install the big teflon seal on the rack piston twice. The first time I must have stretched it slightly as it had a bit of a bulge. When I tried to install into the rack piston into the casing, that bulge snagged and I ended up cutting off a sliver of teflon. I should have known, because the piston met resistance and I pushed too hard to get it to move. For my second teflon seal (I had to buy ANOTHER seal kit to replace it!) I soaked the seal first in boiling water to expand it slightly with heat. It went onto the piston easier and there was less bulge when cooled. For insertion I suggest using an engine piston ring compressor to avoid damaging the seal.

Rack Piston Ball Bearings
Installing the ball bearings into the rack piston really is the catch. I had issue with the grease causing drag so that after 8 or 10 bearings had been inserted, they refused to stay in their track and would pop up. Here is how I was able to complete this leg:

I inserted just the worm gear into the rack as it is supposed to go. Once fully inserted, I turned the worm until its groove matched up with the ports in the rack. This essentially completes the race within which the ball bearings move. I would insert a small amount of grease before each ball is inserted and push a ball in with a small drift pin, giving the worm gear a little bit of rotational jiggle to help with alignment and to coax the balls in. The rotational jiggle gets to be important around the 12th ball, and helps draw the bearings into the race channel. It is important that you do not allow balls past either of the two ports. You can coax the balls in and out of the channel with similar rotation of the worm shaft.

Once all balls have been inserted and the u-channel has been reinstalled, you can rotate the worm shaft out. As you remove the worm shaft, you should insert a place holder, be it the taped up 5/16 hose hutchhiperf recommends, the special tool if you can find it, or something else. Instead of the tape-wrapped tubing, I used a 1/4" drive 7/16" deep socket on an extension to fill the space, which fit perfectly and held everything in place.

The ball bearings are the real trick to this entire job. I attempted their insertion over 10 times! Every time one or more would drop out I had to start over, cleaning each bearing of grease and sorting each bearing by color. It was because of my multiple attempts (with many bad words used) that I came up with the idea to utilize the worm gear to help initial assembly.
 

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Discussion Starter #5
Rag Joint

This lump of metal can look pretty nasty and rusty, but it is easy to pull apart to clean/paint.



My jag joint broke down into three pieces: a cast iron piece, a cast iron mounted on rubber, and a stamped stainless steel piece. Orientation of the two cast iron pieces is a very easy as the two bolts which hold the pieces together are different sizes. It can only sandwich together ONE WAY!




Also, final assembly with gearbox and steering shaft also go one way thanks to the use of bolt recesses in the stub shaft of the gearbox and the intermediate steering column shaft. The bolt connecting to the gearbox stub shaft will point toward the engine. The bolt connecting to the intermediate steering shaft will point straight up.

The one potential head scratcher is the stamped steel piece. It resides on side that faces the gearbox and is positioned out-board, allowing mounting bolt access on the engine-side.

 

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Discussion Starter #6
Other tips

Installing Pitman Shaft into case

It should be stated that reassembly in many areas is simplified by the fact that pieces can only go together one way. The rack piston and pitman arm shaft will only mesh together when the assembly is basically at dead center. This simplifies setup on vehicle, too.



Pitman arm shaft going in. These teeth interface with the rack piston.



To ease the insertion of the pitman shaft, I used the rag joint as a grip to wiggle the input shaft/plug shaft back and forth. This motion was translated down to the rack piston via the worm gear and helped to align the rack with the pitman. You'll find that the rack piston may also need to spin inside the bore to align. The wiggle motion helps accomplish this.
 

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Discussion Starter #9
Thanks, guys. I had done the job a couple of months ago, but I'm only just now getting around to writing about it and posting it.

A major thank you goes to from me to hutchhiperf on YouTube for his initial video series. I don't think I would have been as likely to tackle this with out his work. Hopefully, with the two of us together, more and more people will attempt this very doable rebuild.
 
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