What is the correct method of installing a stamped pulley on a power steering pump?

[Ian H.]

1967, 300 HP, AC, PS.
I have removed the stamped steel pulley retaining nut from my power steering pump with an impact gun and will remove the pulley using a rent-a-tool at the auto parts store.

To install the pulley, the Assembly Instruction Manual (AIM) on UPC N40, A5 states in the Mandatory Assembly Procedure, Step 4, to "use a stall wrench & while applying a brake force in pulley groove, torque nut."

How does one apply 60 lb. ft. of torque to the nut without one of these stall wrenches?

Thanks,
Ian

[Jim S.]

Re: What is the correct method of installing a stamped pulley on a power steering pum

When you remove the nut, you should not have too much of a difficult time removing the pulley. In 1975 Saginaw and GM went to interference fit pulleys on all of their pumps. Before 1975 the pulley and pump driveshaft had keyways and a 1/8x1/2 Woodruff key. The pulley should just sit against a taper on the pump driveshaft. You might have some corrosion that is holding the two parts together. You should not need a puller. If you soak the pulley connection with penetrating oil, you should probably protect the hydraulic seal in the snout of the pump (right behind the pulley hub). I can't think that the penetrating oil will do the rubber seal any good.

The first real high volume, high production torque guns in the assembly plants were the impact type. They were notorious for far exceeding the torque specification because the line worker (or mechanic) let it ratchet for too long of a time. Also impact guns could spin the nut too quickly, galling the nut and/or driveshaft threads and causing the nut to reach high friction (and the gun see high torque values) even though the nut might not be seated and tightened. GM assembly plants consistantly had a difficult time properly torquing the nut on this connection.

Stall guns were far more accurate but since they applied a contant rotating force, you need some type of reaction bar or holding tool to take the twist reaction of the gun when it torqued out. At high torque specifications, your wrists just can't take the contant repeating force of the gun.

Now the AIM is written to give direction to the car assembly plant. Most of the time they do not specify HOW an operation is to be performed. But in this case, there were rather high warranty claims with respect to pumps and loose pulleys. So the AIM was written directing the plant to use stall type torque guns.

On a one time or infrequent basis, a beam type or click type torque wrench is very capable of producing a very repeatable torque. So what the pump spec is saying is for the assembly plant to use a stall type wrench and hold the pulley stationary while torquing the nut in place.

For you to use a beam type or click type torque wrench set at 60 lb-ft and holding the pulley from turning should be very acceptable.

Jim

[Ian H.]

Re: What is the correct method of installing a stamped pulley on a power steering pum

Thank you, Jim for you excellent answer. The pulley came off but not easily by using a puller and an air-driven impact gun. No corrosion is evident on the mating surfaces.

This pulley does not want to fit over the shaft by hand on either the rebuilt pump or the old one. I think it isn't an original and it may not be tapered. I have attached a photo of the pulley's mounting area. Notice that only the rear 1/16" of the end of the I.D. is shiny where it had rubbed as it passed over the shaft.

I guess I'll buy a new pulley, since this one doesn't look all that good anyway.

[Joe L.]

Re: What is the correct method of installing a stamped pulley on a power steering pum

Thank you, Jim for you excellent answer. The pulley came off but not easily by using a puller and an air-driven impact gun. No corrosion is evident on the mating surfaces.

This pulley does not want to fit over the shaft by hand on either the rebuilt pump or the old one. I think it isn't an original and it may not be tapered. I have attached a photo of the pulley's mounting area. Notice that only the rear 1/16" of the end of the I.D. is shiny where it had rubbed as it passed over the shaft.

I guess I'll buy a new pulley, since this one doesn't look all that good anyway.

Ian-----


From what I can see of it, the pulley looks correct for 63-74 applications. I do not understand why it won't fit on the shaft. There should be no tool necessary to install this type of pulley---just put it on the shaft by hand, install the nut and torque it down. I don't see any burrs in the shaft orifice on the pulley, but you might want to wire brush it to be sure.

[Jim S.]

Re: What is the correct method of installing a stamped pulley on a power steering pum

And don't forget the 1/8 x 1/2 Woodruff key.
Jim

[Ian H.]

Re: What is the correct method of installing a stamped pulley on a power steering pum

Jim/Joe;
I now have a new 3770509 pulley from Long Island Corvette Supply and it goes on very easily over the pump shaft. I suspect the old pulley was bored and bushed without a taper. The old pulley looks as if it was salvaged after sitting outside, rusting in an auto graveyard. A previous owner had painted over the pits and bumps. The new pulley looks much nicer - although you can't see much of it when installed. Now to install the rebuilt pump, valve, cylinder and new hoses.

Thanks for your help.