Fan Clutch $ for 66/67

[Mark P.]

Anyone have any idea of the price one would expect to pay for a good original fan cluch on either a small block or a big block (would expect a big block unit is even more valuable)? I've looked around for a while and have seen that there aren't too many available out there. Fred Oliva doesn't have any to sell, he just restores them. Never even seen one show up in the Driveline for the past few years, unless I missed it.

Any help is appreciated.

Mark

[John Daly]

Re: Fan Clutch $ for 66/67

Mark,
I have had luck finding the original Schwitzer bar types at non-Corvette swap meets for $30-$40. They were used on more than Corvettes. I used the best one I found only for judging though. For driving around I use the GM #3916141 which is the service replacement part which is similar in appearance to the original. There's probably a lot more on this subject in the archives.

john

[Bob R.]

Re: Fan Clutch $ for 66/67

They show up on ebay regularly. They usually go for about $50. There are some differences in the early and late mid years so you have to know what you are looking at. Figure you will have to send it to Fred to have it rebuilt. That's how I got mine.

[Joe L.]

Re: Fan Clutch $ for 66/67

Mark-----

I totally agree with John and Bob. These Sweitzer-type clutches are out there and they are not rare. They were used on a lot of different GM products over the course of a lot of years. It's true that many got replaced and the old one trashed, but I'm sure that there are a lot still out there to be stripped off of GM cars of the 1965-70 period.

There were a fair number of different original part numbers for these units and there are slight differences between them. Often, the difference is only in regard to calibration (engagement temperatures, etc). However, there are some slight external differences, too. The primary one is shaft length. These vary but the differences are usually quite small.

You don't want to shop for these at a Corvette swap meet because everyone will want a king's ransom for them. Go to a general automotive swap meet, find what you need, and the seller will probably be glad to get 50 bucks for one (or, maybe a LOT less).

[Mark P.]

Re: Fan Clutch $ for 66/67

Thanks for the input, gentlemen. Very much appreciated. Maybe I'm not in the proper circles, since I don't see any of these out there. Sounds like I need to venture out more into the "swap meet world." I am looking for a big block fan clutch, so I think it may be a little more difficult to find. I haven't seen any big block units with the 1.5 inch shaft, on Ebay or otherwise, so I'm a bit disenchanted. I'll keep looking around and look for more swap meet opportunities of the non-Corvette variety. Hopefully that'll do the trick and I'll get lucky.

Any chance that a small block clutch will work on the big block car? Is there a clearance issue or is was it spec'd due to different calibration, as you stated?

Thanks again!
Mark

[Joe L.]

Re: Fan Clutch $ for 66/67

Mark-----

The small block and big block fan clutches are generally pretty interchangeable. The biggest difference is shaft length, but it's not hugely different. In fact, the current Eaton-manufactured GM replacement for all 60-70 Corvette applications with fan clutch, GM #3916141, "started life" as a big block-only unit. It later became SERVICE for all, big blocks and small blocks.

The 66-67 Corvette big block fan clutch was GM #3857531 and this, particular, unit was uniquely applicable to 66-67 Corvettes with 427. However, I don't know if this unit was a Sweitzer-manufactured clutch or an Eaton. Many big blocks did use Eaton clutches.

[Gary C.]

Re: Fan Clutch $ for 66/67

Mark

You may want to consider one of the current GM service replacements. I am a original stuff nut and have at times obtained original stuff at crazy nutso prices just so I could have the original item. This is one item that makes me feel a little differently, however. The current service item will usually get you a 1 or 2 point deduction on the originiality side and you will get all the condition points.

I do not know exactly how Fred restores the clutches, I do know they look great. If, however, the integrity is the least bit compromised and the clutch has even the smallest increased risk of coming apart, then that is enough for me to avoid a restored original. This is a rotating external part, if it comes loose or fails it could be very detrimental to nearby items, including your nice original hood and expensive paint job, not to mention your radiator, etc. This has probably never happened, but is something to consider.

[Joe L.]

Re: Fan Clutch $ for 66/67

Gary-----

I totally agree. I really think that the GM #3916141 is close enough to the originals and it's NEW. Personally, I would not even consider using a used or rebuilt fan clutch on any car that I drove even a little. For a "trailer queen" where reliability is an entirely secondary concern and judging points a primary concern, going the "strictly original route" may be in order. Otherwise, I really don't recommend it.

Actually, we're fortunate to have a NEW fan clutch still available that's so close to originals in configuration. The last time this clutch was used for any PRODUCTION application was 1970.

One other thing: for the most part, fan clutches were supplied from 2 or 3 different suppliers to the assembly line. Any of the optional fan clutches might have been used for any, particular application. Generally, there was a particular Sweitzer clutch specified for an application and there was an Eaton clutch specified for the same application. In most cases, EITHER could have been originally installed on a car. Generally, one brand will predominate for a particular period. But, that does not mean that every car of a certain configuration was originally built with the same clutch. Of course, only ONE of the original clutches will be catalogued in original SERVICE for the application. However, that does not mean or, in this case, imply that only that clutch was used in PRODUCTION for the application.

The 3 suppliers of fan clutches were Sweitzer (bi-metal thermostat), Eaton (coil spring thermostat), and Delco (coil spring thermostat). I've never seen a known-original clutch that was installed on a Corvette being a Delco. However, they may have been used. They were used for other GM carlines.

[Joe R.]

Re: Fan Clutch $ for 66/67

Hi Mark:

The going rate for used original fan clutch is about $50, plus or minus. They show up on ebay from time to time, although I have not seen any recently. Last year at Carlisle they seemed to be everywhere.

I agree with another poster that the GM '141 service replacement is very close to the original design and typically gets only a 1 point deduction in Flight judging. It also eliminates any worries you might have about long term use of a restored fan clutch. I have a Fred Oliva restored clutch that I use for judging, but I use the '141 clutch for normal driving.

If you do decide to get an original clutch and have it rebuilt, be sure to get one that is correct for your car. The big block clutches have a shorter shaft than the small block clutches. About all you can expect to gain with a restored original clutch over the '141 clutch is one point, so it would be a shame to go to all the trouble to get a restored clutch, only to lose a point anyway for having the wrong version.

[Joe L.]

Addendum

By the way, in one of my earlier posts on this subject I mentioned that the GM #3857531 fan clutch was used on 1966-67 Corvette 427 applications. I really should have said that the GM #3857531 was the SERVICE fan clutch specified for those applications. Very likely, it was one of the fan clutches used in PRODUCTION and, also likely, it was the clutch that predominated in PRODUCTION installations. I would say that virtually without a doubt, the GM #3857531 fan clutch would be a known-correct fan clutch for a 1966-67 Corvette 427. However, that does not mean that others were not used on 66-67 Corvette big block applications.