Saginaw power steering pumps: Need rebuild help

[cudak888]

Hello fellows:

Though not all of our cars came with them, I know most of us have probably had a Ford (or just about anything) with the GM Saginaw TC spam-can power steering pump.

I'm at a bit of a quandary on my first rebuild of one - which has now evolved into the dissection of three otherwise half-decent pumps.

Everything was going well until I had to put the shaft back in the first one I had taken apart. The rebuild core was a pump made in '68 with a threaded shaft end and Woodruff key (at right in picture), and I planned to swap the shaft from the 1989 pump (at left). However, I chose to swap the main shaft bushing, given that there was one in the rebuild kit:

However, the shaft, when reinserted, hardly spins at all without the pump pulley installed, and it wasn't keen on being installed either (required a mallet, though some rebuild threads have noted this, and it does - after all - take a mallet to get it out).

The pump shaft was from a "METRIC" marked pump from 1989, so I started to suspect a metric shaft. So I went ahead and ripped apart a spare SAE Saginaw pump from a '78/9 Lincoln and swapped shafts on each pump. Not only was the '78 shaft tight in the new-bushing '89 pump, the '89 shaft bound tight in the '78 pump.

Grrrrrr. Not all the shafts can be getting bigger at the same time. [insert your favorite Match Game-style dirty joke here]

Is there some special trick to seating these that is escaping me? Or is it one of those parts that wears itself in on the first few times around?

Any and all help appreciated.

-Kurt

 

[Don C]

A lot of bushings are intended to be fit to the shaft by honing. This helps to accommodate variances in shaft sizes due to manufacturing tolerances as well as wear on the shaft.

If too tight the bushing will not wear out to fit the shaft, but due to lack of lubrication it will either seize up or gall, ruining the shaft.

 

[72HCODE]

was the bushing pressed in using a shop press or hammered in using a mallet?

before installing the bushing did you check fit on the shaft?

if you hammered the bushing in it could mushroom and that could be the cause of binding.

there is a trick with tight bushings in a transmission where you install the shaft and it is tight with the bushing body so you use a mallet to smack the sides of the housing to straighten out a bushing, with the shaft installed.

see here: at 5:50 he starts to talk about when a bushing is tight.

 

[cudak888]

A lot of bushings are intended to be fit to the shaft by honing. This helps to accommodate variances in shaft sizes due to manufacturing tolerances as well as wear on the shaft.

If too tight the bushing will not wear out to fit the shaft, but due to lack of lubrication it will either seize up or gall, ruining the shaft.

The bushing has a single angled slot (looks like a single line of rifling from a gun barrel) that runs from the front to the back to provide lubrication to the shaft. I'm not sure it would be possible to hone it out accurately without snagging those edges.

was the bushing pressed in using a shop press or hammered in using a mallet?

before installing the bushing did you check fit on the shaft?

if you hammered the bushing in it could mushroom and that could be the cause of binding.

there is a trick with tight bushings in a transmission where you install the shaft and it is tight with the bushing body so you use a mallet to smack the sides of the housing to straighten out a bushing, with the shaft installed.

see here: at 5:50 he starts to talk about when a bushing is tight.

Pressed in with the same hydraulic press you see in the photo above. The original was also pressed out in the same manner.

Checking fit before installation would not have answered much. The bushing is slotted for installation and is about 0.5mm larger in diameter as a result before being pressed in. Still doesn't explain why the '78 pump - with its original shaft - started binding after the shaft was removed and reinstalled.

I'll try the rubber mallet trick and report back.

-Kurt

 

[cudak888]

I went and swapped as many parts as I could track back onto the '78 Lincoln pump with the original bushing, and installed the shaft with the hydraulic press.

Perfect fit. Of course, now I'm out another rebuild kit, but I'm not complaining.

-Kurt

 

[cudak888]

She's home, right where it was supposed to be two weeks ago:

Excuse the Mopar

-Kurt