Rebuilding Power Steering Pump

[Gene M.]

I'm rebuilding a power steering pump. Not sure what year it came off of. The sheet metal case style with neck area is seperate section welded to main round body. The rebuild kit I got is for a 3/4" shaft. Problem is the shaft on this pump is 11/16" diameter. O-ring seals in the kit all appear OK. Anyone know of a correct kit that will have the bearing and seal for the 11/16" shaft? thank you

[Joe L.]

Re: Rebuilding Power Steering Pump

Gene-----

The pump resevoir that you describe is the 63-74 style resevoir. It was used on Corvettes as well as all other Chevrolet cars and trucks of that period.

As a unit, the pump assemblies for 63-74 are interchangeable. However, the 63-66 versions of this pump are internally a bit different than the 67-74 versions. Although all of the pullies used from 63-74 are interchangeable indicating commonality for the EXTERNAL portion of the shaft, I think that the internal section of the shaft is smaller in OD than the 67-74 style pump. I believe that the 11/16 OD shafts were the 63-66 component and the 3/4" are the 67-74 component. Although the pump housing on the 63-66 units is also different than 67-74, I think that all of the other internal parts, including gaskets and seals, will interchange. I'm not certain of that at the moment, though.

The 63-66 seal has beem GM discontinued for over 20 years. Also, I am not familiar with any bearing as part of the pump assembly. I thought that the bearing was integral with the pump housing but I could be wrong on that. In any event, I don't know of any seperate bearing that has ever been available from GM.

I can't speak to exactly where you could get the parts that you need. However, I think that if you go to a good auto parts store and get a kit for a 63-66 pump, you will have what you need. These kits will be for an application that has not been produced in a LONG while. However, since these pumps were used in a LOT of cars when they were used, I expect that you might still be able to get the kit.

One other thought, though, is this: I feel quite certain that GM went from the 63-66 style pump with 11/16" shaft to the later style with the 3/4" shaft because of some problem with the earlier style. I feel confident that they didn't change the design because the earlier style worked just as well. So, unless this pump has some intrinsic value to you (like an original pump off your car), it might not be worth rebuilding. Obtaining the later style, which will retrofit to all 63-74 applications might be the thing to do. Externally, I don't think there is any significant difference.

By the way, in case you or others are interested, the power steering pump configuration changed again for the 1975 model year for Corvettes as well as other Chevrolet/GM products. The resevoir design changed to the "neckless" type and the shafts also changed. The 63-74 shafts have a slightly tapered shaft end and use a special prevailing torque lock nut to retain the pulley. 75-82 style pumps use a straight shaft which is designed for an interference (press) fit pulley. These shafts have a drilled and tapped fitting on the end which is necessary for removal and installation of the pullies. Both the 67-74 and 75-82 shafts are 3/4" diameter and can be interchanged if one is also willing to interchange the pullies.

[Gene M.]

Re: Rebuilding Power Steering Pump

Joe, thank you for the reply. I found a local jobber that will special order the rebuild kit, only problem takes a week. His books do agree with your information in that 11/16" shaft design was used till 66.