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pcard January 17th, 2012 08:37 AM

Fan Clutch Applications 1970
 
There are three different clutch codes for A (V8) bodies referenced in the 1970 Service manual:
"OU" for HD cooling, A/C or W31
"OR" for 442 with W30 or A/C, W32 and VC with A/C
"OS" for HD cooling and HD Alternator

but the aftermarket clutches available today seem to only come in one flavour.

I have read in other posts that the different original clutches contained different viscousity fluids, which caused them to operate differently at various temperatures.

If I want to install the A/C or HD cooling option in my 70 SX (L31), how important is it to get a clutch that meats the original specifications?
Can I get away with a generic aftermarket clutch?
Does anyone know which specification todays aftermarket clutch most closely resembles?

frankr442 January 19th, 2012 01:27 PM

I have a 71 assembly manual that lists the "OS" clutch as 4950788. The AC Delco catalog crosses that to 15-4947, but their buyers guide shows that number fitting 350's from 70-72 (some 455 usage in later years). For what it's worth, the GM parts catalog as of 1983 showed one part # 4974367, for all V8 from at least 70-72 (disc). I almost didn't post this because I can't really answer your question. After many years and many number changes, it's hard to get specific. If I needed one for my 71 I'd look for HD cooling with the bi-metallic coil.

pcard January 19th, 2012 03:51 PM

Cross-referincing numbers is certainly a challenge! My interpretation of the 1972 edition of the parts catalog, group 1.050 leads me to believe that for 1970 at least:
the "OS" clutch was part number 401797: for all V8 with Y72
the "OU clutch was Part number 403982: for (all V8 with AC, no Y72 nor perf. engine) and W31
the "OR" clutch was part number 4949861: for (SX, 442, VC with AC, no Y72 no OAI) or (442 with OAI)
This is slightly different from the Service Manual which states explicitly that the HD Cooling option V01 clutch is the same as the AC option clutch, but it is consistent.

But the question remains - what is the deifference between these three clutches, and is it critical, or can I safely use any aftermarket clutch.

Allan R January 19th, 2012 04:48 PM

Quote:

Originally Posted by pcard (Post 361084)
But the question remains - what is the deifference between these three clutches, and is it critical, or can I safely use any aftermarket clutch.

I think you can use pretty much anything. Take a look at this article: http://www.4s.com/Upload/Four%20Seas...,%20SEVERE.PDF

oldsconv January 28th, 2012 02:22 PM

Related to this thread.....sort of..... I bought a fan clutch for my 70 SX Conv with no air. I made sure I had correct pulleys and water pump length. Fan was from a 71 so may be different depth, but the clutch I got from Napa put the fan too close to engine and it would touch the PS pump pulley. Napa one was correct according to catalogs and same as another I got from Advanced Auto thinking the Napa one was wrong. I then went to the website of the company that makes them (Dorman maybe?) and you could see all the blueprints and I picked the same one but with an extra 3/4 inch length that put the fan closer to the radiator. The application was early 80's Olds Cutlass, Pontiac GP, etc. It now fits fine - not sure why it was off, but something to look at - maybe the new aftermarket ones, being standardized, went to a different length.

And to answer the other concern, the car runs fine and good temp. I got the clutch that has the bimetallic coil spring at front.

pcard January 28th, 2012 03:33 PM

It is my understanding that the clutches cannot be rebuilt. Is that correct?
Does anyone sell different spec clutches to match the original olds products?

Allan R January 28th, 2012 04:36 PM

Quote:

Originally Posted by pcard (Post 364477)
It is my understanding that the clutches cannot be rebuilt. Is that correct?

Sad answer: some can and some can't. I looked into that not long ago when J_Chicago was going to throw one out. He offered it for free. Only stuff I could find on rebuilding the fan clutch was for the ones that bolt together like Toyota. Couldn't find a reference on these anywhere. Looking at the CSM, I get the impression that the assembly was pressed in at the factory. Don't know how you would get it apart without destroying it. Look at Fig 6k-15 on page 6K -8 in the CSM and you'll see what I mean.

Allan R January 28th, 2012 06:30 PM

Quote:

Originally Posted by joesw31 (Post 364522)
Fan clutch can not be rebuilt. Your choice would be NOS or good used. All of fan clutches offered are consolidated units, and they will say that they are same as your original unit.

thx for the confirmation Joe. That's what my research was telling me too.

Al Graaf January 28th, 2012 08:15 PM

Quote:

Originally Posted by Allan R (Post 361105)
I think you can use pretty much anything. Take a look at this article: http://www.4s.com/Upload/Four%20Seas...,%20SEVERE.PDF

so Allan just what is included in the y72 cooling package. Have heard this in the past. I will have ALL my shrounds on, fan clutch. The fan blade I have was the one that was on it. Do I need a deeper blade depth?
AL:confused:

Al Graaf January 28th, 2012 08:17 PM

Quote:

Originally Posted by joesw31 (Post 364522)
Fan clutch can not be rebuilt. Your choice would be NOS or good used. All of fan clutches offered are consolidated units, and they will say that they are same as your original unit.

I came across an NOS cluthch and they wanted 180+ shipping from AZ.
Didn't get it of course.

pcard January 28th, 2012 09:25 PM

Shimmer: in 1970 the fan blade for the Y72 otpion was different form the one for standard cooling. The six blade fan is part number 401372 (see section 6-1 page 110 of the assembly manual 1970)

Allan R January 28th, 2012 09:51 PM

Quote:

Originally Posted by pcard (Post 364602)
Shimmer: in 1970 the fan blade for the Y72 otpion was different form the one for standard cooling. The six blade fan is part number 401372 (see section 6-1 page 110 of the assembly manual 1970)

I'm not sure what the difference is by looking at the pics. Must have something to do with the pitch of the blades as we were discussing earlier.

oldsconv January 29th, 2012 07:53 AM

Thanks JoesW31. My fan shroud may be a 71 as my original was broken beyond repair and I got a junkyard unit.

ALSO. To previous question, I think my father had his Corvette clutch rebuilt. Check Hemmings under Corvette services. This was 15 hrs ago but there might still be someone out there that still does it. It was not just a repaint. He took it apart new fluid and seals and fixed and pressed back together.

joesw31 January 29th, 2012 08:37 AM

Quote:

Originally Posted by oldsconv (Post 364687)
Thanks JoesW31. My fan shroud may be a 71 as my original was broken beyond repair and I got a junkyard unit.

ALSO. To previous question, I think my father had his Corvette clutch rebuilt. Check Hemmings under Corvette services. This was 15 hrs ago but there might still be someone out there that still does it. It was not just a repaint. He took it apart new fluid and seals and fixed and pressed back together.

Did some checking for the corvette restoration people. And there is a rebuilding service out there. This is what I found http://www.kirkconnellcorvettes.com/

Would be nice to see what kind of work they do.

Al Graaf January 29th, 2012 08:57 AM

1 Attachment(s)
Quote:

Originally Posted by pcard (Post 364602)
Shimmer: in 1970 the fan blade for the Y72 otpion was different form the one for standard cooling. The six blade fan is part number 401372 (see section 6-1 page 110 of the assembly manual 1970)

I've got 71 442. Here is a picture of the complete motor and the fan. So guys is this the right one. It's the original but I am adding AC. Is this part of the Y72 pk? SO how did you get your Olds to Bermuda?
AL

joesw31 January 29th, 2012 09:11 AM

The Y72 package is a cooling package intended for towing. The only cars that I saw with that had the package were cars from the dry climate area of the U.S. Not a popular option, but a great option. You need to measure your fan blade and check the code on the blade. Two letter code. Where did you get your fan clutch?

By adding the A/C you have to use the same water pump that was used in the Y72 package due the pulleys.

Al Graaf January 29th, 2012 09:48 AM

Quote:

Originally Posted by joesw31 (Post 364708)
The Y72 package is a cooling package intended for towing. The only cars that I saw with that had the package were cars from the dry climate area of the U.S. Not a popular option, but a great option. You need to measure your fan blade and check the code on the blade. Two letter code. Where did you get your fan clutch?

By adding the A/C you have to use the same water pump that was used in the Y72 package due the pulleys.

Fan clutch was from ACDelco. I went through the water pump ordeal. This is my first off frame restoration and I did pick up on that during my 4 months of studying prior to beginning.Getting the pulley for the PS pump was a challange as were the brackets-and then the double studs. But thanks to this site I aquired everything I needed. I had Norris Racing here in Versailes rebuild the engine. Thanks for all the information!
AL Graff

pcard February 4th, 2012 11:29 AM

Hey Al: unfortunately my Olds is not in Bermuda. Not much point with the speed limit being 35K (about 25mph), and the roads so narrow.
At the moment it is in Denver, but soon to be Rhode Island, where i go every now and then.
That is one pretty engine!
Not sure if that is the right fan for AC. Does it have a two letter code stamped on the front?

Allan R February 4th, 2012 12:48 PM

Quote:

Originally Posted by shimmer (Post 364705)
I've got 71 442. Here is a picture of the complete motor and the fan. So guys is this the right one. It's the original but I am adding AC. Is this part of the Y72 pk? AL

AL,
That is a great looking 455. Just one question though. Why paint the dual snorkel air cleaner Olds blue? They are supposed to be black. (I have one too BTW). Just was kind of surprised to see that since I thought you were trying to duplicate original look?

Al Graaf February 4th, 2012 01:46 PM

Quote:

Originally Posted by pcard (Post 366963)
Hey Al: unfortunately my Olds is not in Bermuda. Not much point with the speed limit being 35K (about 25mph), and the roads so narrow.
At the moment it is in Denver, but soon to be Rhode Island, where i go every now and then.
That is one pretty engine!
Not sure if that is the right fan for AC. Does it have a two letter code stamped on the front?

Glad you broght that up. I am concerned about the fan as well. So the fan blade it's self has a code as well? Guess I need to check the blade pitch depth as well. Thank you for your input. By the way have a friend who lives in Providence, up dare.
AL

Al Graaf February 4th, 2012 01:53 PM

Quote:

Originally Posted by Allan R (Post 366991)
AL,
That is a great looking 455. Just one question though. Why paint the dual snorkel air cleaner Olds blue? They are supposed to be black. (I have one too BTW). Just was kind of surprised to see that since I thought you were trying to duplicate original look?

You know I've spoke with several guys on this and they agree with you. However, when I gently removed the layers of paint the final color was the blue. When I replaced the vac pods it was bare metal under them. Another knowledgeable friend,Paul Toller, in CT mentioned that it could have been some of that assembly "stuff" the guys may have done on the line to mess with an inspector. I don't know. The blue was up inside the snorkels as well. Maybe they did pull a prank and then painted it black after the fact.:confused:

Allan R February 4th, 2012 02:21 PM

Quote:

Originally Posted by joesw31 (Post 364699)
Did some checking for the corvette restoration people. And there is a rebuilding service out there. This is what I found http://www.kirkconnellcorvettes.com/

Would be nice to see what kind of work they do.

But at 200.00 + shipping a pop? That's serious money

Allan R February 4th, 2012 03:15 PM

Quote:

Originally Posted by shimmer (Post 367005)
You know I've spoke with several guys on this and they agree with you. However, when I gently removed the layers of paint the final color was the blue. When I replaced the vac pods it was bare metal under them. Another knowledgeable friend,Paul Toller, in CT mentioned that it could have been some of that assembly "stuff" the guys may have done on the line to mess with an inspector. I don't know. The blue was up inside the snorkels as well. Maybe they did pull a prank and then painted it black after the fact.:confused:

Black after the fact? Don't think so Al. FWIW I bought a 455 4bbl air cleaner on evilbay a few years ago. It was painted black. I scraped it and it was the original red/orange underneath from a different model year. (thinking 69) Anyway I also have another one that arrived painted black that was chevy blue underneath. But under the blue it was black. (so, 3 layers)

I have only seen one style air cleaner from olds that was blue and that was for the early 2 snorkel Toronados.

It's not uncommon for guys who refinish these air cleaners to bead blast them down to base metal. I did with the one on my car. I think that any air cleaner that got pranked 'blue' would be rejected by a line inspector. Spraying with an air gun will get paint into the snorkels a fair distance.

The reason you saw the bare metal under the vacuum pods is the assembly was always painted after it was put together (well except for the green thermo vacuum unit)

I was just really surprised to see yours painted the engine color.

Al Graaf February 4th, 2012 03:32 PM

Quote:

Originally Posted by Allan R (Post 367038)
Black after the fact? Don't think so Al. FWIW I bought a 455 4bbl air cleaner on evilbay a few years ago. It was painted black. I scraped it and it was the original red/orange underneath from a different model year. (thinking 69) Anyway I also have another one that arrived painted black that was chevy blue underneath. But under the blue it was black. (so, 3 layers)

I have only seen one style air cleaner from olds that was blue and that was for the early 2 snorkel Toronados.

It's not uncommon for guys who refinish these air cleaners to bead blast them down to base metal. I did with the one on my car. I think that any air cleaner that got pranked 'blue' would be rejected by a line inspector. Spraying with an air gun will get paint into the snorkels a fair distance.

The reason you saw the bare metal under the vacuum pods is the assembly was always painted after it was put together (well except for the green thermo vacuum unit)

I was just really surprised to see yours painted the engine color.

It appears I need to repaint. I want it right. Thanks for the advice Allan!
AL

68442Convertible July 5th, 2012 08:51 AM

1968 Fan Clutch
 
I recently replaced my fan clutch with a Hayden 2747. It is the HD model. Same as Imperial 215046, 4-Seasons, etc (these are all made by the same company). Spins fan at 25-35% when disengaged, 70-90% when it engages at 170F. It is not listed by Hayden for my car, but it fit. Hayden lists the Std model for my car - but it did not move enough air - I tried it. Engine ran hot.

My engine is a stock 400 with AC and AT, and the car lives where it gets hot.

The CSM calls for a code OU for my car. I called Hayden and Flexalite and they both said no one makes a fan clutch that meets the old code OU sprecs.

lunaboy January 17th, 2014 10:21 AM

Quote:

Originally Posted by pcard (Post 364602)
Shimmer: in 1970 the fan blade for the Y72 otpion was different form the one for standard cooling. The six blade fan is part number 401372 (see section 6-1 page 110 of the assembly manual 1970)



purchased a OU on ebay, it did not fit the 66 -70 6 blade reg 19 inch cutlass fan. The 4 bolt clutch fan attach bolts where placed closer together. I did pull out an old 19 inch 7 blade fan I had in storage and it bolts up fine.
strange because I have another OU with the reg. dia mount and reg 6 blade 66-70 fan.


also I have an orig. 70 442 with the y72 tow package with 0S clutch, but it uses the reg 66- 70 fan.

pcard January 17th, 2014 11:38 AM

Hi Luna: does your 70 442 with the Y72 also have AC? If not, can you post a photo of the pulleys.

lunaboy January 17th, 2014 02:20 PM

sorry pcard it has a/c and OAI


and joesw31 why is this OU a re-stamp and what is F30A--- could that be the size difference


http://www.ebay.com/itm/NOS-1969-197...vip=true&rt=nc


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