Myths and Misconceptions Continued

If you feel roughness as you rotate it, the bearing is bad.  Most of the time the seals will fail and it will begin to leak long before the bearing fails.

I will now discuss the cover finish. The Eaton covers were zinc plated, not cadmium plated.  There is a difference.  From 1960 until 1966 they were zinc plated and then dipped in a clear chromate conversion solution, which gave you the silver color.  Beginning in 1967 they were zinc plated and then dipped in a yellow chromate conversion solution, which gave you the gold color.

The Eaton date coding has always been, a letter for the month, with January being the letter “A”.  The day of the month is a number and finally another letter for the year.  The first year of each decade is always the letter “A”.  All Eaton clutches received a two letter broadcast code for every application for GM and Ford.  Chrysler clutches had a Chrysler part number ink-stamped on them in lieu of a broadcast code.

Broadcast codes did not start until 1963. The small block code is “CJ” and the big block code is “CK” for the Corvette until 1967.  In 1968 all Corvette clutches received the broadcast code “CA”.  This is because the practice of having two different input shaft lengths for the small block and big block ceased in 1968.  “All” Corvette fan clutches used the shorter big block length regardless of the engine used.  This was true for both Eaton and Schweitzer clutches.

Schweitzer Corporation supplied GM with fan clutches from 1963 until 1974 for all divisions.
They also supplied Ford for a short period of time in the early 1960’s. In my opinion this clutch is a much better design and is of much better quality.  The housing casting is not as porous as the Eaton and the fluid does not bleed through the housing like the Eaton does.  It uses a caged roller bearing with two separate seals.

One issue I have with the seals is the inner seal has been installed backwards in every clutch I have seen so far.  They obviously do this for ease of installation.  To install it the correct way they would have to make an installation tool.  I have made just such a tool and I install the seals in the proper direction during the rebuild.  The original seals were made of Viton.  I use an even better material than Viton which will last a very long time.  The drive disc has facing on both sides similar to your driveline clutch disc.  I have found the gap between the housing, drive disc and the inner plate to be far too much.  With that large gap, even a small amount of fluid loss will render the clutch inoperable.

I tighten up this gap so the clutch will perform much better.  The biggest issue I have with the design is they did not provide any sealing method where the brass plunger inserts into the cover.  This causes the fluid to weep past the plunger.  I have developed a sealing method and they will never leak again in that area.  The input shafts on original clutches have a slight taper from where it exits the housing for a short distance and then transitions to straight over to the flange.  Service replacement input shafts taper from where it exits the housing all the way to the flange.  That is the only difference between an original and service replacement.

Date coding did not begin until around mid 1965.  The date coding is fairly obvious.  The month, day and year are all numbers.  The only plating on the Schweitzer clutch is the mounting bracket for the thermostatic strip.  From 63-66 it was zinc plated with a clear chromate conversion coating.  Beginning in 1967 the bracket was zinc plated with a yellow chromate conversion coating.  Mounting patterns for the fan and water pump are the same as the Eaton.  In 1968 Schweitzer introduced the larger diameter clutch.  Both the large and small were used on the assembly line.  Service replacements were mostly the small diameter clutches.

In conclusion, I could easily make this article twice the length with more information but hopefully this will clear up some myths and misconceptions.  I am more than willing to answer any fan clutch questions.  On my “Welcome”
page of this website is my e-mail address.
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