Fan Clutch and Crank pulley bolt, 1966, L79

[John R.]

This fan clutch came off my 66, L79. Can anyone comment on whether this is aftermarket or what?? If someone could post correct 66 fan clutch photos that would be much appreciated. I do not think this one is correct, but...

Also, when I took this off there were only bolts, no washers, holding the fan to the clutch. Is this correct?

Lastly, when installing the crank pulley I noticed the bolt head on the center mounting bolt (with the huge washer on it) has a hole in it. What is that for and should there be something run through it?

Thanks.

[John H.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

This fan clutch came off my 66, L79. Can anyone comment on whether this is aftermarket or what?? If someone could post correct 66 fan clutch photos that would be much appreciated. I do not think this one is correct, but...

Also, when I took this off there were only bolts, no washers, holding the fan to the clutch. Is this correct?

Lastly, when installing the crank pulley I noticed the bolt head on the center mounting bolt (with the huge washer on it) has a hole in it. What is that for and should there be something run through it?

Thanks.

John -

That's an aftermarket fan clutch that's torque/friction controlled, vs. the original Eaton (coil-type) or Schwitzer (bar-type) clutches that were temperature-modulated. The original clutches had four threaded studs, and the fan was attached with nuts and split lockwashers.

It's common to find a drilled hole in the balancer bolt head; it's for safety-wiring the bolt, although that was never done in production.

Photos below show the typical Eaton and Schwitzer clutches (they were used interchangeably).

[John R.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

Thanks, John. As always appreciate the time our members take to help out.

[Joe L.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

Thanks, John. As always appreciate the time our members take to help out.

John------


In addition to all the features that John mentioned, also note on your clutch the stamped word "VALLEY". Valley was/is an aftermarket supplier of fan clutches. They never supplied clutches to GM.

You can obtain a clutch very similar to the original Eaton clutch under GM #3916141. This clutch is also manufactured by Eaton. It carries a GM list price of 275 bucks but it will perform far better than the one you have and it will be configured very close to original.

[John R.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

John and Joe, thanks for the help! Joe, can I order directly from GM?

[Ronald L.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

You can get the exact same part from paragon for about $80-90 dollars.

[Loren L.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

Be aware that in 1966, they were also dated on the edge of the mounting pedestal.

[Mike G.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

Mr. Richter; I noticed that nobody addressed the issue of the attachment of the fan to the clutch. I believe that originally it was held together with studs, lock washers and nuts. When I replace the fan clutch on my 66 the new clutch came with new lock washers.
Mike

[Ronald L.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

Not the Eaton part, only Schweitzer. The new part will "function", the shaft is not NCRS correct, but it won't let your car over heat and blow up, like a poorly rebuilt original will, don't ask how I know. I'll save the original part until a better rebuild is available.

[John H.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

Mr. Richter; I noticed that nobody addressed the issue of the attachment of the fan to the clutch. I believe that originally it was held together with studs, lock washers and nuts.

Mike -

See post #2.

[Joe L.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

John and Joe, thanks for the help! Joe, can I order directly from GM?

John------


Yes, you can. However, if Paragon offers the same Eaton-manufactured piece for significantly less money, that might be the way to go.

[Joe R.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

Paragon offers the fan clutch for $125.00 and a max discount of 10%. It's part number 714 and it is exactly like the GM part available under pn 3916141.

JR

[Rich G.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

I just pulled the fan clutch off my 66 L79. It has EATON stamped in the metal, not an ink stamp. It has an ink stamp that says L7DA. It looks like pictures above, but the raised potion around the coil spring has tapered "ears" rather than the squared off ones in the picture. It also has mounting holes, not slots.

Any idea what vintage it might be?

Rich

[Scott S.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

It's common to find a drilled hole in the balancer bolt head; it's for safety-wiring the bolt, although that was never done in production.

John,

On UPC L79-A1 of both the 1966 and 1967 AIMs it shows GM #3815933 Bolt for the crankshaft pulley center bolt. This same bolt is also called out for the steering shock/damper bracket to relay rod fastener (UPC 9-A3, Item 10, 1966-67 AIMs).

On my '67 L79 (with steering shock damper, no power steering), I found the same bolt used in both locations, exactly as called out in the AIM. It is a regular hex, Grade 8 bolt with a "TR" headmark. For both locations, this bolt has a cross-drilled hole through the head of the bolt.

Are you saying the holes were not present in the bolt when it was manufactured, therefore the bolts must have been removed, drilled and the bolts reinstalled at a later time (e.g., by owners or mechanics, after the cars were built and sold)? Or do you mean that the bolts came to the factory with the cross-drilled hole, and you were only pointing out that a safety-wire was never used in production?

[David L.]

Re: Fan Clutch and Crank pulley bolt, 1966, L79

I just pulled the fan clutch off my 66 L79. It has EATON stamped in the metal, not an ink stamp. It has an ink stamp that says L7DA. It looks like pictures above, but the raised potion around the coil spring has tapered "ears" rather than the squared off ones in the picture. It also has mounting holes, not slots.

Any idea what vintage it might be?

Rich

Rich,

I believe your Eaton "L7DA" (November 7, ????) fan-clutch was made in the 1970's or 1980's as it has the tapered "ears". I have original 1969 and 1970 Chevrolet Eaton fan-clutches with "tapered ears". I'm not sure if 1968 Eaton fan-clutches had "small ears" or "tapered ears". I have not figured out the "DA" part of the date code.

I had an "early" 1967 Eaton fan-clutch ink stamped "EATON", CJ", and dated "L27G" (November 27, 1966) with "small ears". Refer to the thread listed below. There are other examples of Eaton fan-clutches in this thread as well.

Dave

https://www.forums.ncrs.org/showthread.php?t=85917&uid=1765