C3 Power steering hose finish

[Patrick N.]

Does anyone know if the 68 PS hoses had dichromate finish or any other finish on the metal componants? I have my originals, but after cleaning it is hard to tell if they had any finish at all. It looks like there may be a very faint trace of dichromate in one area, but very hard to tell.

Thanks,
Pat

[Pat M.]

Re: C3 Power steering hose finish

I'll give your post a bump, I'm sure someone can help.

[Jim S.]

Re: C3 Power steering hose finish

From my experience the pump to valve pressure hose and the valve to cylinder pressure hoses had metal fittings that were bright zinc dichromate plated.

The manufacturing process (as I remember it) was as follows: The steel end bodies were furnace brazed to the tubing. The tubing had the nut installed and the end flared. Then the fitting was plated. Finally the tubing was bent and the fitting crimped on the pressure hose. The pump to valve pressure line was 3/8 ID. The valve to cylinder pressure hoses were 1/4 ID.

The low pressure return hose assembly was different. The pipe was welded, thin wall 3/8 diameter with some type of lead-tin based hot coating that was applied to the tubing when it was manufactured. The tubing was bent, flared, etc at Saginaw. There was a simple round collar that was crimped over the 3/8 ID low pressure return hose to hold it in place on the tube. The collar had some type of black plated finish that was applied to the collar before it was crimped in place.

These hoses were unique to the C2 and C3 Corvettes. No other GM cars or trucks used the above design power steering hoses. All other GM cars and trucks used 3/8 OD thick wall tubing that was mechanically retained to an end body.

Jim

[Patrick N.]

Re: C3 Power steering hose finish

Pat, Thanks for the bump!

Jim, great information, many thanks!
This helps me understand how it was created as well as what the factory finish should be.

Anyone know what the black plated finish was that Jim mentioned for the lower return hose collar? Phosphate, Oxide or other?

Thanks again!
Pat

[Jim S.]

Re: C3 Power steering hose finish

Patrick,
I have been oversees for the last three weeks. I think that I will be returning to Saginaw this Sunday. The assembly drawings that I have do not have finishes specified since they were plated at the sub-assembly level.

The good news is that I should run into the plant metallurgist that had responsibility for the power steering hoses when they were manufactured at Saginaw this coming Monday. He might be able to remember the different coatings and finishes (particularly if they were plated at Saginaw).

Jim

[Patrick N.]

Re: C3 Power steering hose finish

Fantastic!

Thanks Jim

[Joe L.]

Re: C3 Power steering hose finish

Jim and Patrick-------


Attached are photos of an NOS GM #3878886 65-74 big block pressure hose and an NOS GM #3826277 63-79 small block pressure hose. You will note from the packaging that these are very old, probably mid-to-late 60's or very early 70's.

The metal components of these hoses appear to be clear zinc plated. There may be a dichromate (gold) overplate but, if so, it's EXTREMELY faint.

[Jim S.]

Re: C3 Power steering hose finish

Joe,
Can you read the date coding that is printed on the rubber of both hoses? They should begin with EHR (Electric Hose & Rubber Co.) or GY (Goodyear).

BTW, I think that dichromate washes can be obtained in different colors or clear. Hopefully my metallurgist friend may clear things up for me. I will take one of my pressure lines to the meeting. I seem to have lost my return hose assembly part. I know that I had one and I never had to use it as a replacement.

Jim

[Joe L.]

Re: C3 Power steering hose finish

Joe,
Can you read the date coding that is printed on the rubber of both hoses? They should begin with EHR (Electric Hose & Rubber Co.) or GY (Goodyear).

BTW, I think that dichromate washes can be obtained in different colors or clear. Hopefully my metallurgist friend may clear things up for me. I will take one of my pressure lines to the meeting. I seem to have lost my return hose assembly part. I know that I had one and I never had to use it as a replacement.

Jim

Jim------

Pressure hoses are as follows:

The 3878886 reads "GY 4749 276-3" (probably indicating the 276th day of 1973---October 3, 1973)

The 3826277 reads "GY 4749 049-4" (probably indicating the 49th day of 1974---February 18, 1974)


The original style return hoses are among the most difficult of all to obtain. For some reason, these were changed to a hose manufactured by an outside supplier (e.g. Gates, etc.) a long time ago. I don't know if this was done for both PRODUCTION and SERVICE or if it just affected SERVICE pieces. However, by at least about 1985, the outside manufactured hoses were what was supplied in SERVICE. Of course, this was after the use of the hoses had ended for PRODUCTION but I don't know how long before 1985 the change took place.

[Patrick N.]

Re: C3 Power steering hose finish

Joe & Jim,

Joe's Pics are what I thought the finish should be, but when I looked cloesly at my connectors after some light cleaning, there is one spot of dichromate you can see in the first pic just above the large nut, ( actually looks like brass in the pic, but is infact a bit of dichromate).

It will be intersting to see what Jim learns from the drawings. It seems prior to your hoses Joe, perhaps the dichromate was used then switch to clear zinc?

Thanks again.
Pat

[Jim S.]

Re: C3 Power steering hose finish

It's Sunday August 8 and I am back in Saginaw. Now that I am home I have had a chance to look at a couple of my C2/C3 power steering hose assemblies. I now need to correct some statements in my posting on August 6 and others.

All of the pressure lines in the C2/C3 Vettes were 1/4 ID. I think that I indicated that the pump to valve hose ID was 3/8.

My pressure line is for a 1980-82 since the pump connection has a 16x1.5mm male nut and an o-ring seal. The date coding on the rubber is 1/4-GY-4749 -- 015-0. (15th day of 1980).

Joe,
I am sure that only the crimped collar was used on return line hoses 1970 through 1982. It is possible that Chevrolet went out and purchased service return line hose assemblies after production ceased. (Although 1985 would seem to be awfully quick timing for a change in sources.)

I took over responsibility for pressure hoses in 1971. I know that Saginaw supplied all of the pressure hoses for all of General Motors passenger cars from around 1970 forward. However, before 1970 I do not think that Chevrolet bought pressure lines from Saginaw. Several of my Corvette pressure line drawings indicate FIRST USED - 1970 Chevrolet and reference a Chevrolet part number. I do remember that we shipped Corvette hoses under Chevrolet part numbers (except the o-ring hose in 1980-82):

Chev 3878886 Saginaw #7809490 1970-74 Big Block Pump to Valve

Chev 3826277 Saginaw #7809129 1970-79 Small Block Pump to Valve

Saginaw #7834409 1980-82 Pump to Valve (with metric o-ring at pump)

Chev 3826275 Saginaw #7809108 1970-82 Valve to Cyl Extend

Chev 3826276 Saginaw #7809109 1970-82 Valve to Cyl Retract

Chev 3826278 Saginaw #7809489 1970-82 Return Line

So all of the pressure lines used on the C2/C3 Vettes after 1969 were 1/4 ID with the Saginaw 8 segment flat crimp brazed end bodies.

So I am afraid that my statements regarding plating and end body finish will only be correct for hose assemblies 1970 through 1982. Sorry if I mislead anyone on the earlier hoses.

One last fact, Saginaw kept the tooling and continued to manufacture service pressure hoses for the Corvette up until a couple years ago. The engineer that took my place indicated that outside sources had a devil of a time trying to validate their hose assemblies to a high temperature pressure cycling test requirement (Saginaw hoses did pass). However, I am quite sure that outside sources may have actually been supplying parts with bends and hose lengths copied from Saginaw originals for years.
Jim

[Joe L.]

Re: C3 Power steering hose finish

It's Sunday August 8 and I am back in Saginaw. Now that I am home I have had a chance to look at a couple of my C2/C3 power steering hose assemblies. I now need to correct some statements in my posting on August 6 and others.

All of the pressure lines in the C2/C3 Vettes were 1/4 ID. I think that I indicated that the pump to valve hose ID was 3/8.

My pressure line is for a 1980-82 since the pump connection has a 16x1.5mm male nut and an o-ring seal. The date coding on the rubber is 1/4-GY-4749 -- 015-0. (15th day of 1980).

Joe,
I am sure that only the crimped collar was used on return line hoses 1970 through 1982. It is possible that Chevrolet went out and purchased service return line hose assemblies after production ceased. (Although 1985 would seem to be awfully quick timing for a change in sources.)

I took over responsibility for pressure hoses in 1971. I know that Saginaw supplied all of the pressure hoses for all of General Motors passenger cars from around 1970 forward. However, before 1970 I do not think that Chevrolet bought pressure lines from Saginaw. Several of my Corvette pressure line drawings indicate FIRST USED - 1970 Chevrolet and reference a Chevrolet part number. I do remember that we shipped Corvette hoses under Chevrolet part numbers (except the o-ring hose in 1980-82):

Chev 3878886 Saginaw #7809490 1970-74 Big Block Pump to Valve

Chev 3826277 Saginaw #7809129 1970-79 Small Block Pump to Valve

Saginaw #7834409 1980-82 Pump to Valve (with metric o-ring at pump)

Chev 3826275 Saginaw #7809108 1970-82 Valve to Cyl Extend

Chev 3826276 Saginaw #7809109 1970-82 Valve to Cyl Retract

Chev 3826278 Saginaw #7809489 1970-82 Return Line

So all of the pressure lines used on the C2/C3 Vettes after 1969 were 1/4 ID with the Saginaw 8 segment flat crimp brazed end bodies.

So I am afraid that my statements regarding plating and end body finish will only be correct for hose assemblies 1970 through 1982. Sorry if I mislead anyone on the earlier hoses.

One last fact, Saginaw kept the tooling and continued to manufacture service pressure hoses for the Corvette up until a couple years ago. The engineer that took my place indicated that outside sources had a devil of a time trying to validate their hose assemblies to a high temperature pressure cycling test requirement (Saginaw hoses did pass). However, I am quite sure that outside sources may have actually been supplying parts with bends and hose lengths copied from Saginaw originals for years.
Jim

Jim------


Attached are photos of the GM #3826278 return hose which GMSPO has been selling for years. Note that in addition to the part number being on the parts tags and labels, the part number is also stamped into the end crimp.

[Patrick N.]

Re: C3 Power steering hose finish

Per my original question on accurate finishes for the 68 PS metal connections, it seems like the images that you posted Joe give me the best clues towards what I should do.

Unless someone with a survivor can post a pic to verify dichromate, I will leave them as is for now. I can always plate them later on if I learn that the 68 hoses for a fact were finished that way.

Thanks again for your help guys. Jim, thanks for your research, great information.

Regards,
Pat

[Jim S.]

Re: C3 Power steering hose finish

Here is a bit more information on plating on Saginaw C3 power steering hoses.

The tubing used on the return hose was plated with a very low cost "terne coat." It was a lead/tin coating that was applied to the tubing at the mill.

Early Saginaw brazed end fittings (1970 or so) may have been cadmium plated. Later cadmium was banned by the EPA and zinc plating with a clear dichromate wash was use. Dichromate was for color and really had no anticorrosion properties. Cadmium had much better corrosion resistance than the later zinc. You cannot just look at the plating and determine cadmium versus zinc. However, if plated parts are rusty, they were most likely originally zinc plated.

I will attempt to obtain some more subassembly information.

Jim

[Jim S.]

Re: C3 Power steering hose finish

The drawings show the following:
Return line crimp collar - zinc plate per GM 4252-M
Brazed end bodies and nuts - cadmium or zinc plate per GM 4252-M

Jim