Control Valve Question for Joe Lucia

[Jim S.]

Joe,
Do you have any part numbers for power steering control valve assemblies after the 1976 model year? There seems to be a difference in the way the housing was sealed against the ball stud adapter sometime after 1976. Originally the two parts were sealed with an o-ring seated in a groove in the housing. Later designs used a thin metal plate with a rubber gasket molded to it. The o-ring groove in the housing was eliminated at that time.

Jim

[Timothy B.]

Re: Control Valve Question for Joe Lucia

Jim,

The valve assembly I installed on my 67 I believe came from a 1981 and I can post a pic of this union if it will help.

[Jim S.]

Re: Control Valve Question for Joe Lucia

I would appreciate knowing how the housing and the adapter went together. A picture would be helpful.
Jim

[Joe L.]

Re: Control Valve Question for Joe Lucia

Joe,
Do you have any part numbers for power steering control valve assemblies after the 1976 model year? There seems to be a difference in the way the housing was sealed against the ball stud adapter sometime after 1976. Originally the two parts were sealed with an o-ring seated in a groove in the housing. Later designs used a thin metal plate with a rubber gasket molded to it. The o-ring groove in the housing was eliminated at that time.

Jim

Jim------


No problem. It's very clear. There was only one part number used for the control valve assembly, PRODUCTION and SERVICE, from 1976 through 1982. It was GM #7825636. After 1976, this valve was also the SERVICE valve for all 1963-75 applications, too.

In fact, it's still available from GM (for about $635, GM list).

[Jim S.]

Re: Control Valve Question for Joe Lucia


As you can see one control valve housing has an o-ring groove in the face of the housing. The other is smooth. All of my engineering drawings show a groove and an o-ring in the face of the housing. The 7825636 valve and adapter assembly (1976-86) has the groove and o-ring which Joe indicates is the latest and last control valve assembly and also back services the control valve back to 1963.

So where did the housing with the smooth face come from?

Jim

[Joe L.]

Re: Control Valve Question for Joe Lucia

As you can see one control valve housing has an o-ring groove in the face of the housing. The other is smooth. All of my engineering drawings show a groove and an o-ring in the face of the housing. The 7825636 valve and adapter assembly (1976-86) has the groove and o-ring which Joe indicates is the latest and last control valve assembly and also back services the control valve back to 1963.

So where did the housing with the smooth face come from?

Jim

Jim-----

That's a good question and I have no definitive answer. However, the various exploded diagrams and service manual instructions I find do not show an o-ring, per se, at this location. What they show is an annulus spacer with an attached seal. I think the seal was always supplied only with the spacer, though. I think the annulus seal would have required the groove in the valve housing. I show this configuration as far back as, at least, 1967 and continuing through 1982.

Might the valve housing without the groove be an aftermarket piece? I don't know that all of these valves available over the years have had the same internal configuration and construction as the Saginaw valves, although they appear externally the same. Vaguely, I recall that there was some problem sourcing either the annulus spacer and seal or the annulus gasket after GM discontinued the parts. Perhaps they "redesigned" the valve internals to accommodate some other sort of "sealing mechanism" after the GM parts were no longer available.

It MIGHT even be that the current GM piece, although still sold under the original GM #7825636, might be an aftermarket piece. In other words, a "sheep in wolf's clothing". As a matter of fact, quite a few years ago I purchased some of the major components of the valve. Among other things, I got a GM #7817308 valve assembly. I can't get at it right now but I believe it said "Made in Brazil" on the GM-labeled container it was packed in.

[Jim S.]

Re: Control Valve Question for Joe Lucia

All of my control valve drawings (with cutaway sections) show the housing with a groove for an o-ring. Also, the o-ring is called out not a gasket seal. I used to be the supervisor whose group was responsible for all of the seals and rubber parts in the steering system including manual gears, power steering pumps, steering gears (both manual and power assist), power steering hoses, and flexible couplings. I can remember something about developing a gasket seal for the control valve, but I can't remember the year however.

There is a gasket seal that is used on the aluminum top cover (aka side cover) of the Saginaw 700 and 800 power gears. It is stamped from thin sheet metal and a rubber gasket is molded to the stamping. The rubber seal sits in an irregulalry shaped groove that is molded into the irregularly shaped top cover. Previously, an o-ring was installed in the groove as a seal. We always had a problem with leaks on the top cover because of the irregular shape of the groove. The gasket seal was much, much, more reliable than trying to snake an o-ring into that irregular groove.

I am continuing to try and study the seals and parts inside the Corvette control valve.

It would be helpful if someone with a 1963, 64, or 65 Chevrolet shop manual could scan and post a blowup picture of the control valve (if there is one in those early manuals.) The 1971 and later Overhaul Manuals show a type of gasket seal between the valve and the ball stud adapter.
Jim

[Timothy B.]

Re: Control Valve Question for Joe Lucia

Jim,

I hope these pics will help. The control valve break down is out of the 1963 shop manual. The valve pics are from my 67 and I believe the valve is from around 1980-81. Note the attachment bolts are not 12 point.

Also, no X on the cap..

[Jim S.]

Re: Control Valve Question for Joe Lucia

Can anyone supply a scan of a 1981 or 82 control valve blowup. I have compared the 1963 blowup (above) against 1971 and 1977 blowups in a couple manuals that I have. There are only two tiny differences between 63 and the 70s blowups. I would like to compare against later ones.

Jim

[Joe L.]

Re: Control Valve Question for Joe Lucia

Can anyone supply a scan of a 1981 or 82 control valve blowup. I have compared the 1963 blowup (above) against 1971 and 1977 blowups in a couple manuals that I have. There are only two tiny differences between 63 and the 70s blowups. I would like to compare against later ones.

Jim

Jim------


Attached are scans of the control valve blow-up drawing taken from the 1979 Corvette Shop Manual and a 1983 edition of the P&A Catalog.

One thing to be cautious of here as with a drawing from any other GM service manual or P&A Catalog: just because a drawing is from a particular calendar year source, that does not necessarily mean that the drawing is updated to that same, particular year. Many of the drawings found in a variety of GM sources are somewhat "generic".

These will open up as kind of small drawings on your monitor. You may have to print them out to be able to read them.